Adaptive Biotechnologies (ADPT) S-1 21 Jan 20 IPO registration Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2019
Cover [Abstract]
Document Type	S-1
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Entity Registrant Name	ADAPTIVE BIOTECHNOLOGIES CORPORATION
Entity Central Index Key	0001478320
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

Condensed Balance Sheets

Condensed Balance Sheets - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 74,941,000	$ 55,030,000	$ 85,305,000
Short-term marketable securities	498,487,000	109,988,000	106,845,000
Accounts receivable, net	9,257,000	4,807,000	5,582,000
Inventory	8,667,000	7,838,000	4,792,000
Prepaid expenses and other current assets	10,004,000	3,055,000	2,723,000
Total current assets	601,356,000	180,718,000	205,247,000
Long-term assets
Property and equipment, net	46,542,000	19,125,000	13,954,000
Long-term marketable securities	135,306,000		8,905,000
Restricted cash	2,138,000	61,000
Restricted cash and other assets		247,000	86,000
Intangible assets, net	12,356,000	13,626,000	15,325,000
Goodwill	118,972,000	118,972,000	118,972,000
Other assets	722,000	186,000
Total assets	917,392,000	332,688,000	362,489,000
Current liabilities
Accounts payable	2,421,000	1,793,000	1,964,000
Accrued liabilities	3,381,000	2,562,000	1,043,000
Accrued compensation and benefits	5,982,000	4,641,000	3,062,000
Current portion of deferred rent	324,000	1,109,000	886,000
Current deferred revenue	61,269,000	12,695,000	14,048,000
Total current liabilities	73,377,000	22,800,000	21,003,000
Long-term liabilities
Convertible preferred stock warrant liability		336,000	342,000
Deferred rent liability, less current portion	6,258,000	6,102,000	4,394,000
Financing obligation	23,449,000
Deferred revenue, less current portion	228,339,000	704,000
Other long-term liabilities	44,000		33,000
Total liabilities	331,467,000	29,942,000	25,772,000
Commitments and contingencies
Convertible preferred stock		560,858,000	561,333,000
Shareholders' equity (deficit)
Preferred stock
Common stock	12,000	1,000	1,000
Additional paid-in capital	930,208,000	37,902,000	24,972,000
Accumulated other comprehensive gain (loss)	572,000	(107,000)	(166,000)
Accumulated deficit	(344,867,000)	(295,908,000)	(249,423,000)
Total shareholders' equity (deficit)	585,925,000	(258,112,000)	(224,616,000)
Total liabilities, convertible preferred stock and shareholders' equity (deficit)	$ 917,392,000	$ 332,688,000	$ 362,489,000

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Convertible preferred stock par value	$ 0.0001	$ 0.0001	$ 0.0001
Convertible preferred stock authorized	0	93,762,517	93,762,517
Convertible preferred stock issued	0	92,790,094	92,656,029
Convertible preferred stock outstanding	0	92,790,094	92,656,029
Convertible preferred stock aggregate liquidation preference	$ 0	$ 572,866	$ 572,057
Preferred stock par value	$ 0.0001	$ 0.0001
Preferred stock authorized	10,000,000	0
Preferred stock issued	0	0
Preferred stock outstanding	0	0
Common stock par value	$ 0.0001	$ 0.0001	$ 0.0001
Common stock authorized	340,000,000	131,000,000	131,000,000
Common stock issued	124,316,080	12,841,536	12,208,731
Common stock outstanding	124,316,080	12,841,536	12,208,731

Condensed Statements of Operati

Condensed Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Revenue
Total revenue	$ 26,058	$ 17,188	$ 60,862	$ 38,471	$ 55,663	$ 38,448
Operating expenses
Cost of revenue	5,601	5,360	16,323	14,393	19,668	15,680
Research and development	20,506	9,783	49,516	28,090	39,157	31,995
Sales and marketing	9,099	6,039	25,813	16,415	24,486	16,765
General and administrative	8,477	4,739	22,143	13,914	20,409	15,949
Amortization of intangible assets	428	428	1,270	1,271	1,699	1,694
Restructuring						840
Total operating expenses	44,111	26,349	115,065	74,083	105,419	82,923
Loss from operations	(18,053)	(9,161)	(54,203)	(35,612)	(49,756)	(44,475)
Interest and other income, net	4,103	869	6,208	2,436	3,309	1,644
Net loss	(13,950)	(8,292)	(47,995)	(33,176)	(46,447)	(42,831)
Fair value adjustment to Series E-1 convertible preferred stock options		(4)	(964)	(2)	102	135
Net loss attributable to common shareholders	$ (13,950)	$ (8,296)	$ (48,959)	$ (33,178)	$ (46,345)	$ (42,696)
Net loss per share attributable to common shareholders, basic and diluted	$ (0.11)	$ (0.66)	$ (0.97)	$ (2.67)	$ (3.67)	$ (3.50)
Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted	124,285,686	12,620,010	50,552,389	12,430,535	12,629,778	12,196,998
Sequencing Revenue
Revenue
Total revenue	$ 11,683	$ 8,463	$ 29,631	$ 22,524	$ 32,978	$ 22,759
Development Revenue
Revenue
Total revenue	$ 14,375	$ 8,725	$ 31,231	$ 15,947	$ 22,685	$ 15,689
Pro Forma
Operating expenses
Net loss per share attributable to common shareholders, basic and diluted					$ (0.44)
Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted					105,433,645

Condensed Statements of Compreh

Condensed Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (13,950)	$ (8,292)	$ (47,995)	$ (33,176)	$ (46,447)	$ (42,831)
Change in unrealized gain (loss) on investments	190	39	679	(35)	59	(84)
Comprehensive loss	$ (13,760)	$ (8,253)	$ (47,316)	$ (33,211)	$ (46,388)	$ (42,915)

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock and Shareholders (Deficit) Equity - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid In Capital	Accumulated Other Comprehensive (Loss) Gain	Accumulated Deficit
Beginning Balance at Dec. 31, 2016	$ (189,734)		$ 1	$ 17,559	$ (82)	$ (207,212)
Beginning Balance, Shares at Dec. 31, 2016			12,154,046
Convertible preferred stock, Beginning Balance at Dec. 31, 2016		$ 511,823
Convertible preferred stock, Beginning Balance, Shares at Dec. 31, 2016		87,797,854
Adjustments to accumulated deficit for adoption of guidance in new accounting principle	485					485
Issuance of Series F-1 convertible preferred stock for cash, net of issuance costs		$ 49,827
Issuance of Series F-1 convertible preferred stock for cash, net of issuance costs, Shares		4,686,649
Vested Series E-1 convertible preferred stock option forfeitures	644			398		246
Vested Series E-1 convertible preferred stock option forfeitures		$ (644)
Issuance of common stock for cash upon exercise of stock options	95			95
Series E-1 convertible preferred stock option share-based compensation	89			89
Issuance of common stock for cash upon exercise of stock options, Shares			54,685
Adjustment to redemption value for vested Series E-1 convertible preferred stock options	89			89
Adjustment to redemption value for vested Series E-1 convertible preferred stock options		89
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value		$ 127
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value, Shares		171,526
Change in redemption value for vested Series E-1 convertible preferred stock options	(111)					(111)
Change in redemption value for vested Series E-1 convertible preferred stock options		$ 111
Common stock option share-based compensation	6,920			6,920
Other comprehensive income	(84)				(84)
Net loss	(42,831)					(42,831)
Ending Balance at Dec. 31, 2017	(224,616)		$ 1	24,972	(166)	(249,423)
Ending Balance, Shares at Dec. 31, 2017			12,208,731
Convertible preferred stock, Ending Balance at Dec. 31, 2017	$ 561,333	$ 561,333
Convertible preferred stock, Ending Balance, Shares at Dec. 31, 2017	92,656,029	92,656,029
Adjustments to accumulated deficit for adoption of guidance in new accounting principle				140		(140)
Vested Series E-1 convertible preferred stock option forfeitures	$ 767			476		291
Vested Series E-1 convertible preferred stock option forfeitures		$ 767
Issuance of common stock for cash upon exercise of stock options	885			885
Series E-1 convertible preferred stock option share-based compensation	3			3
Issuance of common stock for cash upon exercise of stock options, Shares			512,696
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
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
Change in redemption value for vested Series E-1 convertible preferred stock options	(2)					(2)
Change in redemption value for vested Series E-1 convertible preferred stock options		$ 2
Common stock option share-based compensation	8,100			8,100
Other comprehensive income	(35)				(35)
Net loss	(33,176)					(33,176)
Ending Balance at Sep. 30, 2018	(248,077)		$ 1	34,573	(201)	(282,450)
Ending Balance, Shares at Sep. 30, 2018			12,721,427
Convertible preferred stock, Ending Balance at Sep. 30, 2018		$ 560,671
Convertible preferred stock, Ending Balance, Shares at Sep. 30, 2018		92,790,094
Beginning Balance at Dec. 31, 2017	(224,616)		$ 1	24,972	(166)	(249,423)
Beginning Balance, Shares at Dec. 31, 2017			12,208,731
Convertible preferred stock, Beginning Balance at Dec. 31, 2017	$ 561,333	$ 561,333
Convertible preferred stock, Beginning Balance, Shares at Dec. 31, 2017	92,656,029	92,656,029
Adjustments to accumulated deficit for adoption of guidance in new accounting principle				140		(140)
Vested Series E-1 convertible preferred stock option forfeitures	$ 767			476		291
Vested Series E-1 convertible preferred stock option forfeitures		$ (767)
Issuance of common stock for cash upon exercise of stock options	1,168			1,168
Series E-1 convertible preferred stock option share-based compensation	3			3
Issuance of common stock for cash upon exercise of stock options, Shares			632,805
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)
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
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	59				59
Net loss	(46,447)					(46,447)
Ending Balance at Dec. 31, 2018	(258,112)	560,858	$ 1	37,902	(107)	(295,908)
Ending Balance, Shares at Dec. 31, 2018			12,841,536
Convertible preferred stock, Ending Balance at Dec. 31, 2018	$ 560,858	$ 560,858
Convertible preferred stock, Ending Balance, Shares at Dec. 31, 2018	92,790,094	92,790,094
Beginning Balance at Jun. 30, 2018	$ (242,435)		$ 1	31,958	(240)	(274,154)
Beginning Balance, Shares at Jun. 30, 2018			12,546,844
Convertible preferred stock, Beginning Balance at Jun. 30, 2018		$ 560,667
Convertible preferred stock, Beginning Balance, Shares at Jun. 30, 2018		92,790,094
Issuance of common stock for cash upon exercise of stock options	62			62
Issuance of common stock for cash upon exercise of stock options, Shares			174,583
Change in redemption value for vested Series E-1 convertible preferred stock options	(4)					(4)
Change in redemption value for vested Series E-1 convertible preferred stock options		$ 4
Common stock option share-based compensation	2,553			2,553
Other comprehensive income	39				39
Net loss	(8,292)					(8,292)
Ending Balance at Sep. 30, 2018	(248,077)		$ 1	34,573	(201)	(282,450)
Ending Balance, Shares at Sep. 30, 2018			12,721,427
Convertible preferred stock, Ending Balance at Sep. 30, 2018		$ 560,671
Convertible preferred stock, Ending Balance, Shares at Sep. 30, 2018		92,790,094
Beginning Balance at Dec. 31, 2018	(258,112)	$ 560,858	$ 1	37,902	(107)	(295,908)
Beginning Balance, Shares at Dec. 31, 2018			12,841,536
Convertible preferred stock, Beginning Balance at Dec. 31, 2018	$ 560,858	$ 560,858
Convertible preferred stock, Beginning Balance, Shares at Dec. 31, 2018	92,790,094	92,790,094
Proceeds from initial public offering, net of underwriters' discounts and commissions	$ 320,850		$ 2	320,848
Proceeds from initial public offering, net of underwriters' discounts and commissions, 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	$ 2,198			2,198
Issuance of common stock for cash upon exercise of stock options, Shares	1,379,658		1,130,015
Issuance of Series E-1 convertible preferred stock for cash upon exercise of Series E-1 convertible preferred stock options at fair value		$ 109
Common stock option and restricted stock unit share-based compensation	$ 9,713			9,713
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	679				679
Net loss	(47,995)					(47,995)
Ending Balance at Sep. 30, 2019	$ 585,925		$ 12	930,208	572	(344,867)
Ending Balance, Shares at Sep. 30, 2019			124,316,080
Convertible preferred stock, Ending Balance at Sep. 30, 2019		$ 0
Convertible preferred stock, Ending Balance, Shares at Sep. 30, 2019	0	93,039,737
Beginning Balance at Jun. 30, 2019	$ (284,374)		$ 1	46,160	382	(330,917)
Beginning Balance, Shares at Jun. 30, 2019			13,725,381
Convertible preferred stock, Beginning Balance at Jun. 30, 2019		$ 561,931
Convertible preferred stock, Beginning Balance, Shares at Jun. 30, 2019		93,039,737
Proceeds from initial public offering, net of underwriters' discounts and commissions	320,850		$ 2	320,848
Proceeds from initial public offering, net of underwriters' discounts and commissions, 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	318			318
Issuance of common stock for cash upon exercise of stock options, Shares			246,170
Common stock option and restricted stock unit share-based compensation	3,335			3,335
Other comprehensive income	190				190
Net loss	(13,950)					(13,950)
Ending Balance at Sep. 30, 2019	$ 585,925		$ 12	$ 930,208	$ 572	$ (344,867)
Ending Balance, Shares at Sep. 30, 2019			124,316,080
Convertible preferred stock, Ending Balance at Sep. 30, 2019		$ 0
Convertible preferred stock, Ending Balance, Shares at Sep. 30, 2019	0	93,039,737

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (47,995)	$ (33,176)	$ (46,447)	$ (42,831)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation expense	4,446	3,136	4,301	4,102
Share-based compensation expense	9,713	8,103	11,149	7,009
Intangible assets amortization	1,270	1,271	1,699	1,694
Investment amortization	(3,533)	(824)	(1,214)	342
Asset impairment			17	193
Gain on equipment disposals	(72)	(45)	(40)	125
Fair value adjustment of convertible preferred stock warrant	2,266		(6)	(23)
Other	(8)	4	5	6
Changes in operating assets and liabilities:
Accounts receivable, net	(4,398)	(6,787)	775	(2,427)
Inventory	(829)	(2,313)	(3,046)	(2,697)
Prepaid expenses and other current assets	(6,840)	(916)	(318)	(327)
Accounts payable and accrued liabilities	3,131	1,729	2,185	(1,517)
Deferred rent	(628)	(427)	(488)	(1,058)
Deferred revenue	276,209	3,602	(649)	2,527
Other	(537)	(206)	(182)	24
Net cash provided by (used in) operating activities	232,195	(26,849)	(32,259)	(34,858)
Investing activities
Purchases of property and equipment	(8,784)	(3,804)	(6,318)	(2,421)
Proceeds from sales of equipment		19	19	207
Purchases of intangible assets				(85)
Purchases of marketable securities	(772,093)	(137,124)	(146,503)	(125,182)
Proceeds from maturities of marketable securities	252,500	114,016	153,538	163,913
Net cash provided by (used in) investing activities	(528,377)	(26,893)	736	36,432
Financing activities
Proceeds from issuance of convertible preferred stock, net of issuance costs				49,827
Proceeds from exercise of stock options	2,307	985	1,268	222
Proceeds from initial public offering, net of underwriting discounts and commissions	320,850
Payment of deferred initial public offering costs	(4,986)
Proceeds from issuance of common stock upon the exercise of a common stock warrant	9
Other	(10)	(15)	(20)	(15)
Net cash provided by financing activities	318,170	970	1,248	50,034
Net increase (decrease) in cash, cash equivalents and restricted cash	21,988	(52,772)	(30,275)	51,608
Cash, cash equivalents and restricted cash at beginning of year	55,091	85,366	85,366	33,758
Cash, cash equivalents and restricted cash at end of period	77,079	32,594	55,091	85,366
Non-cash investing and financing activities
Purchases of equipment included in accounts payable and accrued liabilities	498	$ 197	832	$ 41
Conversion of convertible preferred stock to common stock upon closing of initial public offering	561,931
Landlord-funded leasehold improvements			$ 2,419
Conversion of convertible preferred stock warrant to common stock warrant upon closing of initial public offering	$ 2,602

