0001564590-21-008124 | 10-K | XBRL Viewer | Adaptive Biotechnologies Corp

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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	ADPT
Entity Registrant Name	ADAPTIVE BIOTECHNOLOGIES CORPORATION
Entity Central Index Key	0001478320
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Public Float			$ 3,590,000,000
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		139,219,503
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity File Number	001-38957
Entity Tax Identification Number	27-0907024
Entity Address, Address Line One	1551 Eastlake Avenue East
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98102
City Area Code	(206)
Local Phone Number	659-0067
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	WA
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	The information required by Part III of this Annual Report on Form 10-K, to the extent not set forth herein, is incorporated herein by reference from the registrant’s definitive proxy statement relating to the Annual Meeting of Shareholders to be held in 2021.

Balance Sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 123,436,000	$ 96,576,000
Short-term marketable securities (amortized cost of $564,036 and $479,791, respectively)	564,833,000	480,290,000
Accounts receivable, net	10,047,000	12,676,000
Inventory	14,063,000	9,069,000
Prepaid expenses and other current assets	14,535,000	14,079,000
Total current assets	726,914,000	612,690,000
Long-term assets
Property and equipment, net	39,692,000	60,355,000
Operating lease right-of-use assets	99,350,000
Long-term marketable securities (amortized cost of $118,429 and $105,263, respectively)	118,525,000	105,435,000
Restricted cash	2,138,000	2,138,000
Intangible assets, net	10,225,000	11,928,000
Goodwill	118,972,000	118,972,000
Other assets	598,000	784,000
Total assets	1,116,414,000	912,302,000
Current liabilities
Accounts payable	3,237,000	4,453,000
Accrued liabilities	13,162,000	4,371,000
Accrued compensation and benefits	11,950,000	8,124,000
Current portion of deferred rent		371,000
Current portion of operating lease liabilities	3,529,000
Current portion of deferred revenue	73,319,000	60,994,000
Total current liabilities	105,197,000	78,313,000
Long-term liabilities
Deferred rent liability, less current portion		6,918,000
Operating lease liabilities, less current portion	104,333,000
Financing obligation		36,607,000
Deferred revenue, less current portion	163,618,000	219,332,000
Other long-term liabilities		93,000
Total liabilities	373,148,000	341,263,000
Commitments and contingencies (Note 11)
Shareholders’ equity
Preferred stock: $0.0001 par value, 10,000,000 shares authorized at December 31, 2020 and 2019; no shares issued and outstanding at December 31, 2020 and 2019
Common stock: $0.0001 par value, 340,000,000 shares authorized at December 31, 2020 and 2019; 137,646,896 and 125,238,142 shares issued and outstanding at December 31, 2020 and 2019, respectively	14,000	12,000
Additional paid-in capital	1,253,971,000	935,834,000
Accumulated other comprehensive gain	893,000	671,000
Accumulated deficit	(511,612,000)	(365,478,000)
Total shareholders’ equity	743,266,000	571,039,000
Total liabilities and shareholders’ equity	$ 1,116,414,000	$ 912,302,000

Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Amortized cost of short-term marketable securities	$ 564,036	$ 479,791
Amortized cost of long-term marketable securities	$ 118,429	$ 105,263
Preferred stock par value	$ 0.0001	$ 0.0001
Preferred stock authorized	10,000,000	10,000,000
Preferred stock issued	0	0
Preferred stock outstanding	0	0
Common stock par value	$ 0.0001	$ 0.0001
Common stock authorized	340,000,000	340,000,000
Common stock issued	137,646,896	125,238,142
Common stock outstanding	137,646,896	125,238,142

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue
Total revenue	$ 98,382	$ 85,071	$ 55,663
Operating expenses
Cost of revenue	22,530	22,274	19,668
Research and development	116,072	70,705	39,157
Sales and marketing	61,358	38,453	24,486
General and administrative	49,536	30,332	20,409
Amortization of intangible assets	1,703	1,698	1,699
Total operating expenses	251,199	163,462	105,419
Loss from operations	(152,817)	(78,391)	(49,756)
Interest and other income, net	6,590	9,785	3,309
Net loss	(146,227)	(68,606)	(46,447)
Fair value adjustment to Series E-1 convertible preferred stock options		(964)	102
Net loss attributable to common shareholders	$ (146,227)	$ (69,570)	$ (46,345)
Net loss per share attributable to common shareholders, basic and diluted	$ (1.11)	$ (1.01)	$ (3.67)
Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted	131,216,468	69,165,315	12,629,778
Sequencing Revenue
Revenue
Total revenue	$ 41,439	$ 43,519	$ 32,978
Development Revenue
Revenue
Total revenue	$ 56,943	$ 41,552	$ 22,685

Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
Statements of Comprehensive Loss - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Net loss	$ (146,227)	$ (68,606)	$ (46,447)
Change in unrealized gain (loss) on investments	222	778	59
Comprehensive loss	$ (146,005)	$ (67,828)	$ (46,388)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Statements of Convertible Preferred Stock and Shareholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Convertible Preferred Stock	Common Stock	Additional Paid In Capital	Additional Paid In Capital Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive (Loss) Gain	Accumulated Deficit	Accumulated Deficit Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance at Dec. 31, 2017	$ (224,616)			$ 1	$ 24,972	$ 140	$ (166)	$ (249,423)	$ (140)
Beginning Balance, Shares at Dec. 31, 2017				12,208,731
Convertible preferred stock, Beginning Balance at Dec. 31, 2017			$ 561,333
Convertible preferred stock, Beginning Balance, Shares at Dec. 31, 2017			92,656,029
Issuance of common stock for cash upon exercise of stock options	1,168				1,168
Issuance of common stock for cash upon exercise of stock options, Shares				632,805
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value			$ 100
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value, Shares			134,065
Vested Series E-1 convertible preferred stock option forfeitures	767				476			291
Vested Series E-1 convertible preferred stock option forfeitures			$ (767)
Series E-1 convertible preferred stock option share-based compensation	3				3
Adjustment to redemption value for vested Series E-1 convertible preferred stock options	(3)				(3)
Adjustment to redemption value for vested Series E-1 convertible preferred stock options			3
Change in redemption value for vested Series E-1 convertible preferred stock options	(189)							(189)
Change in redemption value for vested Series E-1 convertible preferred stock options			$ 189
Common stock option share-based compensation	11,146				11,146
Other comprehensive income (loss)	59						59
Net loss	(46,447)							(46,447)
Ending Balance at Dec. 31, 2018	(258,112)			$ 1	37,902		(107)	(295,908)
Temporary Equity Ending Balance, Shares at Dec. 31, 2018			92,790,094
Temporary Equity, Ending Balance at Dec. 31, 2018			$ 560,858
Ending Balance, Shares at Dec. 31, 2018				12,841,536
Proceeds from initial public offering/ issuance of common stock upon public offering, net of underwriters' discounts and commissions and net offering costs paid by us	320,850			$ 2	320,848
Proceeds from initial public offering/ issuance of common stock upon public offering, net of underwriters' discounts and commissions and net offering costs paid by us, Shares				17,250,000
Initial public offering costs	(4,986)				(4,986)
Conversion of convertible preferred stock to common stock	561,931		$ (561,931)	$ 9	561,922
Conversion of convertible preferred stock to common stock, Shares			(93,039,737)	93,039,737
Conversion of convertible preferred stock warrant to common stock warrant	2,602				2,602
Issuance of common stock upon exercise of common stock warrants	9				9
Issuance of common stock upon exercise of common stock warrants, Shares				54,792
Issuance of common stock for cash upon exercise of stock options	4,413				4,413
Issuance of common stock for cash upon exercise of stock options, Shares				2,043,767
Vesting of restricted stock units				8,310
Common stock option and restricted stock unit share-based compensation	13,124				13,124
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value			$ 109
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value, Shares			249,643
Change in redemption value for vested Series E-1 convertible preferred stock options	(964)							(964)
Change in redemption value for vested Series E-1 convertible preferred stock options			$ 964
Other comprehensive income (loss)	778						778
Net loss	(68,606)							(68,606)
Ending Balance at Dec. 31, 2019	$ 571,039			$ 12	935,834		671	(365,478)
Ending Balance, Shares at Dec. 31, 2019				125,238,142
Accounting Standards Update Extensible List	us-gaap:AccountingStandardsUpdate201602Member
Proceeds from initial public offering/ issuance of common stock upon public offering, net of underwriters' discounts and commissions and net offering costs paid by us	$ 271,839			$ 1	271,838
Proceeds from initial public offering/ issuance of common stock upon public offering, net of underwriters' discounts and commissions and net offering costs paid by us, Shares				7,200,000
Issuance of common stock for cash upon exercise of stock options	$ 21,539			$ 1	21,538
Issuance of common stock for cash upon exercise of stock options, Shares	5,204,254			5,204,254
Vesting of restricted stock units				4,500
Common stock option and restricted stock unit share-based compensation	$ 24,761				24,761
Other comprehensive income (loss)	222						222
Net loss	(146,227)							(146,227)
Ending Balance at Dec. 31, 2020	$ 743,266	$ 93		$ 14	$ 1,253,971		$ 893	$ (511,612)		$ 93
Temporary Equity Ending Balance, Shares at Dec. 31, 2020			0
Ending Balance, Shares at Dec. 31, 2020				137,646,896

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (146,227)	$ (68,606)	$ (46,447)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation expense	6,769	6,093	4,301
Noncash lease expense	3,266
Share-based compensation expense	24,761	13,124	11,149
Intangible assets amortization	1,703	1,698	1,699
Investment amortization	773	(4,463)	(1,214)
Fair value adjustment of convertible preferred stock warrant		2,266	(6)
Other	71	359	(18)
Changes in operating assets and liabilities:
Accounts receivable, net	2,613	(7,817)	775
Inventory	(4,994)	(1,231)	(3,046)
Prepaid expenses and other current assets	(1,362)	(8,576)	(318)
Accounts payable and accrued liabilities	7,495	6,149	2,185
Deferred rent		78	(488)
Operating lease liabilities	(886)
Deferred revenue	(43,389)	266,927	(649)
Other	(276)	(597)	(182)
Net cash (used in) provided by operating activities	(149,683)	205,404	(32,259)
Investing activities
Purchases of property and equipment	(18,803)	(11,200)	(6,299)
Purchases of marketable securities	(694,965)	(884,217)	(146,503)
Proceeds from sales and maturities of marketable securities	596,724	413,720	153,538
Net cash (used in) provided by investing activities	(117,044)	(481,697)	736
Financing activities
Proceeds from exercise of stock options	21,748	4,055	1,268
Proceeds from public offering of common stock, net of underwriting discounts and commissions	272,160	320,850
Payment of public offering costs, net	(321)	(4,986)
Proceeds from issuance of common stock upon the exercise of a common stock warrant		9
Other		(12)	(20)
Net cash provided by financing activities	293,587	319,916	1,248
Net increase (decrease) in cash, cash equivalents and restricted cash	26,860	43,623	(30,275)
Cash, cash equivalents and restricted cash at beginning of year	98,714	55,091	85,366
Cash, cash equivalents and restricted cash at end of year	125,574	98,714	55,091
Noncash investing and financing activities
Purchases of equipment included in accounts payable and accrued liabilities	4,679	773	832
Landlord-funded leasehold improvements			$ 2,419
Noncash additions to property through lease financing arrangements		36,607
Derecognition of lease financing arrangements upon adoption of guidance on accounting for leases	$ 36,607
Conversion of convertible preferred stock to common stock upon closing of initial public offering		561,931
Conversion of convertible preferred stock warrant to common stock warrant upon closing of initial public offering		$ 2,602

Organization and Description of Business

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Description of Business

1.	Organization and Description of Business

Adaptive Biotechnologies Corporation (“we,” “us” or “our”) is a commercial-stage company advancing the field of immune medicine by harnessing the inherent biology of the adaptive immune system to transform the diagnosis and treatment of disease. We believe the adaptive immune system is nature’s most finely tuned diagnostic and therapeutic for most diseases, but the inability to decode it has prevented the medical community from fully leveraging its capabilities. Our immune medicine platform applies our proprietary technologies to read the diverse genetic code of a patient’s immune system and aims to understand precisely how the immune system detects and treats disease in that patient. We capture these insights in our dynamic clinical immunomics database, which is underpinned by computational biology and machine learning, and use them to develop and commercialize clinical products and services that we are tailoring to each individual patient. We have commercial products and services and a robust pipeline of clinical products and services that we are designing to diagnose, monitor and enable the treatment of diseases, such as cancer, autoimmune conditions and infectious diseases.

We were incorporated in the State of Washington on September 8, 2009 under the name Adaptive TCR Corporation. On December 21, 2011, we changed our name to Adaptive Biotechnologies Corporation. We are headquartered in Seattle, Washington.

Initial Public Offering

Our registration statement on Form S-1 related to our initial public offering was declared effective on June 26, 2019 and our common stock began trading on the Nasdaq Global Select Market on June 27, 2019. On July 1, 2019, we completed our initial public offering in which we issued and sold 17,250,000 shares of common stock, including shares issued upon the exercise in full of the underwriters’ over-allotment option, at a public offering price of $20.00 per share. We received $315.9 million in net proceeds, after deducting underwriting discounts and commissions of $24.1 million and offering expenses of $5.0 million.

Follow-On Offering

In July 2020, we completed an underwritten public offering of our common stock in which we issued and sold 7,200,000 shares of common stock, including shares issued upon the exercise in full of the underwriters’ over-allotment option, at a public offering price of $40.00 per share. We received $271.8 million in net proceeds, after deducting underwriting discounts and net offering expenses paid by us.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Significant Accounting Policies

2.	Significant Accounting Policies

Basis of Presentation and Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenues and expenses during the periods presented. We base our estimates on historical experience and other relevant assumptions that we believe to be reasonable under the circumstances. Estimates are used in several areas including, but not limited to, estimates of progress to date for certain performance obligations and the transaction price for certain contracts with customers, share-based compensation, including the fair value of stock, the provision for income taxes, including related reserves, and goodwill, among others. These estimates generally involve complex issues and require judgments, involve the analysis of historical results and prediction of future trends, can require extended periods of time to resolve and are subject to change from period to period. Actual results may differ materially from management’s estimates.

JOBS Act Accounting Election

Effective December 31, 2020, we are no longer an “emerging growth company” within the meaning of the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”). The JOBS Act allows an emerging growth company to delay the adoption of new or revised accounting standards that have different effective dates for public and private companies until those standards apply to private companies. Prior to December 31, 2020, we had elected to use this extended transition period and, as a result, our financial statements may not be comparable to companies that comply with public company effective dates. We can no longer take advantage of this extended transition period.

Cash and Cash Equivalents

Cash and cash equivalents are stated at fair value. Cash equivalents include only securities having an original maturity of three months or less at the time of purchase. We limit our credit risk associated with cash and cash equivalents by placing our investments with banks that we believe are highly creditworthy and with highly rated money market funds. Cash and cash equivalents primarily consist of bank deposits and investments in money market funds.

Restricted Cash

We are required to maintain certain balances under lease arrangements for some of our property and facility leases. We had restricted cash of $2.1 million as of December 31, 2020 and 2019.

Investments in Marketable Securities

Marketable securities are classified as available-for-sale, primarily consist of U.S. government debt securities, commercial paper and corporate bonds and are reported at fair value. Unrealized holding gains and losses are reflected as a separate component of shareholders’ (deficit) equity in accumulated other comprehensive (loss) gain until realized. Realized gains and losses on the sale of these securities are recognized in net income or loss. The cost of marketable securities sold is based on the specific identification method.

