Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statements of Operations
Collaboration revenue	$ 1,597		$ 43,275
Costs and expenses:
Research and development	32,059	$ 34,707	56,616	$ 49,084
General and administrative	11,959	7,570	21,543	13,919
Total costs and expenses	44,018	42,277	78,159	63,003
Loss from operations	(42,421)	(42,277)	(34,884)	(63,003)
Interest income	218	72	291	116
Loss before income tax provision	(42,203)	(42,205)	(34,593)	(62,887)
Income tax (benefit) provision	(5,072)	30,785	(4,098)	30,785
Net loss	$ (37,131)	$ (72,990)	$ (30,495)	$ (93,672)
Net loss per common share:
Basic and diluted (in dollars per share)	$ (1.08)	$ (2.19)	$ (0.89)	$ (2.85)
Weighted average common shares outstanding:
Basic and diluted (in shares)	34,353	33,373	34,254	32,830