Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (542,731)	$ (31,251)	$ (112,485)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	14,012	7,066	3,905
Stock-based compensation	48,626	13,333	2,658
Amortization of right-of-use assets	5,009	0	0
Loss on extinguishment of debt	1,521	0	0
Class A common stock issued for in-process research and development	306,000	0	792
Loss on disposal of property and equipment	29	614	251
Accretion of discount on term loan	17	101	455
Changes in operating assets and liabilities:
Accounts receivable	(17,847)	(5,284)	(14,747)
Inventory	(14,601)	(6,699)	(3,732)
Prepaid expenses and other current assets	(5,265)	(3,535)	(2,429)
Other assets	(2,686)	(251)	(999)
Accounts payable	(7,770)	4,901	2,587
Accrued compensation and other related benefits	2,936	5,292	2,600
Deferred revenue	2,023	634	1,673
Accrued contingent liabilities	(24,485)	30,658	38,000
Accrued expenses and other current liabilities	25,917	5,771	1,701
Deferred rent, noncurrent	0	12,730	3,328
Operating lease liability	(4,832)	0	0
Other noncurrent liabilities	(3,771)	547	33
Net cash (used in) provided by operating activities	(217,898)	34,627	(76,409)
Investing activities:
Purchases of property and equipment	(36,666)	(42,742)	(6,284)
Acquisition of intangible assets	(1,728)	(25)	(425)
Net cash used in investing activities	(38,394)	(42,767)	(6,709)
Financing activities:
Proceeds from term loans	0	0	19,512
Payments on term loans	(31,256)	0	(704)
Proceeds from borrowings under revolver	0	11,000	0
Payments on borrowings under revolver	0	(11,000)	0
Payments on financing arrangement	(5,848)	0	0
Payments on capital lease obligations	0	0	(69)
Proceeds from issuance of common stock upon initial and follow-on public offerings, net of issuance costs	482,267	410,824	0
Proceeds from issuance of preferred stock, net of issuance costs	0	0	84,830
Issuance of common stock from exercise of stock options and employee stock purchase plan purchases	23,743	3,766	1,798
Net cash provided by financing activities	468,906	414,590	105,367
Effect of exchange rates on changes in cash, cash equivalents, and restricted cash	(463)	(45)	(18)
Net increase in cash, cash equivalents, and restricted cash	212,151	406,405	22,231
Cash, cash equivalents, and restricted cash at beginning of year	476,493	70,088	47,857
Cash, cash equivalents, and restricted cash at end of year	688,644	476,493	70,088
Supplemental disclosures of cash flow information:
Cash paid for interest	1,670	2,250	1,824
Cash paid for taxes	280	22	6
Noncash investing and financing activities
Purchases of property and equipment included in accounts payable and accrued expenses and other current liabilities	2,983	4,492	2,260
Right-of-use assets obtained in exchange for new operating lease liabilities	13,562	0	0
Conversion of convertible preferred stock into common stock upon initial public offering	0	243,244	0
Purchase of technology licenses under financing arrangement	$ 0	$ 22,099	$ 0