Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2020		66,432
Beginning balance at Dec. 31, 2020	$ 1,355,056	$ 665	$ 4,260,443	$ (5,505)	$ (2,900,547)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		294
Vesting of restricted stock units	0	$ 3	(3)
Exercise of stock options (in shares)		207
Exercise of stock options	1,219	$ 2	1,217
Purchase of common stock under ESPP (in shares)		67
Purchase of common stock under ESPP	1,707	$ 1	1,706
Stock-based compensation	36,090		36,090
Issuance of unrestricted stock awards to settle accrued employee compensation (in shares)		422
Issuance of unrestricted stock awards to settle accrued employee compensation	12,013	$ 4	12,009
Other comprehensive income	56			56
Net loss	(205,808)				(205,808)
Ending balance, shares (in shares) at Mar. 31, 2021		67,422
Ending balance at Mar. 31, 2021	$ 1,200,333	$ 675	4,311,462	(5,449)	(3,106,355)
Beginning balance (in shares) at Dec. 31, 2021	71,115	71,115
Beginning balance at Dec. 31, 2021	$ 374,277	$ 711	4,096,402	(2,911)	(3,719,925)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		310
Vesting of restricted stock units	$ 0	$ 3	(3)
Exercise of stock options (in shares)	1	1
Exercise of stock options	$ 1		1
Stock-based compensation	12,681		12,681
Issuance of unrestricted stock awards to settle accrued employee compensation (in shares)		12
Other comprehensive income	(1,548)			(1,548)
Net loss	$ (122,152)				(122,152)
Ending balance, shares (in shares) at Mar. 31, 2022	71,438	71,438
Ending balance at Mar. 31, 2022	$ 263,259	$ 714	$ 4,109,081	$ (4,459)	$ (3,842,077)