Organization and Description of

Organization and Description of Business	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
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-driven 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 is the foundation for our expanding suite of products and services. The cornerstone of our immune medicine platform and core immunosequencing product, immunoSEQ, serves as our underlying research and development engine and generates revenue from academic and biopharmaceutical customers. Our first clinical diagnostic product, clonoSEQ, is the first test authorized by the Food and Drug Administration (“FDA”) for the detection and monitoring of minimal residual disease (“MRD”) in patients with select blood cancers. 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 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. On July 1, 2019, in connection with the closing of our initial public offering, our amended and restated articles of incorporation, as filed with the Secretary of State of the State of Washington, and our amended and restated bylaws became effective. Also on July 1, 2019, an initial reserve of 15,519,170 shares under our new 2019 Equity Incentive Plan (“2019 Plan”) became effective.	1. Organization and Description of Business Adaptive Biotechnologies Corporation (“we,” “us” or “our”) is advancing the field of immune-driven 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 is the foundation for our expanding suite of products and services. The cornerstone of our immune medicine platform and core immunosequencing product, immunoSEQ, serves as our underlying research and development engine and generates revenue from academic and biopharmaceutical customers. Our first clinical diagnostic product, clonoSEQ, is the first test authorized by the FDA for the detection and monitoring of minimal residual disease (“MRD”) in patients with select blood cancers. 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.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
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 accounting principles generally accepted in the United States of America (“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. Unaudited Interim Condensed Financial Statements In our opinion, the accompanying unaudited condensed financial statements have been prepared in accordance with GAAP for interim financial information. These unaudited condensed financial statements include all adjustments necessary to fairly state the financial position and the results of our operations and cash flows for interim periods in accordance with GAAP. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The accompanying unaudited condensed financial statements should be read in conjunction with our audited financial statements and notes included in our prospectus dated June 26, 2019 filed with the Securities and Exchange Commission (“SEC”) on June 27, 2019 in connection with our initial public offering (“Prospectus”). Reclassifications In the accompanying audited condensed balance sheet, certain prior year amounts have been reclassified to conform to the current period presentation. Specifically, “restricted cash” and “other assets” were previously included together in the restricted cash and other assets line item and are now separately stated. There was no change to total assets as a result of the reclassification. Restricted Cash We are required to maintain certain balances under lease arrangements for our property and facilities leases. We had restricted cash of $0.1 million and $2.1 million as of December 31, 2018 and September 30, 2019, respectively. 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 which represent more than 10% of our total revenue or accounts receivable, net balances at each respective balance sheet date. 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 periods presented were as follows: Revenue Accounts Receivable, Net Three Months Ended September 30, Nine Months Ended September 30, December 31, 2018 September 30, 2019 2018 2019 2018 2019 (unaudited) (unaudited) Customer A 15.7 % 16.0 % 21.6 % 11.8 % * % 39.6 % Customer B * 10.7 * * 15.1 * Customer C 35.0 * 19.1 * 13.2 * Genentech, Inc. * 43.9 * 43.7 * * * less than 10% Leases Operating Lease Arrangements We have operating lease agreements for the laboratory and office facilities that we occupy. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facility leases, including rent holidays, are capitalized and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. Lease Financing Arrangements Due to our significant involvement during the construction process of a leased building, we qualify as the deemed owner of the building under build-to-suit Revenue Recognition We recognize revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606 (“ASC 606”), Revenue from Contracts with Customers 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 allocate 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 immunoSEQ and clonoSEQ products and services to our research and clinical customers, respectively. 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. For other research customers who choose to purchase a research use only kit, the kits are sold on a price per kit basis with amounts payable upon delivery of the kit. Payments received are recorded as deferred revenue. For these customers, we have identified one performance obligation: the delivery of sample results. We recognize revenue as the results are delivered to the customer based on a proportion of the estimated samples that can be reported on for each kit. For clinical customers, we derive revenues from providing our clonoSEQ test report to ordering physicians, and we bill and receive payments from commercial third-party payors and medical institutions. 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. In January 2019, clonoSEQ received Medicare coverage aligned with the FDA label and National Comprehensive Cancer Network (“NCCN”) guidelines for longitudinal monitoring in multiple myeloma (“MM”) and B cell acute lymphoblastic leukemia (“ALL”). We bill Medicare for 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 is recognized 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. For the three and nine months ended September 30, 2019, we recognized $0.3 million and $1.1 million relating to the coverage policy, respectively; $0.1 million and $0.4 million of this revenue was related to tests delivered in periods prior to the three and nine months ended September 30, 2019, respectively. 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. 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 our proprietary immunoSEQ and clonoSEQ services in the development of the respective customers’ initiatives. The transaction price for these contracts may consist of a combination of non-refundable 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 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. Deferred Offering Costs Deferred offering costs consist of fees and expenses incurred in connection with the sale of our common stock in the initial public offering, including legal, accounting, printing and other initial public offering-related paid-in offering-related paid-in Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation—Stock Compensation (Topic 718) paid-in In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) right-of-use build-to-suit Leases In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments available-for-sale In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other: Internal-Use 350-40)	2. Significant Accounting Policies Basis of Presentation and Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“U.S. 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 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. 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, investments in money market funds and commercial paper. Restricted Cash We are required to maintain certain balances under operating lease arrangements for our facilities. We have a certificate of deposit with a financial institution issued in favor of the lessor for $0.1 million as of December 31, 2017 and 2018. This amount is recorded as restricted cash and other assets in the accompanying balance sheets due to the long-term nature of the underlying facility lease. Investments in Marketable Securities Marketable securities are classified as available-for-sale 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 bonds, commercial paper and corporate bonds with high-quality accredited financial institutions. Significant customers are those which represent more than 10% of our total revenue or accounts receivable balance at each respective balance sheet date. Revenue from these customers reflects their purchase of our products and services and we do not believe their loss would have a material adverse effect on our business. For each significant customer, revenue as a percentage of revenue and accounts receivable as a percentage of accounts receivable were as follows: Revenue Accounts Receivable Year Ended December 31, December 31, 2017 2018 2017 2018 Customer A 31.4 % 18.4 % 29.9 % * % Customer B * 13.5 14.9 15.1 Customer C * 15.4 * 13.2 * less than 10% Accounts Receivable Accounts receivable consist of amounts due from customers for services performed. We review our accounts receivable regularly by analyzing the status of significant past due receivables to determine if any receivable will potentially be uncollectible and to estimate the amount of allowance for doubtful accounts necessary to reduce accounts receivable to its estimated net realizable value. Our allowance for doubtful accounts was $0.1 million as of December 31, 2017 and 2018. Additionally, we had $1.4 million and $0.4 million of unbilled receivables as of December 31, 2017 and 2018, 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 Property and Equipment Property and equipment consist of computer equipment, computer software, laboratory equipment, leasehold improvements and furniture and fixtures. Property and equipment are recorded at cost and depreciation is recognized using the straight-line method based on an 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 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 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 the statements of operations in accordance with the use of the asset, except those gains and losses recognized in conjunction with restructuring activities, which are classified within restructuring expense. We recognized $0.3 million of impairment expense in research and development for obsolete equipment in 2017 and $0.2 million of losses from asset disposals, impairment and accelerated depreciation in restructuring. See Note 14, Restructuring Charges 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 the estimated useful life of the asset on a straight-line basis which approximates the 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. Restructuring We recognize a liability for costs associated with an exit or disposal activity under a restructuring project when the plan has been finalized. Employee termination benefits considered as post-employment benefits are accrued when the obligation is probable and estimable, such as benefits stipulated by human resource policies and practices or statutory requirements. One-time Asset impairments associated with a restructuring project are determined at the asset group level. An impairment may be recognized for assets that are to be abandoned or are to be sold for less than net book value. We may also recognize impairment on an asset group, which is held and used, when the carrying value is not recoverable and exceeds the asset group’s fair value. If the sale of an asset group under a restructuring project results in proceeds that exceed the net book value of the asset group, the resulting gain is recognized within restructuring expense in the statements of operations. Leases We have lease agreements for our laboratory and office facilities. These leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facility leases, including rent holidays, are capitalized and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. 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: • Level 2: • Level 3: 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 Level 3 liabilities. 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, 2017 or 2018. Convertible Preferred Stock Warrant Liability We have 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. The fair value of this warrant is classified as a non-current Revenue Recognition We recognize revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606 (“ASC 606”) , Revenue from Contracts with Customers. 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 allocate 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 through immunoSEQ to research customers and from providing testing services through clonoSEQ to clinical and research customers. 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. For other research customers who choose to purchase a research use only kit, the kits are sold on a price per kit basis with amounts payable upon delivery of the kit. Payments received are recorded as deferred revenue. For these customers we have identified one performance obligation: the delivery of sample results. We recognize revenue as the results are delivered to the customer based on a proportion of the estimated samples that can be reported on for each kit. For clinical customers, we derive revenues from providing our clonoSEQ test report to ordering physicians, and we bill and receive payments from commercial third-party payors and medical institutions. 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 reimbursement rates with the various payors, which are monitored in subsequent periods and adjusted as necessary based on actual collection experience. 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 our proprietary immunoSEQ and clonoSEQ services in the development of the respective customers’ initiatives. The transaction price for these contracts may consist of a combination of non-refundable 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 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 Share-Based Compensation Share-based compensation includes compensation expense for stock option grants to employees and non-employees. non-employees 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, allocated facility costs, information technology and contract service expenses. 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. 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 interest and penalties related to income tax matters as a component of tax expense. We did not record any interest or penalties related to income tax during the years ended December 31, 2017 and 2018. Net Loss Per Share Attributable to Common Shareholders We calculate our basic and diluted net loss per share attributable to common shareholders in conformity with the two-class as-if two-class two-class Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders We have presented the unaudited pro forma basic and diluted net loss per share attributable to common shareholders for the year ended December 31, 2018, which shows the assumed effect of an initial public offering, including (i) the conversion of all convertible preferred stock into shares of common stock as if the conversion had occurred as of the later of the beginning of the period or the original date of issuance; and (ii) the issuance of 20,000 shares of common stock upon the assumed exercise of a common stock warrant prior to the completion of an initial public offering. The pro forma net loss per share attributable to common shareholders does not include proceeds to be received from nor does it include shares expected to be sold in the assumed initial public offering. 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 Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers Subtopic 340-40, Other Assets and Deferred Costs—Contracts with Customers Revenue Recognition In February 2016, the FASB issued ASU No. 2016-02, Leases right-of-use In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation paid-in In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other: Internal-Use 350-40),

Revenue

Revenue	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	3. Revenue Translational Development Agreements On December 18, 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 be entitled to up to $40.0 million over a period of four years, which does not include any separately negotiated research sequencing contracts. If the biopharmaceutical customer terminates 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 has 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 is a consistent level of support throughout the period, and therefore, revenue has been recognized straight-line over the contract term. Revenue recognized from this translational development agreement, excluding separately negotiated research sequencing contracts, was $2.5 million and $0.6 million in the three months ended September 30, 2018 and 2019, respectively, and $7.5 million and $1.7 million in the nine months ended September 30, 2018 and 2019, respectively. MRD Development Agreements We have entered into agreements with biopharmaceutical customers to further develop and commercialize clonoSEQ and the biopharmaceutical customers’ therapeutics. Under each of the agreements, we received or will receive non-refundable Under the contracts, we identify performance obligations, which may include: (i) obligations to provide services supporting the customer’s regulatory submission activities as they relate to our clonoSEQ test; and (ii) sequencing services for 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 constrained 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 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. In the three and nine months ended September 30, 2018 and in the three and nine months ended September 30, 2019, we earned $6.0 million and $2.0 million, respectively, in regulatory milestones upon the achievement of regulatory milestones by us and our respective customers’ therapeutics. All $6.0 million and $2.0 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 $6.1 million and $2.3 million in development revenue related to these contracts in the three months ended September 30, 2018 and 2019, respectively, and $8.0 million and $3.1 million in the nine months ended September 30, 2018 and 2019, respectively. As of September 30, 2019, in future periods we could receive up to an additional $129.0 million in milestone payments if certain regulatory approvals are obtained by our customers’ therapeutics in connection with MRD data generated from our clonoSEQ test. Genentech Collaboration Agreement In December 2018, we entered into a worldwide collaboration and license agreement (“Genentech Agreement”) with Genentech, Inc. (“Genentech”) to leverage our capability to develop cellular therapies in oncology. Subsequent to receipt of regulatory approval in January 2019, we received a non-refundable mid-single mid-teens • Shared Products. The shared products will use “off-the-shelf” • 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 In applying ASC 606, we identified the following performance obligations at the inception of the agreement: 1. License to utilize on an exclusive basis all TCR-specific 2. License to utilize all data and information within each shared antigen data package and any other know-how 3. License to utilize all private antigen TCR product data in connection with research and development activities in the field of use. 4. License to existing shared antigen data packages. 5. Research and development services for shared product development including expansion of shared antigen data packages. 6. Research and development services for private product development. 7. 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 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 as a result of 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 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. 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 $11.4 million and $26.2 million for the three and nine months ended September 30, 2019, respectively, related to the Genentech collaboration. Costs related to the Genentech collaboration are included in research and development expenses.	3. 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 (in thousands): December 31, 2017 2018 Sequencing revenue $ 22,759 $ 32,978 Development revenue: Development support 15,689 12,685 Regulatory milestones — 10,000 Total development revenue 15,689 22,685 Total revenue $ 38,448 $ 55,663 Translational Development Agreements On December 18, 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 customers preclinical, nonclinical and clinical trial testing. Under the terms of the agreement we could be entitled to up to $40.0 million over a period of four years which does not include any separately negotiated research sequencing contracts. If the biopharmaceutical customer terminates 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 has agreed to pay us $0.8 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 is a consistent level of support throughout the period, therefore revenue has been recognized straight line over the contract term. Revenue recognized from this translational development agreement, excluding separately negotiated research sequencing contracts, was $10.0 million and $9.3 million for the years ended December 31, 2017 and 2018, respectively. In 2017, we entered into an agreement with a customer to provide services to accelerate their research initiatives. We identified one performance obligation under the 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. Revenue recognized from this agreement, excluding sequencing revenue, was $0.6 million for each of the years ended December 31, 2017 and 2018. MRD Development Agreements In 2017 and 2018, we entered into agreements with biopharmaceutical customers to further develop and commercialize clonoSEQ and the biopharmaceutical customers’ therapeutics. Under each of the agreements, we received or will receive non-refundable Under the contracts, we identify performance obligations, which may include: (i) obligations to provide services supporting the customer’s regulatory submission activities as they relate to our clonoSEQ test; and (ii) sequencing services for 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 constrained 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 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. In 2018, we earned $10.0 million in regulatory milestones upon the achievement of the regulatory milestones by us and our respective customers’ therapeutics. All $10.0 million was recognized as revenue as we determined these amounts were consistent with our estimated standalone selling price and the respective performance obligations were complete. We recognized $5.1 million and $12.8 million in development revenue related to these contracts in 2017 and 2018, respectively. As of December 31, 2018, in future periods we could receive up to an additional $99.5 million in milestone payments if certain regulatory approvals are obtained by our customers’ therapeutics in connection with MRD data generated from our clonoSEQ test. Genentech Collaboration Agreement In December 2018, we entered into a collaboration with Genentech to leverage our capability to develop cellular therapies in oncology. Subsequent to receipt of regulatory approval in January 2019, we received an 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 $1.4 billion upon the achievement of specified commercial milestones. In addition, we are eligible to receive tiered royalties at a rate ranging from the mid-single mid-teens

Fair Value Measurements

Fair Value Measurements	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following tables set forth the fair value of financial assets and liabilities as of December 31, 2018 and September 30, 2019 that were measured at fair value on a recurring basis (in thousands): December 31, 2018 Level 1 Level 2 Level 3 Total Financial assets Money market funds $ 45,998 $ — $ — $ 45,998 Commercial paper — 16,887 — 16,887 U.S. government debt and agency securities — 85,623 — 85,623 Corporate bonds — 7,478 — 7,478 Total financial assets $ 45,998 $ 109,988 $ — $ 155,986 Financial liabilities Convertible preferred stock warrant liability $ — $ — $ 336 $ 336 Total financial liabilities $ — $ — $ 336 $ 336 September 30, 2019 Level 1 Level 2 Level 3 Total (unaudited) Financial assets Money market funds $ 86,374 $ — $ — $ 86,374 Commercial paper — 136,842 — 136,842 U.S. government debt and agency securities — 419,011 — 419,011 Corporate bonds — 77,940 — 77,940 Total financial assets $ 86,374 $ 633,793 $ — $ 720,167 Level 1 securities include highly liquid money market funds, 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, U.S. government agency 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. Level 3 liabilities that were measured at fair value on a recurring basis consisted of a convertible preferred stock warrant liability. During the nine months ended September 30, 2019 and prior to the completion of our initial public offering on July 1, 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 unaudited condensed statements of operations. Immediately prior to the completion of our initial public offering, the convertible preferred stock warrant liability converted to a common stock warrant and the financial liability was reclassified to the additional paid-in	4. Fair Value Measurements The following table sets forth the fair value of financial assets and liabilities that were measured at fair value on a recurring basis (in thousands): December 31, 2017 Level 1 Level 2 Level 3 Total Financial assets Money market funds $ 68,034 $ — $ — $ 68,034 Commercial paper — 22,360 — 22,360 U.S. government and agency securities — 83,717 — 83,717 Corporate bonds — 21,264 — 21,264 Total financial assets $ 68,034 $ 127,341 $ — $ 195,375 Financial liabilities Convertible preferred stock warrant liability $ — $ — $ 342 $ 342 Total financial liabilities $ — $ — $ 342 $ 342 December 31, 2018 Level 1 Level 2 Level 3 Total Financial assets Money market funds $ 45,998 $ — $ — $ 45,998 Commercial paper — 16,887 — 16,887 U.S. government and agency securities — 85,623 — 85,623 Corporate bonds — 7,478 — 7,478 Total financial assets $ 45,998 $ 109,988 $ — $ 155,986 Financial liabilities Convertible preferred stock warrant liability $ — $ — $ 336 $ 336 Total financial liabilities $ — $ — $ 336 $ 336 Level 1 securities include highly liquid money market funds, 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, U.S. government agency bonds, 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. Level 3 liabilities that are measured at fair value on a recurring basis consist of a convertible preferred stock warrant liability. The fair value of the convertible preferred stock warrant liability is estimated using the Black-Scholes option-pricing model. Certain inputs were utilized in the option-pricing model as follows: December 31, 2017 December 31, 2018 Fair value estimate $ 7.67 $ 8.27 Expected term (in years) 3.31 2.31 Risk-free interest rate 2.0 % 2.5 % Expected volatility 61.5 % 55.3 % Expected dividend yield — —

