Condensed Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands	Class A common stock Common Stock	Additional paid-in capital	Accumulated deficit	Total
Balance at Dec. 31, 2018	$ 154	$ 1,394,603	$ (1,591,128)	$ (196,371)
Balance (in shares) at Dec. 31, 2018	154,414,691
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to share-based awards and employee stock purchase plan	$ 2	3,486		3,488
Issuance of common stock related to share-based awards and employee stock purchase plan (in shares)	1,210,858
Share-based compensation expense related to share-based awards and employee stock purchase plan		14,988		14,988
Net loss			(59,284)	(59,284)
Balance at Mar. 31, 2019	$ 156	1,413,077	(1,650,412)	(237,179)
Balance (in shares) at Mar. 31, 2019	155,625,549
Balance at Dec. 31, 2019	$ 158	1,478,823	(1,572,232)	$ (93,251)
Balance (in shares) at Dec. 31, 2019	157,535,962			157,535,962
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to share-based awards and employee stock purchase plan	$ 1	11,984		$ 11,985
Issuance of common stock related to share-based awards and employee stock purchase plan (in shares)	1,832,164
Share-based compensation expense related to share-based awards and employee stock purchase plan		6,364		6,364
Net loss			3,345	3,345
Balance at Mar. 31, 2020	$ 159	$ 1,497,171	$ (1,568,887)	$ (71,557)
Balance (in shares) at Mar. 31, 2020	159,368,126			159,368,126