Concentrations of Risk

We are subject to a concentration of risk from a limited number of suppliers, or in some cases, single suppliers for some of our laboratory instruments and materials. This risk is managed by targeting a quantity of surplus stock.

Cash, cash equivalents and marketable securities are financial instruments that potentially subject us to concentrations of credit risk. We invest in money market funds, U.S. government debt securities, U.S. government agency securities, commercial paper and corporate bonds with high-quality accredited financial institutions.

Significant customers are those that represent more than 10% of our total revenue or accounts receivable, net balances for the periods and as of each balance sheet date presented, respectively. Revenue from these customers reflects their purchase of our products and services and our collaboration efforts with Genentech.

For each significant customer, revenue as a percentage of total revenue for the periods presented and accounts receivable, net as a percentage of total accounts receivable, net as of the dates presented were as follows:

	Revenue			Accounts Receivable, Net
	Year Ended December 31,			December 31,
	2020	2019	2018	2020	2019
Customer A	*%	13.9%	18.4%	19.1%	41.8%
Customer B	*	*	13.5	12.2	*
Customer C	*	*	15.4	*	*
Genentech, Inc. and Roche Group	55.8	42.1	*	*	*
* less than 10%

Accounts Receivable

Accounts receivable consists of amounts due from customers for services performed. We review our accounts receivable for credit impairment and regularly analyze the status of significant past due receivables to determine if any will potentially be uncollectible to estimate the amount of allowance necessary to reduce accounts receivable to its estimated net realizable value.

Additionally, we had $0.9 million and $2.4 million of unbilled receivables as of December 31, 2020 and 2019, respectively. The unbilled receivables are amounts that will become due for which we have an unconditional right to consideration.

Inventory

Inventory consists of laboratory materials and supplies used in lab analysis. We capitalize inventory when purchased and record expense upon order fulfillment for servicing revenue or utilization in our research and development laboratories. Inventory is valued at the lower of cost or market on a first-in, first-out basis. We periodically perform obsolescence assessments and write off any inventory that is no longer usable.

Property and Equipment

Property and equipment consists of computer equipment, computer software, laboratory equipment, leasehold improvements and furniture and office equipment. Property and equipment are recorded at cost and depreciation is recognized using the straight-line method based on estimated useful life. Maintenance and repairs are charged to expense as incurred and costs of improvements are capitalized.

Useful lives assigned to property and equipment are as follows:


Laboratory equipment		3 years to 7 years
Leasehold improvements		Shorter of estimated useful life or remaining lease term
Computer equipment and software		3 years
Furniture and office equipment		5 years to 10 years

We review long-lived assets for impairment whenever events or circumstances indicate the carrying amount of an asset group may not be recoverable. Gains and losses from asset disposals and impairment losses are classified within our statements of operations in accordance with the use of the asset.

Goodwill

Goodwill represents the excess of the purchase price over the net amount of identifiable assets acquired and liabilities assumed in a business combination measured at fair value. We assess goodwill for impairment annually on October 1, or more frequently if events or changes in circumstances would more likely than not reduce the fair value of our single reporting unit below its carrying value. We evaluate goodwill for impairment by first assessing qualitative factors to determine whether it is more likely than not that the fair value of our reporting unit is less than its carrying amount. If we so determine, or if we choose to bypass the qualitative assessment, we perform a quantitative goodwill impairment test. Goodwill impairment exists when the estimated fair value of our one reporting unit is less than its carrying value. If impairment exists, the carrying value of the goodwill is reduced to fair value through an impairment charge recorded in our statements of operations. To date, we have not recognized any impairment of goodwill.

Intangible Assets

Intangible assets acquired in a business combination are recognized separately from goodwill and are initially recognized at their fair value at the acquisition date, which is regarded as their cost.

Intangible assets may also result from the purchase of assets and intellectual property in a transaction that does not qualify as a business combination. Intangible assets are amortized over their estimated useful lives on a straight-line basis which approximates their usage pattern. Intangible assets are reviewed for impairment at least annually or if indicators of potential impairment exist. We have not recognized any impairment losses on intangible assets.

Leases

We determine if an arrangement contains a lease at inception. We have operating lease agreements for the laboratory and office facilities that we occupy, as well as server space. Operating lease right-of-use (“ROU”) assets and operating lease liabilities are recognized at the date the underlying asset becomes available for our use and are based on the present value of the future minimum lease payments over the lease term. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. As our leases generally do not provide an implicit interest rate, the present value of our future minimum lease payments is determined using our incremental borrowing rate. This rate is an estimate of the collateralized borrowing rate we would incur on our future lease payments over a similar term and is based on the information available to us at the lease commencement date, or as of January 1, 2020 for commenced leases that existed as of our adoption of the new lease standard, discussed in more detail below.

Certain of our leases contain options to extend or terminate the lease; lease terms are adjusted for these options only when it is reasonably certain we will exercise these options. Our lease agreements do not contain residual value guarantees or covenants.

We have made a policy election regarding our real estate leases not to separate nonlease components from lease components, to the extent they are fixed. Nonlease components that are not fixed are expensed as incurred as variable lease expense. Our leases for laboratory and office facilities typically include variable nonlease components, such as common-area maintenance costs. We have also elected not to record on the balance sheet a lease that has a lease term of twelve months or less and does not contain a purchase option that we are reasonably certain to exercise.

Lease expense is recognized on a straight-line basis over the terms of the leases. Incentives granted under our facilities leases, including rent holidays, are recognized as adjustments to lease expense on a straight-line basis over the terms of the leases.

Lease Financing Arrangements

In 2019, due to our significant involvement during the construction process of a leased building, we qualified as the deemed owner of the building under build-to-suit lease accounting guidance. Prior to our adoption of the new lease standard, the cost of the related building was recorded in property and equipment, net and the offsetting lease financing obligation was recorded as a long-term financing obligation on our balance sheet. As of December 31, 2019, $36.6 million of building costs was recorded in property and equipment, net.

Fair Value of Financial Instruments

The Financial Accounting Standards Board (“FASB”) has defined fair value as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for that asset or liability in an orderly transaction between market participants on the measurement date. The FASB established a fair value hierarchy that requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The hierarchy defines three levels of inputs that may be used to measure fair value:

•

Level 1: Quoted prices in active markets for identical assets or liabilities.

•

Level 2: Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•

Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities

A financial instrument categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

Our financial instruments consist of Level 1 and Level 2 assets and has included Level 3 liabilities in the past. In certain cases, where there is limited activity or less transparency around inputs to valuation, financial instruments are classified as Level 3 within the valuation hierarchy. The carrying amounts of certain financial instruments approximate fair value due to their short maturities.

We did not have any nonfinancial assets or liabilities that were measured or disclosed at fair value on a recurring basis as of December 31, 2020 or 2019.

Convertible Preferred Stock Warrant Liability

We had issued a freestanding warrant to a venture capital firm to purchase 56,875 shares of Series C convertible preferred stock with an exercise price of $2.64 in connection with a $5.0 million credit facility entered into in 2014. Immediately prior to and in connection with the completion of our initial public offering, the convertible preferred stock warrant converted to a common stock warrant.

Prior to the conversion, the fair value of this warrant was classified as a non-current liability in the balance sheets, since the underlying convertible preferred stock had been classified as temporary equity instead of shareholders’ deficit in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities. Upon certain change in control events that were outside of our control, including liquidation, sale or transfer of control, holders of the convertible preferred stock may have caused its redemption. Prior to conversion, the warrant was subject to remeasurement at each balance sheet date, with changes in estimated fair value recognized as a component of interest and other income, net on our statements of operations. During the year ended December 31, 2019, we recognized $2.3 million of expense related to the revaluation of the convertible preferred stock warrant liability in the interest and other income, net line item on our statements of operations.

When the convertible preferred stock warrant converted to a common stock warrant immediately prior to and in connection with the completion of the initial public offering, the $2.6 million financial liability was reclassified to the additional paid-in capital line item on our balance sheet, thereby concluding the need for revaluation.

Revenue Recognition

We recognize revenue in accordance with ASC Topic 606 (“ASC 606”), Revenue from Contracts with Customers. Under ASC 606, for all revenue-generating contracts, we perform the following steps to determine the amount of revenue to be recognized: (1) identify the contract or contracts; (2) determine whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (3) measure the transaction price, including the constraint on variable consideration; (4) allocate the transaction price to the performance obligations based on estimated selling prices; and (5) recognize revenue when (or as) we satisfy each performance obligation. The following is a summary of the application of the respective model to each of our revenue classifications.

Overview

Our revenue is generated from immunosequencing (“sequencing”) products and services (“sequencing revenue”) and from regulatory or development support services leveraging our immune medicine platform (“development revenue”). When revenue generating contracts have elements of both sequencing revenue and development revenue, we classify revenue based on the nature of the performance obligation and the allocated transaction price.

Sequencing Revenue

Sequencing revenue reflects the amounts generated from providing sequencing services and testing through our clonoSEQ and immunoSEQ products and services to our clinical and research customers, respectively.

For clinical customers, we derive revenues from providing our clonoSEQ test report to ordering physicians, and we bill and receive payments from medical institutions and commercial and government third-party payors. In these transactions, we have identified one performance obligation: the delivery of a clonoSEQ report. As payment from the respective payors may vary based on the various reimbursement rates and patient responsibilities, we consider the transaction price to be variable and record an estimate of the transaction price, subject to the constraint for variable consideration, as revenue at the time of delivery. The estimate of transaction price is based on historical and expected reimbursement rates with the various payors, which are monitored in subsequent periods and adjusted as necessary based on actual collection experience.

For our clonoSEQ coverage under Medicare, we bill an episode of treatment when we deliver the first eligible test results. This billing contemplates all necessary tests required during a patient’s treatment cycle, which is currently estimated at approximately four tests per patient, including the initial sequence identification test. Revenue recognition commences at the time the initial billable test result is delivered and is based upon cumulative tests delivered to date. We estimate the number of tests we expect to deliver over a patient’s treatment cycle based on historical testing frequencies for patients by indication. These estimates are subject to change as we develop more information about utilization over time. Any unrecognized revenue from the initial billable test is recorded as deferred revenue and is recognized as we deliver the remaining tests in a patient’s treatment cycle or when it becomes remote that a patient will receive additional testing and we have not delivered our estimate of total tests.

For research customers, contracts typically include an amount billed in advance of services (“upfront”) and subsequent billings as sample results are delivered to the customer. Upfront amounts received are recorded as deferred revenue, which we recognize as revenue upon satisfaction of performance obligations. We have identified two typical performance obligations under the terms of our research service contracts: sequencing services and related data analysis. We recognize revenue for both identified performance obligations as sample results are delivered to the customer.

Development Revenue

We derive revenue by providing services through development agreements to biopharmaceutical customers who seek access to our immune medicine platform technologies. We generate revenues from the delivery of professional support activities pertaining to the use of immunoSEQ and our MRD product in the development of the respective customers’ initiatives. The transaction price for these contracts may consist of a combination of non-refundable upfront fees, separately priced sequencing fees, progress-based milestones and regulatory milestones. The development agreements may include single or multiple performance obligations, depending on the contract. For certain contracts, we may perform services to support the biopharmaceutical customers’ regulatory submissions as part of their registrational trials. These services include regulatory support pertaining to our technology intended to be utilized as part of the submission, development of analytical plans for our sequencing data, participation on joint research committees and assistance in completing a regulatory submission. Generally, these services are not distinct within the context of the contract and they are accounted for as a single performance obligation.

When sequencing services are separately priced customer options, we assess if a material right exists and, if not, the customer option to purchase additional sequencing services is not considered part of the contract. Except for any non-refundable upfront fees, the other forms of compensation represent variable consideration. Variable consideration related to progress-based and regulatory milestones is estimated using the most likely amount method, where variable consideration is constrained until it is probable that a significant reversal of cumulative revenue recognized will not occur. Progress milestones, such as the first sample result delivered or final patient enrollment in a customer trial, are customer dependent and are included in the transaction price when the respective milestone is probable of occurring. Milestone payments that are not within our customers’ control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. Determining whether regulatory milestone payments are probable is an area that requires significant judgment. In making this assessment, we evaluate scientific, clinical, regulatory and other risks, as well as the level of effort and investment required to achieve the respective milestone.

The primary method used to estimate standalone selling price for performance obligations is the adjusted market assessment approach. Using this approach, we evaluate the market in which we sell our services and estimate the price that a customer in that market would be willing to pay for our services. We recognize revenue using either an input or output measure of progress that faithfully depicts performance on a contract, depending on the contract. The measure used is dependent on the nature of the service to be provided in each contract. Selecting the measure of progress and estimating progress to date requires significant judgment.

Contract Balances

In certain circumstances, billing may occur prior to services being performed. Upfront payments are recorded as deferred revenue, contract liabilities. We classify deferred revenue as current for sequencing revenue, as we expect our performance obligations will be completed within the next twelve months; however, we do not control the timing of customer provided samples. For development services, we assess the performance obligations and recognize deferred revenue as current or non-current based upon forecasted delivery times, which are customer coordinated. In certain circumstances, the customer project may be cancelled or terminated prior to the delivery of all related services covered by a customer’s upfront payment. In these circumstances, we recognize revenue when sufficient evidence is obtained that a reversal of revenue is not probable.

Share-Based Compensation

Share-based compensation includes compensation expense for stock option and restricted stock unit grants to employees and non-employees. It represents the grant date fair value of the grants and is recognized over the requisite service period of the awards, usually the vesting period, on a straight-line basis, net of actual forfeitures. We estimate the grant date fair value of stock option grants using the Black-Scholes option-pricing model.

Advertising

Advertising costs are expensed as incurred. Advertising expenses were $14.5 million, $6.6 million and $3.5 million for the year ended December 31, 2020, 2019 and 2018, respectively.

Cost of Revenue

Cost of revenue includes the cost of materials, personnel-related expenses (comprised of salaries, benefits and share-based compensation), shipping and handling, equipment and allocated facility costs associated with processing samples and professional support for our sequencing revenue. Allocated facility costs include depreciation of laboratory equipment, allocated facility occupancy and information technology costs. Costs associated with processing samples are recorded as expense, regardless of the timing of revenue recognition.

Research and Development Expenses

Research and development expenses are comprised of laboratory materials costs, personnel-related expenses, equipment costs, allocated facility costs, information technology expenses and contract service expenses. We also include in research and development expenses the costs associated with software development of applications to support future commercial opportunities, as well as development activities to support laboratory scaling and workflow. Research and development costs are expensed as incurred. Upfront payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized, then are recognized as an expense as the goods are consumed or the related services are performed. Costs to support our Genentech Agreement are a component of our research and development activities.

Sales and Marketing Expenses

Sales and marketing expenses consist primarily of personnel-related expenses for commercial sales, account management, marketing, reimbursement, medical education and business development personnel that support commercialization of our platform products. In addition, these expenses include external costs such as advertising expenses, customer education and promotional expenses, market analysis expenses, conference fees, travel expenses and allocated facility costs.

Income Taxes

Income taxes are accounted for under the liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and the operating loss and tax credit carryforwards. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized.

Deferred tax assets and liabilities are measured at the balance sheet date using the enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities due to a change in tax rates is recognized in the period such tax rate changes are enacted. Our net deferred tax assets are fully offset by a valuation allowance, because of our history of losses.

We recognize the effect of income tax positions only if those positions are more likely than not of being sustained upon examination.