Investments

Investments	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	5. Investments Available-for-sale December 31, 2018 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value Short-term marketable securities Commercial paper $ 16,887 $ — $ — $ 16,887 U.S. government debt and agency securities 85,722 — (99 ) 85,623 Corporate bonds 7,486 — (8 ) 7,478 Total short-term marketable securities $ 110,095 $ — $ (107 ) $ 109,988 September 30, 2019 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value (unaudited) Short-term marketable securities Commercial paper $ 136,843 $ — $ — $ 136,843 U.S. government debt and agency securities 331,770 354 (15 ) 332,109 Corporate bonds 29,486 49 — 29,535 Total short-term marketable securities $ 498,099 $ 403 $ (15 ) $ 498,487 Long-term marketable securities: U.S. government debt and agency securities $ 86,813 $ 112 $ (23 ) $ 86,902 Corporate bonds 48,309 95 — 48,404 Total long-term marketable securities $ 135,122 $ 207 $ (23 ) $ 135,306 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 September 30, 2019 (in thousands): Less Than 12 Months 12 Months Or Greater Fair Value Unrealized Loss Fair Value Unrealized Loss (unaudited) U.S. government debt and agency securities $ 53,975 $ (38 ) $ — $ — Total available-for-sale $ 53,975 $ (38 ) $ — $ — We evaluated our securities for other-than-temporary impairment and considered the decline in market value for the securities to be primarily attributable to current economic and market conditions. It is not more likely than not that we will be required to sell the securities, and we do not intend to do so prior to the recovery of the amortized cost basis. Based on this analysis, these marketable securities were not considered to be other-than-temporarily impaired as of September 30, 2019. All the commercial paper, U.S. government debt and agency securities and corporate bonds designated as short-term marketable securities have an effective maturity date that is less than one year from September 30, 2019. Those that are designated as long-term marketable securities have an effective maturity date that is more than one year from September 30, 2019.	5. Investments Available-for-sale December 31, 2017 Amortized cost Unrealized gain Unrealized loss Estimated fair value Short-term marketable securities Commercial paper $ 10,769 $ — $ — $ 10,769 U.S. government and agency securities 74,937 — (125 ) 74,812 Corporate bonds 21,284 — (20 ) 21,264 Total short-term marketable securities $ 106,990 $ — $ (145 ) $ 106,845 Long-term marketable securities U.S. government and agency securities $ 8,926 $ — $ (21 ) $ 8,905 Total long-term marketable securities $ 8,926 $ — $ (21 ) $ 8,905 December 31, 2018 Amortized cost Unrealized gain Unrealized loss Estimated fair value Short-term marketable securities Commercial paper $ 16,887 $ — $ — $ 16,887 U.S. government and agency securities 85,722 — (99 ) 85,623 Corporate bonds 7,486 — (8 ) 7,478 Total short-term marketable securities $ 110,095 $ — $ (107 ) $ 109,988 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, 2018 (in thousands): December 31, 2018 Less than 12 months 12 months or greater Fair value Unrealized loss Fair value Unrealized loss Short-term marketable securities Corporate bonds $ 7,478 $ (8 ) $ — $ — U.S. government and agency securities 76,654 (85 ) 8,969 (14 ) Total short-term marketable securities $ 84,132 $ (93 ) $ 8,969 $ (14 ) We evaluated our securities for other-than-temporary impairment and considered the decline in market value for the securities to be primarily attributable to current economic and market conditions. It is not more likely than not that we will be required to sell the securities, and we do not intend to do so prior to the recovery of the amortized cost basis. Based on this analysis, these marketable securities were not considered to be other-than-temporarily impaired as of December 31, 2018. All the corporate debt, U.S. government and agency securities, and commercial paper have an effective maturity date of less than one year.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	6. Property and Equipment, Net Property and equipment consist of the following (in thousands): December 31, 2017 2018 Laboratory equipment $ 12,330 $ 14,009 Computer equipment 1,507 1,819 Furniture and equipment 971 1,300 Computer software 464 429 Construction in progress 376 3,942 Leasehold improvements 7,631 10,078 Property and equipment, at cost 23,279 31,577 Less accumulated depreciation (9,325 ) (12,452 ) Property and equipment, net $ 13,954 $ 19,125 Depreciation expense was $4.1 million and $4.3 million for the years ended December 31, 2017 and 2018, respectively

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	6. 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, 2018 and September 30, 2019 consisted of the following (in thousands): December 31, 2018 Gross Carrying Accumulated Amortization Net Carrying Acquired developed technology $ 20,000 $ (6,636 ) $ 13,364 Purchased intellectual property 325 (63 ) 262 Balance at December 31, 2018 $ 20,325 $ (6,699 ) $ 13,626 September 30, 2019 Gross Carrying Accumulated Amortization Net Carrying (unaudited) Acquired developed technology $ 20,000 $ (7,882 ) $ 12,118 Purchased intellectual property 325 (87 ) 238 Balance at September 30, 2019 $ 20,325 $ (7,969 ) $ 12,356 The developed technology was acquired in connection with our acquisition of Sequenta, Inc. (“Sequenta”) in 2015. The remaining balance of the acquired technology and the purchased intellectual property is expected to be amortized over the next approximately 7.3 years. As of September 30, 2019, expected future amortization expense for intangible assets was as follows (in thousands) (unaudited): 2019 $ 428 2020 1,698 2021 1,698 2022 1,698 2023 1,698 Thereafter 5,136 Total future amortization expense $ 12,356	7. Goodwill and Intangible Assets Intangible assets subject to amortization as of the dates presented consist of the following (in thousands): December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Acquired developed technology $ 20,000 $ (4,969 ) $ 15,031 Purchased intellectual property 325 (31 ) 294 Balance at December 31, 2017 $ 20,325 $ (5,000 ) $ 15,325 December 31, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Acquired developed technology $ 20,000 $ (6,636 ) $ 13,364 Purchased intellectual property 325 (63 ) 262 Balance at December 31, 2018 $ 20,325 $ (6,699 ) $ 13,626 The developed technology was acquired in connection with our acquisition of Sequenta, Inc. in 2015. The remaining balance of the acquired technology and the purchased intellectual property is expected to be amortized over the next approximately eight years in the amount of $1.7 million per year. There have been no changes in the carrying amount of goodwill since its recognition in 2015.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued Liabilities	8. Accrued Liabilities Accrued liabilities consist of the following (in thousands): December 31, 2017 2018 Accrued legal and professional fees $ 598 $ 1,634 Accrued royalties 22 31 Accrued travel and entertainment 44 73 Other vendor accruals 379 824 Total accrued liabilities $ 1,043 $ 2,562

Deferred Revenue

Deferred Revenue	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Deferred Revenue	7. Deferred Revenue Deferred revenue by revenue classification as of December 31, 2018 and September 30, 2019 was as follows (in thousands): December 31, 2018 September 30, 2019 (unaudited) Current deferred revenue Sequencing $ 11,238 $ 12,419 Development 1,457 48,850 Total current deferred revenue 12,695 61,269 Non-current Sequencing 516 1,195 Development 188 227,144 Total non-current 704 228,339 Total current and non-current $ 13,399 $ 289,608 Genentech deferred revenue represents $47.4 million and $226.4 million of the current and non-current non-current Changes in deferred revenue during the nine months ended September 30, 2019 were as follows (in thousands): Deferred revenue balance at December 31, 2018 $ 13,399 Additions to deferred revenue during the period (unaudited) 312,248 Revenue recognized during the period (unaudited) (36,039 ) Deferred revenue balance at September 30, 2019 (unaudited) $ 289,608 As of September 30, 2019, $6.4 million was recognized that was included in the deferred revenue balance at December 31, 2018. As a result of cancelled customer sequencing contracts, we recognized $1.5 million of sequencing revenue during the nine months ended September 30, 2019.	9. Deferred Revenue Deferred revenue by revenue classification was as follows (in thousands): December 31, 2017 2018 Deferred sequencing revenue $ 11,747 $ 11,754 Deferred development revenue 2,301 1,645 Total deferred revenue $ 14,048 $ 13,399 The opening balance of deferred revenue was $10.4 million as of January 1, 2017. In 2018, as a result of cancelled customer sequencing contracts, we recognized $3.4 million of sequencing revenue. Changes in deferred revenue were as follows (in thousands): December 31, 2018 Deferred revenue balance at December 31, 2017 $ 14,048 Additions to deferred revenue during the period 9,727 Revenue recognized during the period (10,376 ) Deferred revenue balance at December 31, 2018 $ 13,399

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Operating Leases We have entered into various non-cancelable In July 2011, we entered into a non-cancelable In August 2019, we entered into an operating lease to rent 100,000 square feet in a to-be-constructed In October 2016, we entered into an agreement to sublease certain laboratory and office space in South San Francisco, California. The lease commenced in October 2016 and terminated in March 2019. The lease required us to pay additional amounts for operating and maintenance expenses. In April 2018, we entered into a lease agreement to lease additional space in South San Francisco, California. The lease term is through March 2026 and provides for one five-year option. We will be 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 prior to the lease commencement date of December 12, 2018. The landlord was solely responsible for the $2.4 million cost of such improvements, which we recognized as a leasehold improvement asset that depreciates beginning from the commencement date to the initial lease term, and a corresponding leasehold incentive obligation, which is amortized over the life of the lease. As of September 30, 2019, future minimum lease payments, exclusive of operating and maintenance costs and inclusive of payments to be made under the financing obligation, were as follows (in thousands) (unaudited): 2019 $ 901 2020 3,963 2021 6,745 2022 10,681 2023 10,985 Thereafter 107,570 Total future minimum lease payments $ 140,845 Rent expenses, inclusive of operating and maintenance costs, were $1.1 million and $1.3 million for the three months ended September 30, 2018 and 2019, respectively, and $2.9 million and $3.6 million for the nine months ended September 30, 2018 and 2019, respectively. 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 currently party to any material legal proceedings. 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.	10. Commitments and Contingencies Operating Leases We have entered into various non-cancelable In July 2011, we entered into a non-cancelable In October 2016, we entered into an agreement to sublease certain laboratory and office space in South San Francisco, California. The lease commenced in October 2016 and terminates in March 2019. The lease requires us to pay additional amounts for operating and maintenance expenses. In April 2018, we entered into a lease agreement to lease additional space in South San Francisco, California. The lease term is through March 2026 and provides for one five-year option. We will be 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 prior to the lease commencement date of December 12, 2018. The landlord was solely responsible for the $2.4 million cost of such improvements, which we recognized as a leasehold improvement asset that depreciates beginning from the commencement date to the initial lease term, and a corresponding leasehold incentive obligation, which is amortized over the life of the lease. As of December 31, 2018, future minimum lease payments, exclusive of operating and maintenance costs, are as follows (in thousands): 2019 $ 3,561 2020 3,819 2021 3,917 2022 4,017 2023 2,295 Thereafter 2,315 Total future minimum lease payments $ 19,924 Rent expenses, inclusive of operating and maintenance costs, were $3.7 million and $4.1 million for the years ended December 31, 2017 and 2018, respectively. 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 currently party to any material legal proceedings. 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 such agreements 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.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Convertible Preferred Stock	11. Convertible Preferred Stock Convertible preferred stock at December 31, 2018 consists of the following (in thousands, except share data): Shares authorized Shares issued and outstanding Amount Liquidation preference Series A 4,550,000 4,550,000 $ 12,405 $ 4,550 Series B 5,645,706 5,645,706 16,017 9,669 Series C 4,804,227 4,747,352 14,425 12,521 Series D 19,269,117 19,269,117 106,905 106,999 Series E 15,524,350 15,524,350 93,698 93,750 Series E-1 17,407,441 16,605,244 72,568 (1) 100,277 Series F 21,761,676 21,761,676 195,013 195,100 Series F-1 4,800,000 4,686,649 49,827 50,000 Total convertible preferred stock 93,762,517 92,790,094 $ 560,858 $ 572,866 (1) Includes vested Series E-1 Conversion Each share of convertible preferred stock is convertible at the option of the holder into one fully paid and non-assessable E-1 F-1 Shares of convertible preferred stock are automatically converted into shares of the common stock upon the closing of a public offering, provided that our gross proceeds are not less than $25.0 million. Shares of Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock are automatically converted into shares of the common stock upon the affirmative vote of the holders of a majority of such shares, voting together as a single class on an as-converted as-converted E-1 as-converted F-1 as-converted Dividends The holders of convertible preferred stock shall be entitled to receive dividends, when and if declared by our board of directors, out of any assets legally available, prior and in preference to any declaration or payment of any dividend on the common stock, equal to the greater of (a) in the case of the Series F-1 Liquidation Preference In the event of any liquidation event, the holders of Series F convertible preferred stock and Series F-1 pari passu Upon completion of the distribution noted above, the holders of Series E convertible preferred stock and Series D convertible preferred stock shall be entitled to receive, on a pari passu Upon completion of the distribution noted above, the holders of Series A convertible preferred stock, Series B convertible preferred stock, and Series C convertible preferred stock shall be entitled to receive, on a pari passu Series E-1 Upon completion of the distribution noted above, our remaining assets available for distribution to shareholders shall be distributed with equal priority and pro rata among the holders of Series E-1 Series F-1 as-if Voting Each holder of convertible preferred stock shall be entitled to vote on all matters submitted to a vote by shareholders and shall be entitled to that number of votes equal to the number of shares of common stock into which such holder’s shares of convertible preferred stock are convertible, at the record date. Except as otherwise expressed, the holders of shares of convertible preferred stock and common stock shall vote together as a single class on all matters. Redemption So long as 4.0 million shares of our Series D convertible preferred stock, Series E convertible preferred stock, Series F convertible preferred stock and Series F-1 as-converted Classification We have classified convertible preferred stock as mezzanine equity in the balance sheets as the shares are contingently redeemable upon a deemed liquidation such as a change in control and in that event there is no guarantee that all shareholders would be entitled to receive the same form of consideration. No accretion was recorded during the years ended December 31, 2017 and 2018 as a deemed liquidation event was not considered probable. Series E-1 Included in convertible preferred stock is $1.8 million for the redemption value of outstanding Series E-1 one-for-one

Shareholders' Equity

Shareholders' Equity	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Equity [Abstract]
Shareholders' Equity	9. 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 September 30, 2019, 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 September 30, 2019, 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, 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. As of September 30, 2019, we had 124,316,080 shares of common stock outstanding. We have reserved shares of common stock for the following as of September 30, 2019 (unaudited): Shares issuable upon the exercise of outstanding common stock options and the vesting of outstanding common restricted stock units (“RSUs”) granted 17,495,253 Shares available for future grant under the 2019 Plan 15,474,217 Shares available for future grant under the Employee Stock Purchase Plan 1,551,917 Shares to be issued upon conversion of a common stock warrant 56,875 Total shares of common stock reserved for future issuance 34,578,262 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 is immaterial to the unaudited condensed 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 was exercisable at any time 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, this convertible preferred stock warrant, which was 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	12. Shareholders’ Deficit Common Stock We are authorized to issue 131,000,000 shares of common stock. Our common stock has a par value of $0.0001, 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. We have reserved shares of common stock for the following as of December 31, 2018: Shares to be issued upon conversion of all series of convertible preferred stock 92,790,094 Shares to be issued upon exercise of outstanding common stock options 14,893,253 Shares available for future stock option grants 6,827,996 Shares to be issued upon exercise of outstanding Series E-1 264,677 Shares to be issued upon conversion of Series C convertible preferred stock in connection with warrant exercise 56,875 Shares to be issued upon conversion of common stock warrants 55,032 Shares of common stock reserved for future issuance 114,887,927 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. The warrants are exercisable at any time for a period of ten years from the date of issuance at an average exercise price of $0.37, except in the case of warrants to purchase 20,000 shares of common stock at an exercise price of $0.45 per share that may expire if unexercised prior to the closing of a public offering.

