Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net loss	$ (228,302)	$ (340,141)	$ (306,620)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on sale of ATOM Facility	(50,237)	0	0
Stock-based compensation expense	53,838	53,865	51,351
Depreciation and amortization expense	5,653	9,345	8,332
Non-cash operating lease expense	8,915	1,948	1,457
Amortization of investment premiums	1,024	1,769	828
Other non-cash items, net	147	108	208
Changes in operating assets and liabilities:
Accounts receivable	(39,235)	264	(1,250)
Increase (Decrease) in Inventories	(1,586)	0	0
Other current assets	1,836	8,182	(8,666)
Operating lease assets	0	0	886
Other assets	(266)	(1,727)	(219)
Accounts payable	(9,211)	9,067	(815)
Accrued compensation	(7,491)	4,692	5,752
Accrued research and development expenses	11,541	(2,362)	7,472
Other current liabilities	2,067	1,618	(187)
Deferred revenue	(11,468)	35,218	61,250
Operating lease liabilities	(8,009)	(1,859)	(1,316)
Other long-term liabilities	354	(509)	778
Net cash used in operating activities	(270,430)	(220,522)	(180,759)
Investing activities
Purchases of short-term investments	(180,589)	(301,129)	(425,868)
Proceeds from maturities and sales of short-term investments	292,973	333,967	309,653
Purchases of property and equipment	(4,193)	(10,580)	(4,513)
Net proceeds from sale of ATOM Facility	94,765	0	0
Net cash provided by (used in) investing activities	202,956	22,258	(120,728)
Financing activities
Proceeds from sale of common stock and pre-funded warrants in underwritten offerings, net	0	0	353,780
Proceeds from issuance of common stock through ATM facilities, net	21,891	98,697	69,189
Proceeds from employee stock awards	1,921	6,762	6,680
Proceeds from sale of future revenues, net	30,605	0	0
Taxes paid related to net share settlement of restricted stock units	(623)	(1,244)	(1,521)
Principal payments on finance lease obligations	(518)	(254)	(389)
Other financing activities, net	(192)	(17)	(165)
Net cash provided by financing activities	53,084	103,944	427,574
Increase (decrease) in cash, cash equivalents and restricted cash	(14,390)	(94,320)	126,087
Cash, cash equivalents and restricted cash at beginning of period	107,478	201,798	75,711
Cash, cash equivalents and restricted cash at end of period	93,088	107,478	201,798
Non-cash investing and financing activities
Property and equipment purchases included in accounts payable and other accrued liabilities	61	2,139	326
Accrued costs related to underwritten public offering	0	0	192
Accrued costs related to ATM facility	0	87	0
Accrued transaction costs related to sale of future revenues	332	0	0
Supplemental cash flow disclosure
Cash paid for interest	335	32	62
Cash paid for income taxes	$ 19	$ 15	$ 10