Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income	Treasury Stock	Accumulated Deficit	Total
Balance at Dec. 31, 2017	$ 2,291	$ 1,250,899	$ 2,194	$ (3,102)	$ (1,178,636)	$ 73,646
Balance (in shares) at Dec. 31, 2017	229,073,517			587,151
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company					(19,835)	(19,835)
Other comprehensive loss			412			412
Stock-based compensation		2,005				2,005
Stock-based compensation (in shares)	21,292
Stock dividend		13			(13)
Stock dividend (in shares)	6,721
Stock option exercises	$ 1	49				50
Stock option exercises (in shares)	91,001
Equity component of convertible senior notes, net of issuance costs and income tax benefit		34,829				34,829
Purchase of capped call		(16,000)				(16,000)
Purchase of common stock forward				$ (27,500)		(27,500)
Purchase of common stock forward (in shares)				14,397,906
Exercise of warrants (in shares)	100
Provision for common stock warrants		1,885				1,885
Balance at Mar. 31, 2018	$ 2,292	1,273,680	2,606	$ (30,602)	(1,198,484)	49,492
Balance (in shares) at Mar. 31, 2018	229,192,631			14,985,057
Balance at Dec. 31, 2018	$ 2,342	1,289,714	1,584	$ (30,637)	(1,260,290)	$ 2,713
Balance (in shares) at Dec. 31, 2018	234,160,661			15,002,663		234,160,661
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company					(33,938)	$ (33,938)
Other comprehensive loss			(210)			(210)
Stock-based compensation	$ 3	2,494				2,497
Stock-based compensation (in shares)	324,073
Stock dividend		13			(13)
Stock dividend (in shares)	5,034
Issuance of common stock, net	$ 100	23,398				$ 23,498
Issuance of common stock, net (in shares)	10,000,000					10,000,000
Stock option exercises		81				$ 81
Stock option exercises (in shares)	47,467
Provision for common stock warrants		4,179				4,179
Balance at Mar. 31, 2019	$ 2,445	$ 1,319,879	$ 1,374	$ (30,637)	$ (1,294,241)	$ (1,180)
Balance (in shares) at Mar. 31, 2019	244,537,235			15,002,663		244,537,235