Unaudited Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	0.375%Convertible Senior Notes Due 2025 as Liability Component [Member]	0.25% Convertible Senior Notes Due 2022 as Liability Component [Member]	Common Stock [Member]	Common Stock [Member] 0.25% Convertible Senior Notes Due 2022 as Liability Component [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] 0.375%Convertible Senior Notes Due 2025 as Liability Component [Member]	Additional Paid-In Capital [Member] 0.25% Convertible Senior Notes Due 2022 as Liability Component [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance, Amount at Dec. 31, 2020	$ 762,655			$ 46			$ 1,241,167			$ 4,603	$ (483,161)
Beginning Balance, Shares at Dec. 31, 2020				46,115		12
Issuance of common stock under stock plans, net of shares withheld for employee taxes	6,583			$ 1			6,582
Issuance of common stock under stock plans, net of shares withheld for employee taxes, Shares				482
Stock-based compensation	32,947						32,947
Equity component of the 2022 Notes conversions			$ (2,307)						$ (2,307)
Equity component of the 2022 Notes conversions, Shares					363
Settlement of Convertible Note Hedges	724						724
Settlement of Convertible Note Hedges, Shares				(364)		364
Cumulative translation adjustment	(2,489)									(2,489)
Unrealized gain (loss) on investments, net of income taxes of $0, $0, ($36) and ($7)	(240)									(240)
Net loss	(23,159)										(23,159)
Ending Balance, Amount at Mar. 31, 2021	774,714			$ 47			1,279,113			1,874	(506,320)
Ending Balance, Shares at Mar. 31, 2021				46,596		376
Beginning Balance, Amount at Dec. 31, 2020	762,655			$ 46			1,241,167			4,603	(483,161)
Beginning Balance, Shares at Dec. 31, 2020				46,115		12
Net loss	(47,731)
Ending Balance, Amount at Jun. 30, 2021	805,684			$ 47			1,334,301			2,228	(530,892)
Ending Balance, Shares at Jun. 30, 2021				46,859		485
Beginning Balance, Amount at Mar. 31, 2021	774,714			$ 47			1,279,113			1,874	(506,320)
Beginning Balance, Shares at Mar. 31, 2021				46,596		376
Issuance of common stock under stock plans, net of shares withheld for employee taxes	10,677						10,677
Issuance of common stock under stock plans, net of shares withheld for employee taxes, Shares				264
Stock-based compensation	44,659						44,659
Equity component of the 2022 Notes conversions			(148)						(148)
Equity component of the 2022 Notes conversions, Shares					108
Settlement of Convertible Note Hedges, Shares				(109)		109
Cumulative translation adjustment	534									534
Unrealized gain (loss) on investments, net of income taxes of $0, $0, ($36) and ($7)	(180)									(180)
Net loss	(24,572)										(24,572)
Ending Balance, Amount at Jun. 30, 2021	805,684			$ 47			1,334,301			2,228	(530,892)
Ending Balance, Shares at Jun. 30, 2021				46,859		485
Beginning Balance, Amount at Dec. 31, 2021	873,799			$ 47			1,436,089			(1,339)	(560,998)
Beginning Balance, Shares at Dec. 31, 2021				47,390		910
Issuance of common stock under stock plans, net of shares withheld for employee taxes	2,145			$ 1			2,144
Issuance of common stock under stock plans, net of shares withheld for employee taxes, Shares				250
Restricted stock units taxes paid in cash	(4,354)						(4,354)
Stock-based compensation	46,436						46,436
Conversion of Notes		$ (691)						$ (691)
Cumulative adjustment from adoption of convertible debt standard (Note 8)	(69,801)						(101,167)				31,366
Cumulative translation adjustment	(356)									(356)
Unrealized gain (loss) on investments, net of income taxes of $0, $0, ($36) and ($7)	(4,001)									(4,001)
Net loss	(9,341)										(9,341)
Ending Balance, Amount at Mar. 31, 2022	833,836			$ 48			1,378,457			(5,696)	(538,973)
Ending Balance, Shares at Mar. 31, 2022				47,640		910
Beginning Balance, Amount at Dec. 31, 2021	873,799			$ 47			1,436,089			(1,339)	(560,998)
Beginning Balance, Shares at Dec. 31, 2021				47,390		910
Net loss	(65,702)
Ending Balance, Amount at Jun. 30, 2022	871,467			$ 48			1,477,770			(11,017)	(595,334)
Ending Balance, Shares at Jun. 30, 2022				47,896		910
Beginning Balance, Amount at Mar. 31, 2022	833,836			$ 48			1,378,457			(5,696)	(538,973)
Beginning Balance, Shares at Mar. 31, 2022				47,640		910
Issuance of common stock under stock plans, net of shares withheld for employee taxes	18,548						18,548
Issuance of common stock under stock plans, net of shares withheld for employee taxes, Shares				256
Restricted stock units taxes paid in cash	(3,409)						(3,409)
Stock-based compensation	84,113						84,113
Conversion of Notes			$ (60,422)						$ (60,422)
Settlement of Convertible Note Hedges	60,483						60,483
Cumulative translation adjustment	(2,669)									(2,669)
Unrealized gain (loss) on investments, net of income taxes of $0, $0, ($36) and ($7)	(2,652)									(2,652)
Net loss	(56,361)										(56,361)
Ending Balance, Amount at Jun. 30, 2022	$ 871,467			$ 48			$ 1,477,770			$ (11,017)	$ (595,334)
Ending Balance, Shares at Jun. 30, 2022				47,896		910