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 stock awards (in shares)		422
Issuance of stock awards	12,013	$ 4	12,009
Other comprehensive income (loss)	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 (loss)	(401)
Net loss	(664,326)
Ending balance, shares (in shares) at Sep. 30, 2021		70,097
Ending balance at Sep. 30, 2021	870,527	$ 701	4,440,605	(5,906)	(3,564,873)
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 (loss)	(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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		80
Vesting of restricted stock units	0	$ 1	(1)
Exercise of stock options (in shares)		10
Exercise of stock options	233		233
Purchase of common stock under ESPP (in shares)		53
Purchase of common stock under ESPP	875	$ 1	874
Issuance of common stock (in shares)		2,273
Issuance of common stock	37,499	$ 22	37,477
Stock-based compensation	24,352		24,352
Issuance of stock awards (in shares)		130
Issuance of stock awards	2,475	$ 1	2,474
Issuance of pre-funded warrants	37,477		37,477
Other comprehensive income (loss)	(129)			(129)
Net loss	(216,816)				(216,816)
Ending balance, shares (in shares) at Sep. 30, 2021		70,097
Ending balance at Sep. 30, 2021	$ 870,527	$ 701	4,440,605	(5,906)	(3,564,873)
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 stock awards (in shares)		12
Other comprehensive income (loss)	(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 (loss)	$ (1,719)
Net loss	$ (298,810)
Ending balance, shares (in shares) at Sep. 30, 2022	82,880	82,880
Ending balance at Sep. 30, 2022	$ 158,857	$ 829	4,181,393	(4,630)	(4,018,735)
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
Issuance of common stock (in shares)		2,052
Issuance of common stock	8,043	$ 20	8,023
Stock-based compensation	8,908		8,908
Other comprehensive income (loss)	43			43
Net loss	(100,138)				(100,138)
Ending balance, shares (in shares) at Jun. 30, 2022		73,551
Ending balance at Jun. 30, 2022	180,116	$ 735	4,126,012	(4,416)	(3,942,215)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		572
Vesting of restricted stock units	0	$ 6	(6)
Purchase of common stock under ESPP (in shares)		67
Purchase of common stock under ESPP	239	$ 1	238
Issuance of common stock (in shares)		8,690
Issuance of common stock	46,024	$ 87	45,937
Stock-based compensation	9,212		9,212
Other comprehensive income (loss)	(214)			(214)
Net loss	$ (76,520)				(76,520)
Ending balance, shares (in shares) at Sep. 30, 2022	82,880	82,880
Ending balance at Sep. 30, 2022	$ 158,857	$ 829	$ 4,181,393	$ (4,630)	$ (4,018,735)