Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2015

Accounting Policies [Abstract]

Percentage of Revenue from Significant Customers

Customers who accounted for 10% or more of total collaboration and license revenues were as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
	2015			2014			2015			2014
Bristol-Myers Squibb Company and Pfizer Inc.		16	%		21	%		16	%		20	%
Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		34	%		49	%		34	%		44	%
Daiichi Sankyo, Inc.		48	%		27	%		48	%		34	%