Condensed Consolidated Statements of Changes in Stockholders' (Deficit) Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated (Deficit) Equity [Member]	Total
Balance at Dec. 31, 2018	$ 30	$ 1,800,144	$ (2,259)	$ (1,778,785)	$ 19,130
Balance (in shares) at Dec. 31, 2018	29,694
Stock-based compensation		14,897			14,897
Net proceeds from exercise of stock options		943			943
Net proceeds from exercise of stock options (in shares)	83
Employee withholding taxes related to stock-based awards		(791)			(791)
Other comprehensive income (loss)			1,090		1,090
Net loss				(90,270)	(90,270)
Balance at Mar. 31, 2019	$ 30	1,815,193	(1,169)	(1,869,055)	(55,001)
Balance (in shares) at Mar. 31, 2019	29,777
Balance at Dec. 31, 2019	$ 33	2,176,133	(1,144)	(2,123,466)	51,556
Balance (in shares) at Dec. 31, 2019	32,853
Stock-based compensation		12,473			12,473
Net proceeds from exercise of stock options		(1,783)			$ (1,783)
Net proceeds from exercise of stock options (in shares)	88				9
Employee withholding taxes related to stock-based awards		(1,322)			$ (1,322)
Employee withholding taxes related to stock-based awards, (in shares)	(4)
Other comprehensive income (loss)			(2,660)		(2,660)
Net loss				(92,983)	(92,983)
Balance at Mar. 31, 2020	$ 33	$ 2,185,501	$ (3,804)	$ (2,216,449)	$ (34,719)
Balance (in shares) at Mar. 31, 2020	32,937