Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income/(loss) [Member]
Beginning Balance at Dec. 31, 2012	$ 89,086	$ 861	$ 435,915	$ (347,937)	$ 247
Beginning Balance, shares at Dec. 31, 2012		86,136
Net loss	(31,238)			(31,238)
Other comprehensive income (loss)	(236)				(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
Exercise of stock options and issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes, shares		642
Non-cash compensation expense related to grant of equity based compensation	3,466		3,466
Ending Balance at Dec. 31, 2013	61,412	$ 868	439,708	(379,175)	11
Ending Balance, shares at Dec. 31, 2013		86,778
Net loss	(16,492)			(16,492)
Other comprehensive income (loss)	(23)				(23)
Issuance of common stock	3,923	$ 33	3,890
Issuance of common stock, shares		3,292
Issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes	(57)	$ 2	(59)
Issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes, shares		264
Non-cash compensation expense related to grant of equity based compensation	3,159		3,159
Ending Balance at Dec. 31, 2014	$ 51,922	$ 903	446,698	(395,667)	(12)
Ending Balance, shares at Dec. 31, 2014	90,334	90,334
Net loss	$ (9,238)			(9,238)
Other comprehensive income (loss)	52				52
Issuance of common stock	775	$ 9	766
Issuance of common stock, shares		861
Issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes	(20)	$ 3	(23)
Issuance of common stock underlying restricted stock units net of shares withheld to settle withholding taxes, shares		349
Non-cash compensation expense related to grant of equity based compensation	1,902		1,902
Ending Balance at Dec. 31, 2015	$ 45,393	$ 915	$ 449,343	$ (404,905)	$ 40
Ending Balance, shares at Dec. 31, 2015	91,544	91,544