CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Capital Contributed in Excess of Par	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest	Convertible Preferred Stock
Beginning balance (in shares) at Dec. 31, 2018		190,446						0
Beginning Balance at Dec. 31, 2018	$ 265,849	$ 1,905	$ 1,219,237	$ (824)	$ (953,216)	$ (351)	$ (902)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		1,063
Exercise of stock options, net	1,825	$ 10	3,086	(1,271)
Stock-based compensation	1,743		1,743
Other comprehensive income (loss)	(209)					(209)
Net loss	(87,404)				(87,337)		(67)
Ending balance (in shares) at Mar. 31, 2019		191,509						0
Ending Balance at Mar. 31, 2019	181,804	$ 1,915	1,224,066	(2,095)	(1,040,553)	(560)	(969)	$ 0
Beginning balance (in shares) at Dec. 31, 2019		212,529						0
Beginning Balance at Dec. 31, 2019	267,230	$ 2,125	1,579,205	(2,095)	(1,310,406)	(568)	(1,031)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		7
Exercise of stock options, net	32		32
Stock-based compensation	3,848		3,848
Issuance of common stock due to debt conversion (in shares)		1,393
Issuance of common stock due to debt conversion	7,114	$ 14	7,100
Other comprehensive income (loss)	(234)					(234)
Net loss	(93,079)				(93,047)		(32)
Ending balance (in shares) at Mar. 31, 2020		213,929						0
Ending Balance at Mar. 31, 2020	$ 184,911	$ 2,139	$ 1,590,185	$ (2,095)	$ (1,403,453)	$ (802)	$ (1,063)	$ 0