Net Loss Per Share Attributable to Common Shareholders

We calculate basic net loss per share attributable to common shareholders by dividing the net loss attributable to common shareholders by the weighted-average number of shares of common stock outstanding for the period. The diluted net loss per share attributable to common shareholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, common stock warrants, stock options and nonvested restricted stock units are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common shareholders, as their effect is anti-dilutive.

Prior to the closing of our initial public offering in July 2019 and the related conversion of our convertible preferred stock into common stock, we calculated our basic and diluted net loss per share attributable to common shareholders in conformity with the two-class method required for companies with participating securities. We considered our convertible preferred stock to be participating securities. In the event a dividend had been declared or paid on common stock, holders of convertible preferred stock would have been entitled to a share of such dividend in proportion to the holders of common stock on an as-if converted basis. Under the two-class method, basic net loss per share attributable to common shareholders is calculated by dividing the net loss attributable to common shareholders by the weighted-average number of shares of common stock outstanding for the period. Net loss attributable to common shareholders is determined by allocating undistributed earnings between common and preferred shareholders. The net loss attributable to common shareholders was not allocated to the convertible preferred stock under the two-class method, as the convertible preferred stock did not have a contractual obligation to share in our losses. The diluted net loss per share attributable to common shareholders was computed by giving effect to all potential dilutive common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, convertible preferred stock, convertible preferred stock warrants, common stock warrants and stock options were considered common stock equivalents but were excluded from the calculation of diluted net loss per share attributable to common shareholders, as their effect was anti-dilutive.

Segment Information

We have determined that our chief executive officer is the chief operating decision maker (“CODM”). The CODM reviews financial information presented on a regular basis at the entity level. Resource allocation decisions are made by the CODM based on the results at the entity level, which is determined to be a single reporting unit. There are no segment managers who are held accountable by the CODM for operations, operating results or planning for levels or components below the entity. As such, we have concluded that we operate as one segment. We present disaggregated revenue from contracts with customers by type of service. See Note 3, Revenue.

Recently Adopted Accounting Pronouncements

In February 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) (“ASC 842”), intended to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheets and disclosing key information about leasing arrangements. We adopted the guidance effective January 1, 2020 using the optional transition method described in ASU 2018-11, Leases (Topic 842) Targeted Improvements. Under the optional transition method, we recognized a cumulative-effect adjustment in the period of adoption. Prior period amounts were not adjusted and continue to be reported in accordance with the previous accounting under ASC 840, Leases (“ASC 840”).

In adopting the new standard, we utilized certain practical expedients available. These practical expedients include waiving reassessment of (1) whether any expired or existing contracts are or contain leases; (2) lease classification of expired or existing leases; and (3) initial direct costs for existing leases. We also elected to use hindsight in determining the lease term and in assessing impairment of our ROU assets. Furthermore, we have made a policy decision regarding our real estate leases not to separate nonlease components from lease components, to the extent they are fixed. We have also elected not to record on the balance sheet a lease that has a lease term of twelve months or less and does not contain a purchase option that we are reasonably certain to exercise.

The standard had a material impact on our balance sheet as of December 31, 2020, but did not have a material impact on our statements of operations or statements of cash flows. The most significant impact was the recognition of $33.0 million and $39.7 million of operating lease ROU assets and liabilities, respectively, and the derecognition of a $36.6 million asset and corresponding liability previously recorded pursuant to build-to-suit lease accounting guidance under ASC 840, which resulted in an increase to retained earnings of $0.1 million. The operating lease ROU assets and liabilities recorded at adoption included the derecognition of $7.3 million of deferred rent recognized as of December 31, 2019, as well as a $0.5 million reclassification of tenant incentive receivables previously recognized in the prepaid expenses and other current assets line item on our balance sheet. See Note 10, Leases, for additional information regarding leases.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables. The expected credit losses are recorded through an allowance account that is deducted from the amortized cost basis of the financial asset, and the net carrying value of the financial asset is presented on the balance sheet. The guidance also amends the previous other-than-temporary impairment model for available-for-sale debt securities by requiring the recognition of impairments relating to credit losses through an allowance account, limited to the difference between a security’s amortized cost basis and its fair value. Furthermore, the standard update removes the distinction between whether an impairment is temporary or other-than temporary. We adopted the guidance effective January 1, 2020. Given the short-term nature of our accounts receivable, the adoption as it relates to trade receivables did not have a significant impact on our financial statements. Furthermore, impairment of available-for-sale debt securities as of the adoption date was determined to be due to factors other than credit loss; therefore, a credit allowance was not recognized.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other: Internal-Use Software (Subtopic 350-40) to provide additional guidance on the accounting for costs of implementation activities performed in a cloud computing arrangement. We adopted this guidance effective January 1, 2020 on a prospective basis, and the adoption did not have any impact on our financial statements.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. Among other things, this guidance also clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. This guidance is effective for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. Early adoption is permitted, and the guidance is to be applied prospectively, except for certain amendments. We early adopted the guidance on January 1, 2020 and the adoption did not have a material impact on our financial statements.

Revenue

12 Months Ended

Dec. 31, 2020

Revenue From Contract With Customer [Abstract]

Revenue

We disaggregate our revenue from contracts with customers by type of service, as we believe this best depicts how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. The following table presents our revenue disaggregated by type of products and services for the periods presented (in thousands):

	Year Ended December 31,
	2020		2019		2018
Sequencing revenue	$	41,439	$	43,519	$	32,978
Development revenue
Development support		54,443		39,552		12,685
Regulatory milestones		2,500		2,000		10,000
Total development revenue		56,943		41,552		22,685
Total revenue	$	98,382	$	85,071	$	55,663

Translational Development Agreement

In December 2015, we entered into a translational development agreement with a biopharmaceutical customer for access to certain of our oncology immunosequencing research datasets, including full-time employee support, to accelerate the customer’s preclinical, nonclinical and clinical trial testing. Under the initial terms of the agreement, we could have been entitled to up to $40.0 million over a period of four years, which did not include any separately negotiated research sequencing contracts. If the biopharmaceutical customer terminated the agreement prior to the end of the initial four-year research term for any reason other than a material uncured breach by us, then the biopharmaceutical partner agreed to pay us $0.8 million. In May 2019, the agreement was subsequently amended to reduce the services provided, which in turn reduced the fourth year of eligible payments to $2.3 million.

We identified one performance obligation under this agreement, as the services were determined to be highly interrelated. We determined that any separately negotiated sequencing contracts are not performance obligations under the contract, as the contract did not contain any material rights related to such sequencing contracts. For the identified performance obligation, we assessed the work to be performed over the duration of the contract and determined that it was a consistent level of support throughout the period, and therefore, revenue was recognized on a straight-line basis over the contract term.

Revenue recognized from this translational development agreement, excluding separately negotiated research sequencing contracts, was $2.3 million and $9.3 million during the year ended December 31, 2019 and 2018, respectively.

MRD Development Agreements

We have entered into agreements with biopharmaceutical customers to further develop and commercialize our MRD product and the biopharmaceutical customers’ therapeutics. Under each of the agreements, we received or will receive non-refundable upfront payments and could receive substantial additional payments upon reaching certain progress milestones or achievement of certain regulatory milestones pertaining to the customers’ therapeutics and our MRD product.

Under the contracts, we identify performance obligations, which may include: (1) obligations to provide services supporting the customer’s regulatory submission activities as they relate to our MRD product; and (2) sequencing services related to customer-provided samples for their regulatory submissions. The transaction price allocated to the respective performance obligations is estimated using an adjusted market assessment approach for the regulatory support services and a standalone selling price for the estimated immunosequencing services. At contract inception, we fully constrain any consideration related to the regulatory milestones, as the achievement of such milestones is subject to third-party regulatory approval and the customers’ own submission decision-making. We recognize revenue relating to the sequencing services as sequencing revenue over time using an output method based on the proportion of sample results delivered relative to the total amount of sample results expected to be delivered and when expected to be a faithful depiction of progress. We use the same method to recognize the regulatory support services. When an output method based on the proportion of sample results delivered is not expected to be a faithful depiction of progress, we utilize an input method based on estimates of effort completed using a cost-based model.

We earned $2.5 million, $2.0 million and $10.0 million during the year ended December 31, 2020, 2019 and 2018, respectively, upon the achievement of certain regulatory milestones by us and our respective customers’ therapeutics. All $2.5 million, $2.0 million and $10.0 million was recognized as revenue within the respective periods, as we determined these amounts were consistent with our estimated standalone selling price and the respective performance obligations were complete. We recognized $3.4 million, $3.7 million and $12.8 million in development revenue related to these contracts, inclusive of the milestones, during the year ended December 31, 2020, 2019 and 2018, respectively.

As of December 31, 2020, in future periods we could receive up to an additional $313.5 million in milestone payments if certain regulatory approvals are obtained by our customers’ therapeutics in connection with MRD data generated from our MRD product.

Genentech Collaboration Agreement

In December 2018, we entered into a worldwide collaboration and license agreement with Genentech (“Genentech Agreement”) to leverage our capability to develop cellular therapies in oncology. Subsequent to receipt of regulatory approval in January 2019, we received a non-refundable, upfront payment of $300.0 million in February 2019 and may be eligible to receive more than $1.8 billion over time, including payments of up to $75.0 million upon the achievement of specified regulatory milestones, up to $300.0 million upon the achievement of specified development milestones and up to $1,430.0 million upon the achievement of specified commercial milestones. In addition, we are separately able to receive tiered royalties at a rate ranging from the mid-single digits to the mid-teens on aggregate worldwide net sales of products arising from the strategic collaboration, subject to certain reductions, with aggregate minimum floors. Under the agreement, we are pursuing two product development pathways for novel T cell immunotherapies in which Genentech intends to use TCRs screened by our immune medicine platform to engineer and manufacture cellular medicines:

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Shared Products. The shared products will use “off-the-shelf” TCRs identified against cancer antigens shared among patients (“Shared Products”).

•

Personalized Product. The personalized product will use patient-specific TCRs identified by real-time screening of TCRs against cancer antigens in each patient (“Personalized Product”).

Under the terms of the agreement, we granted Genentech exclusive worldwide licenses to develop and commercialize TCR-based cellular therapies in the field of oncology, including licenses to existing shared antigen data packages. Additionally, Genentech has the right to determine which product candidates to further develop for commercialization purposes. We determined that this arrangement meets the criteria set forth in ASC Topic 808, Collaborative Arrangements (“ASC 808”), because both parties are active participants in the activity and are exposed to significant risks and rewards depending on the activity’s commercial failure or success. Because ASC 808 does not provide guidance on how to account for the activities under a collaborative arrangement, we applied the guidance in ASC 606 to account for the activities related to the Genentech Agreement.

In applying ASC 606, we identified the following performance obligations at the inception of the agreement:

License to utilize on an exclusive basis all TCR-specific platform intellectual property to develop and commercialize any licensed products in the field of oncology.

License to utilize all data and information within each shared antigen data package and any other know-how disclosed by us to Genentech in oncology.

License to utilize all private antigen TCR product data in connection with research and development activities in the field of use.

License to existing shared antigen data packages.

Research and development services for shared product development, including expansion of shared antigen data packages.

Research and development services for private product development.

Obligations to participate on various joint research, development and project committees.

We determined that none of the licenses, research and development services or obligations to participate on various committees were distinct within the context of the contract, given such rights and activities were highly interrelated and there was substantial additional research and development to further develop the licenses. We considered factors such as the stage of development of the respective existing antigen data packages, the subsequent development that would be required to both identify and submit a potential target for investigational new drug acceptance under both product pathways and the variability in research and development pathways given Genentech’s control of product commercialization. Specifically, under the agreement, Genentech is not required to pursue development or commercialization activities pertaining to both product pathways and may choose to proceed with one or the other, as opposed to both. Accordingly, we determined that all of the identified performance obligations were attributable to one general performance obligation, which is to further the development of our TCR-specific platform, including data packages, and continue to make our TCR identification process available to Genentech to pursue either product pathway.

Separately, we have a responsibility to Genentech to enter into a supply and manufacturing agreement for patient-specific TCRs as it pertains to any Personalized Product therapeutic. We determined this was an option right of Genentech should they pursue commercialization of a Personalized Product therapy. Because of the uncertainty resulting from the early stage of development, the novel approach of our collaboration with Genentech and our rights to future commercial milestones and royalty payments, we determined that this option right was not a material right that should be accounted for at inception. As such, we will account for the supply and manufacturing agreement when entered into between the parties.

We determined the initial transaction price shall be made up of only the $300.0 million upfront, non-refundable payment, as all potential regulatory and development milestone payments were probable of significant revenue reversal given their achievement was highly dependent on factors outside our control. As a result, these payments were fully constrained and were not included in the transaction price as of December 31, 2020. We excluded the commercial milestones and potential royalties from the transaction price, as those items relate predominantly to the license rights granted to Genentech and will be assessed when and if such events occur.

As there are potential substantive developments necessary, which Genentech may be able to direct, we determined that we would apply a proportional performance model to recognize revenue for our performance obligation. We measure proportional performance using an input method based on costs incurred relative to the total estimated costs of research and development efforts to pursue both the Shared Product and Personalized Product pathways. When any of the potential regulatory and development milestones are no longer fully constrained and included in the transaction price, such amounts will be recognized using the cumulative catch-up method based on proportional performance at such time. We currently expect to recognize the revenue over a period of approximately seven to eight years from the effective date. This estimate of the research and development period considers pursuit options of development activities supporting both the Shared Product and the Personalized Product, but may be reduced or increased based on the various activities as directed by the joint committees, decisions made by Genentech, regulatory feedback or other factors not currently known.

We recognized revenue of $52.8 million and $35.1 million during the year ended December 31, 2020 and 2019, respectively, related to the Genentech Agreement. Costs related to the Genentech Agreement are included in research and development expenses.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

4.	Fair Value Measurements

The following tables set forth the fair value of financial assets as of December 31, 2020 and 2019 that were measured at fair value on a recurring basis (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Financial assets
Money market funds	$	103,283	$	—	$	—	$	103,283
U.S. government debt securities		—		671,777		—		671,777
Corporate bonds		—		11,581		—		11,581
Total financial assets	$	103,283	$	683,358	$	—	$	786,641

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Financial assets
Money market funds	$	88,683	$	—	$	—	$	88,683
Commercial paper		—		121,867		—		121,867
U.S. government debt securities		—		377,243		—		377,243
Corporate bonds		—		86,615		—		86,615
Total financial assets	$	88,683	$	585,725	$	—	$	674,408

Level 1 securities include highly liquid money market funds, for which we measure the fair value based on quoted prices in active markets for identical assets or liabilities. Level 2 securities consist of U.S. government debt securities, commercial paper and corporate bonds, and are valued based on recent trades of securities in inactive markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Investments

12 Months Ended

Dec. 31, 2020

Investments Debt And Equity Securities [Abstract]

Investments

5.	Investments

Available-for-sale investments consisted of the following as of December 31, 2020 and 2019 (in thousands):

	December 31, 2020
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Short-term marketable securities
U.S. government debt securities	$	552,539	$	723	$	(10	)	$	553,252
Corporate bonds		11,497		86		(2	)		11,581
Total short-term marketable securities	$	564,036	$	809	$	(12	)	$	564,833
Long-term marketable securities
U.S. government debt securities	$	118,429	$	98	$	(2	)	$	118,525
Total long-term marketable securities	$	118,429	$	98	$	(2	)	$	118,525

	December 31, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Short-term marketable securities
Commercial paper	$	121,866	$	—	$	—		$	121,866
U.S. government debt securities		285,963		394		(1	)		286,356
Corporate bonds		71,962		109		(3	)		72,068
Total short-term marketable securities	$	479,791	$	503	$	(4	)	$	480,290
Long-term marketable securities
U.S. government debt securities	$	90,750	$	146	$	(9	)	$	90,887
Corporate bonds		14,513		35		—			14,548
Total long-term marketable securities	$	105,263	$	181	$	(9	)	$	105,435

All the commercial paper, U.S. government debt securities and corporate bonds designated as short-term marketable securities have an effective maturity date that is equal to or less than one year from the respective balance sheet date. Those that are designated as long-term marketable securities have an effective maturity date that is more than one year from the respective balance sheet date.

