Revenue Accounted for 10% or More of Total Revenues (Detail)	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2012 Novartis AG ("Novartis")	Sep. 30, 2012 Novartis AG ("Novartis")	Sep. 30, 2013 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Sep. 30, 2013 Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")	Sep. 30, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Sep. 30, 2013 Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen")	Sep. 30, 2013 Daiichi Sankyo, Inc ("Daiichi")	Sep. 30, 2013 Daiichi Sankyo, Inc ("Daiichi")
Concentration Risk [Line Items]
Percentage of major customers revenue accounted for 10% or more of total revenues	100.00%	100.00%	28.00%	46.00%	37.00%	41.00%	32.00%	12.00%