CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2013		30,151
Balance at Dec. 31, 2013	$ 228,264	$ 301	$ 315,975	$ (88,012)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reverse stock split	0	$ 1	(1)
Stock issued in a private transaction, net of offering cost (in shares)		6,525
Stock issued in a private transaction, net of offering cost	103,949	$ 65	103,884
Bankruptcy claim settlements (in shares)		146
Bankruptcy claim settlements	2,677	$ 1	2,676
Exercise of common stock warrants (in shares)		51
Exercise of common stock warrants	786	$ 1	785
Share-based compensation (in shares)		196
Stock-based compensation	3,970	$ 2	3,968
Other comprehensive loss	(446)				(446)
Net income (loss)	(47,041)			(47,041)
Balance (in shares) at Dec. 31, 2014		37,069
Balance at Dec. 31, 2014	292,159	$ 371	427,287	(135,053)	(446)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued in a private transaction, net of offering cost (in shares)		3,500
Stock issued in a private transaction, net of offering cost	76,056	$ 35	76,021
Bankruptcy claim settlements	0
Exercise of common stock warrants (in shares)		404
Exercise of common stock warrants	7,730	$ 4	7,726
Share-based compensation (in shares)		98
Stock-based compensation	5,165	$ 1	5,164
Purchase of common stock for retirement (in shares)		(61)
Purchase of common stock for retirement	(1,034)	$ (1)	(1,033)
Other comprehensive loss	446				446
Net income (loss)	(39,911)			(39,911)
Balance (in shares) at Dec. 31, 2015		41,010
Balance at Dec. 31, 2015	340,611	$ 410	515,165	(174,964)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued in a private transaction, net of offering cost (in shares)		4,075
Stock issued in a private transaction, net of offering cost	49,044	$ 41	49,003
Bankruptcy claim settlements	0
Share-based compensation (in shares)		218
Stock-based compensation	6,625	$ 3	6,622
Equity component of 5% Convertible Senior Notes due 2021, net of tax of $8.6 million	13,526		13,526
Conversion of Bridge Notes (in shares)		273
Conversion of Bridge Notes	3,340	$ 2	3,338
Purchase of common stock for retirement (in shares)		(42)
Purchase of common stock for retirement	(598)	$ (1)	(597)
Other comprehensive loss	2,196
Net income (loss)	(45,835)			(45,835)
Balance (in shares) at Dec. 31, 2016		45,534
Balance at Dec. 31, 2016	$ 368,909	$ 455	$ 587,057	$ (220,799)	$ 2,196