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, 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]
Other comprehensive income	(272)
Net loss	(447,510)
Ending balance, shares (in shares) at Jun. 30, 2021		67,551
Ending balance at Jun. 30, 2021	984,561	$ 676	4,337,719	(5,777)	(3,348,057)
Beginning balance (in shares) at Mar. 31, 2021		67,422
Beginning balance at Mar. 31, 2021	1,200,333	$ 675	4,311,462	(5,449)	(3,106,355)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		127
Vesting of restricted stock units	0	$ 1	(1)
Exercise of stock options (in shares)		2
Exercise of stock options	36		36
Stock-based compensation	26,222		26,222
Other comprehensive income	(328)			(328)
Net loss	(241,702)				(241,702)
Ending balance, shares (in shares) at Jun. 30, 2021		67,551
Ending balance at Jun. 30, 2021	$ 984,561	$ 676	4,337,719	(5,777)	(3,348,057)
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
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
Ending balance at Mar. 31, 2022	$ 263,259	$ 714	4,109,081	(4,459)	(3,842,077)
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]
Exercise of stock options (in shares)	2
Other comprehensive income	$ (1,505)
Net loss	$ (222,290)
Ending balance, shares (in shares) at Jun. 30, 2022	73,551	73,551
Ending balance at Jun. 30, 2022	$ 180,116	$ 735	4,126,012	(4,416)	(3,942,215)
Beginning balance (in shares) at Mar. 31, 2022		71,438
Beginning balance at Mar. 31, 2022	263,259	$ 714	4,109,081	(4,459)	(3,842,077)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		60
Vesting of restricted stock units	0	$ 1	(1)
Exercise of stock options (in shares)		1
Exercise of stock options	1		1
Stock-based compensation	8,908		8,908
Issuance of unrestricted stock awards to settle accrued employee compensation (in shares)		2,052
Issuance of unrestricted stock awards to settle accrued employee compensation	8,043	$ 20	8,023
Other comprehensive income	43			43
Net loss	$ (100,138)				(100,138)
Ending balance, shares (in shares) at Jun. 30, 2022	73,551	73,551
Ending balance at Jun. 30, 2022	$ 180,116	$ 735	$ 4,126,012	$ (4,416)	$ (3,942,215)