STATEMENT OF STOCKHOLDERS' EQUITY (DEFICIT) - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital Common Stock	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2015		131,718,579
Beginning Balance at Dec. 31, 2015	$ 87,371	$ 132	$ 579,939	$ (492,700)
Stock-based compensation	$ 4,075		4,075
Exercise of employee stock options (in shares)	169,000	137,346
Exercise of employee stock options	$ 551	$ 1	550
Repurchase of common stock (in shares)		(168)
Repurchase of common stock	(2)		(2)
Restricted stock buy-back at vesting to cover taxes (in shares)		(123,334)
Restricted stock buy-back at vesting to cover taxes	(853)	$ (1)	(852)
Issuance of common stock in a license agreement	87		87
Net loss	(143,219)			(143,219)
Ending Balance (in shares) at Jun. 30, 2016		131,732,423
Ending Balance at Jun. 30, 2016	$ (51,990)	$ 132	$ 583,797	$ (635,919)