Accrued interest receivables are excluded from the amortized cost and estimated fair value of our marketable securities. Accrued interest receivables of $2.5 million and $2.2 million were presented separately within the prepaid expenses and other current assets line item on our balance sheet as of December 31, 2020 and 2019, respectively. We have made an accounting policy election to not measure an allowance for credit losses for accrued interest receivables.

The following table presents the gross unrealized holding losses and fair value for investments in an unrealized loss position and the length of time that individual securities have been in a continuous loss position as of December 31, 2020 (in thousands):

	Less Than 12 Months					12 Months Or Greater
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
U.S. government debt securities	$	177,554	$	(12	)	$	—	$	—
Corporate bonds		1,512		(2	)		—		—
Total available-for-sale securities	$	179,066	$	(14	)	$	—	$	—

We periodically review our available-for-sale securities to assess for credit impairment. Some of the factors considered in assessing impairment include the extent to which the fair value is less than the amortized cost basis, adverse conditions related to the security, an industry or geographic area, changes to security ratings or sector credit ratings and other relevant market data.

As of December 31, 2020, we did not intend, nor were we more likely than not to be required, to sell our available-for-sale investments before the recovery of their amortized cost basis, which may be maturity. Based on our assessment, we concluded all impairment as of December 31, 2020 to be due to factors other than credit loss, such as changes in interest rates. A credit allowance was not recognized and the impairment of our available-for-sale securities was recorded in other comprehensive loss.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Property and Equipment, Net

6.	Property and Equipment, Net

Property and equipment, net as of December 31, 2020 and 2019 consisted of the following (in thousands):

	December 31,
	2020			2019
Laboratory equipment	$	27,767		$	20,773
Computer equipment		3,600			2,450
Furniture and office equipment		2,717			1,568
Computer software		860			505
Construction in progress		7,185			1,852
Leasehold improvements		21,945			14,716
Build-to-suit asset cost		—			36,607
Property and equipment, at cost		64,074			78,471
Less: accumulated depreciation		(24,382	)		(18,116	)
Property and equipment, net	$	39,692		$	60,355

Depreciation expense was $6.8 million, $6.1 million and $4.3 million for the year ended December 31, 2020, 2019 and 2018, respectively.

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

7.	Goodwill and Intangible Assets

There have been no changes in the carrying amount of goodwill since its recognition in 2015.

Intangible assets subject to amortization as of December 31, 2020 and 2019 consisted of the following (in thousands):

	December 31, 2020
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired developed technology	$	20,000	$	(9,972	)	$	10,028
Purchased intellectual property		325		(128	)		197
Balance at December 31, 2020	$	20,325	$	(10,100	)	$	10,225

	December 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired developed technology	$	20,000	$	(8,301	)	$	11,699
Purchased intellectual property		325		(96	)		229
Balance at December 31, 2019	$	20,325	$	(8,397	)	$	11,928

The developed technology was acquired in connection with our acquisition of Sequenta in 2015. The remaining balance of the acquired technology and the purchased intellectual property is expected to be amortized over the next 6.0 years.

As of December 31, 2020, expected future amortization expense for intangible assets was as follows (in thousands):

2021	$	1,699
2022		1,699
2023		1,699
2024		1,703
2025		1,699
Thereafter		1,726
Total future amortization expense	$	10,225

Accrued Liabilities

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Accrued Liabilities

8.	Accrued Liabilities

Accrued liabilities as of December 31, 2020 and 2019 consisted of the following (in thousands):

	December 31,
	2020		2019
Professional fees	$	3,219	$	1,011
Clinical and contract research organization costs		1,781		30
Travel and entertainment		91		157
Tax liabilities		1,767		2,062
Purchases of property and equipment		4,423		555
Other		1,881		556
Total accrued liabilities	$	13,162	$	4,371

The accrued tax liabilities balance as of December 31, 2020 includes a $1.4 million tax withholding liability related to unsettled option exercises as of December 31, 2020. The accrued tax liabilities balance as of December 31, 2019 includes a $1.9 million tax withholding liability related to unsettled option exercises as of December 31, 2019.

Deferred Revenue

12 Months Ended

Dec. 31, 2020

Revenue From Contract With Customer [Abstract]

Deferred Revenue

9.	Deferred Revenue

Deferred revenue by revenue classification as of December 31, 2020 and 2019 was as follows (in thousands):

	December 31,
	2020		2019
Current deferred revenue
Sequencing	$	15,463	$	12,482
Development		57,856		48,512
Total current deferred revenue		73,319		60,994
Non-current deferred revenue
Sequencing		724		1,459
Development		162,894		217,873
Total non-current deferred revenue		163,618		219,332
Total current and non-current deferred revenue	$	236,937	$	280,326

Deferred revenue from our Genentech Agreement represents $55.1 million and $157.0 million of the current and non-current development deferred revenue balances, respectively, as of December 31, 2020 and $48.1 million and $216.8 million of the current and non-current development deferred revenue balances, respectively, as of December 31, 2019. In general, we expect that the current amounts will be recognized as revenue within 12 months and the non-current amounts will be recognized as revenue over a period of approximately six to seven years. This period of time represents an estimate of the research and development period to develop cellular therapies in oncology, which may be reduced or increased based on the various development activities.

Changes in deferred revenue during the year ended December 31, 2020 were as follows (in thousands):

Deferred revenue balance at December 31, 2019	$	280,326
Additions to deferred revenue during the period		26,434
Revenue recognized during the period		(69,823	)
Deferred revenue balance at December 31, 2020	$	236,937

As of December 31, 2020, $61.6 million was recognized as revenue that was included in the deferred revenue balance at December 31, 2019. This is inclusive of $1.0 million of sequencing revenue recognized as a result of cancelled biopharmaceutical customer sequencing contracts and $0.6 million of sequencing revenue related to Medicare that was recognized due to our determination that additional testing for specific patients was remote.

Leases

12 Months Ended

Dec. 31, 2020

Lessee Disclosure [Abstract]

Leases

10.

Leases

We have operating lease agreements for the laboratory and office facilities that we occupy in various locations, as well as server space.

In July 2011, we entered into a non-cancelable lease agreement with an, at the time, minority shareholder for our current headquarters in Seattle, Washington. The lease terms were subsequently amended multiple times, most recently in August 2019, when we expanded the existing premises to approximately 65,500 square feet. Cash payment for rent of the expanded premises commenced January 2020, four months after the landlord delivered the expanded premises to us for construction of certain tenant improvements, and the lease term for both the existing premises and the expanded premises ends October 2032, subject to our option to twice extend the lease for five years. The amended lease also requires us to pay additional amounts for operating and maintenance expenses.

In August 2019, we entered into an agreement to rent approximately 100,000 square feet in a to-be-constructed building in Seattle, Washington. In connection with the lease, we entered into a $2.1 million letter of credit with one of our existing financial institutions. Due to our significant involvement during the construction process of the leased building, we qualified as the deemed owner of the building under build-to-suit lease accounting guidance that proceeded ASC 842. The resulting asset and long-term financing obligation recorded on our balance sheet as of December 31, 2019 for the cost of the building was derecognized upon adoption of ASC 842. The lease commenced in December 2020, when the landlord delivered the premises to us for construction of certain tenant improvements. Cash payment for rent begins in October 2021 and the lease term ends in August 2033, subject to our option to twice extend the lease for five years. We plan to occupy the new building in 2021, once interior construction is finished. In connection with this lease, the landlord agreed to fund $20.0 million in improvements, which was subsequently reduced to $14.8 million as a result of our change requests made during landlord construction of the building, net of an administration fee. As of December 31, 2020, we have incurred $5.2 million in certain tenant improvement costs, of which $0.7 million has been reimbursed by the landlord. The remaining $4.5 million is presented as a reduction in the cash flows used to measure our ROU asset and lease liabilities on our balance sheet as of December 31, 2020 and will be reimbursed by the landlord. The lease also requires us to pay additional amounts for operating and maintenance expenses.

In October 2019, we entered into an agreement to lease approximately 14,750 square feet in a separate Seattle, Washington location, pursuant to a lease expiring in October 2029, which is subject to our ability to exercise an early termination right after the third year. In connection with the lease, the landlord has agreed to provide a tenant improvement allowance in the maximum amount of $0.7 million. The lease also requires us to pay additional amounts for operating expenses.

In April 2018, we entered into a lease agreement to lease approximately 13,400 square feet in South San Francisco, California. The lease term is through March 2026 and provides for one five-year extension option. We are responsible for our share of allocable operating expenses, tax expenses and utilities cost during the duration of the lease term. In connection with the lease, the landlord funded agreed-upon improvements. The landlord was solely responsible for the $2.4 million cost of such improvements. The lease agreement was amended in February 2020 to lease approximately 19,900 additional square feet and provides for a $0.6 million tenant improvement allowance.

In December 2019, we entered into an agreement to lease approximately 3,100 square feet of office space in New York City, New York, pursuant to a lease that expires November 2025, subject to our ability to exercise an early termination right in 2023.

As of December 31, 2020, we were not party to any finance leases. Our leases have remaining terms of 1.3 years to 12.7 years and include options to extend certain of the leases up to 10.0 years and terminate certain of the leases after 3.0 years. We adjust lease terms for these options only when it is reasonably certain we will exercise these options. As of December 31, 2020, it was reasonably certain that we would exercise our option to terminate two of our leases after 3.0 years.

Other information related to our operating leases as of December 31, 2020 was as follows:

Weighted-average remaining lease term (in years)			11.33
Weighted-average discount rate			4.6	%

The following table reconciles our undiscounted operating lease cash flows to our operating lease liabilities as of December 31, 2020 (in thousands):

2021	$	7,828
2022		13,554
2023		13,318
2024		13,030
2025		13,419
Thereafter		88,463
Total undiscounted lease payments		149,612
Less:
Imputed interest rate		(35,848	)
Tenant improvement receivables		(5,902	)
Total operating lease liabilities	$	107,862
Less: current portion		(3,529	)
Operating lease liabilities, less current portion	$	104,333

Operating lease expense was $5.5 million for the year ended December 31, 2020. Variable lease expense for operating leases was $2.6 million for the year ended December 31, 2020. Rent expense recognized under ASC 840, inclusive of operating and maintenance costs, was $5.3 million and $4.1 million for the year ended December 31, 2019 and 2018, respectively.

Cash paid for amounts included in the measurement of lease liabilities for the year ended December 31, 2020 was $3.2 million, net of $2.5 million of cash received for tenant improvement allowances. For the year ended December 31, 2020, ROU assets obtained in exchange for operating lease liabilities was $109.1 million, inclusive of the $33.0 million recognized from the adoption of ASC 842.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

11.	Commitments and Contingencies

Legal Proceedings

We are subject to claims and assessments from time to time in the ordinary course of business. We will accrue a liability for such matters when it is probable that a liability has been incurred and the amount can be reasonably estimated. When only a range of possible loss can be established, the most probable amount in the range is accrued. If no amount within this range is a better estimate than any other amount within the range, the minimum amount in the range is accrued. We are not party to any material legal proceedings as of December 31, 2020.

Indemnification Agreements

In the ordinary course of business, we may provide indemnification of varying scope and terms to vendors, lessors, customers and other parties with respect to certain matters including, but not limited to, losses arising out of breach of our agreements with them or from intellectual property infringement claims made by third parties. In addition, we have entered into indemnification agreements with members of our board of directors and certain of our executive officers that will require us to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments that we could be required to make under these indemnification agreements is, in many cases, unlimited. We have not incurred any material costs as a result of such indemnifications and are not currently aware of any indemnification claims.

Shareholders' Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Shareholders' Equity

12.	Shareholders’ Equity

Convertible Preferred Stock

Immediately prior to the completion of our initial public offering on July 1, 2019, 93,039,737 shares of convertible preferred stock then outstanding converted into an equivalent number of shares of common stock. As of December 31, 2020, no shares of convertible preferred stock were outstanding.

Preferred Stock

We are authorized to issue 10,000,000 shares of preferred stock, par value $0.0001 per share. As of December 31, 2020, no shares of preferred stock were outstanding.

Common Stock

We are authorized to issue 340,000,000 shares of common stock. Our common stock has a par value of $0.0001 per share, no preferences or privileges and is not redeemable. Holders of our common stock are entitled to one vote for each share of common stock held. The holders of record of outstanding shares of common stock shall be entitled to receive, when, as and if declared, out of funds legally available, such cash and other dividends as may be declared from time to time. As of December 31, 2020, we had 137,646,896 shares of common stock outstanding.

As of December 31, 2020, we have reserved shares of common stock for the following:

Shares issuable upon the exercise of outstanding common stock options and the vesting of outstanding common restricted stock units granted			14,483,560
Shares available for future grant under the 2019 Equity Incentive Plan			18,617,001
Shares available for future grant under the Employee Stock Purchase Plan			2,804,298
Shares to be issued upon exercise of a common stock warrant			56,875
Total shares of common stock reserved for future issuance			35,961,734

Our 2019 Equity Incentive Plan (“2019 Plan”) provides for annual increases in the number of shares that may be issued under the 2019 Plan on January 1, 2020 and on each subsequent January 1, thereafter, by a number of shares equal to the lesser of (a) 5% of the number of shares of common stock issued and outstanding on the immediately preceding December 31, or (b) an amount determined by our board of directors.

Furthermore, our Employee Stock Purchase Plan (“ESPP”) provides for annual increases in the number of shares available for issuance under our ESPP on January 1, 2020 and on each January 1, thereafter, by a number of shares equal to the smallest of (a) 1% of the number of shares of common stock issued and outstanding on the immediately preceding December 31, or (b) an amount determined by our board of directors.

Effective January 1, 2020, our 2019 Plan and ESPP reserves increased by 6,261,907 shares and 1,252,381 shares, respectively. Effective January 1, 2021, our 2019 Plan reserve increased by 6,882,344 shares.

Common Stock Warrants

In connection with two transactions in 2012 and 2013, we granted warrants to purchase up to 55,032 shares of common stock. These warrants were exercisable at any time for a period of ten years from the date of issuance at a weighted-average exercise price of $0.37, except in the case of a warrant to purchase 20,000 shares of common stock at an exercise price of $0.45 per share that would have expired if unexercised prior to the closing of our initial public offering. On July 1, 2019, we issued 54,792 shares of common stock through both a cash and cashless exercise of the warrants. The impact of these exercises was immaterial to the financial statements.

Separately, in 2014, we issued a warrant to purchase 56,875 shares of Series C convertible preferred stock at an exercise price of $2.64. The warrant is exercisable for a period of seven years from the date of issuance. Immediately prior to and in connection with the completion of our initial public offering on July 1, 2019, this convertible preferred stock warrant, which was previously recorded as a financial liability, was converted to a warrant to purchase the same number of shares of common stock. Upon conversion, the financial liability was reclassified to the additional paid-in capital line item on our balance sheet. The warrant to purchase 56,875 shares of common stock remains outstanding as of December 31, 2020.

