Consolidated Statements of Convertible Redeemable Preferred Stock, Redeemable Noncontrolling Interest, Stockholders' Equity and Noncontrolling Interest - USD ($) $ in Thousands	Total	Total Stockholders' Equity (Deficit)	Total Stockholders' Equity (Deficit) Cumulative effect upon adoption of new accounting standard	Redeemable Noncontrolling  Interest	Common Stock	Additional Paid-In Capital	Additional Paid-In Capital Cumulative effect upon adoption of new accounting standard	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative effect upon adoption of new accounting standard	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2019					121,036,289
Beginning balance at Dec. 31, 2019		$ (259,594)		$ 443	$ 12	$ 2,686,759		$ 19	$ (2,946,384)		$ 91,291
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment of embedded derivative for debt modification		(24,071)				(24,071)
Issuance of restricted stock awards (in shares)					3,010,606
ESPP purchase (in shares)					992,846
ESPP purchase		4,177				4,177
Exercise of stock options (in shares)					110,949
Exercise of stock options		667				667
Stock-based compensation		21,676				21,676
Change in effective portion of interest rate swap agreement	$ (8,214)	(5)						(5)			(8,209)
Distributions to noncontrolling interests				(1)							(3,897)
Foreign currency translation adjustment	0
Net loss	(81,642)	(75,949)		(375)					(75,949)		(5,318)
Ending balance (in shares) at Mar. 31, 2020					125,150,690
Ending balance at Mar. 31, 2020		(333,099)		67	$ 12	2,689,208		14	(3,022,333)		73,867
Beginning balance (in shares) at Dec. 31, 2020					168,002,726
Beginning balance at Dec. 31, 2020		78,824	$ (121,491)	377	$ 17	3,182,753	$ (126,799)	(9)	(3,103,937)	$ 5,308	62,195
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock awards (in shares)					1,140,502
ESPP purchase (in shares)					977,508
ESPP purchase		4,726				4,726
Exercise of stock options (in shares)					1,978,717
Exercise of stock options		53,227				53,227
Stock-based compensation		15,780				15,780
Change in effective portion of interest rate swap agreement	(4,653)										4,653
Distributions to noncontrolling interests				(17)							(3,863)
Foreign currency translation adjustment	(228)	(117)						(117)			(111)
Net loss	$ (29,781)	(24,889)		(4)					(24,889)		(4,888)
Ending balance (in shares) at Mar. 31, 2021					172,099,453
Ending balance at Mar. 31, 2021		$ 6,060		$ 356	$ 17	$ 3,129,687		$ (126)	$ (3,123,518)		$ 57,986