Summary of Notional Amounts of Outstanding Foreign Exchange Forwards, Net Investment Hedging (Detail) - Net Investment Hedging [Member] € in Millions, ¥ in Millions, £ in Millions	Sep. 30, 2015 EUR (€)	Sep. 30, 2015 GBP (£)	Sep. 30, 2015 JPY (¥)	Dec. 31, 2014 EUR (€)	Dec. 31, 2014 GBP (£)	Dec. 31, 2014 JPY (¥)
Long Term Debt [Member]
Derivative [Line Items]
Derivative Notional Amount	€ 400.0
Forward Contracts [Member] | Contracts to Sell Euros for USD [Member]
Derivative [Line Items]
Derivative Notional Amount | €				€ 50.0
Forward Contracts [Member] | Contracts to Sell GBP for Euros [Member]
Derivative [Line Items]
Derivative Notional Amount		£ 20.4
Forward Contracts [Member] | Contracts to Sell Japanese Yen for USD [Member]
Derivative [Line Items]
Derivative Notional Amount | ¥			¥ 19,400.0			¥ 19,400.0