Equity Incentive Plans

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity Incentive Plans

13.	Equity Incentive Plans

Sequenta 2008 Stock Plan, as amended

In connection with our acquisition of Sequenta in January 2015, we assumed Sequenta’s Equity Incentive Plan (“2008 Plan”), including all outstanding options and shares available for future issuance under the 2008 Plan, which, prior to the completion of our initial public offering, were all exercisable for Series E-1 convertible preferred stock. Upon completion of our initial public offering in July 2019, the outstanding options were exercisable for common stock. No shares are available for future issuance under this plan and no equity awards are outstanding under this plan as of December 31, 2020.

Adaptive 2009 Equity Incentive Plan

We adopted an equity incentive plan in 2009 (“2009 Plan”) that provided for the issuance of incentive and nonqualified common stock options and other share-based awards for employees, directors and consultants. Under the 2009 Plan, the option exercise price for incentive and nonqualified stock options were not to be less than the fair market value of our common stock at the date of grant. Options granted under this plan expire no later than ten years from the grant date and vesting was established at the time of grant. Pursuant to the terms of the 2019 Plan, any shares subject to outstanding options originally granted under the 2009 Plan that terminate, expire or lapse for any reason without the delivery of shares to the holder thereof shall become available for issuance pursuant to awards granted under the 2019 Plan. While no shares are available for future issuance under the 2009 Plan, it continues to govern outstanding equity awards granted thereunder.

2019 Equity Incentive Plan

The 2019 Plan was approved by our shareholders on June 13, 2019 and, pursuant to the resolutions adopted by our board of directors, became effective immediately prior to the closing of our initial public offering. The 2019 Plan provides for the issuance of awards in the form of options and other share-based awards for employees, directors and consultants. Under the 2019 Plan, the option exercise price per share shall not be less than the fair market value of a share of stock on the grant date of the option, as defined by the 2019 Plan, unless explicitly qualified under the provisions of Section 409A or Section 424(a) of the Internal Revenue Code of 1986. Additionally, unless otherwise specified, options granted under this plan expire no later than ten years from the grant date and vesting is established at the time of grant. Except for certain option grants made to non-employee directors, stock options granted under the 2019 Plan generally vest over a four-year period, subject to continuous service through each applicable vesting date. As of December 31, 2020, we have authorized 22,109,217 shares of common stock for issuance under the 2019 Plan.

Changes in shares available for grant during the year ended December 31, 2020 were as follows:

	Shares Available for Grant
Shares available for grant at December 31, 2019		15,396,254
2019 Plan reserve increase on January 1, 2020		6,261,907
Options and restricted stock units granted		(3,291,701	)
Options forfeited, cancelled or expired		250,541
Shares available for grant at December 31, 2020		18,617,001

Stock option activity under the 2008 Plan, 2009 Plan and 2019 Plan during the year ended December 31, 2020 was as follows:

	Shares Subject to Outstanding Options			Weighted- Average Exercise Price per Share		Aggregate Intrinsic Value (in thousands)
Options outstanding at December 31, 2019		16,646,654		$	6.14	$	398,379
Options granted		3,241,701			33.36
Options forfeited or cancelled		(235,541	)		16.17
Options expired		(15,000	)		0.16
Options exercised		(5,204,254	)		4.14
Options outstanding at December 31, 2020		14,433,560		$	12.82	$	668,458
Options vested and exercisable at December 31, 2020		7,924,779		$	6.41	$	417,801

The weighted-average remaining contractual life for options outstanding as of December 31, 2020 was 7.1 years. The weighted-average remaining contractual life for vested and exercisable options outstanding as of December 31, 2020 was 5.9 years.

The weighted-average grant date fair value per share of options granted was $21.11, $6.87 and $4.15 during the year ended December 31, 2020, 2019 and 2018, respectively. The total intrinsic value of options exercised was $190.4 million, $39.1 million and $3.8 million during the year ended December 31, 2020, 2019 and 2018, respectively.

As of December 31, 2020, $0.3 million was included in the prepaid expenses and other current assets line item on our balance sheet for unsettled cash proceeds related to options exercised during the year ended December 31, 2020. As of December 31, 2019, $0.5 million was included in the prepaid expenses and other current assets line item on our balance sheet for unsettled cash proceeds related to options exercised during the year ended December 31, 2019. The $21.7 million proceeds from exercise of stock options on our statements of cash flows for the year ended December 31, 2020 includes this $0.5 million, as the related proceeds settled during the year ended December 31, 2020.

Restricted stock unit activity under the 2019 Plan during the year ended December 31, 2020 was as follows:

	Restricted Stock Units Outstanding			Weighted- Average Grant Date Fair Value per Share
Nonvested outstanding restricted stock units at December 31, 2019		4,500		$	41.63
Restricted stock units granted		50,000			28.10
Restricted stock units vested		(4,500	)		41.63
Nonvested outstanding restricted stock units at December 31, 2020		50,000		$	28.10

The weighted-average grant date fair value per share of restricted stock units granted during the year ended December 31, 2019 was $41.63.

Grant Date Fair Value of Options and Restricted Stock Units Granted

The estimated grant date fair value of options granted during the year ended December 31, 2020, 2019 and 2018 was estimated using the Black-Scholes option-pricing model with the following assumptions:

	Year Ended December 31,
	2020		2019		2018
Fair value of common stock	$17.68 - $55.23		$7.80 - $47.81		$6.55
Expected term (in years)	5.27 - 6.08		5.27 - 6.08		6.08 - 10.00
Risk-free interest rate	0.4% - 1.7%		1.4% - 2.5%		2.6% - 3.0%
Expected volatility	70.5% - 73.3%		64.3% - 72.9%		65.0% - 69.2%
Expected dividend yield		—		—		—

The weighted-average volatility used in the grant date fair value calculations of options granted during the year ended December 31, 2020, 2019 and 2018 was 71.4%, 68.1% and 68.1%, respectively.

The determination of the fair value of stock options on the date of grant using a Black-Scholes option-pricing model is affected by the estimated fair value of our common stock, as well as assumptions regarding a number of variables that are complex, subjective and generally require significant judgment to determine. The valuation assumptions were determined as follows:

Fair value of common stock—Prior to the closing of our initial public offering, the fair value of our common stock was determined with input from management using valuation methodologies which utilized certain assumptions, including probability weighting of events, volatility, time to liquidation, a risk-free interest rate and an assumption for a discount for lack of marketability (Level 3 inputs). In determining the fair value of our common stock, the methodologies used to estimate the enterprise value were performed using methodologies, approaches and assumptions consistent with the American Institute of Certified Public Accountants Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. For valuations of grants made after the closing of our initial public offering, the fair value of each share of common stock is based on the closing price of our common stock on the date of grant, or other relevant determination date, as reported on The Nasdaq Global Select Market.

Expected term—The expected term of options granted to employees and non-employee directors is determined using the “simplified” method, as illustrated in ASC Topic 718, Compensation—Stock Compensation, as we do not have sufficient exercise history to determine a better estimate of expected term. Under this approach, the expected term is based on the midpoint between the vesting date and the end of the contractual term of the option.

Risk-free interest rate—We utilize a risk-free interest rate in the option valuation model based on U.S. Treasury zero-coupon issues with remaining terms similar to the expected terms of the options.

Expected volatility—As we do not have sufficient trading history for our common stock, the expected volatility is based on the historical volatility of our publicly traded industry peers utilizing a period of time consistent with our estimate of the expected term.

Expected dividend yield—We do not anticipate paying any cash dividends in the foreseeable future and, therefore, use an expected dividend yield of zero in the option valuation model.

The grant date fair value of restricted stock units granted after the closing of our initial public offering is based on the closing price of our common stock on the date of grant, or other relevant determination date, as reported on The Nasdaq Global Select Market.

Share-based compensation expense of $24.8 million, $13.1 million and $11.1 million was recognized during the year ended December 31, 2020, 2019 and 2018, respectively.

The compensation costs related to stock options and restricted stock units for the years ended December 31, 2020, 2019 and 2018 are included on our statements of operations as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Cost of revenue	$	817	$	555	$	398
Research and development		8,519		3,934		2,896
Sales and marketing		6,627		3,480		2,891
General and administration		8,798		5,155		4,964
Total share-based compensation expense	$	24,761	$	13,124	$	11,149

During the year ended December 31, 2018, there was one employee option modification to extend the option exercise period, which resulted in incremental stock compensation of $0.5 million.

As of December 31, 2020, unrecognized share-based compensation expense related to unvested stock options was $74.9 million, which is expected to be recognized over a remaining weighted-average period of 3.0 years. Additionally, as of December 31, 2020, unrecognized share-based compensation expense related to nonvested restricted stock units was $1.1 million, which is expected to be recognized over a remaining weighted-average period of 3.3 years.

Microsoft Collaboration Agreement

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Microsoft Collaboration Agreement

14.	Microsoft Collaboration Agreement

Summary of Agreement

In December 2017, we entered into a collaboration agreement with Microsoft (“Microsoft Agreement”) to computationally derive a comprehensive TCR antigen map for purposes of developing a universal diagnostic based on a single blood test.

Contemporaneously with the Microsoft Agreement, we entered into a separate agreement to use Microsoft’s Azure cloud services at standard volume pricing with a minimum Azure consumption requirement of $12.0 million over the seven-year term of the Microsoft Agreement, which we expect to meet in the ordinary course of business.

In addition, contemporaneously with entering into the Microsoft Agreement, Microsoft made a preferred stock investment of approximately $45.0 million as a part of our Series F-1 convertible preferred stock issuance.

Summary of Accounting

The terms of the Microsoft Agreement meet the criteria under ASC Topic 808, Collaborative Arrangements (“ASC 808”), as both parties are active participants in the activity and are exposed to significant risks and rewards dependent on the commercial success of the activity. ASC 808 does not provide guidance on how to account for the activities under the collaboration and we determined that Microsoft did not meet the definition of a customer under ASC 606. Accordingly, we looked to other guidance to determine the accounting for the respective elements.

We determined that the preferred stock issuance and commitment to use Microsoft’s Azure cloud services were made at terms consistent with market rates. All consideration received as part of the Series F-1 convertible preferred stock issuance was accounted for as part of the Series F-1 preferred stock issuance. Since the commitment to use Microsoft’s Azure cloud services was at market terms and we expect to meet the commitment in the ordinary course of business during the seven-year term, we record the expenses in the period in which the services are consumed. These costs are recorded in our statements of operations based on the underlying activities for which they support.

The remaining elements of the agreement were highly interrelated, so we evaluated them in the aggregate to determine the appropriate accounting application. Specifically, we determined that the transfer of license rights between the parties, our commitment to provide data and immunomics, diagnostic and bioinformatics expertise to Microsoft and Microsoft’s commitment to provide machine learning software and related development services to us were highly interrelated because they were necessary for the parties to perform the activities under the Microsoft Agreement and, therefore, should be evaluated as one unit of account.

We accounted for these collaboration activities by analogy to ASC Topic 845, Nonmonetary Transactions, and determined that major uncertainties exist about the realizability of the value that would be assigned to an asset received from or provided to Microsoft under the collaboration and, therefore, fair value could not be reliably measured. As a result, we did not recognize any non-monetary assets or corresponding non-monetary income or expenses pertaining to the rights provided to us or to be received by us under the Microsoft Agreement.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

15.	Income Taxes

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of our deferred tax assets and liabilities for the periods presented are as follows (in thousands):

	December 31,
	2020			2019
Deferred tax assets
Net operating losses	$	105,433		$	79,035
Tax credit carryforward		18,981			11,152
Non qualifying stock options		12,096			9,150
Deferred rent		—			11,755
Operating lease liabilities		31,052			—
Deferred revenue		59,713			1,706
Other		2,983			1,892
Total deferred tax assets		230,258			114,690
Valuation allowance		(197,527	)		(100,906	)
Deferred tax assets, net of valuation allowance		32,731			13,784
Deferred tax liabilities
Tangible and intangible assets		(5,760	)		(13,784	)
ROU assets		(26,971	)		—
Net deferred taxes	$	—		$	—

ASC Topic 740, Income Taxes, requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management assesses that realization is “more likely than not.” Realization of the future tax benefits is dependent on our ability to generate sufficient taxable income within the carryforward period. Because of our history of operating losses, management believes that recognition of the deferred tax assets arising from the above-mentioned future tax benefits is currently not likely to be realized and, accordingly, has provided a valuation allowance. The valuation allowance increased by $96.6 million and $30.2 million during the year ended December 31, 2020 and 2019, respectively.

In March 2020, the CARES Act was enacted and signed into law in response to COVID-19. The CARES Act, among other things, included several significant provisions that impacted corporate taxpayers' accounting for income taxes, including modification to the utilization of net operating losses and interest expense deduction limitations. However, none of these provisions have an impact on our tax provision.

Federal tax laws impose substantial restrictions on the utilization of net operating loss and credit carryforwards in the event of an ownership change, as defined in Section 382 of the Internal Revenue Code. Accordingly, our ability to utilize these carryforwards may be limited due to such ownership changes. We have completed a Section 382 analysis for changes in ownership through December 31, 2018 and an analysis is ongoing for ownership changes through December 31, 2020. Based on these analyses, we do not expect to have any permanent limitations on the utilization of our federal net operating losses. Under the TCJA federal income tax law, federal net operating losses incurred in 2018 and in future years may be carried forward indefinitely, but the deductibility of such federal net operating losses is limited. Net operating losses generated prior to 2018 are eligible to be carried forward up to 20 years. As of December 31, 2020, we had U.S. federal net operating losses of $192.5 million and U.S. federal tax credits of $18.8 million that will begin to expire in 2028. We also have $211.9 million of net operating losses that do not expire.

The effective tax rate of our provision for income taxes differs from the federal statutory rate for the periods presented as follows:

	Year Ended December 31,
	2020	2019	2018
Statutory rate	21.0%	21.0%	21.0%
State tax	13.8	8.1	5.5
Stock compensation	25.2	9.8	0.5
Permanent items	(0.1)	(1.0)	0.5
Credits	5.7	6.1	2.7
Other	0.5	0.3	0.1
Change in valuation allowance	(66.1)	(44.3)	(30.3)
Total	0.0%	0.0%	0.0%

We recognize, in our financial statements, the effect of a tax position when it is more likely than not, based on the technical merits, that the position will be sustained upon examination. We had unrecognized tax benefits of $3.5 million as of December 31, 2020. A reconciliation of the beginning and ending amounts of unrecognized tax benefits during the periods presented are as follows (in thousands):

Balance at December 31, 2017	$	1,031
Additions in 2018		229
Balance at December 31, 2018		1,260
Additions in 2019		792
Balance at December 31, 2019		2,052
Additions in 2020		1,437
Balance at December 31, 2020	$	3,489

During the year ended December 31, 2020 and 2019, we recognized uncertain tax positions of $1.4 million and $0.8 million, respectively, related to a reduction of the research and development credit deferred tax asset. Unrecognized tax benefits may change during the next twelve months for items that arise in the ordinary course of business. We do not anticipate a material change to our unrecognized tax benefits over the next twelve months that would have an adverse effect on our operating results.

We recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. We had no accrued interest or penalties related to uncertain tax positions as of December 31, 2020 and 2019.

