Summary of Notional Amounts of Outstanding Foreign Exchange Forwards, Cash Flow Hedging (Detail) € in Millions, ¥ in Millions, £ in Millions, SGD in Millions, CAD in Millions, $ in Millions	Jun. 30, 2017 CAD	Jun. 30, 2017 EUR (€)	Jun. 30, 2017 GBP (£)	Jun. 30, 2017 JPY (¥)	Jun. 30, 2017 SGD	Jun. 30, 2017 USD ($)	Dec. 31, 2016 EUR (€)	Dec. 31, 2016 GBP (£)	Dec. 31, 2016 SGD
Contracts to Sell US Dollars for GBP [Member] | Sell [Member]
Derivative [Line Items]
Derivative Notional Amount | $						$ 232.2
Contracts to Sell US Dollars for GBP [Member] | Buy [Member]
Derivative [Line Items]
Derivative Notional Amount | £			£ 184.1
Contracts to Sell USD for JPY [Member] | Sell [Member]
Derivative [Line Items]
Derivative Notional Amount | $						$ 20.5
Contracts to Sell USD for JPY [Member] | Buy [Member]
Derivative [Line Items]
Derivative Notional Amount | ¥				¥ 2,284.9
Contracts to Sell USD for CAD [Member] | Sell [Member]
Derivative [Line Items]
Derivative Notional Amount | SGD					SGD 38.6
Contracts to Sell USD for CAD [Member] | Buy [Member]
Derivative [Line Items]
Derivative Notional Amount | CAD	CAD 51.1
Contracts to Purchase Euros with SGD [Member] | Sell [Member]
Derivative [Line Items]
Derivative Notional Amount | SGD									SGD 55.5
Contracts to Purchase Euros with SGD [Member] | Buy [Member]
Derivative [Line Items]
Derivative Notional Amount | €							€ 36.0
Contracts to Sell Euros for GBP [Member] | Sell [Member]
Derivative [Line Items]
Derivative Notional Amount | €		€ 181.0					€ 31.0
Contracts to Sell Euros for GBP [Member] | Buy [Member]
Derivative [Line Items]
Derivative Notional Amount | £			£ 157.9					£ 25.9