Equity Incentive Plans

Equity Incentive Plans	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Equity Incentive Plans	10. 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 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 as determined by our board of directors. 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 with an initial reserve of 15,519,170 shares immediately prior to and contingent upon 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. Changes in shares available for grant during the nine months ended September 30, 2019 were as follows: Shares Shares available for grant at December 31, 2018 6,827,996 2019 Plan reserve (unaudited) 12,363,202 Options and RSUs granted (unaudited) (4,084,656 ) Options and RSUs forfeited or cancelled (unaudited) 367,675 Shares available for grant at September 30, 2019 (unaudited) 15,474,217 Stock option activity under the 2008 Plan, 2009 Plan and 2019 Plan during the nine months ended September 30, 2019 is as follows: Shares Subject to Outstanding Options Weighted- Average Exercise Price per Share Aggregate Intrinsic Value (in thousands) Options outstanding at December 31, 2018 15,157,930 $ 4.52 $ 41,690 Options granted (unaudited) 4,071,846 9.15 Options forfeited or cancelled (unaudited) (367,675 ) 6.08 Options exercised (unaudited) (1,379,658 ) 1.67 Options outstanding at September 30, 2019 (unaudited) 17,482,443 5.79 438,968 During the nine months ended September 30, 2019, we granted 12,810 shares of RSUs at a weighted-average grant date fair value per share of $41.63, all of which have not vested and remain outstanding at September 30, 2019. Fair Value of Options Granted The estimated fair value of options granted during the nine months ended September 30, 2018 and 2019 was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions: Nine Months Ended September 30, 2018 2019 (unaudited) Grant date fair value $ 6.55 $ 10.08 Expected term (in years) 6.15 6.06 Risk-free interest rate 2.7 % 2.4 % Expected volatility 68.9 % 68.0 % Expected dividend yield — — 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— Expected term— non-employee Compensation—Stock Compensation Risk-free interest rate— zero-coupon Expected volatility— Expected dividend yield— Share-based compensation expense of $2.6 million and $3.3 million was recognized during the three months ended September 30, 2018 and 2019, respectively, and $8.1 million and $9.7 million was recognized during the nine months ended September 30, 2018 and 2019, respectively. The compensation costs for the three and nine months ended September 30, 2018 and 2019, respectively, related to stock options and RSUs are included on our unaudited condensed statements of operations as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 (unaudited) Cost of revenue $ 97 $ 133 $ 273 $ 376 Research and development 700 943 2,168 2,838 Sales and marketing 620 798 2,169 2,647 General and administration 1,136 1,461 3,493 3,852 Total share-based compensation expense $ 2,553 $ 3,335 $ 8,103 $ 9,713 At September 30, 2019, unrecognized share-based compensation expense related to unvested stock options was $34.5 million, which is expected to be recognized over a remaining weighted-average period of 3.06 years. Additionally, at September 30, 2019, unrecognized share-based compensation expense related to unvested RSUs was $0.3 million, which is expected to be recognized over a remaining weighted-average period of 0.73 years.	13. Equity Incentive Plans Adaptive 2009 Equity Incentive Plan We adopted an equity incentive plan during 2009 (“2009 Plan”) that provides 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 may not be less than the fair market value of our common stock at the date of grant as determined by the board of directors. Options expire no later than ten years from the grant date, and vesting is established at the time of grant. As of December 31, 2018, we have authorized 21,721,249 shares of common stock for issuance under the 2009 Plan. A summary of our option and restricted stock unit (“RSU”) activity is as follows: Shares available for grant Shares subject to outstanding options Weighted- average exercise price per share Aggregate intrinsic value (in thousands) Outstanding at December 31, 2016 3,423,473 12,985,266 $ 3.46 $ 37,138 Authorized — — — Options granted (1,604,496 ) 1,604,496 6.27 RSUs forfeited 880,487 (880,487 ) — Forfeited 2,086,035 (2,086,035 ) 5.80 Exercised — (54,685 ) 1.73 Outstanding at December 31, 2017 4,785,499 11,568,555 3.70 32,970 Authorized 6,000,000 — — Options granted (4,764,625 ) 4,764,625 6.55 Forfeited 807,122 (807,122 ) 5.54 Exercised — (632,805 ) 1.85 Outstanding at December 31, 2018 6,827,996 14,893,253 4.59 39,864 In 2016, we granted 880,487 RSUs. The vesting of the shares required the satisfaction of both a service and an event condition. In 2017, these RSUs were forfeited due to the employee’s termination prior to the occurrence of either conditions. The following table summarizes information about stock options outstanding and exercisable at December 31, 2018: Exercise price Options outstanding Weighted- average remaining contractual life (years) Options exercisable Aggregate intrinsic value (in thousands) $ 0.16 469,109 1.36 469,109 0.33 1,428,959 2.90 1,428,959 0.45 641,000 3.95 641,000 0.84 1,115,225 5.05 1,115,225 1.98 1,040,500 5.65 1,040,500 4.07 409,194 6.22 395,005 6.27 672,353 6.73 402,321 6.32 4,431,538 6.71 3,623,123 6.55 4,685,375 9.29 947,049 14,893,253 6.66 10,062,291 $ 36,089 The weighted-average exercise price for options exercisable as of December 31, 2018 was $3.68. The weighted-average grant date fair value of options granted was $4.00 and $4.15 during the years ended December 31, 2017 and 2018, respectively. The total intrinsic value of awards exercised was $0.3 million and $3.0 million during the years ended December 31, 2017 and 2018, respectively. Sequenta, Inc. 2008 Stock Plan, as amended In connection with our acquisition of Sequenta Inc. 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 are all exercisable for Series E-1 A summary of our Series E-1 Convertible preferred shares subject to outstanding options Weighted- average exercise price per share Aggregate intrinsic value (in thousands) Outstanding at December 31, 2016 814,563 $ 0.56 $ 4,814 Options granted — — Forfeited (121,898 ) 0.55 Exercised (171,526 ) 0.74 Outstanding at December 31, 2017 521,139 0.50 3,195 Options granted — — Forfeited (122,397 ) 0.36 Exercised (134,065 ) 0.75 Outstanding at December 31, 2018 264,677 0.44 1,826 The following table summarizes information about convertible preferred stock options outstanding and exercisable at December 31, 2018: Exercise price Options outstanding Weighted- average remaining contractual life (years) Options exercisable Aggregated intrinsic value (in thousands) $ 0.10 104,652 0.63 104,652 0.28 10,153 2.23 10,153 0.55 74,473 4.08 74,473 0.82 70,518 5.12 70,480 0.92 4,881 5.37 4,881 264,677 2.94 264,639 $ 1,826 There were no preferred options granted during the years ended December 31, 2017 and 2018. The total intrinsic value of awards exercised was $1.0 million and $0.8 million during the years ended December 31, 2017 and 2018, respectively. Fair value of options granted The estimated fair value of options granted during 2017 and 2018 was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions for our 2009 Plan: Year Ended December 31, 2017 2018 Grant date fair value $ 6.27 $ 6.55 Expected term (in years) 6.12 6.14 Risk-free interest rate 2.0 % 2.7 % Expected volatility 70.2 % 68.1 % Expected dividend yield — — 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 Valuation of Privately-Held-Company Equity Securities Issued as Compensation Expected term Compensation—Stock Compensation Risk-free interest rate zero-coupon Expected volatility Expected dividend yield Share-based compensation expense of $7.0 million and $11.1 million was recognized during the years ended December 31, 2017 and 2018, respectively. The compensation costs related to stock options are included in the statements of operations as follows (in thousands): Year Ended December 31, 2017 2018 Cost of revenue $ 237 $ 398 Research and development 2,375 2,896 Sales and marketing 1,344 2,891 General and administration 3,053 4,964 Total share-based compensation expense $ 7,009 $ 11,149 There were no stock option modifications during the year ended December 31, 2017. During the year ended December 31, 2018, there was one option modification to extend the option exercise period which resulted in incremental stock compensation of $0.5 million. The total grant date fair value of the stock options that vested during the years ended December 31, 2017 and 2018, excluding the impact of modifications, approximated the share-based compensation expense recorded during the respective periods. At December 31, 2018, unrecognized share-based compensation expense related to unvested stock options was $18.3 million, which is expected to be recognized over a remaining weighted-average period of 2.72 years.

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring Charges	14. Restructuring Charges On June 17, 2016, we announced that we were consolidating our South San Francisco, California laboratory operations into our Seattle, Washington location to recognize cost savings. The transition of activities was completed in April 2017. The following table summarizes the activity within the restructuring related balance sheet accounts during the year ended December 31, 2017 (in thousands): One-time termination benefits Asset impairments and net loss on sale or disposal Other (1) Total Balance at December 31, 2016 $ 2,564 $ — $ — $ 2,564 Costs incurred and charged to expense 512 210 118 840 Cash payments (3,076 ) — (118 ) (3,194 ) Non-cash — (210 ) — (210 ) Balance at December 31, 2017 $ — $ — $ — $ — (1) “Other” primarily reflects activities associated with the consolidation of our facilities and manufacturing operations, including contract termination costs.

Microsoft Collaboration Agreeme

Microsoft Collaboration Agreement	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Microsoft Collaboration Agreement	15. Microsoft Collaboration Agreement Summary of Agreement In December 2017, we entered into a collaboration agreement with Microsoft Corporation (“Microsoft Agreement”) to computationally derive a comprehensive TCR antigen map for purposes of developing a universal diagnostic based on a single blood test. During the term of the Microsoft Agreement, each party has granted the other certain limited use licenses to one another’s intellectual property rights and has agreed to certain defined exclusivity obligations with respect to collaborations and projects that are substantially similar. The licenses, exclusivity, data, software and related development services are for the purposes of achieving the objectives of the collaboration. We retain all license rights to commercialize any immunological research, diagnostic and therapeutic products and services that arise out of the collaboration, and we have no financial commitments to Microsoft other than our commitment to purchase Microsoft’s Azure cloud services. 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. We have also agreed to host each diagnostic product developed as a direct result of the Microsoft Agreement on Microsoft’s Azure cloud services throughout the term of the Microsoft Agreement and for a period of five years thereafter. Each party must make good faith and reasonable efforts to carry out its obligations under the Microsoft Agreement, but there are no contractual minimums or maximums of resource efforts aside from our commitment pertaining to the purchase of Microsoft’s Azure cloud services. Each party is responsible for its own costs incurred over the course of the collaboration, and there is no other cash consideration, royalty rights or other economic interests provided by Microsoft or payable by us to Microsoft, aside from our commitment to utilize Microsoft’s Azure cloud services. 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 Summary of Accounting The terms of the Microsoft Agreement meet the criteria under ASC Topic 808, Collaborative Arrangements 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 F-1 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 the statement 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 non-monetary non-monetary We will use our employees, laboratory resources and related overhead to perform our obligations under the Microsoft Agreement. Our existing research and development activities relate to the development of a TCR-antigen For the year ended December 31, 2018, we recognized $0.5 million in research and development expense related to Microsoft’s Azure cloud services provided to us.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	16. 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 are as follows (in thousands): December 31, 2017 2018 Deferred tax assets: Net operating losses $ 47,840 $ 56,555 Tax credit carryforward 5,463 6,709 Non qualifying stock options 4,865 7,861 Other 3,774 4,523 Total deferred tax assets 61,942 75,648 Valuation allowance (56,679 ) (70,722 ) Deferred tax assets, net of valuation allowance 5,263 4,926 Deferred tax liabilities: Tangible and intangible assets (5,263 ) (4,926 ) Net deferred taxes $ — $ — ASC Topic 740, Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“TCJA”) was signed into law, making significant changes to the Internal Revenue Code, including a decrease in the federal corporate tax rate from 35% to 21%. Taxpayers are required to recognize the effect of tax law changes in the period of enactment. The re-measurement 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 change. We have completed a Section 382 analysis for approximately $186.9 million of our federal operating losses and there are no permanent limitations on the utilization of our federal net operating losses as of December 31, 2018. Net operating losses generated by Sequenta, Inc. of approximately $38.5 million prior to the our acquisition in January of 2015 were excluded from this analysis and maybe limited as we have not completed a Section 382 analysis. Under the newly enacted 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 carried forward up to 20 years. As of December 31, 2018, we had U.S. federal net operating losses of $47.3 million and U.S. federal tax credits of $6.0 million. The tax credit and net operating loss carryforwards will begin to expire in 2028. The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows: Year ended December 31, 2017 2018 Statutory rate 34.0 % 21.0 % State tax 1.8 5.5 Stock compensation (1.7 ) 0.5 Permanent items (0.1 ) 0.5 Credits 2.7 2.7 TCJA change in federal rate (58.4 ) — Other (0.7 ) 0.2 Change in valuation allowance 22.3 (30.3 ) Total 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 approximately $1.3 million as of December 31, 2018. A reconciliation of the beginning and ending amounts of unrecognized tax benefits during the two years ended December 31, 2017 and 2018 are as follows (in thousands): Balance at December 31, 2016 $ 844 Additions in 2017 187 Balance at December 31, 2017 1,031 Additions in 2018 229 Balance at December 31, 2018 $ 1,260 During the years ended December 31, 2017 and 2018, we recognized uncertain tax positions of $0.2 million 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, 2017 and 2018. 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.

Net Loss and Unaudited Pro Form

Net Loss and Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss and Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders	11. 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 three and nine months ended September 30, 2018 and 2019, respectively (in thousands, except shares and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 (unaudited) Net loss $ (8,292 ) $ (13,950 ) $ (33,176 ) $ (47,995 ) Fair value adjustments to redemption value for Series E-1 (4 ) — (2 ) (964 ) Net loss attributable to common shareholders, basic and diluted $ (8,296 ) $ (13,950 ) $ (33,178 ) $ (48,959 ) Weighted-average shares used in computing net loss per share 12,620,010 124,285,686 12,430,535 50,552,389 Net loss per share attributable to common shareholders, basic and diluted $ (0.66 ) $ (0.11 ) $ (2.67 ) $ (0.97 ) 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 three and nine months ended September 30, 2018 and 2019, respectively, as they had an anti-dilutive effect: Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 (unaudited) Convertible preferred stock (on as if converted basis) 92,790,094 — 92,764,348 61,641,506 Stock options issued and outstanding 14,801,784 17,466,409 14,489,718 17,096,516 Unvested restricted stock units — 7,380 — 2,487 Common stock warrants 55,032 56,875 55,032 55,653 Convertible preferred stock warrant 56,875 — 56,875 37,708 Total 107,703,785 17,530,664 107,365,973 78,833,870	17. Net Loss and Unaudited Pro Forma 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 (in thousands, except shares and per share amounts): Year ended December 31, 2017 2018 Net loss $ (42,831 ) $ (46,447 ) Fair value adjustments to redemption value for Series E-1 135 102 Net loss attributable to common shareholders, basic and diluted $ (42,696 ) $ (46,345 ) Weighted-average shares used in computing net loss per share 12,196,998 12,629,778 Net loss per share attributable to common shareholders, basic and diluted $ (3.50 ) $ (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 periods presented as they had an anti-dilutive effect: Year ended December 31, 2017 2018 Convertible preferred stock (on as if converted basis) 88,473,431 92,783,867 2009 Plan stock options issued and outstanding 12,022,454 14,368,063 2008 Plan stock options issued and outstanding 622,472 333,563 Common stock warrants 55,032 55,032 Convertible preferred stock warrants 56,875 56,875 Total 101,230,264 107,597,400 Unaudited Pro Forma Net Loss Per Share The following table sets forth the computation of the unaudited pro forma basic and diluted net loss per share attributable to common shareholders (in thousands, except shares and per share amounts): Year Ended December 31, 2018 Numerator: Pro forma net loss attributable to common shareholders, basic and diluted $ (46,345 ) Denominator: Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted 12,629,778 Weighted-average shares of common stock issued upon assumed conversion of convertible preferred stock in an initial public offering 92,783,867 Weighted-average shares of common stock issued upon assumed conversion of a common stock warrant in an initial public offering 20,000 Weighted-average shares used in computing pro forma net loss per share attributable to common shareholders, basic and diluted 105,433,645 Pro forma net loss per share attributable to common shareholders, basic and diluted $ (0.44 )

