STATEMENT OF STOCKHOLDERS' EQUITY - Entity [Domain] - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital Common Stock	Accumulated Deficit
Balance (in shares) at Dec. 31, 2014		104,452,105
Balance at Dec. 31, 2014	$ 33,841	$ 104	$ 406,349	$ (372,612)
Stock-based compensation	$ 4,577		4,577
Exercise of employee stock options (in shares)	2,860,299	2,135,408
Exercise of employee stock options	$ 3,140	$ 2	3,138
Restricted stock awards (in shares)		1,050,000
Restricted stock awards		$ 1	(1)
Repurchase of common stock (Shares)		(3,711)
Repurchase of common stock	(34)		(34)
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	(92,442)			(92,442)
Balance (in shares) at Jun. 30, 2015		130,822,034
Balance at Jun. 30, 2015	$ 110,441	$ 131	$ 575,364	$ (465,054)