Consolidated Net Product Revenue Concentrations Based on Patient Location (Detail) - Net Product Revenue	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	89.00%	86.00%	85.00%
Geographic Concentration Risk | United States
Concentration Risk [Line Items]
Concentration risk, percentage	39.00%	37.00%	36.00%
Geographic Concentration Risk | Europe
Concentration Risk [Line Items]
Concentration risk, percentage	20.00%	20.00%	22.00%
Geographic Concentration Risk | Latin America
Concentration Risk [Line Items]
Concentration risk, percentage	16.00%	16.00%	14.00%
Geographic Concentration Risk | Rest of World
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%	13.00%	13.00%
Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	49.00%	52.00%	51.00%
Customer Concentration Risk | Genzyme | Product Four
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	14.00%	15.00%
Credit Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%