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Retirement Plan	18. 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 did not make any discretionary contributions during the years ended December 31, 2017 and 2018.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	19. Subsequent Events In January 2019, clonoSEQ received Medicare coverage aligned with the FDA label and National Comprehensive Cancer Network guidelines for longitudinal monitoring in certain blood cancers. In the first quarter of 2019, the board of directors approved additional stock option grants under our 2009 Plan of 2,045,000 shares to certain employees and 105,000 shares to non-employee Management has reviewed and evaluated material subsequent events from the balance sheet date of December 31, 2018, through the date the financial statements were available to be issued, March 29, 2019. Other than the matters noted above, no subsequent events have been identified for disclosure.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“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.	Basis of Presentation and Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“U.S. 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 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.
Cash and Cash Equivalents		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, investments in money market funds and commercial paper.
Restricted Cash	Restricted Cash We are required to maintain certain balances under lease arrangements for our property and facilities leases. We had restricted cash of $0.1 million and $2.1 million as of December 31, 2018 and September 30, 2019, respectively.	Restricted Cash We are required to maintain certain balances under operating lease arrangements for our facilities. We have a certificate of deposit with a financial institution issued in favor of the lessor for $0.1 million as of December 31, 2017 and 2018. This amount is recorded as restricted cash and other assets in the accompanying balance sheets due to the long-term nature of the underlying facility lease.
Investments in Marketable Securities		Investments in Marketable Securities Marketable securities are classified as available-for-sale
Concentrations of Risk	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 which represent more than 10% of our total revenue or accounts receivable, net balances at each respective balance sheet date. 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 periods presented were as follows: Revenue Accounts Receivable, Net Three Months September 30, Nine Months Ended September 30, December 31, 2018 September 30, 2019 2018 2019 2018 2019 (unaudited) (unaudited) Customer A 15.7 % 16.0 % 21.6 % 11.8 % * % 39.6 % Customer B * 10.7 * * 15.1 * Customer C 35.0 * 19.1 * 13.2 * Genentech, Inc. * 43.9 * 43.7 * * * less than 10%	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 bonds, commercial paper and corporate bonds with high-quality accredited financial institutions. Significant customers are those which represent more than 10% of our total revenue or accounts receivable balance at each respective balance sheet date. Revenue from these customers reflects their purchase of our products and services and we do not believe their loss would have a material adverse effect on our business. For each significant customer, revenue as a percentage of revenue and accounts receivable as a percentage of accounts receivable were as follows: Revenue Accounts Receivable Year Ended December 31, December 31, 2017 2018 2017 2018 Customer A 31.4 % 18.4 % 29.9 % * % Customer B * 13.5 14.9 15.1 Customer C * 15.4 * 13.2 * less than 10%
Accounts Receivable		Accounts Receivable Accounts receivable consist of amounts due from customers for services performed. We review our accounts receivable regularly by analyzing the status of significant past due receivables to determine if any receivable will potentially be uncollectible and to estimate the amount of allowance for doubtful accounts necessary to reduce accounts receivable to its estimated net realizable value. Our allowance for doubtful accounts was $0.1 million as of December 31, 2017 and 2018. Additionally, we had $1.4 million and $0.4 million of unbilled receivables as of December 31, 2017 and 2018, respectively. The unbilled receivables are amounts that will become due for which we have an unconditional right to consideration.
Inventory		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
Property and Equipment		Property and Equipment Property and equipment consist of computer equipment, computer software, laboratory equipment, leasehold improvements and furniture and fixtures. Property and equipment are recorded at cost and depreciation is recognized using the straight-line method based on an 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 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 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 the statements of operations in accordance with the use of the asset, except those gains and losses recognized in conjunction with restructuring activities, which are classified within restructuring expense. We recognized $0.3 million of impairment expense in research and development for obsolete equipment in 2017 and $0.2 million of losses from asset disposals, impairment and accelerated depreciation in restructuring. See Note 14, Restructuring Charges
Goodwill		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 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 the estimated useful life of the asset on a straight-line basis which approximates the 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.
Restructuring		Restructuring We recognize a liability for costs associated with an exit or disposal activity under a restructuring project when the plan has been finalized. Employee termination benefits considered as post-employment benefits are accrued when the obligation is probable and estimable, such as benefits stipulated by human resource policies and practices or statutory requirements. One-time Asset impairments associated with a restructuring project are determined at the asset group level. An impairment may be recognized for assets that are to be abandoned or are to be sold for less than net book value. We may also recognize impairment on an asset group, which is held and used, when the carrying value is not recoverable and exceeds the asset group’s fair value. If the sale of an asset group under a restructuring project results in proceeds that exceed the net book value of the asset group, the resulting gain is recognized within restructuring expense in the statements of operations.
Leases	Leases Operating Lease Arrangements We have operating lease agreements for the laboratory and office facilities that we occupy. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facility leases, including rent holidays, are capitalized and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. Lease Financing Arrangements Due to our significant involvement during the construction process of a leased building, we qualify as the deemed owner of the building under build-to-suit	Leases We have lease agreements for our laboratory and office facilities. These leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the term of the lease. Incentives granted under our facility leases, including rent holidays, are capitalized and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease.
Fair Value of Financial Instruments		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: • Level 2: • Level 3: 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 Level 3 liabilities. 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, 2017 or 2018.
Convertible Preferred Stock Warrant Liability		Convertible Preferred Stock Warrant Liability We have 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. The fair value of this warrant is classified as a non-current
Revenue Recognition	Revenue Recognition We recognize revenue in accordance with Accounting Standards Codification (“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: (i) identify the contract or contracts; (ii) determine whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measure the transaction price, including the constraint on variable consideration; (iv) allocate the transaction price to the performance obligations based on estimated selling prices; and (v) 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 allocate 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 immunoSEQ and clonoSEQ products and services to our research and clinical customers, respectively. 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. For other research customers who choose to purchase a research use only kit, the kits are sold on a price per kit basis with amounts payable upon delivery of the kit. Payments received are recorded as deferred revenue. For these customers, we have identified one performance obligation: the delivery of sample results. We recognize revenue as the results are delivered to the customer based on a proportion of the estimated samples that can be reported on for each kit. For clinical customers, we derive revenues from providing our clonoSEQ test report to ordering physicians, and we bill and receive payments from commercial third-party payors and medical institutions. 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. In January 2019, clonoSEQ received Medicare coverage aligned with the FDA label and National Comprehensive Cancer Network (“NCCN”) guidelines for longitudinal monitoring in multiple myeloma (“MM”) and B cell acute lymphoblastic leukemia (“ALL”). We bill Medicare for 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 is recognized 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. For the three and nine months ended September 30, 2019, we recognized $0.3 million and $1.1 million relating to the coverage policy, respectively; $0.1 million and $0.4 million of this revenue was related to tests delivered in periods prior to the three and nine months ended September 30, 2019, respectively. 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. 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 our proprietary immunoSEQ and clonoSEQ services in the development of the respective customers’ initiatives. The transaction price for these contracts may consist of a combination of non-refundable 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 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.	Revenue Recognition We recognize revenue in accordance with Accounting Standards Codification (“ASC”) Topic 606 (“ASC 606”) , Revenue from Contracts with Customers. 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 allocate 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 through immunoSEQ to research customers and from providing testing services through clonoSEQ to clinical and research customers. 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. For other research customers who choose to purchase a research use only kit, the kits are sold on a price per kit basis with amounts payable upon delivery of the kit. Payments received are recorded as deferred revenue. For these customers we have identified one performance obligation: the delivery of sample results. We recognize revenue as the results are delivered to the customer based on a proportion of the estimated samples that can be reported on for each kit. For clinical customers, we derive revenues from providing our clonoSEQ test report to ordering physicians, and we bill and receive payments from commercial third-party payors and medical institutions. 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 reimbursement rates with the various payors, which are monitored in subsequent periods and adjusted as necessary based on actual collection experience. 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 our proprietary immunoSEQ and clonoSEQ services in the development of the respective customers’ initiatives. The transaction price for these contracts may consist of a combination of non-refundable 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 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		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
Share-Based Compensation		Share-Based Compensation Share-based compensation includes compensation expense for stock option grants to employees and non-employees. non-employees
Cost of Revenue		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 Research and development expenses are comprised of laboratory materials costs, personnel-related expenses, allocated facility costs, information technology and contract service expenses. 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.
Sales and Marketing Expenses		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 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 interest and penalties related to income tax matters as a component of tax expense. We did not record any interest or penalties related to income tax during the years ended December 31, 2017 and 2018.
Net Loss Per Share Attributable to Common Shareholders		Net Loss Per Share Attributable to Common Shareholders We calculate our basic and diluted net loss per share attributable to common shareholders in conformity with the two-class as-if two-class two-class
Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders		Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders We have presented the unaudited pro forma basic and diluted net loss per share attributable to common shareholders for the year ended December 31, 2018, which shows the assumed effect of an initial public offering, including (i) the conversion of all convertible preferred stock into shares of common stock as if the conversion had occurred as of the later of the beginning of the period or the original date of issuance; and (ii) the issuance of 20,000 shares of common stock upon the assumed exercise of a common stock warrant prior to the completion of an initial public offering. The pro forma net loss per share attributable to common shareholders does not include proceeds to be received from nor does it include shares expected to be sold in the assumed initial public offering.
Segment Information		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
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation—Stock Compensation (Topic 718) paid-in In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting	Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers Subtopic 340-40, Other Assets and Deferred Costs—Contracts with Customers Revenue Recognition In February 2016, the FASB issued ASU No. 2016-02, Leases right-of-use In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation paid-in In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other: Internal-Use 350-40),
Unaudited Interim Condensed Financial Statements	Unaudited Interim Condensed Financial Statements In our opinion, the accompanying unaudited condensed financial statements have been prepared in accordance with GAAP for interim financial information. These unaudited condensed financial statements include all adjustments necessary to fairly state the financial position and the results of our operations and cash flows for interim periods in accordance with GAAP. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The accompanying unaudited condensed financial statements should be read in conjunction with our audited financial statements and notes included in our prospectus dated June 26, 2019 filed with the Securities and Exchange Commission (“SEC”) on June 27, 2019 in connection with our initial public offering (“Prospectus”).
Reclassifications	Reclassifications In the accompanying audited condensed balance sheet, certain prior year amounts have been reclassified to conform to the current period presentation. Specifically, “restricted cash” and “other assets” were previously included together in the restricted cash and other assets line item and are now separately stated. There was no change to total assets as a result of the reclassification.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs consist of fees and expenses incurred in connection with the sale of our common stock in the initial public offering, including legal, accounting, printing and other initial public offering-related paid-in offering-related paid-in
New Accounting Pronouncements Not Yet Adopted	New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) right-of-use build-to-suit Leases In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments available-for-sale In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other: Internal-Use 350-40)

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Concentrations of Risk Percentage	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 periods presented were as follows: Revenue Accounts Receivable, Net Three Months Ended September 30, Nine Months Ended September 30, December 31, 2018 September 30, 2019 2018 2019 2018 2019 (unaudited) (unaudited) Customer A 15.7 % 16.0 % 21.6 % 11.8 % * % 39.6 % Customer B * 10.7 * * 15.1 * Customer C 35.0 * 19.1 * 13.2 * Genentech, Inc. * 43.9 * 43.7 * * * less than 10%	For each significant customer, revenue as a percentage of revenue and accounts receivable as a percentage of accounts receivable were as follows: Revenue Accounts Receivable Year Ended December 31, December 31, 2017 2018 2017 2018 Customer A 31.4 % 18.4 % 29.9 % * % Customer B * 13.5 14.9 15.1 Customer C * 15.4 * 13.2 * less than 10%
Schedule of Useful lives Property and Equipment		Useful lives assigned to property and equipment are as follows: Laboratory equipment 3 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 to 10 years

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
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 (in thousands): December 31, 2017 2018 Sequencing revenue $ 22,759 $ 32,978 Development revenue: Development support 15,689 12,685 Regulatory milestones — 10,000 Total development revenue 15,689 22,685 Total revenue $ 38,448 $ 55,663

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
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 and liabilities as of December 31, 2018 and September 30, 2019 that were measured at fair value on a recurring basis (in thousands): December 31, 2018 Level 1 Level 2 Level 3 Total Financial assets Money market funds $ 45,998 $ — $ — $ 45,998 Commercial paper — 16,887 — 16,887 U.S. government debt and agency securities — 85,623 — 85,623 Corporate bonds — 7,478 — 7,478 Total financial assets $ 45,998 $ 109,988 $ — $ 155,986 Financial liabilities Convertible preferred stock warrant liability $ — $ — $ 336 $ 336 Total financial liabilities $ — $ — $ 336 $ 336 September 30, 2019 Level 1 Level 2 Level 3 Total (unaudited) Financial assets Money market funds $ 86,374 $ — $ — $ 86,374 Commercial paper — 136,842 — 136,842 U.S. government debt and agency securities — 419,011 — 419,011 Corporate bonds — 77,940 — 77,940 Total financial assets $ 86,374 $ 633,793 $ — $ 720,167	The following table sets forth the fair value of financial assets and liabilities that were measured at fair value on a recurring basis (in thousands): December 31, 2017 Level 1 Level 2 Level 3 Total Financial assets Money market funds $ 68,034 $ — $ — $ 68,034 Commercial paper — 22,360 — 22,360 U.S. government and agency securities — 83,717 — 83,717 Corporate bonds — 21,264 — 21,264 Total financial assets $ 68,034 $ 127,341 $ — $ 195,375 Financial liabilities Convertible preferred stock warrant liability $ — $ — $ 342 $ 342 Total financial liabilities $ — $ — $ 342 $ 342 December 31, 2018 Level 1 Level 2 Level 3 Total Financial assets Money market funds $ 45,998 $ — $ — $ 45,998 Commercial paper — 16,887 — 16,887 U.S. government and agency securities — 85,623 — 85,623 Corporate bonds — 7,478 — 7,478 Total financial assets $ 45,998 $ 109,988 $ — $ 155,986 Financial liabilities Convertible preferred stock warrant liability $ — $ — $ 336 $ 336 Total financial liabilities $ — $ — $ 336 $ 336
Summary of Fair Value of Convertible Preferred Stock Warrant Liability Estimated Using Black-Scholes Option Pricing Model		The fair value of the convertible preferred stock warrant liability is estimated using the Black-Scholes option-pricing model. Certain inputs were utilized in the option-pricing model as follows: December 31, 2017 December 31, 2018 Fair value estimate $ 7.67 $ 8.27 Expected term (in years) 3.31 2.31 Risk-free interest rate 2.0 % 2.5 % Expected volatility 61.5 % 55.3 % Expected dividend yield — —

Investments (Tables)

Investments (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Investments	Available-for-sale December 31, 2018 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value Short-term marketable securities Commercial paper $ 16,887 $ — $ — $ 16,887 U.S. government debt and agency securities 85,722 — (99 ) 85,623 Corporate bonds 7,486 — (8 ) 7,478 Total short-term marketable securities $ 110,095 $ — $ (107 ) $ 109,988 September 30, 2019 Amortized Cost Unrealized Gain Unrealized Loss Estimated Fair Value (unaudited) Short-term marketable securities Commercial paper $ 136,843 $ — $ — $ 136,843 U.S. government debt and agency securities 331,770 354 (15 ) 332,109 Corporate bonds 29,486 49 — 29,535 Total short-term marketable securities $ 498,099 $ 403 $ (15 ) $ 498,487 Long-term marketable securities: U.S. government debt and agency securities $ 86,813 $ 112 $ (23 ) $ 86,902 Corporate bonds 48,309 95 — 48,404 Total long-term marketable securities $ 135,122 $ 207 $ (23 ) $ 135,306	Available-for-sale December 31, 2017 Amortized cost Unrealized gain Unrealized loss Estimated fair value Short-term marketable securities Commercial paper $ 10,769 $ — $ — $ 10,769 U.S. government and agency securities 74,937 — (125 ) 74,812 Corporate bonds 21,284 — (20 ) 21,264 Total short-term marketable securities $ 106,990 $ — $ (145 ) $ 106,845 Long-term marketable securities U.S. government and agency securities $ 8,926 $ — $ (21 ) $ 8,905 Total long-term marketable securities $ 8,926 $ — $ (21 ) $ 8,905 December 31, 2018 Amortized cost Unrealized gain Unrealized loss Estimated fair value Short-term marketable securities Commercial paper $ 16,887 $ — $ — $ 16,887 U.S. government and agency securities 85,722 — (99 ) 85,623 Corporate bonds 7,486 — (8 ) 7,478 Total short-term marketable securities $ 110,095 $ — $ (107 ) $ 109,988
Schedule of Gross Unrealized Holding Losses and Fair Value for Investments in Unrealized Loss Position	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 September 30, 2019 (in thousands): Less Than 12 Months 12 Months Or Greater Fair Value Unrealized Loss Fair Value Unrealized Loss (unaudited) U.S. government debt and agency securities $ 53,975 $ (38 ) $ — $ — Total available-for-sale $ 53,975 $ (38 ) $ — $ —	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, 2018 (in thousands): December 31, 2018 Less than 12 months 12 months or greater Fair value Unrealized loss Fair value Unrealized loss Short-term marketable securities Corporate bonds $ 7,478 $ (8 ) $ — $ — U.S. government and agency securities 76,654 (85 ) 8,969 (14 ) Total short-term marketable securities $ 84,132 $ (93 ) $ 8,969 $ (14 )

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule Of Property and Equipment	Property and equipment consist of the following (in thousands): December 31, 2017 2018 Laboratory equipment $ 12,330 $ 14,009 Computer equipment 1,507 1,819 Furniture and equipment 971 1,300 Computer software 464 429 Construction in progress 376 3,942 Leasehold improvements 7,631 10,078 Property and equipment, at cost 23,279 31,577 Less accumulated depreciation (9,325 ) (12,452 ) Property and equipment, net $ 13,954 $ 19,125

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets Subject to Amortization	Intangible assets subject to amortization as of December 31, 2018 and September 30, 2019 consisted of the following (in thousands): December 31, 2018 Gross Carrying Accumulated Amortization Net Carrying Acquired developed technology $ 20,000 $ (6,636 ) $ 13,364 Purchased intellectual property 325 (63 ) 262 Balance at December 31, 2018 $ 20,325 $ (6,699 ) $ 13,626 September 30, 2019 Gross Carrying Accumulated Amortization Net Carrying (unaudited) Acquired developed technology $ 20,000 $ (7,882 ) $ 12,118 Purchased intellectual property 325 (87 ) 238 Balance at September 30, 2019 $ 20,325 $ (7,969 ) $ 12,356	Intangible assets subject to amortization as of the dates presented consist of the following (in thousands): December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Acquired developed technology $ 20,000 $ (4,969 ) $ 15,031 Purchased intellectual property 325 (31 ) 294 Balance at December 31, 2017 $ 20,325 $ (5,000 ) $ 15,325 December 31, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Acquired developed technology $ 20,000 $ (6,636 ) $ 13,364 Purchased intellectual property 325 (63 ) 262 Balance at December 31, 2018 $ 20,325 $ (6,699 ) $ 13,626
Schedule of Future Amortization Expense for Intangible Assets	As of September 30, 2019, expected future amortization expense for intangible assets was as follows (in thousands) (unaudited): 2019 $ 428 2020 1,698 2021 1,698 2022 1,698 2023 1,698 Thereafter 5,136 Total future amortization expense $ 12,356

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Schedule of Accrued liabilities	Accrued liabilities consist of the following (in thousands): December 31, 2017 2018 Accrued legal and professional fees $ 598 $ 1,634 Accrued royalties 22 31 Accrued travel and entertainment 44 73 Other vendor accruals 379 824 Total accrued liabilities $ 1,043 $ 2,562

Deferred Revenue (Tables)

Deferred Revenue (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Deferred Revenue by Revenue Classification	Deferred revenue by revenue classification as of December 31, 2018 and September 30, 2019 was as follows (in thousands): December 31, 2018 September 30, 2019 (unaudited) Current deferred revenue Sequencing $ 11,238 $ 12,419 Development 1,457 48,850 Total current deferred revenue 12,695 61,269 Non-current Sequencing 516 1,195 Development 188 227,144 Total non-current 704 228,339 Total current and non-current $ 13,399 $ 289,608	Deferred revenue by revenue classification was as follows (in thousands): December 31, 2017 2018 Deferred sequencing revenue $ 11,747 $ 11,754 Deferred development revenue 2,301 1,645 Total deferred revenue $ 14,048 $ 13,399
Changes in Deferred Revenue	Changes in deferred revenue during the nine months ended September 30, 2019 were as follows (in thousands): Deferred revenue balance at December 31, 2018 $ 13,399 Additions to deferred revenue during the period (unaudited) 312,248 Revenue recognized during the period (unaudited) (36,039 ) Deferred revenue balance at September 30, 2019 (unaudited) $ 289,608	Changes in deferred revenue were as follows (in thousands): December 31, 2018 Deferred revenue balance at December 31, 2017 $ 14,048 Additions to deferred revenue during the period 9,727 Revenue recognized during the period (10,376 ) Deferred revenue balance at December 31, 2018 $ 13,399

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	As of September 30, 2019, future minimum lease payments, exclusive of operating and maintenance costs and inclusive of payments to be made under the financing obligation, were as follows (in thousands) (unaudited): 2019 $ 901 2020 3,963 2021 6,745 2022 10,681 2023 10,985 Thereafter 107,570 Total future minimum lease payments $ 140,845	As of December 31, 2018, future minimum lease payments, exclusive of operating and maintenance costs, are as follows (in thousands): 2019 $ 3,561 2020 3,819 2021 3,917 2022 4,017 2023 2,295 Thereafter 2,315 Total future minimum lease payments $ 19,924

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Convertible Preferred Stock	Convertible preferred stock at December 31, 2018 consists of the following (in thousands, except share data): Shares authorized Shares issued and outstanding Amount Liquidation preference Series A 4,550,000 4,550,000 $ 12,405 $ 4,550 Series B 5,645,706 5,645,706 16,017 9,669 Series C 4,804,227 4,747,352 14,425 12,521 Series D 19,269,117 19,269,117 106,905 106,999 Series E 15,524,350 15,524,350 93,698 93,750 Series E-1 17,407,441 16,605,244 72,568 (1) 100,277 Series F 21,761,676 21,761,676 195,013 195,100 Series F-1 4,800,000 4,686,649 49,827 50,000 Total convertible preferred stock 93,762,517 92,790,094 $ 560,858 $ 572,866 (1) Includes vested Series E-1

