CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common stock and additional paid-in capital	Accumulated deficit	Accumulated deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss)	Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the adoption of new accounting standard	$ 158,900	$ 331,359	$ (172,422)	$ 0	$ (37)
Beginning balance at Dec. 31, 2018	158,900	331,359	(172,422)	0	(37)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense		40,510
Exercise of stock options		15,694
Shares acquired to settle the exercise of stock options		(941)
Proceeds from issuance of common stock, net of issuance costs		195,290
Equity component of convertible notes, less issuance costs		81,550
Equity component of early extinguishment of convertible notes		0
Settlement of convertible note hedges		0
Settlement of warrants		0
Purchase of capped call transactions		(40,765)
Net loss	(70,877)		(70,877)
Other comprehensive income (loss)					51
Ending balance at Dec. 31, 2019	$ 379,412	622,697	(243,299)	(268)	14
Beginning balance (in shares) at Dec. 31, 2018						43,535
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares acquired to settle the exercise of stock options (in shares)						(12)
Exercise of stock options (in shares)						1,059
Shares issued for the vesting of restricted stock awards (in shares)						770
Proceeds from issuance of common stock, net of issuance costs (in shares)						3,034
Equity component of early extinguishment of convertible notes (in shares)						0
Ending balance (in shares) at Dec. 31, 2019						48,386
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	Accounting Standards Update 2016-13 [Member]
Cumulative effect of the adoption of new accounting standard	$ 379,412	622,697	(243,299)	(268)	14
Stock-based compensation expense		50,682
Exercise of stock options		14,283
Shares acquired to settle the exercise of stock options		(966)
Proceeds from issuance of common stock, net of issuance costs		311,321
Equity component of convertible notes, less issuance costs		73,097
Equity component of early extinguishment of convertible notes		(40,842)
Settlement of convertible note hedges		171,679
Settlement of warrants		(137,538)
Purchase of capped call transactions		(39,830)
Net loss	(137,620)		(137,620)
Other comprehensive income (loss)					(46)
Ending balance at Dec. 31, 2020	$ 643,364	1,024,583	(381,187)	0	(32)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares acquired to settle the exercise of stock options (in shares)						(9)
Exercise of stock options (in shares)						720
Shares issued for the vesting of restricted stock awards (in shares)						916
Proceeds from issuance of common stock, net of issuance costs (in shares)						4,235
Equity component of early extinguishment of convertible notes (in shares)						1,314
Ending balance (in shares) at Dec. 31, 2020	55,562					55,562
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the adoption of new accounting standard	$ 643,364	1,024,583	(381,187)	$ 0	(32)
Stock-based compensation expense		55,903
Exercise of stock options		5,892
Shares acquired to settle the exercise of stock options		(200)
Proceeds from issuance of common stock, net of issuance costs		0
Equity component of convertible notes, less issuance costs		0
Equity component of early extinguishment of convertible notes		(28,454)
Settlement of convertible note hedges		26,295
Settlement of warrants		(19,655)
Purchase of capped call transactions		0
Net loss	(112,746)		(112,746)
Other comprehensive income (loss)					(103)
Ending balance at Dec. 31, 2021	$ 570,296	1,064,364	(493,933)		(135)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares acquired to settle the exercise of stock options (in shares)						(2)
Exercise of stock options (in shares)						307
Shares issued for the vesting of restricted stock awards (in shares)						1,061
Proceeds from issuance of common stock, net of issuance costs (in shares)						0
Equity component of early extinguishment of convertible notes (in shares)						0
Ending balance (in shares) at Dec. 31, 2021	56,928					56,928
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of the adoption of new accounting standard	$ 570,296	$ 1,064,364	$ (493,933)		$ (135)