We file federal and certain state income tax returns, which provide varying statutes of limitations on assessments. However, because of net operating loss carryforwards, substantially all tax years since inception remain open to federal and state tax examination.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Net Loss Per Share Attributable to Common Shareholders

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Shareholders

16.	Net Loss Per Share Attributable to Common Shareholders

Net Loss Per Share

The following table sets forth the computation of the basic and diluted net loss per share attributable to common shareholders for the periods presented (in thousands, except share and per share amounts):

	Year Ended December 31,
	2020			2019			2018
Net loss	$	(146,227	)	$	(68,606	)	$	(46,447	)
Fair value adjustments to redemption value for Series E-1 convertible preferred stock options		—			(964	)		102
Net loss attributable to common shareholders, basic and diluted	$	(146,227	)	$	(69,570	)	$	(46,345	)
Weighted-average shares used in computing net loss per share		131,216,468			69,165,315			12,629,778
Net loss per share attributable to common shareholders, basic and diluted	$	(1.11	)	$	(1.01	)	$	(3.67	)

Since we were in a loss position for all periods presented, basic net loss per share attributable to common shareholders is the same as diluted net loss per share attributable to common shareholders, as the inclusion of all potential shares of common stock outstanding would have been anti-dilutive. The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common shareholders for the year ended December 31, 2020, 2019 and 2018, respectively, as they had an anti-dilutive effect:

	Year Ended December 31,
	2020		2019		2018
Convertible preferred stock (on as if converted basis)		—		46,104,469		92,783,867
Stock options issued and outstanding		16,125,548		17,183,546		14,701,626
Nonvested restricted stock units		38,125		4,952		—
Common stock warrants		56,875		55,961		55,032
Convertible preferred stock warrants		—		28,204		56,875
Total		16,220,548		63,377,132		107,597,400

Retirement Plan

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

Retirement Plan

17.	Retirement Plan

We maintain a salary deferral 401(k) plan (“401(k) Plan”) covering employees who have met certain eligibility requirements. Employees may defer up to 100% of their compensation to the 401(k) Plan, subject to federal limits. We made $1.6 million in discretionary contributions during the year ended December 31, 2020, which are fully vested after one year of employee service. We did not make any discretionary contributions during the years ended December 31, 2019 and 2018.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation and Use of Estimates

JOBS Act Accounting Election

Cash and Cash Equivalents

Restricted Cash

We are required to maintain certain balances under lease arrangements for some of our property and facility leases. We had restricted cash of $2.1 million as of December 31, 2020 and 2019.

Investments in Marketable Securities

Concentrations of Risk

	Revenue			Accounts Receivable, Net
	Year Ended December 31,			December 31,
	2020	2019	2018	2020	2019
Customer A	*%	13.9%	18.4%	19.1%	41.8%
Customer B	*	*	13.5	12.2	*
Customer C	*	*	15.4	*	*
Genentech, Inc. and Roche Group	55.8	42.1	*	*	*
* less than 10%

Accounts Receivable

Inventory

Property and Equipment

Useful lives assigned to property and equipment are as follows:


Laboratory equipment		3 years to 7 years
Leasehold improvements		Shorter of estimated useful life or remaining lease term
Computer equipment and software		3 years
Furniture and office equipment		5 years to 10 years

Goodwill

Intangible Assets

Intangible assets acquired in a business combination are recognized separately from goodwill and are initially recognized at their fair value at the acquisition date, which is regarded as their cost.

Leases

Lease Financing Arrangements

Fair Value of Financial Instruments

•

Level 1: Quoted prices in active markets for identical assets or liabilities.

•

Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities

A financial instrument categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

We did not have any nonfinancial assets or liabilities that were measured or disclosed at fair value on a recurring basis as of December 31, 2020 or 2019.

Convertible Preferred Stock Warrant Liability

Revenue Recognition

Overview

Sequencing Revenue

Development Revenue

Contract Balances

Share-Based Compensation

Advertising

Advertising costs are expensed as incurred. Advertising expenses were $14.5 million, $6.6 million and $3.5 million for the year ended December 31, 2020, 2019 and 2018, respectively.

Cost of Revenue

Research and Development Expenses

Sales and Marketing Expenses

Income Taxes

We recognize the effect of income tax positions only if those positions are more likely than not of being sustained upon examination.

Net Loss Per Share Attributable to Common Shareholders

Segment Information

Recently Adopted Accounting Pronouncements

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Concentrations of Risk Percentage

	Revenue			Accounts Receivable, Net
	Year Ended December 31,			December 31,
	2020	2019	2018	2020	2019
Customer A	*%	13.9%	18.4%	19.1%	41.8%
Customer B	*	*	13.5	12.2	*
Customer C	*	*	15.4	*	*
Genentech, Inc. and Roche Group	55.8	42.1	*	*	*
* less than 10%

Summary of Useful Lives Assigned to Property and Equipment

Useful lives assigned to property and equipment are as follows:


Laboratory equipment		3 years to 7 years
Leasehold improvements		Shorter of estimated useful life or remaining lease term
Computer equipment and software		3 years
Furniture and office equipment		5 years to 10 years

Revenue (Tables)

12 Months Ended

Dec. 31, 2020

Revenue From Contract With Customer [Abstract]

Schedule of Revenue Disaggregated by Type of Products and Services

The following table presents our revenue disaggregated by type of products and services for the periods presented (in thousands):

	Year Ended December 31,
	2020		2019		2018
Sequencing revenue	$	41,439	$	43,519	$	32,978
Development revenue
Development support		54,443		39,552		12,685
Regulatory milestones		2,500		2,000		10,000
Total development revenue		56,943		41,552		22,685
Total revenue	$	98,382	$	85,071	$	55,663

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following tables set forth the fair value of financial assets as of December 31, 2020 and 2019 that were measured at fair value on a recurring basis (in thousands):

	December 31, 2020
	Level 1		Level 2		Level 3		Total
Financial assets
Money market funds	$	103,283	$	—	$	—	$	103,283
U.S. government debt securities		—		671,777		—		671,777
Corporate bonds		—		11,581		—		11,581
Total financial assets	$	103,283	$	683,358	$	—	$	786,641

	December 31, 2019
	Level 1		Level 2		Level 3		Total
Financial assets
Money market funds	$	88,683	$	—	$	—	$	88,683
Commercial paper		—		121,867		—		121,867
U.S. government debt securities		—		377,243		—		377,243
Corporate bonds		—		86,615		—		86,615
Total financial assets	$	88,683	$	585,725	$	—	$	674,408

Investments (Tables)

12 Months Ended

Dec. 31, 2020

Investments Debt And Equity Securities [Abstract]

Schedule of Available-for-sale Investments

Available-for-sale investments consisted of the following as of December 31, 2020 and 2019 (in thousands):

	December 31, 2020
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Short-term marketable securities
U.S. government debt securities	$	552,539	$	723	$	(10	)	$	553,252
Corporate bonds		11,497		86		(2	)		11,581
Total short-term marketable securities	$	564,036	$	809	$	(12	)	$	564,833
Long-term marketable securities
U.S. government debt securities	$	118,429	$	98	$	(2	)	$	118,525
Total long-term marketable securities	$	118,429	$	98	$	(2	)	$	118,525

	December 31, 2019
	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Short-term marketable securities
Commercial paper	$	121,866	$	—	$	—		$	121,866
U.S. government debt securities		285,963		394		(1	)		286,356
Corporate bonds		71,962		109		(3	)		72,068
Total short-term marketable securities	$	479,791	$	503	$	(4	)	$	480,290
Long-term marketable securities
U.S. government debt securities	$	90,750	$	146	$	(9	)	$	90,887
Corporate bonds		14,513		35		—			14,548
Total long-term marketable securities	$	105,263	$	181	$	(9	)	$	105,435

Schedule of Gross Unrealized Holding Losses and Fair Value for Investments in Unrealized Loss Position

	Less Than 12 Months					12 Months Or Greater
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
U.S. government debt securities	$	177,554	$	(12	)	$	—	$	—
Corporate bonds		1,512		(2	)		—		—
Total available-for-sale securities	$	179,066	$	(14	)	$	—	$	—

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment, net as of December 31, 2020 and 2019 consisted of the following (in thousands):

	December 31,
	2020			2019
Laboratory equipment	$	27,767		$	20,773
Computer equipment		3,600			2,450
Furniture and office equipment		2,717			1,568
Computer software		860			505
Construction in progress		7,185			1,852
Leasehold improvements		21,945			14,716
Build-to-suit asset cost		—			36,607
Property and equipment, at cost		64,074			78,471
Less: accumulated depreciation		(24,382	)		(18,116	)
Property and equipment, net	$	39,692		$	60,355

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Summary of Intangible Assets Subject to Amortization

Intangible assets subject to amortization as of December 31, 2020 and 2019 consisted of the following (in thousands):

	December 31, 2020
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired developed technology	$	20,000	$	(9,972	)	$	10,028
Purchased intellectual property		325		(128	)		197
Balance at December 31, 2020	$	20,325	$	(10,100	)	$	10,225

	December 31, 2019
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired developed technology	$	20,000	$	(8,301	)	$	11,699
Purchased intellectual property		325		(96	)		229
Balance at December 31, 2019	$	20,325	$	(8,397	)	$	11,928

Schedule of Future Amortization Expense for Intangible Assets

As of December 31, 2020, expected future amortization expense for intangible assets was as follows (in thousands):

2021	$	1,699
2022		1,699
2023		1,699
2024		1,703
2025		1,699
Thereafter		1,726
Total future amortization expense	$	10,225

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities as of December 31, 2020 and 2019 consisted of the following (in thousands):

	December 31,
	2020		2019
Professional fees	$	3,219	$	1,011
Clinical and contract research organization costs		1,781		30
Travel and entertainment		91		157
Tax liabilities		1,767		2,062
Purchases of property and equipment		4,423		555
Other		1,881		556
Total accrued liabilities	$	13,162	$	4,371

Deferred Revenue (Tables)

12 Months Ended

Dec. 31, 2020

Revenue From Contract With Customer [Abstract]

Schedule of Deferred Revenue by Revenue Classification

Deferred revenue by revenue classification as of December 31, 2020 and 2019 was as follows (in thousands):

	December 31,
	2020		2019
Current deferred revenue
Sequencing	$	15,463	$	12,482
Development		57,856		48,512
Total current deferred revenue		73,319		60,994
Non-current deferred revenue
Sequencing		724		1,459
Development		162,894		217,873
Total non-current deferred revenue		163,618		219,332
Total current and non-current deferred revenue	$	236,937	$	280,326

Schedule of Changes in Deferred Revenue

Changes in deferred revenue during the year ended December 31, 2020 were as follows (in thousands):

Deferred revenue balance at December 31, 2019	$	280,326
Additions to deferred revenue during the period		26,434
Revenue recognized during the period		(69,823	)
Deferred revenue balance at December 31, 2020	$	236,937

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Lessee Disclosure [Abstract]

Summary of Other Information Related to Operating Lease

Other information related to our operating leases as of December 31, 2020 was as follows:

Weighted-average remaining lease term (in years)			11.33
Weighted-average discount rate			4.6	%

Summary of Reconciles Undiscounted Operating Lease Cash Flows

The following table reconciles our undiscounted operating lease cash flows to our operating lease liabilities as of December 31, 2020 (in thousands):

2021	$	7,828
2022		13,554
2023		13,318
2024		13,030
2025		13,419
Thereafter		88,463
Total undiscounted lease payments		149,612
Less:
Imputed interest rate		(35,848	)
Tenant improvement receivables		(5,902	)
Total operating lease liabilities	$	107,862
Less: current portion		(3,529	)
Operating lease liabilities, less current portion	$	104,333

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Summary of Reserved Shares of Common Stock

As of December 31, 2020, we have reserved shares of common stock for the following:

Shares issuable upon the exercise of outstanding common stock options and the vesting of outstanding common restricted stock units granted			14,483,560
Shares available for future grant under the 2019 Equity Incentive Plan			18,617,001
Shares available for future grant under the Employee Stock Purchase Plan			2,804,298
Shares to be issued upon exercise of a common stock warrant			56,875
Total shares of common stock reserved for future issuance			35,961,734

Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Changes in Shares Available for Grant

Changes in shares available for grant during the year ended December 31, 2020 were as follows:

	Shares Available for Grant
Shares available for grant at December 31, 2019		15,396,254
2019 Plan reserve increase on January 1, 2020		6,261,907
Options and restricted stock units granted		(3,291,701	)
Options forfeited, cancelled or expired		250,541
Shares available for grant at December 31, 2020		18,617,001

Summary of Stock Option Activity Under 2008 Plan 2009 Plan and 2019 Plan

Stock option activity under the 2008 Plan, 2009 Plan and 2019 Plan during the year ended December 31, 2020 was as follows:

	Shares Subject to Outstanding Options			Weighted- Average Exercise Price per Share		Aggregate Intrinsic Value (in thousands)
Options outstanding at December 31, 2019		16,646,654		$	6.14	$	398,379
Options granted		3,241,701			33.36
Options forfeited or cancelled		(235,541	)		16.17
Options expired		(15,000	)		0.16
Options exercised		(5,204,254	)		4.14
Options outstanding at December 31, 2020		14,433,560		$	12.82	$	668,458
Options vested and exercisable at December 31, 2020		7,924,779		$	6.41	$	417,801

Summary of Restricted Stock Unit Activity

Restricted stock unit activity under the 2019 Plan during the year ended December 31, 2020 was as follows:

	Restricted Stock Units Outstanding			Weighted- Average Grant Date Fair Value per Share
Nonvested outstanding restricted stock units at December 31, 2019		4,500		$	41.63
Restricted stock units granted		50,000			28.10
Restricted stock units vested		(4,500	)		41.63
Nonvested outstanding restricted stock units at December 31, 2020		50,000		$	28.10

Summary of Estimated Grant Date Fair Value of Options Granted

	Year Ended December 31,
	2020		2019		2018
Fair value of common stock	$17.68 - $55.23		$7.80 - $47.81		$6.55
Expected term (in years)	5.27 - 6.08		5.27 - 6.08		6.08 - 10.00
Risk-free interest rate	0.4% - 1.7%		1.4% - 2.5%		2.6% - 3.0%
Expected volatility	70.5% - 73.3%		64.3% - 72.9%		65.0% - 69.2%
Expected dividend yield		—		—		—

Summary of Compensation Costs Related to Stock Options and RSUs Included on Statements of Operations

The compensation costs related to stock options and restricted stock units for the years ended December 31, 2020, 2019 and 2018 are included on our statements of operations as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Cost of revenue	$	817	$	555	$	398
Research and development		8,519		3,934		2,896
Sales and marketing		6,627		3,480		2,891
General and administration		8,798		5,155		4,964
Total share-based compensation expense	$	24,761	$	13,124	$	11,149

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Components of Deferred Tax Assets and Liabilities

The significant components of our deferred tax assets and liabilities for the periods presented are as follows (in thousands):

	December 31,
	2020			2019
Deferred tax assets
Net operating losses	$	105,433		$	79,035
Tax credit carryforward		18,981			11,152
Non qualifying stock options		12,096			9,150
Deferred rent		—			11,755
Operating lease liabilities		31,052			—
Deferred revenue		59,713			1,706
Other		2,983			1,892
Total deferred tax assets		230,258			114,690
Valuation allowance		(197,527	)		(100,906	)
Deferred tax assets, net of valuation allowance		32,731			13,784
Deferred tax liabilities
Tangible and intangible assets		(5,760	)		(13,784	)
ROU assets		(26,971	)		—
Net deferred taxes	$	—		$	—

Schedule of Reconciliation of Effective Tax Rate of Provision for Income Taxes Differs from Federal Statutory Rate

The effective tax rate of our provision for income taxes differs from the federal statutory rate for the periods presented as follows:

