Condensed Consolidated Statements Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock Including Additional Paid in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative effect of adoption of new accounting standard [Member]
Beginning Balance at Dec. 31, 2017	$ 298,705	$ 854,452	$ (113,613)	$ (442,134)
Beginning Balance (shares) at Dec. 31, 2017		137,000
Common stock issued under employee benefit plans, net of shares withheld for tax	5,099	$ 5,099
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(6,650)	$ 6,650
Common stock issued under employee benefit plans, net of shares withheld for tax (shares)		4,067
Allocated share-based compensation expense	41,854	$ 41,854
Net loss	(109,034)			(109,034)
Ending Balance at Dec. 31, 2018	212,112	$ 894,755	(113,613)	(569,030)	$ (17,862)
Ending Balance (shares) at Dec. 31, 2018		141,067
Common stock issued under employee benefit plans, net of shares withheld for tax	5,553	$ 5,553
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(6,618)	$ 6,618
Common stock issued under employee benefit plans, net of shares withheld for tax (shares)		5,751
Allocated share-based compensation expense	37,185	$ 37,185
Net loss	(14,642)			(14,642)
Ending Balance at Dec. 31, 2019	233,529	$ 930,875	(113,613)	(583,733)	$ (61)
Ending Balance (shares) at Dec. 31, 2019		146,818
Common stock issued under employee benefit plans, net of shares withheld for tax	5,481	$ 5,481
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(6,207)	$ 6,207
Common stock issued under employee benefit plans, net of shares withheld for tax (shares)		4,301
Allocated share-based compensation expense		$ 29,963
Convertible debt, equity portion	35,674
Net loss	(66,783)			(66,783)
Ending Balance at Dec. 31, 2020	216,018	$ 980,147	$ (113,613)	$ (650,516)
Ending Balance (shares) at Dec. 31, 2020		151,119
Adjustments to Additional Paid in Capital, Capped Call Option, Issuance Costs	(10,249)
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Repurchases	$ (5,390)