Revenue Accounted for 10% or More of Total Revenues (Detail) (Customer Concentration Risk, Sales Revenue, Net)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")
Concentration Risk [Line Items]
Concentration risk percentage	16.00%	19.00%
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")
Concentration Risk [Line Items]
Concentration risk percentage	34.00%	38.00%
Daiichi Sankyo, Inc ("Daiichi")
Concentration Risk [Line Items]
Concentration risk percentage	48.00%	40.00%