Revenue Accounted for 10% or More of Total Collaboration and License Revenues (Detail) - Customer Concentration Risk - Sales Revenue, Net	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")
Concentration Risk [Line Items]
Concentration risk percentage	16.00%	21.00%	16.00%	20.00%
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")
Concentration Risk [Line Items]
Concentration risk percentage	34.00%	49.00%	34.00%	44.00%
Daiichi Sankyo, Inc ("Daiichi")
Concentration Risk [Line Items]
Concentration risk percentage	48.00%	27.00%	48.00%	34.00%