Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income/(loss) [Member]
Beginning Balance at Dec. 31, 2011	$ 60,348	$ 719	$ 384,087	$ (325,038)	$ 580
Beginning Balance, shares at Dec. 31, 2011		71,913,000
Net loss	(22,899)	0	0	(22,899)	0
Other comprehensive loss	(333)	0	0	0	(333)
Issuance of common stock	48,709	139	48,570	0	0
Issuance of common stock, shares		13,909,000
Exercise of stock options and issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes	(29)	3	(32)	0	0
Exercise of stock options and issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes, shares		314,000
Non-cash compensation expense related to grant of equity based compensation	3,290	0	3,290	0	0
Ending Balance at Dec. 31, 2012	89,086	861	435,915	(347,937)	247
Ending Balance, shares at Dec. 31, 2012		86,136,000
Net loss	(31,238)	0	0	(31,238)	0
Other comprehensive loss	(236)	0	0	0	(236)
Exercise of stock options and issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes	334	7	327	0	0
Exercise of stock options and issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes, shares		642,000
Non-cash compensation expense related to grant of equity based compensation	3,466	0	3,466	0	0
Ending Balance at Dec. 31, 2013	61,412	868	439,708	(379,175)	11
Ending Balance, shares at Dec. 31, 2013	86,778,000	86,778,000
Net loss	(16,492)	0	0	(16,492)	0
Other comprehensive loss	(23)	0	0	0	(23)
Issuance of common stock	3,923	33	3,890	0	0
Issuance of common stock, shares		3,292,000
Issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes	(57)	2	(59)	0	0
Issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes, shares		264,000
Non-cash compensation expense related to grant of equity based compensation	3,159	0	3,159	0	0
Ending Balance at Dec. 31, 2014	$ 51,922	$ 903	$ 446,698	$ (395,667)	$ (12)
Ending Balance, shares at Dec. 31, 2014	90,334,000	90,334,000