STATEMENT OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital Common Stock	Accumulated Deficit
Beginning Balance at Dec. 31, 2014	$ 33,841	$ 104	$ 406,349	$ (372,612)
Beginning Balance (in shares) at Dec. 31, 2014		104,452,105
Stock-based compensation	1,093		1,093
Exercise of employee stock options (in shares)	592,200	592,200
Exercise of employee stock options	2,541		2,541
Repurchase of restricted common stock (in shares)		(33,931)
Repurchase of restricted common stock	(246)		(246)
Issuance of common stock in public offering (in shares)		11,500,000
Issuance of common stock in public offering	94,320	12	94,308
Issuance of common stock in licensing agreement (in shares)		11,722,163
Issuance of common stock in licensing agreement	67,285	12	67,273
Net loss	(78,231)			(78,231)
Ending Balance at Mar. 31, 2015	$ 120,603	$ 128	$ 571,318	$ (450,843)
Ending Balance (in shares) at Mar. 31, 2015		128,232,537