Litigation and contingencies - Additional Information (Detail) € in Millions, $ in Millions	1 Months Ended	115 Months Ended
	Apr. 30, 2007 EUR (€)	Jul. 31, 2011 USD ($)	Dec. 31, 2016 USD ($)	Apr. 30, 2008 EUR (€)
Loss Contingencies [Line Items]
Amount related to unreserved tax-related matters, inclusive of interest | $			$ 126.0
Ministry Of Justice Of Belgium
Loss Contingencies [Line Items]
Loss contingency, damages sought value | €	€ 28.0
Counterclaim against termination of contract | €				€ 18.5
Pharmaceutical Claims
Loss Contingencies [Line Items]
Loss contingency, damages sought value | $		$ 68.0