Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2016

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 June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
Daiichi Sankyo, Inc.		31	%		48	%		37	%		48	%
Bayer Pharma, AG and Janssen Pharmaceuticals, Inc.		19	%		34	%		33	%		34	%
Bristol-Myers Squibb Company and Pfizer Inc.		41	%		16	%		24	%		16	%