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Equity [Abstract]
Summary of Reserved Shares of Common Stock	We have reserved shares of common stock for the following as of September 30, 2019 (unaudited): Shares issuable upon the exercise of outstanding common stock options and the vesting of outstanding common restricted stock units (“RSUs”) granted 17,495,253 Shares available for future grant under the 2019 Plan 15,474,217 Shares available for future grant under the Employee Stock Purchase Plan 1,551,917 Shares to be issued upon conversion of a common stock warrant 56,875 Total shares of common stock reserved for future issuance 34,578,262	We have reserved shares of common stock for the following as of December 31, 2018: Shares to be issued upon conversion of all series of convertible preferred stock 92,790,094 Shares to be issued upon exercise of outstanding common stock options 14,893,253 Shares available for future stock option grants 6,827,996 Shares to be issued upon exercise of outstanding Series E-1 264,677 Shares to be issued upon conversion of Series C convertible preferred stock in connection with warrant exercise 56,875 Shares to be issued upon conversion of common stock warrants 55,032 Shares of common stock reserved for future issuance 114,887,927

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Summary of Option Activity	Stock option activity under the 2008 Plan, 2009 Plan and 2019 Plan during the nine months ended September 30, 2019 is as follows: Shares Subject to Outstanding Options Weighted- Average Exercise Price per Share Aggregate Intrinsic Value (in thousands) Options outstanding at December 31, 2018 15,157,930 $ 4.52 $ 41,690 Options granted (unaudited) 4,071,846 9.15 Options forfeited or cancelled (unaudited) (367,675 ) 6.08 Options exercised (unaudited) (1,379,658 ) 1.67 Options outstanding at September 30, 2019 (unaudited) 17,482,443 5.79 438,968
Summary of Estimated Fair Value of Options Granted	The estimated fair value of options granted during the nine months ended September 30, 2018 and 2019 was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions: Nine Months Ended September 30, 2018 2019 (unaudited) Grant date fair value $ 6.55 $ 10.08 Expected term (in years) 6.15 6.06 Risk-free interest rate 2.7 % 2.4 % Expected volatility 68.9 % 68.0 % Expected dividend yield — —	The estimated fair value of options granted during 2017 and 2018 was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions for our 2009 Plan: Year Ended December 31, 2017 2018 Grant date fair value $ 6.27 $ 6.55 Expected term (in years) 6.12 6.14 Risk-free interest rate 2.0 % 2.7 % Expected volatility 70.2 % 68.1 % Expected dividend yield — —
Summary of Compensation Costs Related to Stock Options and RSUs Included on Statements of Operations	The compensation costs for the three and nine months ended September 30, 2018 and 2019, respectively, related to stock options and RSUs are included on our unaudited condensed statements of operations as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 (unaudited) Cost of revenue $ 97 $ 133 $ 273 $ 376 Research and development 700 943 2,168 2,838 Sales and marketing 620 798 2,169 2,647 General and administration 1,136 1,461 3,493 3,852 Total share-based compensation expense $ 2,553 $ 3,335 $ 8,103 $ 9,713	The compensation costs related to stock options are included in the statements of operations as follows (in thousands): Year Ended December 31, 2017 2018 Cost of revenue $ 237 $ 398 Research and development 2,375 2,896 Sales and marketing 1,344 2,891 General and administration 3,053 4,964 Total share-based compensation expense $ 7,009 $ 11,149
Summary of Changes in Shares Available for Grant	Changes in shares available for grant during the nine months ended September 30, 2019 were as follows: Shares Shares available for grant at December 31, 2018 6,827,996 2019 Plan reserve (unaudited) 12,363,202 Options and RSUs granted (unaudited) (4,084,656 ) Options and RSUs forfeited or cancelled (unaudited) 367,675 Shares available for grant at September 30, 2019 (unaudited) 15,474,217
2009 Equity Incentive Plan
Summary of Option Activity		A summary of our option and restricted stock unit (“RSU”) activity is as follows: Shares available for grant Shares subject to outstanding options Weighted- average exercise price per share Aggregate intrinsic value (in thousands) Outstanding at December 31, 2016 3,423,473 12,985,266 $ 3.46 $ 37,138 Authorized — — — Options granted (1,604,496 ) 1,604,496 6.27 RSUs forfeited 880,487 (880,487 ) — Forfeited 2,086,035 (2,086,035 ) 5.80 Exercised — (54,685 ) 1.73 Outstanding at December 31, 2017 4,785,499 11,568,555 3.70 32,970 Authorized 6,000,000 — — Options granted (4,764,625 ) 4,764,625 6.55 Forfeited 807,122 (807,122 ) 5.54 Exercised — (632,805 ) 1.85 Outstanding at December 31, 2018 6,827,996 14,893,253 4.59 39,864
Summary Of Stock Options Outstanding and Exercisable		The following table summarizes information about stock options outstanding and exercisable at December 31, 2018: Exercise price Options outstanding Weighted- average remaining contractual life (years) Options exercisable Aggregate intrinsic value (in thousands) $ 0.16 469,109 1.36 469,109 0.33 1,428,959 2.90 1,428,959 0.45 641,000 3.95 641,000 0.84 1,115,225 5.05 1,115,225 1.98 1,040,500 5.65 1,040,500 4.07 409,194 6.22 395,005 6.27 672,353 6.73 402,321 6.32 4,431,538 6.71 3,623,123 6.55 4,685,375 9.29 947,049 14,893,253 6.66 10,062,291 $ 36,089
Sequenta, Inc. 2008 Stock Plan | Series E-1 Convertible Preferred Stock Options
Summary of Option Activity		A summary of our Series E-1 Convertible preferred shares subject to outstanding options Weighted- average exercise price per share Aggregate intrinsic value (in thousands) Outstanding at December 31, 2016 814,563 $ 0.56 $ 4,814 Options granted — — Forfeited (121,898 ) 0.55 Exercised (171,526 ) 0.74 Outstanding at December 31, 2017 521,139 0.50 3,195 Options granted — — Forfeited (122,397 ) 0.36 Exercised (134,065 ) 0.75 Outstanding at December 31, 2018 264,677 0.44 1,826
Summary Of Stock Options Outstanding and Exercisable		The following table summarizes information about convertible preferred stock options outstanding and exercisable at December 31, 2018: Exercise price Options outstanding Weighted- average remaining contractual life (years) Options exercisable Aggregated intrinsic value (in thousands) $ 0.10 104,652 0.63 104,652 0.28 10,153 2.23 10,153 0.55 74,473 4.08 74,473 0.82 70,518 5.12 70,480 0.92 4,881 5.37 4,881 264,677 2.94 264,639 $ 1,826

Restructuring Charges (Tables)

Restructuring Charges (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Summary of Restructuring Related Balance Sheet Accounts	The following table summarizes the activity within the restructuring related balance sheet accounts during the year ended December 31, 2017 (in thousands): One-time termination benefits Asset impairments and net loss on sale or disposal Other (1) Total Balance at December 31, 2016 $ 2,564 $ — $ — $ 2,564 Costs incurred and charged to expense 512 210 118 840 Cash payments (3,076 ) — (118 ) (3,194 ) Non-cash — (210 ) — (210 ) Balance at December 31, 2017 $ — $ — $ — $ — (1) “Other” primarily reflects activities associated with the consolidation of our facilities and manufacturing operations, including contract termination costs.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Deferred Tax Assets and Liabilities	The significant components of our deferred tax assets and liabilities are as follows (in thousands): December 31, 2017 2018 Deferred tax assets: Net operating losses $ 47,840 $ 56,555 Tax credit carryforward 5,463 6,709 Non qualifying stock options 4,865 7,861 Other 3,774 4,523 Total deferred tax assets 61,942 75,648 Valuation allowance (56,679 ) (70,722 ) Deferred tax assets, net of valuation allowance 5,263 4,926 Deferred tax liabilities: Tangible and intangible assets (5,263 ) (4,926 ) Net deferred taxes $ — $ —
Schedule of Reconciliation of effective tax rate of provision for income taxes with federal statutory rate	The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows: Year ended December 31, 2017 2018 Statutory rate 34.0 % 21.0 % State tax 1.8 5.5 Stock compensation (1.7 ) 0.5 Permanent items (0.1 ) 0.5 Credits 2.7 2.7 TCJA change in federal rate (58.4 ) — Other (0.7 ) 0.2 Change in valuation allowance 22.3 (30.3 ) Total 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 two years ended December 31, 2017 and 2018 are as follows (in thousands): Balance at December 31, 2016 $ 844 Additions in 2017 187 Balance at December 31, 2017 1,031 Additions in 2018 229 Balance at December 31, 2018 $ 1,260

Net Loss and Unaudited Pro Fo_2

Net Loss and Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Computation of the Basic and Diluted Net Loss Per Share Attributable to Common Shareholders	The following table sets forth the computation of the basic and diluted net loss per share attributable to common shareholders for the three and nine months ended September 30, 2018 and 2019, respectively (in thousands, except shares and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 (unaudited) Net loss $ (8,292 ) $ (13,950 ) $ (33,176 ) $ (47,995 ) Fair value adjustments to redemption value for Series E-1 (4 ) — (2 ) (964 ) Net loss attributable to common shareholders, basic and diluted $ (8,296 ) $ (13,950 ) $ (33,178 ) $ (48,959 ) Weighted-average shares used in computing net loss per share 12,620,010 124,285,686 12,430,535 50,552,389 Net loss per share attributable to common shareholders, basic and diluted $ (0.66 ) $ (0.11 ) $ (2.67 ) $ (0.97 )	The following table sets forth the computation of the basic and diluted net loss per share attributable to common shareholders (in thousands, except shares and per share amounts): Year ended December 31, 2017 2018 Net loss $ (42,831 ) $ (46,447 ) Fair value adjustments to redemption value for Series E-1 135 102 Net loss attributable to common shareholders, basic and diluted $ (42,696 ) $ (46,345 ) Weighted-average shares used in computing net loss per share 12,196,998 12,629,778 Net loss per share attributable to common shareholders, basic and diluted $ (3.50 ) $ (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 three and nine months ended September 30, 2018 and 2019, respectively, as they had an anti-dilutive effect: Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 (unaudited) Convertible preferred stock (on as if converted basis) 92,790,094 — 92,764,348 61,641,506 Stock options issued and outstanding 14,801,784 17,466,409 14,489,718 17,096,516 Unvested restricted stock units — 7,380 — 2,487 Common stock warrants 55,032 56,875 55,032 55,653 Convertible preferred stock warrant 56,875 — 56,875 37,708 Total 107,703,785 17,530,664 107,365,973 78,833,870	The following weighted-average common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common shareholders for the periods presented as they had an anti-dilutive effect: Year ended December 31, 2017 2018 Convertible preferred stock (on as if converted basis) 88,473,431 92,783,867 2009 Plan stock options issued and outstanding 12,022,454 14,368,063 2008 Plan stock options issued and outstanding 622,472 333,563 Common stock warrants 55,032 55,032 Convertible preferred stock warrants 56,875 56,875 Total 101,230,264 107,597,400
Summary of unaudited pro forma basic and diluted net loss per share attributable to common shareholders		The following table sets forth the computation of the unaudited pro forma basic and diluted net loss per share attributable to common shareholders (in thousands, except shares and per share amounts): Year Ended December 31, 2018 Numerator: Pro forma net loss attributable to common shareholders, basic and diluted $ (46,345 ) Denominator: Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted 12,629,778 Weighted-average shares of common stock issued upon assumed conversion of convertible preferred stock in an initial public offering 92,783,867 Weighted-average shares of common stock issued upon assumed conversion of a common stock warrant in an initial public offering 20,000 Weighted-average shares used in computing pro forma net loss per share attributable to common shareholders, basic and diluted 105,433,645 Pro forma net loss per share attributable to common shareholders, basic and diluted $ (0.44 )

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)shares	Sep. 30, 2019USD ($)Performance_Obligationshares	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)Segmentshares	Dec. 31, 2017USD ($)	Dec. 31, 2014USD ($)$ / sharesshares
Significant Accounting Policies [Line Items]
Restricted cash	$ 2,100,000	$ 2,100,000		$ 100,000	$ 100,000
Allowance for doubtful accounts				100,000	100,000
Unbilled receivables				400,000	1,400,000
Impairment expense in research and development					300,000
Impairment expense from asset disposals					200,000
Impairment of goodwill				0
Impairment losses on intangible assets				0
Warrants issued to purchase stock | shares	56,875	56,875
Fair value adjustment of warrants		$ 2,266,000		$ (6,000)	(23,000)
Interest or penalties related to income tax					0
Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares | shares				20,000
Number of operating segment | Segment				1
Increase (decrease) in accounts receivable		4,398,000	$ 6,787,000	$ (775,000)	2,427,000
Accounting Standards Update 2016-09
Significant Accounting Policies [Line Items]
Cumulative impact to accumulated deficit		$ 100,000		100,000
Accounting Standards Update 2014-09 [Member]
Significant Accounting Policies [Line Items]
Increase (decrease) in accounts receivable					400,000
Increase (decrease) in deferred revenue					(100,000)
Sequencing Revenue
Significant Accounting Policies [Line Items]
Number of revenue performance obligations | Performance_Obligation		2
Sequencing Revenue From Coverage Policy
Significant Accounting Policies [Line Items]
Revenue recognized	$ 300,000	$ 1,100,000
Sequencing Revenue From Test Deliver
Significant Accounting Policies [Line Items]
Revenue recognized	100,000	400,000
Property and Equipment, Net
Significant Accounting Policies [Line Items]
Building costs	23,400,000	23,400,000
Additional Paid In Capital
Significant Accounting Policies [Line Items]
Deferred offering costs	$ 5,000,000	$ 5,000,000
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
Fair value adjustment of warrants				$ (6,000)	$ (23,000)

Significant Accounting Polici_5

Significant Accounting Policies - Schedule of Concentrations of Risk Percentage (Detail) - Customer Concentration Risk	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Customer A | Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage	16.00%	15.70%	11.80%	21.60%	18.40%	31.40%
Customer A | Accounts Receivable, Net
Significant Accounting Policies [Line Items]
Concentration risk, percentage			39.60%			29.90%
Customer B | Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage	10.70%				13.50%
Customer B | Accounts Receivable, Net
Significant Accounting Policies [Line Items]
Concentration risk, percentage					15.10%	14.90%
Customer C | Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage		35.00%		19.10%	15.40%
Customer C | Accounts Receivable, Net
Significant Accounting Policies [Line Items]
Concentration risk, percentage					13.20%
Genentech, Inc. | Revenue
Significant Accounting Policies [Line Items]
Concentration risk, percentage	43.90%		43.70%

Significant Accounting Polici_6

Significant Accounting Policies - Schedule of Useful Lives of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2018
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 D

Revenue - Schedule of Revenue Disaggregated by Type of Products and Services (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 26,058	$ 17,188	$ 60,862	$ 38,471	$ 55,663	$ 38,448
Sequencing Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	11,683	8,463	29,631	22,524	32,978	22,759
Development Support Revenue
Disaggregation Of Revenue [Line Items]
Total revenue					12,685	15,689
Development Revenue Regulatory Milestones
Disaggregation Of Revenue [Line Items]
Total revenue					10,000
Development Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	$ 14,375	$ 8,725	$ 31,231	$ 15,947	$ 22,685	$ 15,689

Revenue - Additional Informatio

Revenue - Additional Information (Detail) - USD ($)	Sep. 30, 2019	Dec. 18, 2015	Feb. 28, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Revenue recognized	$ 6,400,000					$ 36,039,000		$ 10,376,000
Revenue from collaboration agreement				$ 26,058,000	$ 17,188,000	60,862,000	$ 38,471,000	55,663,000	$ 38,448,000
Translational Development Agreements
Disaggregation Of Revenue [Line Items]
Term of agreement		4 years
Agreement termination amount receivable		$ 800,000
Revenue recognized excluding separately negotiated research sequencing contracts				600,000	2,500,000	1,700,000	7,500,000	9,300,000	10,000,000
Revenue recognized excluding sequencing revenue								600,000	600,000
Eligible payments receivable		2,300,000
Translational Development Agreements | Maximum
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		$ 40,000,000
MRD Development Agreements
Disaggregation Of Revenue [Line Items]
Milestone revenue recognized				2,000,000	2,000,000	6,000,000	6,000,000	10,000,000
Revenue recognized				2,300,000	$ 6,100,000	3,100,000	$ 8,000,000	12,800,000	$ 5,100,000
MRD Development Agreements | Maximum
Disaggregation Of Revenue [Line Items]
Additional milestone payment receivable	129,000,000			129,000,000		129,000,000		$ 99,500,000
Genentech Collaboration Agreement
Disaggregation Of Revenue [Line Items]
Non-refundable upfront payments received			$ 300,000,000			300,000,000
Revenue from collaboration agreement				11,400,000		$ 26,200,000
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		75,000,000	75,000,000		$ 75,000,000
Genentech Collaboration Agreement | Maximum | Development Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	300,000,000		300,000,000	300,000,000		300,000,000
Genentech Collaboration Agreement | Maximum | Commercial Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	1,430,000,000		1,400,000,000	1,430,000,000		1,430,000,000
Genentech Collaboration Agreement | Minimum
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments	$ 1,800,000,000		$ 1,800,000,000	$ 1,800,000,000		$ 1,800,000,000
Revenue recognition expected period						7 years

