Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (437,987)	$ (521,960)	$ (615,117)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	11,680	14,559	19,451
Amortization of premiums (accretion of discounts) on investments, net	9,474	5,397	(8,706)
Noncash lease expense	4,980	5,248	7,658
Change in fair value of equity investments	(1,729)	5,528	21,888
Change in estimated fair value of contingent consideration	11,490	14,149	1,024
Payment of contingent consideration in excess of acquisition date fair value	(17,140)	0	0
Stock-based compensation	49,072	78,457	111,316
In-process research and development impairment	0	14,550	9,658
Non-cash restructuring, long-lived assets impairment and related charges	654	24,173	7,662
Other non-cash items, net	172	(3,131)	(910)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,075	4,358	36,287
Other assets	(12,642)	353	2,161
Accounts payable	4,997	(988)	732
Accrued liabilities and other long-term liabilities	(9,509)	(64,018)	(358,843)
Operating lease liabilities	(7,368)	(23,027)	(13,046)
Net cash used in operating activities	(391,781)	(446,352)	(778,785)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sale of equipment	253	3,372	0
Purchases of long-lived assets	(4,832)	(7,301)	(21,573)
Purchases of investments	(886,334)	(1,235,339)	(2,016,189)
Maturities and sales of investments	1,201,284	1,738,635	2,202,391
Net cash provided by investing activities	310,371	499,367	164,629
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	1,349	790	3,484
Proceeds from issuance of common stock under ESPP	2,797	3,763	4,283
Other financing activities	(361)	(165)	(287)
Net cash provided by financing activities	3,785	4,388	7,480
Net (decrease) increase in cash, cash equivalents and restricted cash and cash equivalents	(77,625)	57,403	(606,676)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	318,695	261,292	867,968
Cash, cash equivalents and restricted cash and cash equivalents at end of period	241,070	318,695	261,292
NONCASH INVESTING AND FINANCING ACTIVITIES:
Operating lease liabilities obtained in exchange of right-of-use asset	7,329	0	0
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH AND CASH EQUIVALENTS TO THE CONSOLIDATED BALANCE SHEETS:
Cash and cash equivalents	232,185	222,947	241,576
Restricted cash and cash equivalents, current	1,922	89,385	13,268
Restricted cash and cash equivalents, noncurrent	6,963	6,363	6,448
Total cash, cash equivalents and restricted cash and cash equivalents	$ 241,070	$ 318,695	$ 261,292