	Year Ended December 31,
	2020	2019	2018
Statutory rate	21.0%	21.0%	21.0%
State tax	13.8	8.1	5.5
Stock compensation	25.2	9.8	0.5
Permanent items	(0.1)	(1.0)	0.5
Credits	5.7	6.1	2.7
Other	0.5	0.3	0.1
Change in valuation allowance	(66.1)	(44.3)	(30.3)
Total	0.0%	0.0%	0.0%

Schedule of Change in Unrecognized Tax Benefits

A reconciliation of the beginning and ending amounts of unrecognized tax benefits during the periods presented are as follows (in thousands):

Balance at December 31, 2017	$	1,031
Additions in 2018		229
Balance at December 31, 2018		1,260
Additions in 2019		792
Balance at December 31, 2019		2,052
Additions in 2020		1,437
Balance at December 31, 2020	$	3,489

Net Loss Per Share Attributable to Common Shareholders (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Computation of the Basic and Diluted Net Loss Per Share Attributable to Common Shareholders

	Year Ended December 31,
	2020			2019			2018
Net loss	$	(146,227	)	$	(68,606	)	$	(46,447	)
Fair value adjustments to redemption value for Series E-1 convertible preferred stock options		—			(964	)		102
Net loss attributable to common shareholders, basic and diluted	$	(146,227	)	$	(69,570	)	$	(46,345	)
Weighted-average shares used in computing net loss per share		131,216,468			69,165,315			12,629,778
Net loss per share attributable to common shareholders, basic and diluted	$	(1.11	)	$	(1.01	)	$	(3.67	)

Weighted-Average Common Stock Equivalents were Excluded From Calculation of Diluted Net Loss Per Share Attributable to Common Shareholders

The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common shareholders for the year ended December 31, 2020, 2019 and 2018, respectively, as they had an anti-dilutive effect:

	Year Ended December 31,
	2020		2019		2018
Convertible preferred stock (on as if converted basis)		—		46,104,469		92,783,867
Stock options issued and outstanding		16,125,548		17,183,546		14,701,626
Nonvested restricted stock units		38,125		4,952		—
Common stock warrants		56,875		55,961		55,032
Convertible preferred stock warrants		—		28,204		56,875
Total		16,220,548		63,377,132		107,597,400

Organization and Description of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 01, 2019	Jul. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Subsidiary Or Equity Method Investee [Line Items]
Net proceeds from issuance of common stock			$ 272,160	$ 320,850
Initial Public Offering
Subsidiary Or Equity Method Investee [Line Items]
Shares issued	17,250,000
Public offering price	$ 20.00
Net proceeds	$ 315,900
Underwriting discounts, commissions and other costs	24,100
Offering expenses	$ 5,000
Over-allotment Option, at Underwritten Public Offering
Subsidiary Or Equity Method Investee [Line Items]
Shares issued		7,200,000
Public offering price		$ 40.00
Net proceeds from issuance of common stock		$ 271,800

Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Performance_Obligation Segment shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2014 USD ($) $ / shares shares
Significant Accounting Policies [Line Items]
Restricted cash	$ 2,138,000	$ 2,138,000
Unbilled receivables	900,000	2,400,000
Impairment of goodwill	0
Impairment losses on intangible assets	$ 0
Warrants issued to purchase stock \| shares	56,875
Fair value adjustment of warrants		2,266,000	$ (6,000)
Advertising expenses	$ 14,500,000	6,600,000	$ 3,500,000
Number of operating segment \| Segment	1
Operating lease right-of-use assets	$ 99,350,000
Operating lease liabilities	107,862,000
Accumulated deficit	$ (511,612,000)	(365,478,000)
ASU 2016-02 (Topic 842)
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption	false
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	false
Operating lease right-of-use assets	$ 33,000,000.0
Operating lease liabilities	39,700,000
Derecognized portion of build-to-suit asset	36,600,000
Derecognition of build-to-suit liabilities	36,600,000
Accumulated deficit	100,000
Derecognition of deferred rent	7,300,000
Reclassification of tenant incentive receivables	$ 500,000
Accounting Standards Update 2016-13
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption	false
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
Accounting Standards Update 2018-15
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption	false
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
Accounting Standards Update 2019-12
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption	true
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
Sequencing Revenue
Significant Accounting Policies [Line Items]
Number of revenue performance obligations \| Performance_Obligation	2
Series C Convertible Preferred Stock
Significant Accounting Policies [Line Items]
Warrants issued to purchase stock \| shares				56,875
Weighted-average exercise price of warrants \| $ / shares				$ 2.64
Line of credit facility				$ 5,000,000.0
Fair value adjustment of warrants		2,300,000
Financial liabilities	$ 2,600,000
Property and Equipment, Net
Significant Accounting Policies [Line Items]
Building costs		$ 36,600,000

Significant Accounting Policies - Schedule of Concentrations of Risk Percentage (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Customer A \| Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage		13.90%	18.40%
Customer A \| Accounts Receivable, Net
Significant Accounting Policies [Line Items]
Concentration risk, percentage	19.10%	41.80%
Customer B \| Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage			13.50%
Customer B \| Accounts Receivable, Net
Significant Accounting Policies [Line Items]
Concentration risk, percentage	12.20%
Customer C \| Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage			15.40%
Genentech, Inc. and Roche Group \| Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage	55.80%	42.10%

Significant Accounting Policies - Summary of Useful Lives Assigned to Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Laboratory Equipment \| Minimum
Property Plant And Equipment [Line Items]
Property and equipment, useful lives	3 years
Laboratory Equipment \| Maximum
Property Plant And Equipment [Line Items]
Property and equipment, useful lives	7 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, useful lives	Shorter of estimated useful life or remaining lease term
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, useful lives	3 years
Furniture and Office Equipment \| Minimum
Property Plant And Equipment [Line Items]
Property and equipment, useful lives	5 years
Furniture and Office Equipment \| Maximum
Property Plant And Equipment [Line Items]
Property and equipment, useful lives	10 years

Revenue - Schedule of Revenue Disaggregated by Type of Products and Services (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 98,382	$ 85,071	$ 55,663
Sequencing Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	41,439	43,519	32,978
Development Support Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	54,443	39,552	12,685
Development Revenue Regulatory Milestones
Disaggregation Of Revenue [Line Items]
Total revenue	2,500	2,000	10,000
Development Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	$ 56,943	$ 41,552	$ 22,685

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Revenue - Additional Information (Details) - USD ($)		1 Months Ended		12 Months Ended
Revenue - Additional Information (Details) - USD ($)	Dec. 31, 2020	Feb. 28, 2019	Dec. 31, 2015	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Revenue recognized	$ 61,600,000			$ (69,823,000)
Revenue from collaboration agreement				98,382,000	$ 85,071,000	$ 55,663,000
Translational Development Agreements
Disaggregation Of Revenue [Line Items]
Term of agreement			4 years
Agreement termination amount receivable			$ 800,000
Eligible payments receivable			2,300,000
Revenue recognized excluding separately negotiated research sequencing contracts					2,300,000	9,300,000
Translational Development Agreements \| Maximum
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments			$ 40,000,000.0
MRD Development Agreements
Disaggregation Of Revenue [Line Items]
Milestone revenue recognized				2,500,000	2,000,000.0	10,000,000.0
Revenue recognized				3,400,000	3,700,000	$ 12,800,000
MRD Development Agreements \| Maximum
Disaggregation Of Revenue [Line Items]
Additional milestone payment receivable	313,500,000			313,500,000
Genentech Collaboration Agreement
Disaggregation Of Revenue [Line Items]
Non-refundable upfront payments received		$ 300,000,000.0		300,000,000.0
Revenue from collaboration agreement				$ 52,800,000	$ 35,100,000
Genentech Collaboration Agreement \| Maximum
Disaggregation Of Revenue [Line Items]
Revenue recognition expected period				8 years
Genentech Collaboration Agreement \| Maximum \| Regulatory Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	75,000,000.0			$ 75,000,000.0
Genentech Collaboration Agreement \| Maximum \| Development Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	300,000,000.0			300,000,000.0
Genentech Collaboration Agreement \| Maximum \| Commercial Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	1,430,000,000.0			1,430,000,000.0
Genentech Collaboration Agreement \| Minimum
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	$ 1,800,000			$ 1,800,000
Revenue recognition expected period				7 years

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets
Total financial assets	$ 786,641	$ 674,408
Level 1
Financial assets
Total financial assets	103,283	88,683
Level 2
Financial assets
Total financial assets	683,358	585,725
Money Market Funds
Financial assets
Total financial assets	103,283	88,683
Money Market Funds \| Level 1
Financial assets
Total financial assets	103,283	88,683
U.S. Government Debt Securities
Financial assets
Total financial assets	671,777	377,243
U.S. Government Debt Securities \| Level 2
Financial assets
Total financial assets	671,777	377,243
Corporate Bonds
Financial assets
Total financial assets	11,581	86,615
Corporate Bonds \| Level 2
Financial assets
Total financial assets	$ 11,581	86,615
Commercial Paper
Financial assets
Total financial assets		121,867
Commercial Paper \| Level 2
Financial assets
Total financial assets		$ 121,867

Investments - Schedule of Available-for-sale Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	$ 564,036	$ 479,791
Unrealized Gain	809	503
Unrealized Loss	(12)	(4)
Estimated Fair Value	564,833	480,290
Long-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	118,429	105,263
Unrealized Gain	98	181
Unrealized Loss	(2)	(9)
Estimated Fair Value	118,525	105,435
Commercial Paper \| Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost		121,866
Estimated Fair Value		121,866
U.S. Government Debt Securities \| Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	552,539	285,963
Unrealized Gain	723	394
Unrealized Loss	(10)	(1)
Estimated Fair Value	553,252	286,356
U.S. Government Debt Securities \| Long-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	118,429	90,750
Unrealized Gain	98	146
Unrealized Loss	(2)	(9)
Estimated Fair Value	118,525	90,887
Corporate Bonds \| Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	11,497	71,962
Unrealized Gain	86	109
Unrealized Loss	(2)	(3)
Estimated Fair Value	$ 11,581	72,068
Corporate Bonds \| Long-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost		14,513
Unrealized Gain		35
Estimated Fair Value		$ 14,548

Investments - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Prepaid Expenses and Other Current Assets
Schedule of Available-for-Sale Securities [Line Items]
Accrued interest receivable	$ 2.5	$ 2.2

Investments - Schedule of Gross Unrealized Holding Losses and Fair Value for Investments in Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Schedule of Available-for-Sale Securities [Line Items]
Less than 12 months, Fair value	$ 179,066
Less than 12 months, Unrealized loss	(14)
U.S. Government Debt Securities
Schedule of Available-for-Sale Securities [Line Items]
Less than 12 months, Fair value	177,554
Less than 12 months, Unrealized loss	(12)
Corporate Bonds
Schedule of Available-for-Sale Securities [Line Items]
Less than 12 months, Fair value	1,512
Less than 12 months, Unrealized loss	$ (2)

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 64,074	$ 78,471
Less: accumulated depreciation	(24,382)	(18,116)
Property and equipment, net	39,692	60,355
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	27,767	20,773
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	3,600	2,450
Furniture and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	2,717	1,568
Computer Software
Property Plant And Equipment [Line Items]
Property and equipment, at cost	860	505
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, at cost	7,185	1,852
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 21,945	14,716
Build-to-suit Asset Cost
Property Plant And Equipment [Line Items]
Property and equipment, at cost		$ 36,607

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation	$ 6,769	$ 6,093	$ 4,301

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 118,972,000	$ 118,972,000	$ 0
Purchased Intellectual Property
Goodwill [Line Items]
Amortization period of intangible assets	6 years

Goodwill and Intangible Assets - Summary of Intangible Assets Subject to Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 20,325	$ 20,325
Accumulated Amortization	(10,100)	(8,397)
Net Carrying Amount	10,225	11,928
Acquired Developed Technology
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	20,000	20,000
Accumulated Amortization	(9,972)	(8,301)
Net Carrying Amount	10,028	11,699
Purchased Intellectual Property
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	325	325
Accumulated Amortization	(128)	(96)
Net Carrying Amount	$ 197	$ 229

Goodwill and Intangible Assets - Schedule of Future Amortization Expense for Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
2021	$ 1,699
2022	1,699
2023	1,699
2024	1,703
2025	1,699
Thereafter	1,726
Net Carrying Amount	$ 10,225	$ 11,928

Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Professional fees	$ 3,219	$ 1,011
Clinical and contract research organization costs	1,781	30
Travel and entertainment	91	157
Tax liabilities	1,767	2,062
Purchases of property and equipment	4,423	555
Other	1,881	556
Total accrued liabilities	$ 13,162	$ 4,371

Accrued Liabilities - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued tax withholding liability related to unsettled option exercises	$ 1.4	$ 1.9

Deferred Revenue - Schedule of Deferred Revenue by Revenue Classification (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current deferred revenue
Total current deferred revenue	$ 73,319	$ 60,994
Non-current deferred revenue
Total non-current deferred revenue	163,618	219,332
Total current and non-current deferred revenue	236,937	280,326
Sequencing Revenue
Current deferred revenue
Total current deferred revenue	15,463	12,482
Non-current deferred revenue
Total non-current deferred revenue	724	1,459
Development Revenue
Current deferred revenue
Total current deferred revenue	57,856	48,512
Non-current deferred revenue
Total non-current deferred revenue	$ 162,894	$ 217,873

Deferred Revenue - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Current deferred revenue	$ 73,319	$ 73,319	$ 60,994
Deferred revenue, less current portion	163,618	163,618	219,332
Revenue recognized	61,600	(69,823)
Development Revenue
Disaggregation Of Revenue [Line Items]
Current deferred revenue	57,856	57,856	48,512
Deferred revenue, less current portion	162,894	162,894	217,873
Development Revenue \| Genentech, Inc.
Disaggregation Of Revenue [Line Items]
Current deferred revenue	55,100	55,100	48,100
Deferred revenue, less current portion	157,000	157,000	216,800
Sequencing Revenue
Disaggregation Of Revenue [Line Items]
Current deferred revenue	15,463	15,463	12,482
Deferred revenue, less current portion	$ 724	724	1,459
Revenue recognized		$ 1,000
Medicare \| Specific Patients
Disaggregation Of Revenue [Line Items]
Revenue recognized			$ 600

Deferred Revenue - Additional Information (Details1) - Genentech, Inc. - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01	Dec. 31, 2020
Disaggregation Of Revenue [Line Items]
Deferred revenue, expected to be recognized	12 months
Minimum
Disaggregation Of Revenue [Line Items]
Deferred revenue, expected to be recognized	6 years
Maximum
Disaggregation Of Revenue [Line Items]
Deferred revenue, expected to be recognized	7 years

Deferred Revenue - Schedule of Changes in Deferred Revenue (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Deferred revenue balance at December 31, 2019		$ 280,326
Additions to deferred revenue during the period		26,434
Revenue recognized during the period	$ 61,600	(69,823)
Deferred revenue balance at December 31, 2020	$ 236,937	$ 236,937

