STATEMENT OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital Common Stock	Additional Paid-in Capital Warrants	Accumulated Deficit
Beginning Balance at Dec. 31, 2013	$ 49,383	$ 100	$ 386,511	$ 3,603	$ (340,831)
Beginning Balance (in shares) at Dec. 31, 2013		100,159,618
Warrant exercise (in shares)		1,991,409
Warrant exercise	3,700	1	7,283	(3,584)
Warrant expiration			19	(19)
Stock-based compensation	3,583		3,583
Exercise of employee stock options (in shares)	585,638	585,638
Exercise of employee stock options	1,323	2	1,321
Cancelled restricted stock (in shares)		(22,050)
Cancelled restricted stock	0
Repurchase of shares of restricted common stock (in shares)		(30,631)
Repurchase of shares of restricted common stock	(132)		(132)
Net loss	(21,380)				(21,380)
Ending Balance at Sep. 30, 2014	$ 36,477	$ 103	$ 398,585	$ 0	$ (362,211)
Ending Balance (in shares) at Sep. 30, 2014		102,683,984