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Financial assets
Total financial assets	$ 720,167	$ 155,986	$ 195,375
Financial liabilities
Total financial liabilities		336	342
Convertible Preferred Stock Warrant Liability
Financial liabilities
Total financial liabilities		336	342
Level 1
Financial assets
Total financial assets	86,374	45,998	68,034
Level 2
Financial assets
Total financial assets	633,793	109,988	127,341
Level 3
Financial liabilities
Total financial liabilities		336	342
Level 3 | Convertible Preferred Stock Warrant Liability
Financial liabilities
Total financial liabilities		336	342
Money Market Funds
Financial assets
Total financial assets	86,374	45,998	68,034
Money Market Funds | Level 1
Financial assets
Total financial assets	86,374	45,998	68,034
Commercial Paper
Financial assets
Total financial assets	136,842	16,887	22,360
Commercial Paper | Level 2
Financial assets
Total financial assets	136,842	16,887	22,360
U.S. Government Debt and Agency Securities
Financial assets
Total financial assets	419,011	85,623	83,717
U.S. Government Debt and Agency Securities | Level 2
Financial assets
Total financial assets	419,011	85,623	83,717
Corporate Bonds
Financial assets
Total financial assets	77,940	7,478	21,264
Corporate Bonds | Level 2
Financial assets
Total financial assets	$ 77,940	$ 7,478	$ 21,264

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Fair Value of Convertible Preferred Stock Warrant Liability Estimated Using Black-Scholes Option Pricing Model (Detail) - Convertible Preferred Stock Warrant Liability	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Measurement Input, Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value estimates	$ 8.27	$ 7.67
Measurement Input, Expected Term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Expected term (in years)	2 years 3 months 21 days	3 years 3 months 21 days
Measurement Input, Risk Free Interest Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement input	0.025	0.020
Measurement Input, Price Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement input	0.553	0.615

Investments - Schedule of Avail

Investments - Schedule of Available-for-sale Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	$ 498,099	$ 110,095	$ 106,990
Unrealized Gain	403
Unrealized Loss	(15)	(107)	(145)
Estimated Fair Value	498,487	109,988	106,845
Long-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	135,122		8,926
Unrealized Gain	207
Unrealized Loss	(23)		(21)
Estimated Fair Value	135,306		8,905
Commercial Paper | Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	136,843	16,887	10,769
Estimated Fair Value	136,843	16,887	10,769
U.S. Government Debt and Agency Securities | Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	331,770	85,722	74,937
Unrealized Gain	354
Unrealized Loss	(15)	(99)	(125)
Estimated Fair Value	332,109	85,623	74,812
U.S. Government Debt and Agency Securities | Long-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	86,813		8,926
Unrealized Gain	112
Unrealized Loss	(23)		(21)
Estimated Fair Value	86,902		8,905
Corporate Bonds | Short-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	29,486	7,486	21,284
Unrealized Gain	49
Unrealized Loss		(8)	(20)
Estimated Fair Value	29,535	$ 7,478	$ 21,264
Corporate Bonds | Long-Term Marketable Securities
Schedule of Available-for-Sale Securities [Line Items]
Amortized Cost	48,309
Unrealized Gain	95
Estimated Fair Value	$ 48,404

Investments - Schedule of Gross

Investments - Schedule of Gross Unrealized Holding Losses and Fair Value for Investments in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-Sale Securities [Line Items]
Less than 12 months, Fair value	$ 53,975	$ 84,132
Less than 12 months, Unrealized loss	(38)	(93)
12 months or greater, Fair value		8,969
12 months or greater, Unrealized loss		(14)
U.S. Government Debt and Agency Securities
Schedule of Available-for-Sale Securities [Line Items]
Less than 12 months, Fair value	53,975	76,654
Less than 12 months, Unrealized loss	$ (38)	(85)
12 months or greater, Fair value		8,969
12 months or greater, Unrealized loss		(14)
Corporate Bonds
Schedule of Available-for-Sale Securities [Line Items]
Less than 12 months, Fair value		7,478
Less than 12 months, Unrealized loss		$ (8)

Property and Equipment, Net - S

Property and Equipment, Net - Schedule Of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property and equipment, at cost		$ 31,577	$ 23,279
Less accumulated depreciation		(12,452)	(9,325)
Property and equipment, net	$ 46,542	19,125	13,954
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost		14,009	12,330
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost		1,819	1,507
Furniture and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost		1,300	971
Computer Software
Property Plant And Equipment [Line Items]
Property and equipment, at cost		429	464
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, at cost		3,942	376
Leaseholds and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, at cost		$ 10,078	$ 7,631

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation	$ 4,446	$ 3,136	$ 4,301	$ 4,102

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Summary of Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 20,325	$ 20,325	$ 20,325
Accumulated Amortization	(7,969)	(6,699)	(5,000)
Net Carrying Amount	12,356	13,626	15,325
Acquired Developed Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	20,000	20,000	20,000
Accumulated Amortization	(7,882)	(6,636)	(4,969)
Net Carrying Amount	12,118	13,364	15,031
Purchased Intellectual Property
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	325	325	325
Accumulated Amortization	(87)	(63)	(31)
Net Carrying Amount	$ 238	$ 262	$ 294

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Goodwill [Line Items]
Amortization of intangible assets	$ 428,000	$ 428,000	$ 1,270,000	$ 1,271,000	$ 1,699,000	$ 1,694,000
Goodwill	$ 118,972,000		$ 118,972,000		$ 118,972,000	$ 118,972,000	$ 0
Purchased Intellectual Property
Goodwill [Line Items]
Amortization period of intangible assets			7 years 3 months 18 days		8 years
Amortization of intangible assets					$ 1,700,000

Accrued liabilities - Schedule

Accrued liabilities - Schedule of Accrued liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued legal and professional fees		$ 1,634	$ 598
Accrued royalties		31	22
Accrued travel and entertainment		73	44
Other vendor accruals		824	379
Total accrued liabilities	$ 3,381	$ 2,562	$ 1,043

Deferred Revenue - Schedule of

Deferred Revenue - Schedule of Deferred Revenue by Revenue Classification (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Current deferred revenue
Total current deferred revenue	$ 61,269	$ 12,695	$ 14,048
Non-current deferred revenue
Total non-current deferred revenue	228,339	704
Total current and non-current deferred revenue	289,608	13,399	14,048
Sequencing Revenue
Current deferred revenue
Total current deferred revenue	12,419	11,238
Non-current deferred revenue
Total non-current deferred revenue	1,195	516
Total current and non-current deferred revenue		11,754	11,747
Development Revenue
Current deferred revenue
Total current deferred revenue	48,850	1,457
Non-current deferred revenue
Total non-current deferred revenue	$ 227,144	188
Total current and non-current deferred revenue		$ 1,645	$ 2,301

Deferred Revenue - Additional I

Deferred Revenue - Additional Information (Details) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2017
Disaggregation Of Revenue [Line Items]
Revenue recognized	$ 6,400	$ 36,039	$ 10,376
Deferred revenue					$ 10,400
Current deferred revenue	61,269	61,269	12,695	$ 14,048
Deferred revenue, less current portion	228,339	228,339	704
Sequencing Revenue
Disaggregation Of Revenue [Line Items]
Revenue recognized		1,500	3,400
Current deferred revenue	12,419	12,419	11,238
Deferred revenue, less current portion	1,195	1,195	516
Development Revenue
Disaggregation Of Revenue [Line Items]
Current deferred revenue	48,850	48,850	1,457
Deferred revenue, less current portion	227,144	227,144	$ 188
Genentech, Inc. | Development Revenue
Disaggregation Of Revenue [Line Items]
Current deferred revenue	47,400	47,400
Deferred revenue, less current portion	$ 226,400	$ 226,400

Deferred Revenue - Schedule o_2

Deferred Revenue - Schedule of Changes in Deferred Revenue (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Beginning balance		$ 13,399	$ 14,048
Additions to deferred revenue during the period		312,248	9,727
Revenue recognized during the period	$ (6,400)	(36,039)	(10,376)
Ending balance	$ 289,608	$ 289,608	$ 13,399

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2019USD ($)ft²	Apr. 30, 2018	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Lease term description					The lease term is through March 2026 and provides for one five-year option.		The lease term is through March 2026 and provides for one five-year option.
Payments for tenant improvements					$ 2.4		$ 2.4
Lessee, operating lease, extended term of contract	5 years	5 years
Rent expenses			$ 1.3	$ 1.1	$ 3.6	$ 2.9	$ 4.1	$ 3.7
Lease expiration date	Mar. 31, 2024
Number of square feet to-be-constructed | ft²	100,000
Lessee operating lease, rent obligations to commence period	10 months
Lessee, operating lease, term of contract	142 months
Lessee, operating lease, option to extend	Rent obligations commence 10 months thereafter, and the lease term ends 142 months from the date rent commences, subject to our option to twice extend the lease for five years.
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Landlord contribution for leasehold improvements	$ 20
Letter of credit	$ 2.1

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Operating Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	$ 901	$ 3,561
2020	3,963	3,819
2021	6,745	3,917
2022	10,681	4,017
2023	10,985	2,295
Thereafter	107,570	2,315
Total future minimum lease payments	$ 140,845	$ 19,924

Convertible Preferred Stock - S

Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized	0	93,762,517	93,762,517
Convertible preferred stock,Shares issued and outstanding		92,790,094
Convertible preferred stock,Amount		$ 560,858	$ 561,333
Convertible preferred stock,Liquidation Preference	$ 0	$ 572,866	$ 572,057
Series A
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		4,550,000
Convertible preferred stock,Shares issued and outstanding		4,550,000
Convertible preferred stock,Amount		$ 12,405
Convertible preferred stock,Liquidation Preference		$ 4,550
Series B
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		5,645,706
Convertible preferred stock,Shares issued and outstanding		5,645,706
Convertible preferred stock,Amount		$ 16,017
Convertible preferred stock,Liquidation Preference		$ 9,669
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		4,804,227
Convertible preferred stock,Shares issued and outstanding		4,747,352
Convertible preferred stock,Amount		$ 14,425
Convertible preferred stock,Liquidation Preference		$ 12,521
Series D
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		19,269,117
Convertible preferred stock,Shares issued and outstanding		19,269,117
Convertible preferred stock,Amount		$ 106,905
Convertible preferred stock,Liquidation Preference		$ 106,999
Series E
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		15,524,350
Convertible preferred stock,Shares issued and outstanding		15,524,350
Convertible preferred stock,Amount		$ 93,698
Convertible preferred stock,Liquidation Preference		$ 93,750
Series E-1 Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		17,407,441
Convertible preferred stock,Shares issued and outstanding		16,605,244
Convertible preferred stock,Amount		$ 72,568
Convertible preferred stock,Liquidation Preference		$ 100,277
Series F
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		21,761,676
Convertible preferred stock,Shares issued and outstanding		21,761,676
Convertible preferred stock,Amount		$ 195,013
Convertible preferred stock,Liquidation Preference		$ 195,100
Series F-1
Temporary Equity [Line Items]
Convertible preferred stock,Shares authorized		4,800,000
Convertible preferred stock,Shares issued and outstanding		4,686,649
Convertible preferred stock,Amount		$ 49,827
Convertible preferred stock,Liquidation Preference		$ 50,000

Convertible Preferred Stock -_2

Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Series E-1 Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock options, vested	$ 1.8

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Proceeds from public offering	$ 320,850
Convertible preferred stock outstanding	0	92,790,094	92,656,029
Minimum
Temporary Equity [Line Items]
Proceeds from public offering		$ 25,000
Series A
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		$ 1
Series B
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		1.7127
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		2.6374
Series D
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		5.5529
Convertible preferred stock dividends per share		$ 0.4442
Convertible preferred stock outstanding		4,000,000
Series E
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		$ 6.0389
Convertible preferred stock dividends per share		$ 0.4831
Convertible preferred stock outstanding		4,000,000
Series E-1 Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		$ 6.0389
Redemption of preferred stock		$ 1,800
Series F
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		$ 8.9653
Convertible preferred stock dividends per share		$ 0.7172
Convertible preferred stock outstanding		4,000,000
Series F-1
Temporary Equity [Line Items]
Convertible preferred stock Conversion price per share		$ 10.6686
Convertible preferred stock dividends per share		$ 0.8535
Convertible preferred stock outstanding		4,000,000

Shareholders' Deficit - Additio

Shareholders' Deficit - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2019Vote$ / sharesshares	Dec. 31, 2018Vote$ / sharesshares	Dec. 31, 2017$ / sharesshares
Class of Stock [Line Items]
Common stock authorized	340,000,000	131,000,000	131,000,000
Common stock par value | $ / shares	$ 0.0001	$ 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.	Holders of our common stock are entitled to one vote for each share of common stock held.
Number of vote for each share | Vote	0	0
Warrants issued to purchase stock	56,875
Common Stock
Class of Stock [Line Items]
Warrants issued to purchase stock	20,000	20,000
Warrant exercisable term	10 years	10 years
Weighted-average exercise price of warrants | $ / shares	$ 0.37	$ 0.37
Exercise price of warrants | $ / shares	$ 0.45	$ 0.45
Common Stock | Maximum
Class of Stock [Line Items]
Warrants issued to purchase stock	55,032	55,032

Shareholders' Deficit - Summary

Shareholders' Deficit - Summary of Reserved Shares of Common Stock (Detail) - shares	Sep. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	34,578,262	114,887,927
Convertible Preferred Stock
Class of Stock [Line Items]
Shares of common stock reserved for future issuance		92,790,094
Common Shares Outstanding For Stock Options
Class of Stock [Line Items]
Shares of common stock reserved for future issuance		14,893,253
Future Stock Option Grants
Class of Stock [Line Items]
Shares of common stock reserved for future issuance		6,827,996
Series E-1 Convertible Preferred Stock Options
Class of Stock [Line Items]
Shares of common stock reserved for future issuance		264,677
Series C Convertible Preferred Stock With Warrant Exercise
Class of Stock [Line Items]
Shares of common stock reserved for future issuance		56,875
Conversion Of Common Stock Warrants [Member]
Class of Stock [Line Items]
Shares of common stock reserved for future issuance		55,032

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 01, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of options granted			$ 10.08	$ 6.55	$ 6.55	$ 6.27
Number of options granted			4,071,846
Expected dividend yield			0.00%	0.00%	0.00%	0.00%
Share-based compensation expense	$ 3,335	$ 2,553	$ 9,713	$ 8,103	$ 11,149	$ 7,009
Unrecognized share-based compensation expense related to unvested stock options	$ 34,500		$ 34,500		$ 18,300
Unrecognized share-based compensation expense related to unvested stock options, weighted-average period for recognition			3 years 21 days		2 years 8 months 19 days
Initial share reserve	34,578,262		34,578,262		114,887,927
Option Valuation Model
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield				0.00%	0.00%
Stock Option Modifications [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation resulted from option modification					$ 500
Convertible Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Initial share reserve					92,790,094
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			8 months 23 days
Unrecognized share-based compensation expense related to unvested RSUs	$ 300		$ 300
2009 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance					6,827,996	4,785,499	3,423,473
Share-based compensation forfeited shares						880,487
Weighted-average exercise price for options exercisable					$ 3.68
Weighted-average grant date fair value of options granted					$ 4.15	$ 4
Intrinsic value of awards exercised					$ 3,000	$ 300
Number of options granted					4,764,625	1,604,496
2009 Equity Incentive Plan | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance		0		0	21,721,249
2009 Equity Incentive Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation granted shares							880,487
Share-based compensation forfeited shares						880,487
2019 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance	15,474,217,000		15,474,217,000		6,827,996,000
Initial share reserve								15,519,170
2019 Plan | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Initial share reserve	15,519,170		15,519,170
2019 Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation granted shares			12,810
Weighted-average grant date fair value per share			$ 41.63
Sequenta 2008 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for issuance		0		0
Sequenta, Inc. 2008 Stock Plan | Convertible Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of awards exercised					$ 800	$ 1,000
Number of options granted					0	0
Maximum | 2009 Equity Incentive Plan | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period			10 years		10 years
Maximum | 2019 Plan | Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period			10 years

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Option and Restricted Stock Unit Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares subject to outstanding options, Beginning balance	15,157,930
Shares subject to outstanding options, Options granted	4,071,846
Shares subject to outstanding, Forfeited	(367,675)
Shares subject to outstanding, Exercised	(1,379,658)
Shares subject to outstanding, Ending balance	17,482,443	15,157,930
Weighted Average Exercise Price per Share, Options granted	$ 9.15
2009 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant, Beginning balance	6,827,996	4,785,499	3,423,473
Shares available for grant, Authorized		6,000,000
Shares available for grant, Options granted		(4,764,625)	(1,604,496)
Shares available for grant, RSUs forfeited			880,487
Shares available for grant, Forfeited		807,122	2,086,035
Shares available for grant, Exercised		0	0
Shares available for grant, Ending balance		6,827,996	4,785,499
Shares subject to outstanding options, Beginning balance	14,893,253	11,568,555	12,985,266
Shares subject to outstanding options, Authorized		0	0
Shares subject to outstanding options, Options granted		4,764,625	1,604,496
Shares subject to outstanding, RSUs forfeited			(880,487)
Shares subject to outstanding, Forfeited		(807,122)	(2,086,035)
Shares subject to outstanding, Exercised		(632,805)	(54,685)
Shares subject to outstanding, Ending balance		14,893,253	11,568,555
Weighted average exercise price per share, Outstanding, Beginning Balance	$ 4.59	$ 3.70	$ 3.46
Weighted average exercise price per share, Authorized		0	0
Weighted Average Exercise Price per Share, Options granted		6.55	6.27
Weighted average exercise price per share, RSUs forfeited			0
Weighted average exercise price per share, Forfeited		5.54	5.80
Weighted average exercise price per share, Exercise		1.85	1.73
Weighted average exercise price per share, Outstanding, Ending Balance		$ 4.59	$ 3.70
Aggregate intrinsic value, Outstanding		$ 39,864	$ 32,970	$ 37,138

