CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY - USD ($) $ in Thousands	Common Stock Series C Redeemable Convertible Preferred Stock	Common Stock Series D Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-in-Capital Series C Redeemable Convertible Preferred Stock	Additional Paid-in-Capital Series D Redeemable Convertible Preferred Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income	Treasury Stock	Accumulated Deficit	Series C Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock	Total
Balance at Dec. 31, 2016			$ 1,917			$ 1,137,482	$ 247	$ (3,091)	$ (1,051,467)			$ 85,088
Balance (in shares) at Dec. 31, 2016			191,723,974					582,328
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company									(127,080)			(127,080)
Other comprehensive income/loss							1,947					1,947
Stock-based compensation			$ 1			9,208						9,209
Stock-based compensation (in shares)			148,077
Stock dividend			$ 1			88			(89)
Stock dividend (in shares)			54,130
Public offerings, common stock, net			$ 102			22,890						22,992
Public offerings, common stock, net (in shares)			10,170,759
Stock option exercises			$ 2			106		$ (11)				97
Stock option exercises (in shares)			154,166					4,823
Exercise of warrants			$ 145			39,713						39,858
Exercise of warrants (in shares)			14,501,500
Conversion of preferred stock	$ 28	$ 95		$ 416	$ 7,683					$ 444	$ 7,778
Conversion of preferred stock (in shares)	2,772,518	9,548,393
Provision for common stock warrants						36,322						36,322
Accretion of discount						(3,009)						(3,009)
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									(78,115)			(78,115)
Other comprehensive income/loss							(610)					(610)
Stock-based compensation			$ 8			8,763						8,771
Stock-based compensation (in shares)			741,216
Stock dividend						52			(52)
Stock dividend (in shares)			29,762
Public offerings, common stock, net			$ 38			6,978						7,016
Public offerings, common stock, net (in shares)			3,804,654
Stock option exercises			$ 5			168		$ (35)				138
Stock option exercises (in shares)			511,412					17,606
Equity component of convertible senior notes, net of issuance costs and income tax benefit						28,664						28,664
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						10,190						10,190
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
Cumulative effect from adoption of ASC 842									(3,487)			$ (3,487)
Net loss attributable to the Company									(85,465)			(85,465)
Other comprehensive income/loss							(184)					(184)
Stock-based compensation			$ 19			10,871						10,890
Stock-based compensation (in shares)			1,876,503
Stock dividend						52			(52)
Stock dividend (in shares)			19,286
Public offerings, common stock, net			$ 622			157,807						158,429
Public offerings, common stock, net (in shares)			62,333,585
Stock option exercises			$ 12			1,784		$ (579)				1,217
Stock option exercises (in shares)			1,151,307					256,382
Exercise of warrants			$ 53			14,099						14,152
Exercise of warrants (in shares)			5,250,750
Conversion of preferred stock (in shares)			13,845,468
Provision for common stock warrants						6,513						6,513
Accretion of discount, preferred stock						(1,978)						(1,978)
Conversion of preferred stock			$ 138			28,254						28,392
Balance at Dec. 31, 2019			$ 3,186			$ 1,507,116	$ 1,400	$ (31,216)	$ (1,345,807)			$ 134,679
Balance (in shares) at Dec. 31, 2019			318,637,560					15,259,045				318,637,560