Consolidated Statements of Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data	Total	Private Placement [Member]	Common Stock [Member]	Common Stock [Member] Private Placement [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Private Placement [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Series A Preferred Stock [Member]	Series A Preferred Stock [Member] Private Placement [Member]
Beginning Balance at Dec. 31, 2011	$ 4,122		$ 30		$ 99,710		$ (47)	$ (95,571)
Beginning Balance, shares at Dec. 31, 2011			29,577,146
Stock-based compensation	1,619				1,619
Stock option exercise	2,054		1		2,053
Stock option exercise, shares	789,305		789,305
Restricted stock awards	0		0		0		0	0	0
Restricted stock awards, shares			57,500
Warrant derivative liability reclassified to equity	1,037				1,037
Warrant exercises	920				920
Warrant exercises, shares			281,865
Stock offering, net		38,374		7		38,364				3
Stock offering, net shares			6,791,887	6,791,887						2,709,300
Net income (loss)	1,652							1,652
Ending Balance at Dec. 31, 2012	49,778		38		143,703		(47)	(93,919)	3
Ending Balance, shares at Dec. 31, 2012			37,497,703						2,709,300
Stock-based compensation	3,327				3,327
Stock option exercise	357				357
Stock option exercise, shares	115,667		115,667
Restricted stock awards	0		0		0		0	0	0
Restricted stock awards, shares			80,498
Warrant derivative liability reclassified to equity	11				11
Warrant exercises	50				50
Warrant exercises, shares			10,000
Shares issued to Arcion in acquisition of research and development license	2,073		1		2,072
Shares issued to Arcion in acquisition of research and development license, shares			500,516
Warrants issued in connection with notes payable	986				986
Net income (loss)	(57,394)							(57,394)
Ending Balance at Dec. 31, 2013	(812)		39		150,506		(47)	(151,313)	3
Ending Balance, shares at Dec. 31, 2013			38,204,384						2,709,300
Stock-based compensation	6,883				6,883
Stock option exercise	4,580		1		4,579
Stock option exercise, shares	1,332,563		1,332,563
Restricted stock awards	0		0		0		0	0	0
Restricted stock awards, shares			473,893
Warrant derivative liability reclassified to equity	17,478				17,478
Warrant exercises	7,741		2		7,739
Warrant exercises, shares			1,999,153
Cashless exercise of warrants	0		0		0		0	0	0
Cashless exercise of warrants, shares			218,367
Stock offering, net	58,182		8		58,174
Stock offering, net shares			7,500,000
Shares issued pursuant to an at the market offering, net	14,480		1		14,479
Shares issued pursuant to an at the market offering, shares			1,304,410
Short swing profit return	82				82
Short swing profit return, shares	0		0		0		0	0	0
Conversion of preferred shares to common shares			1						(1)
Conversion of preferred shares to common shares, shares			570,300						(570,300)
Net income (loss)	(54,218)							(54,218)
Ending Balance at Dec. 31, 2014	$ 54,396		$ 52		$ 259,920		$ (47)	$ (205,531)	$ 2
Ending Balance, shares at Dec. 31, 2014			51,603,070						2,139,000