Consolidated Statements of Shareholders' Equity (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjustment	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2020			102,763
Balance at Dec. 31, 2020	$ 275,884		$ 1,028	$ 2,105,252		$ (1,830,589)		$ 193
Comprehensive loss:
Net loss	(208,962)					(208,962)
Other comprehensive income (loss)	231							231
Exercise of stock options and ESPP shares issuance (in shares)			760
Exercise of stock options and ESPP shares issuance	13,525		$ 7	13,518
Net proceeds from issuance of common stock (in shares)			11,500
Equity component of convertible debt redemption	269,886		$ 115	269,771
Equity component of convertible debt issuance	196,063			196,063
Equity component of convertible debt redemption	(37,846)			(37,846)
Issuance of common stock for vesting of RSUs (in shares)			216
Issuance of common stock for vesting of RSUs	2		$ 2
Stock-based compensation expense	22,270			22,270
Balance (in shares) at Jun. 30, 2021			115,239
Balance at Jun. 30, 2021	531,053		$ 1,152	2,569,028		(2,039,551)		424
Balance (in shares) at Dec. 31, 2020			102,763
Balance at Dec. 31, 2020	275,884		$ 1,028	2,105,252		(1,830,589)		193
Balance (in shares) at Dec. 31, 2021			118,738
Balance at Dec. 31, 2021	$ 410,468	$ (214,410)	$ 1,187	2,673,556	$ (264,609)	(2,265,243)	$ 50,199	968
Comprehensive loss:
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2020-06
Balance (in shares) at Mar. 31, 2021			103,279
Balance at Mar. 31, 2021	$ 201,636		$ 1,033	2,122,743		(1,922,230)		90
Comprehensive loss:
Net loss	(117,321)					(117,321)
Other comprehensive income (loss)	334							334
Exercise of stock options and ESPP shares issuance (in shares)			344
Exercise of stock options and ESPP shares issuance	6,565		$ 3	6,562
Net proceeds from issuance of common stock (in shares)			11,500
Equity component of convertible debt redemption	269,886		$ 115	269,771
Equity component of convertible debt issuance	196,063			196,063
Equity component of convertible debt redemption	(37,846)			(37,846)
Issuance of common stock for vesting of RSUs (in shares)			116
Issuance of common stock for vesting of RSUs	1		$ 1
Stock-based compensation expense	11,735			11,735
Balance (in shares) at Jun. 30, 2021			115,239
Balance at Jun. 30, 2021	531,053		$ 1,152	2,569,028		(2,039,551)		424
Balance (in shares) at Dec. 31, 2021			118,738
Balance at Dec. 31, 2021	410,468	$ (214,410)	$ 1,187	2,673,556	$ (264,609)	(2,265,243)	$ 50,199	968
Comprehensive loss:
Net loss	(190,266)					(190,266)
Other comprehensive income (loss)	(1,897)							(1,897)
Exercise of stock options and ESPP shares issuance (in shares)			795
Exercise of stock options and ESPP shares issuance	13,260		$ 8	13,252
Issuance of common stock for vesting of RSUs (in shares)			332
Issuance of common stock for vesting of RSUs	4		$ 4
Stock-based compensation expense	27,082			27,082
Balance (in shares) at Jun. 30, 2022			119,865
Balance at Jun. 30, 2022	$ 44,241		$ 1,199	2,449,281		(2,405,310)		(929)
Comprehensive loss:
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2020-06
Balance (in shares) at Mar. 31, 2022			119,346
Balance at Mar. 31, 2022	$ 119,880		$ 1,193	2,428,582		(2,309,665)		(230)
Comprehensive loss:
Net loss	(95,645)					(95,645)
Other comprehensive income (loss)	(699)							(699)
Exercise of stock options and ESPP shares issuance (in shares)			345
Exercise of stock options and ESPP shares issuance	6,444		$ 4	6,440
Issuance of common stock for vesting of RSUs (in shares)			174
Issuance of common stock for vesting of RSUs	2		$ 2
Stock-based compensation expense	14,259			14,259
Balance (in shares) at Jun. 30, 2022			119,865
Balance at Jun. 30, 2022	$ 44,241		$ 1,199	$ 2,449,281		$ (2,405,310)		$ (929)