Leases- Additional Information (Details)	1 Months Ended					12 Months Ended
Leases- Additional Information (Details)	Feb. 29, 2020 USD ($) ft²	Dec. 31, 2019 ft²	Oct. 31, 2019 USD ($) ft²	Aug. 31, 2019 USD ($) ft²	Apr. 30, 2018 USD ($) ft²	Dec. 31, 2020 USD ($) Lease	Dec. 31, 2019 USD ($) ft²	Dec. 31, 2018 USD ($)
Lessee Lease Description [Line Items]
Number of square feet \| ft²	19,900	3,100	14,750	100,000	13,400		3,100
Lessee, operating lease, option to extend				Cash payment for rent begins in October 2021 and the lease term ends in August 2033,	The lease term is through March 2026 and provides for one five-year extension option.	options to extend certain of the leases up to 10.0 years
Lessee, operating lease, rent commencement month and year				2021-10
Lessee, Operating Lease, Existence of Option to Extend [true false]				true	true	true
Lessee, operating lease, extended term of contract				5 years	5 years
Lease expiration month and year		2025-11	2029-10	2033-08	2026-03
Letter of credit				$ 2,100,000
Lease commenced moth and year				2020-12
Landlord contribution for leasehold improvements				$ 20,000,000.0		$ 14,800,000
Proceeds from landlord reimbursements						700,000
Tenant improvement costs incurred						5,200,000
Tenant improvement costs receivable						$ 4,500,000
Tenant improvement allowance					$ 2,400,000
Tenant improvement allowance and commenced	$ 600,000
Operating lease renewal term						10 years
Operating lease termination period						3 years
Number of operating lease terminate \| Lease						2
Operating lease expense						$ 5,500,000
Operating lease variable lease expense						2,600,000
Rent expenses							$ 5,300,000	$ 4,100,000
Cash paid for amounts included in measurement of lease liabilities, net of tenant improvement allowances received						3,200,000
Cash received for tenant improvement allowances						2,500,000
ROU assets obtained in exchange for operating lease liabilities						109,100,000
Operating lease right-of-use assets						99,350,000
ASU 2016-02 (Topic 842)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets						$ 33,000,000.0
Maximum
Lessee Lease Description [Line Items]
Tenant improvement allowance			$ 700,000
Operating lease remaining lease term						12 years 8 months 12 days
Minimum
Lessee Lease Description [Line Items]
Operating lease remaining lease term						1 year 3 months 18 days
Seattle, Washington
Lessee Lease Description [Line Items]
Number of square feet \| ft²				65,500
Lessee, operating lease, option to extend				Cash payment for rent of the expanded premises commenced January 2020, four months after the landlord delivered the expanded premises to us for construction of certain tenant improvements, and the lease term for both the existing premises and the expanded premises ends October 2032, subject to our option to twice extend the lease for five years.
Lessee, operating lease, rent commencement month and year				2020-01
Lessee, Operating Lease, Existence of Option to Extend [true false]				true
Lessee, operating lease, extended term of contract				5 years
Lease expiration month and year				2032-10

Leases- Summary of Other Information Related to Operating Lease (Details)	Dec. 31, 2020
Lessee Disclosure [Abstract]
Weighted-average remaining lease term (in years)	11 years 3 months 29 days
Weighted-average discount rate	4.60%

Leases- Summary of Reconciles Undiscounted Operating Lease Cash Flows (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Lessee Disclosure [Abstract]
2021	$ 7,828
2022	13,554
2023	13,318
2024	13,030
2025	13,419
Thereafter	88,463
Total undiscounted lease payments	149,612
Imputed interest rate	(35,848)
Tenant improvement receivables	(5,902)
Total operating lease liabilities	107,862
Less: current portion	(3,529)
Operating lease liabilities, less current portion	$ 104,333

Shareholders' Equity - Additional Information (Details)					12 Months Ended
Shareholders' Equity - Additional Information (Details)	Jan. 01, 2021 shares	Jan. 01, 2020 shares	Jul. 01, 2019 shares	Jun. 30, 2019 shares	Dec. 31, 2020 Vote $ / shares shares	Dec. 31, 2019 $ / shares shares	Dec. 31, 2014 $ / shares shares	Dec. 31, 2018 shares	Dec. 31, 2017 shares
Class Of Stock [Line Items]
Preferred stock, shares authorized					10,000,000	10,000,000
Preferred stock, par value \| $ / shares					$ 0.0001	$ 0.0001
Preferred stock, shares outstanding					0	0
Common stock authorized					340,000,000	340,000,000
Common stock par value \| $ / shares					$ 0.0001	$ 0.0001
Common stock voting rights description					Holders of our common stock are entitled to one vote for each share of common stock held
Number of vote for each share \| Vote					1
Common stock outstanding					137,646,896	125,238,142
Warrants issued to purchase stock					56,875
Common Stock
Class Of Stock [Line Items]
Warrants issued to purchase stock					20,000
Warrant exercisable term					10 years
Weighted-average exercise price of warrants \| $ / shares					$ 0.37
Exercise price of warrants \| $ / shares					$ 0.45
Stock issued during period, common stock			54,792			54,792
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Warrants issued to purchase stock							56,875
Warrant exercisable term							7 years
Weighted-average exercise price of warrants \| $ / shares							$ 2.64
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Increase in share reserve		1,252,381
Maximum \| Common Stock
Class Of Stock [Line Items]
Warrants issued to purchase stock					55,032
Maximum \| Employee Stock Purchase Plan
Class Of Stock [Line Items]
Percentage of annual increases in number of shares		1.00%
2019 Equity Incentive Plan
Class Of Stock [Line Items]
Increase in share reserve		6,261,907
2019 Equity Incentive Plan \| Subsequent Event
Class Of Stock [Line Items]
Increase in share reserve	6,882,344
2019 Equity Incentive Plan \| Maximum
Class Of Stock [Line Items]
Percentage of annual increases in number of shares		5.00%
Convertible Preferred Stock
Class Of Stock [Line Items]
Conversion of convertible preferred stock				93,039,737
Convertible preferred stock outstanding					0			92,790,094	92,656,029

Shareholders' Equity - Summary of Reserved Shares of Common Stock (Details)	Dec. 31, 2020 shares
Class Of Stock [Line Items]
Total shares of common stock reserved for future issuance	35,961,734
Exercise of Outstanding Common Stock Options and Vesting of Outstanding Common Restricted Stock Units Granted
Class Of Stock [Line Items]
Total shares of common stock reserved for future issuance	14,483,560
Grant \| 2019 Equity Incentive Plan
Class Of Stock [Line Items]
Total shares of common stock reserved for future issuance	18,617,001
Grant \| Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total shares of common stock reserved for future issuance	2,804,298
Exercise of Common Stock Warrant
Class Of Stock [Line Items]
Total shares of common stock reserved for future issuance	56,875

Equity Incentive Plans - Additional Information (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) Option $ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average remaining contractual life options outstanding	7 years 1 month 6 days
Weighted-average remaining contractual life vested and exercisable options outstanding	5 years 10 months 24 days
Weighted-average grant date fair value \| $ / shares	$ 21.11	$ 6.87	$ 4.15
Total intrinsic value of options exercised	$ 190,400	$ 39,100	$ 3,800
Proceeds from exercise of stock options	$ 21,748	$ 4,055	$ 1,268
Weighted-average volatility	71.40%	68.10%	68.10%
Share-based compensation expense	$ 24,761	$ 13,124	$ 11,149
Number of employee option modification \| Option			1
Incremental stock compensation			$ 500
Unrecognized share-based compensation expense related to unvested stock options	$ 74,900
Unrecognized share-based compensation expense related to unvested stock options, weighted-average period for recognition	3 years
Option Valuation Model
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense related to unvested stock options, weighted-average period for recognition	3 years 3 months 18 days
Unrecognized share-based compensation expense related to unvested RSUs	$ 1,100
Sequenta 2008 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future issuance \| shares	0
Equity awards outstanding \| shares	0
2009 Equity Incentive Plan \| Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future issuance \| shares	0
2009 Equity Incentive Plan \| Grant \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option expiration period	10 years
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future issuance \| shares	18,617,001	15,396,254
2019 Equity Incentive Plan \| Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance \| shares	22,109,217
2019 Equity Incentive Plan \| Grant \| Non Employee Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	4 years
2019 Equity Incentive Plan \| Grant \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option expiration period	10 years
2019 Equity Incentive Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value \| $ / shares	$ 28.10	$ 41.63
Proceeds from exercise of stock options	$ 500
2019 Equity Incentive Plan \| Restricted Stock Units \| Prepaid Expenses and Other Current Assets
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unsettled cash proceeds related to stock options exercised	$ 300	$ 500

Equity Incentive Plans - Summary of Changes in Shares Available for Grant (Details) - 2019 Equity Incentive Plan	12 Months Ended
	Dec. 31, 2020 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Grant, Outstanding, Beginning Balance	15,396,254
Shares Available for Grant, 2019 Plan reserve increase	6,261,907
Shares Available for Grant, Options and restricted stock units granted	(3,291,701)
Shares Available for Grant, Options and forfeited, cancelled or expired	250,541
Shares Available for Grant, Outstanding, Ending Balance	18,617,001

Equity Incentive Plans - Summary of Stock Option Activity Under 2008 Plan 2009 Plan and 2019 Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Subject to Outstanding Options, Options outstanding, Beginning Balance	16,646,654
Shares Subject to Outstanding Options, Options granted	3,241,701
Shares Subject to Outstanding Options, Options forfeited or cancelled	(235,541)
Shares Subject to Outstanding Options, Options expired	(15,000)
Shares Subject to Outstanding Options, Options exercised	(5,204,254)
Shares Subject to Outstanding Options, Options outstanding, Ending Balance	14,433,560	16,646,654
Shares Subject to Outstanding Options, Options vested and exercisable	7,924,779
Weighted Average Exercise Price per Share, Options outstanding, Beginning Balance	$ 6.14
Weighted Average Exercise Price per Share, Options granted	33.36
Weighted Average Exercise Price per Share, Options forfeited or cancelled	16.17
Weighted Average Exercise Price per Share, Options expired	0.16
Weighted Average Exercise Price per Share, Options exercised	4.14
Weighted Average Exercise Price per Share, Options outstanding, Ending Balance	12.82	$ 6.14
Weighted Average Exercise Price per Share, Options vested and exercisable	$ 6.41
Aggregate Intrinsic Value, Option outstanding	$ 668,458	$ 398,379
Aggregate Intrinsic Value, Options vested and exercisable	$ 417,801

Equity Incentive Plans - Summary of Restricted Stock Unit Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted-Average Grant Date Fair Value per Share
Weighted-average grant date fair value	$ 21.11	$ 6.87	$ 4.15
Restricted Stock Units \| 2019 Equity Incentive Plan
Restricted Stock Units Outstanding
Restricted Stock Units Outstanding, Nonvested Outstanding, Beginning Balance	4,500
Restricted Stock Units Outstanding, Granted	50,000
Restricted Stock Units Outstanding, Vested	(4,500)
Restricted Stock Units Outstanding, Nonvested Outstanding, Ending Balance	50,000	4,500
Weighted-Average Grant Date Fair Value per Share
Weighted-Average Grant Date Fair Value per Share, Nonvested Outstanding, Beginning Balance	$ 41.63
Weighted-average grant date fair value	28.10	$ 41.63
Weighted-Average Grant Date Fair Value per Share, Nonvested Outstanding, Vested	41.63
Weighted-Average Grant Date Fair Value per Share, Nonvested Outstanding, Ending Balance	$ 28.10	$ 41.63

Equity Incentive Plans - Summary of Estimated Grant Date Fair Value of Options Granted (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock			$ 6.55
Risk-free interest rate, minimum	0.40%	1.40%	2.60%
Risk-free interest rate, maximum	1.70%	2.50%	3.00%
Expected volatility, minimum	70.50%	64.30%	65.00%
Expected volatility, maximum	73.30%	72.90%	69.20%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 17.68	$ 7.80
Expected term (in years)	5 years 3 months 7 days	5 years 3 months 7 days	6 years 29 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 55.23	$ 47.81
Expected term (in years)	6 years 29 days	6 years 29 days	10 years

Equity incentive Plans - Summary of Compensation Costs Related to Stock Options and RSUS Included on Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 24,761	$ 13,124	$ 11,149
Cost of Revenue
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	817	555	398
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	8,519	3,934	2,896
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	6,627	3,480	2,891
General and Administration
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 8,798	$ 5,155	$ 4,964

Microsoft Collaboration Agreement - Additional Information (Details) - USD ($)	1 Months Ended
	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
preferred stock investment
Microsoft Collaboration Agreement
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Minimum service consumption requirement amount	$ 12,000,000.0
Minimum service consumption requirement term	7 years
Microsoft Collaboration Agreement \| Series F-1 Convertible Preferred Stock
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
preferred stock investment	$ 45,000,000.0

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating losses	$ 105,433	$ 79,035
Tax credit carryforward	18,981	11,152
Non qualifying stock options	12,096	9,150
Deferred rent		11,755
Operating lease liabilities	31,052
Deferred revenue	59,713	1,706
Other	2,983	1,892
Total deferred tax assets	230,258	114,690
Valuation allowance	(197,527)	(100,906)
Deferred tax assets, net of valuation allowance	32,731	13,784
Deferred tax liabilities
Tangible and intangible assets	(5,760)	(13,784)
ROU assets	(26,971)
Net deferred taxes	$ 0	$ 0

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Increase in valuation allowance	$ 96,600,000	$ 30,200,000
Maturity period for net operating loss carryovers	20 years
U.S. federal net operating losses	$ 211,900,000
Unrecognized tax benefits	3,489,000	2,052,000	$ 1,260,000	$ 1,031,000
Uncertain tax positions	1,437,000	792,000	$ 229,000
Accrued interest or penalties related to uncertain tax positions	0	$ 0
Domestic Tax Authority [Member]
Income Taxes [Line Items]
U.S. federal net operating losses	192,500,000
U.S. federal tax credits	$ 18,800,000
Tax credit carryforwards expiration year	2028
Net operating loss expiration year	2028

Income Taxes - Schedule of Reconciliation of Effective Tax Rate of Provision for Income Taxes Differs from Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	21.00%
State tax	13.80%	8.10%	5.50%
Stock compensation	25.20%	9.80%	0.50%
Permanent items	(0.10%)	(1.00%)	0.50%
Credits	5.70%	6.10%	2.70%
Other	0.50%	0.30%	0.10%
Change in valuation allowance	(66.10%)	(44.30%)	(30.30%)
Total	0.00%	0.00%	0.00%

Income Taxes - Schedule of Change In Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Balance	$ 2,052	$ 1,260	$ 1,031
Additions	1,437	792	229
Balance	$ 3,489	$ 2,052	$ 1,260

Net Loss Per Share Attributable to Common Shareholders - Computation of the Basic and Diluted Net Loss Per Share Attributable to Common Shareholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net loss	$ (146,227)	$ (68,606)	$ (46,447)
Fair value adjustments to redemption value for Series E-1 convertible preferred stock options		(964)	102
Net loss attributable to common shareholders	$ (146,227)	$ (69,570)	$ (46,345)
Weighted-average shares used in computing net loss per share	131,216,468	69,165,315	12,629,778
Net loss per share attributable to common shareholders, basic and diluted	$ (1.11)	$ (1.01)	$ (3.67)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

+ Details

Net Loss Per Share Attributable to Common Shareholders - Weighted-Average Common Stock Equivalents were Excluded From Calculation of Diluted Net Loss Per Share Attributable to Common Shareholders (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	16,220,548	63,377,132	107,597,400
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities		46,104,469	92,783,867
Grant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	16,125,548	17,183,546	14,701,626
Nonvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	38,125	4,952
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	56,875	55,961	55,032
Convertible Preferred Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities		28,204	56,875

Retirement Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Employees maximum annual contribution of their compensation	100.00%
Employer discretionary contribution amount	$ 1,600,000	$ 0	$ 0
Employee service period for vesting	1 year