Equity Incentive Plans - Summ_2

Equity Incentive Plans - Summary of Stock Options Outstanding and Exercisable (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2016
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding	15,157,930	17,482,443
2009 Equity Incentive Plan
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 3.68
Options outstanding	14,893,253		11,568,555	12,985,266
2009 Equity Incentive Plan | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding	14,893,253
Weighted- average remaining contractual life (years)	6 years 7 months 28 days
Options exercisable	10,062,291
Aggregate intrinsic value (in thousands)	$ 36,089
2009 Equity Incentive Plan | Exercise Price One | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.16
Options outstanding	469,109
Weighted- average remaining contractual life (years)	1 year 4 months 9 days
Options exercisable	469,109
2009 Equity Incentive Plan | Exercise Price Two | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.33
Options outstanding	1,428,959
Weighted- average remaining contractual life (years)	2 years 10 months 24 days
Options exercisable	1,428,959
2009 Equity Incentive Plan | Exercise Price Three. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.45
Options outstanding	641,000
Weighted- average remaining contractual life (years)	3 years 11 months 12 days
Options exercisable	641,000
2009 Equity Incentive Plan | Exercise Price Four. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.84
Options outstanding	1,115,225
Weighted- average remaining contractual life (years)	5 years 18 months
Options exercisable	1,115,225
2009 Equity Incentive Plan | Exercise Price Five. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 1.98
Options outstanding	1,040,500
Weighted- average remaining contractual life (years)	5 years 7 months 24 days
Options exercisable	1,040,500
2009 Equity Incentive Plan | Exercise Price Six. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 4.07
Options outstanding	409,194
Weighted- average remaining contractual life (years)	6 years 2 months 19 days
Options exercisable	395,005
2009 Equity Incentive Plan | Exercise Price Seven. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 6.27
Options outstanding	672,353
Weighted- average remaining contractual life (years)	6 years 8 months 23 days
Options exercisable	402,321
2009 Equity Incentive Plan | Exercise Price Eight. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 6.32
Options outstanding	4,431,538
Weighted- average remaining contractual life (years)	6 years 8 months 15 days
Options exercisable	3,623,123
2009 Equity Incentive Plan | Exercise Price Nine. | Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 6.55
Options outstanding	4,685,375
Weighted- average remaining contractual life (years)	9 years 3 months 14 days
Options exercisable	947,049
Sequenta, Inc. 2008 Stock Plan | Convertible Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding	264,677
Weighted- average remaining contractual life (years)	2 years 11 months 8 days
Options exercisable	264,639
Aggregate intrinsic value (in thousands)	$ 1,826
Sequenta, Inc. 2008 Stock Plan | Exercise Price One | Convertible Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.10
Options outstanding	104,652
Weighted- average remaining contractual life (years)	7 months 17 days
Options exercisable	104,652
Sequenta, Inc. 2008 Stock Plan | Exercise Price Two | Convertible Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.28
Options outstanding	10,153
Weighted- average remaining contractual life (years)	2 years 2 months 23 days
Options exercisable	10,153
Sequenta, Inc. 2008 Stock Plan | Exercise Price Three. | Convertible Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.55
Options outstanding	74,473
Weighted- average remaining contractual life (years)	4 years 29 days
Options exercisable	74,473
Sequenta, Inc. 2008 Stock Plan | Exercise Price Four. | Convertible Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.82
Options outstanding	70,518
Weighted- average remaining contractual life (years)	5 years 1 month 13 days
Options exercisable	70,480
Sequenta, Inc. 2008 Stock Plan | Exercise Price Five. | Convertible Preferred Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price	$ 0.92
Options outstanding	4,881
Weighted- average remaining contractual life (years)	5 years 4 months 13 days
Options exercisable	4,881

Equity Incentive Plans - Summ_3

Equity Incentive Plans - Summary of Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares subject to outstanding options, Beginning balance	15,157,930
Stock Options, Granted	4,071,846
Shares subject to outstanding, Exercised	(1,379,658)
Shares subject to outstanding, Ending balance	17,482,443	15,157,930
Weighted Average Exercise Price per Share, Options outstanding, Beginning Balance	$ 4.52
Weighted Average Exercise Price per Share, Options granted	9.15
Weighted Average Exercise Price per Share, Forfeited	6.08
Weighted Average Exercise Price per Share, Exercised	1.67
Weighted Average Exercise Price per Share, Options outstanding, Ending Balance (unaudited)	$ 5.79	$ 4.52
Aggregate Intrinsic Value, Outstanding	$ 438,968	$ 41,690
Series E-1 Convertible Preferred Stock | Sequenta, Inc. 2008 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares subject to outstanding options, Beginning balance	264,677	521,139	814,563
Stock Options, Granted		0	0
Stock Options, Forfeited		(122,397)	(121,898)
Shares subject to outstanding, Exercised		(134,065)	(171,526)
Shares subject to outstanding, Ending balance		264,677	521,139
Weighted Average Exercise Price per Share, Options outstanding, Beginning Balance	$ 0.44	$ 0.50	$ 0.56
Weighted Average Exercise Price per Share, Options granted		0	0
Weighted Average Exercise Price per Share, Forfeited		0.36	0.55
Weighted Average Exercise Price per Share, Exercised		0.75	0.74
Weighted Average Exercise Price per Share, Options outstanding, Ending Balance (unaudited)		$ 0.44	$ 0.50
Aggregate Intrinsic Value, Outstanding		$ 1,826	$ 3,195	$ 4,814

Equity Incentive Plans - Summ_4

Equity Incentive Plans - Summary of Estimated Fair Value of Options Granted (Detail) - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Grant date fair value	$ 10.08	$ 6.55	$ 6.55	$ 6.27
Expected term (in years)	6 years 21 days	6 years 1 month 24 days	6 years 1 month 20 days	6 years 1 month 13 days
Risk-free interest rate	2.40%	2.70%	2.70%	2.00%
Expected volatility	68.00%	68.90%	68.10%	70.20%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Equity incentive Plans - Summ_5

Equity incentive Plans - Summary of Compensation Costs Related to Stock Options and RSUS Included on Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 3,335	$ 2,553	$ 9,713	$ 8,103	$ 11,149	$ 7,009
Cost of Revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	133	97	376	273	398	237
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	943	700	2,838	2,168	2,896	2,375
Sales and Marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	798	620	2,647	2,169	2,891	1,344
General and Administration
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1,461	$ 1,136	$ 3,852	$ 3,493	$ 4,964	$ 3,053

Restructuring Charges - Restruc

Restructuring Charges - Restructuring Related Balance sheet Accounts (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Balance at December 31, 2016	$ 2,564
Costs incurred and charged to expense	840
Cash payments	(3,194)
Non-cash items	(210)
One-time Termination Benefits [Member]
Balance at December 31, 2016	2,564
Costs incurred and charged to expense	512
Cash payments	(3,076)
Asset Impairment and Net Gain Loss On Sale Or Disposal [Member]
Costs incurred and charged to expense	210
Non-cash items	(210)
Other Restructuring [Member]
Costs incurred and charged to expense	118
Cash payments	$ (118)

Microsoft Collaboration Agree_2

Microsoft Collaboration Agreement - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
License Costs	$ 5,601	$ 5,360	$ 16,323	$ 14,393	$ 19,668	$ 15,680
Agreement Period					7 years
Research and development expense	$ 20,506	$ 9,783	$ 49,516	$ 28,090	$ 39,157	$ 31,995
Microsofts Azure Cloud [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Research and development expense					500
Minimum
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
License Costs					12,000
Series F-1
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
preferred stock investment					$ 45,000

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets And Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Net operating losses	$ 56,555	$ 47,840
Tax credit carryforward	6,709	5,463
Non qualifying stock options	7,861	4,865
Other	4,523	3,774
Total deferred tax assets	75,648	61,942
Valuation allowance	(70,722)	(56,679)
Deferred tax assets, net of valuation allowance	4,926	5,263
Tangible and intangible assets	(4,926)	(5,263)
Net deferred taxes	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Increase [ decrease ] in valuation allowance	$ 14,000,000	$ (9,700,000)
U.S. statutory income tax rate	2100.00%	3400.00%
Changes in deferred tax assets related to Tax Cuts and Jobs Act of 2017	$ 25,000,000
Federal net operating loss carryforwards	$ 186,900,000
Maturity period for net operating loss carryovers	20 years
unrecognized tax benefits	$ 1,300,000
Unrecognized Tax Benefits Arising From Research And Development Tax Credits	200,000	$ 200,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	0	$ 0
Domestic Tax Authority [Member]
U.S. federal net operating losses	47,300,000
U.S. federal tax credits	$ 6,000,000
Tax credit carryforwards expiration year	2028
Net operating loss expiration year	2028
Sequenta Inc [Member]
Federal net operating loss carryforwards	$ 38,500,000

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of effective tax rate of provision for income taxes with federal statutory rate (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory rate	2100.00%	3400.00%
State tax	550.00%	180.00%
Stock compensation	50.00%	(170.00%)
Permanent items	0.50%	(0.10%)
Credits	270.00%	270.00%
TCJA change in federal rate		(5840.00%)
Other	20.00%	(70.00%)
Change in valuation allowance	(3030.00%)	2230.00%
Total	0.00%	0.00%

Income Taxes - Schedule of Chan

Income Taxes - Schedule of Change In Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Balance	$ 1,031	$ 844
Additions	229	187
Balance	$ 1,260	$ 1,031

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Shareholders - Computation of the Basic and Diluted Net Loss Per Share Attributable to Common Shareholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Net loss	$ (13,950)	$ (8,292)	$ (47,995)	$ (33,176)	$ (46,447)	$ (42,831)
Fair value adjustments to redemption value for Series E-1 convertible preferred stock options		(4)	(964)	(2)	102	135
Net loss attributable to common shareholders, basic and diluted	$ (13,950)	$ (8,296)	$ (48,959)	$ (33,178)	$ (46,345)	$ (42,696)
Weighted-average shares used in computing net loss per share	124,285,686	12,620,010	50,552,389	12,430,535	12,629,778	12,196,998
Net loss per share attributable to common shareholders, basic and diluted	$ (0.11)	$ (0.66)	$ (0.97)	$ (2.67)	$ (3.67)	$ (3.50)
Series E-1 Convertible Preferred Stock
Fair value adjustments to redemption value for Series E-1 convertible preferred stock options		$ (4)	$ (964)	$ (2)	$ 102	$ 135

Net Loss Per Share Attributab_2

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 (Detail) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities	17,530,664	107,703,785	78,833,870	107,365,973	107,597,400	101,230,264
Convertible Preferred Stock
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities		92,790,094	61,641,506	92,764,348	92,783,867	88,473,431
Option
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities	17,466,409	14,801,784	17,096,516	14,489,718
Option | 2009 Plan
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities					14,368,063	12,022,454
Option | 2008 Plan
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities					333,563	622,472
Unvested Restricted Stock Units
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities	7,380		2,487
Common Stock Warrants
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities	56,875	55,032	55,653	55,032	55,032	55,032
Convertible Preferred Stock Warrants
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities		56,875	37,708	56,875	56,875	56,875

Net Loss and Unaudited Pro Fo_3

Net Loss and Unaudited Pro Forma Net Loss Per Share Attributable to Common Shareholders -Summary of unaudited pro forma basic and diluted net loss per share attributable to common shareholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic and Diluted [Abstract]
Pro forma net loss attributable to common shareholders, basic and diluted	$ (13,950)	$ (8,296)	$ (48,959)	$ (33,178)	$ (46,345)	$ (42,696)
Weighted-average shares used in computing net loss per share attributable to common shareholders, basic and diluted	124,285,686	12,620,010	50,552,389	12,430,535	12,629,778	12,196,998
Weighted-average shares of common stock issued upon assumed conversion of convertible preferred stock in an initial public offering					92,783,867
Weighted-average shares of common stock issued upon assumed conversion of a common stock warrant in an initial public offering					20,000
Weighted-average shares used in computing pro forma net loss per share attributable to common shareholders, basic and diluted					105,433,645
Pro forma net loss per share attributable to common shareholders, basic and diluted					$ (0.44)

Retirement Plan - Additional In

Retirement Plan - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employees maximum annual contribution of their compensation	100.00%

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Stock Option Granted	4,071,846
Stock option exercise prices	$ 9.15
2009 Plan
Stock option exercise prices		$ 7.27
Employees | 2009 Plan
Stock Option Granted		2,045,000
Non Employee Directors | 2009 Plan
Stock Option Granted		105,000

Organization and Description _2

Organization and Description of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jul. 01, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsidiary Or Equity Method Investee [Line Items]
Convertible preferred stock outstanding		0		92,790,094			92,656,029
Initial share reserve		34,578,262		114,887,927
2019 Plan
Subsidiary Or Equity Method Investee [Line Items]
Initial share reserve	15,519,170
Convertible Preferred Stock
Subsidiary Or Equity Method Investee [Line Items]
Convertible preferred stock outstanding		93,039,737	93,039,737	92,790,094	92,790,094	92,790,094	92,656,029	87,797,854
Initial share reserve				92,790,094
Initial Public Offering
Subsidiary Or Equity Method Investee [Line Items]
Shares issued	17,250,000
Public offering price	$ 20
Net proceeds	$ 315.9
Underwriting discounts, commissions and other costs	24.1
Offering expenses	$ 5

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Convertible Preferred Stock Warrant Liability
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other income, net	$ 2.3

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Schedule of Future Amortization Expense for Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2019	$ 428
2020	1,698
2021	1,698
2022	1,698
2023	1,698
Thereafter	5,136
Net Carrying Amount	$ 12,356	$ 13,626	$ 15,325

Deferred Revenue - Additional_2

Deferred Revenue - Additional Information (Details1) (Detail) - Genentech, Inc.	Sep. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Disaggregation Of Revenue [Line Items]
Deferred revenue, expected to be recognized	12 months
Minimum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-10-01
Disaggregation Of Revenue [Line Items]
Deferred revenue, expected to be recognized	7 years
Maximum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-10-01
Disaggregation Of Revenue [Line Items]
Deferred revenue, expected to be recognized	8 years

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail)	Jul. 01, 2019shares	Jun. 30, 2019shares	Sep. 30, 2019Vote$ / sharesshares	Sep. 30, 2019Vote$ / sharesshares	Dec. 31, 2018Vote$ / sharesshares	Dec. 31, 2014$ / sharesshares	Sep. 30, 2018shares	Jun. 30, 2018shares	Dec. 31, 2017$ / sharesshares	Dec. 31, 2016shares
Class of Stock [Line Items]
Convertible preferred stock outstanding			0	0	92,790,094				92,656,029
Preferred stock, shares authorized			10,000,000	10,000,000	0
Preferred stock, par value | $ / shares			$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares outstanding			0	0	0
Common stock authorized			340,000,000	340,000,000	131,000,000				131,000,000
Common stock par value | $ / shares			$ 0.0001	$ 0.0001	$ 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.	Holders of our common stock are entitled to one vote for each share of common stock held.
Number of vote for each share | Vote			0	0	0
Common stock outstanding			124,316,080	124,316,080	12,841,536				12,208,731
Warrants issued to purchase stock			56,875	56,875
Warrants issued to purchase stock			56,875	56,875
Common Stock
Class of Stock [Line Items]
Warrants issued to purchase stock			20,000	20,000	20,000
Warrant exercisable term				10 years	10 years
Weighted-average exercise price of warrants | $ / shares			$ 0.37	$ 0.37	$ 0.37
Exercise price of warrants | $ / shares			$ 0.45	$ 0.45	$ 0.45
Stock issued during period, common stock	54,792		54,792	54,792
Warrants issued to purchase stock			20,000	20,000	20,000
Warrant exercisable term				10 years	10 years
Weighted-average exercise price of warrants | $ / shares			$ 0.37	$ 0.37	$ 0.37
Common Stock | Maximum
Class of Stock [Line Items]
Warrants issued to purchase stock			55,032	55,032	55,032
Warrants issued to purchase stock			55,032	55,032	55,032
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
Warrants issued to purchase stock						56,875
Warrant exercisable term						7 years
Weighted-average exercise price of warrants | $ / shares						$ 2.64
Convertible Preferred Stock
Class of Stock [Line Items]
Conversion of convertible preferred stock		93,039,737
Convertible preferred stock outstanding		93,039,737	93,039,737	93,039,737	92,790,094		92,790,094	92,790,094	92,656,029	87,797,854

Shareholders' Equity - Summary

Shareholders' Equity - Summary of Reserved Shares of Common Stock (Detail) - shares	Sep. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	34,578,262	114,887,927
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	17,495,253
Options | 2019 Plan
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	15,474,217
Options | Employee Stock Purchase Plan
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	1,551,917
Conversion of Common Stock Warrant
Class of Stock [Line Items]
Total shares of common stock reserved for future issuance	56,875

Equity Incentive Plans - Summ_6

Equity Incentive Plans - Summary of Changes in Shares Available for Grant (Detail) - 2019 Plan	9 Months Ended
	Sep. 30, 2019shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant, Beginning balance	6,827,996,000
Shares Available for Grant, 2019 Plan reserve (unaudited)	12,363,202,000
Shares Available for Grant, Options and RSUs granted (unaudited)	(4,084,656,000)
Shares Available for Grant, Options and RSUs forfeited or cancelled (unaudited)	367,675,000
Shares available for grant, Ending balance	15,474,217,000

Equity incentive Plans - Summ_7

Equity incentive Plans - Summary of Stock Option Activity Under 2008 Plan 2009 Plan and 2019 Plan (Detail) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Share-based Payment Arrangement [Abstract]
Shares subject to outstanding options, Beginning balance | shares	15,157,930
Stock Options, Options granted | shares	4,071,846
Stock Options, Options forfeited or canceled | shares	(367,675)
Stock Options, Options exercised | shares	(1,379,658)
Shares subject to outstanding, Ending balance | shares	17,482,443	15,157,930
Weighted Average Exercise Price per Share, Options outstanding, Beginning Balance | $ / shares	$ 4.52
Weighted Average Exercise Price per Share, Options granted (unaudited) | $ / shares	9.15
Weighted Average Exercise Price per Share, Options forfeited or cancelled (unaudited) | $ / shares	6.08
Weighted Average Exercise Price per Share, Options exercised (unaudited) | $ / shares	1.67
Weighted Average Exercise Price per Share, Options outstanding, Ending Balance (unaudited) | $ / shares	$ 5.79	$ 4.52
Aggregate Intrinsic Value, Option outstanding | $	$ 438,968	$ 41,690