Summary of Notional Amounts of Outstanding Foreign Exchange Forwards, Cash Flow Hedging (Detail) - Forward Contracts [Member] € in Millions, $ in Millions	Sep. 30, 2015 EUR (€)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 EUR (€)	Dec. 31, 2014 USD ($)
Foreign Currency Forward Contracts to Purchase US Dollars with Euros [Member]
Derivative [Line Items]
Derivative Notional Amount				$ 38.5
Foreign Currency Forward Contracts To Sell US Dollars For Euros [Member]
Derivative [Line Items]
Derivative Notional Amount		$ 48.3		51.5
Foreign Currency Forward Contracts to Purchase US Dollars With GBP [Member]
Derivative [Line Items]
Derivative Notional Amount				0.2
Foreign Currency Forward Contracts To Sell US Dollars for GBP [Member]
Derivative [Line Items]
Derivative Notional Amount
Foreign Currency Forward Contracts To Purchase US Dollars With Other Foreign Currencies [Member]
Derivative [Line Items]
Derivative Notional Amount				$ 1.2
Foreign Currency Forward Contracts to Sell US Dollars for Other Foreign Currencies [Member]
Derivative [Line Items]
Derivative Notional Amount
Foreign Currency Forward Contracts To Purchase Euros With Other Foreign Currencies [Member]
Derivative [Line Items]
Derivative Notional Amount | €	€ 36.0		€ 34.0
Foreign Currency Forward Contracts To Purchase Euros With GBP [Member]
Derivative [Line Items]
Derivative Notional Amount | €			25.0
Foreign Currency Forward Contracts to Sell Euros for GBP [Member]
Derivative [Line Items]
Derivative Notional Amount | €	€ 27.3		€ 38.2