Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2015

Accounting Policies [Abstract]

Percentage of Revenue from Significant Collaboration Customers

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Daiichi Sankyo, Inc.		40	%		63	%		45	%		43	%
Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		45	%		28	%		38	%		39	%
Bristol-Myers Squibb Company and Pfizer Inc.		13	%		7	%		15	%		15	%