Derivative Instruments And Hedging Activities - Summary of Notional Amounts of Outstanding Foreign Exchange Forwards, Cash Flow Hedging (Detail) € in Millions, ¥ in Millions, £ in Millions, $ in Millions, $ in Millions, $ in Millions	Jun. 30, 2019 CAD ($)	Jun. 30, 2019 EUR (€)	Jun. 30, 2019 GBP (£)	Jun. 30, 2019 JPY (¥)	Jun. 30, 2019 SGD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 CAD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2018 JPY (¥)	Dec. 31, 2018 USD ($)
Contracts to Sell US Dollars for GBP [Member] | Sell [Member]
Derivative Notional Amount [Abstract]
Notional amount						$ 382.7				$ 310.3
Contracts to Sell US Dollars for GBP [Member] | Buy [Member]
Derivative Notional Amount [Abstract]
Notional amount			£ 299.5					€ 241.2
Contracts to Sell USD for JPY [Member] | Sell [Member]
Derivative Notional Amount [Abstract]
Notional amount						15.0				14.3
Contracts to Sell USD for JPY [Member] | Buy [Member]
Derivative Notional Amount [Abstract]
Notional amount | ¥				¥ 1,600.0					¥ 1,600.0
Contracts to Sell USD for CAD [Member] | Sell [Member]
Derivative Notional Amount [Abstract]
Notional amount						96.8				99.0
Contracts to Sell USD for CAD [Member] | Buy [Member]
Derivative Notional Amount [Abstract]
Notional amount	$ 130.0						$ 130.0
Contracts to Sell US Dollars for Singapore dollars [Member] | Sell [Member]
Derivative Notional Amount [Abstract]
Notional amount						35.0
Contracts to Sell US Dollars for Singapore dollars [Member] | Buy [Member]
Derivative Notional Amount [Abstract]
Notional amount					$ 48.0
Contracts to Sell USD for Euros [Member] | Sell [Member]
Derivative Notional Amount [Abstract]
Notional amount						$ 135.8				$ 212.8
Contracts to Sell USD for Euros [Member] | Buy [Member]
Derivative Notional Amount [Abstract]
Notional amount | €		€ 120.0						€ 184.6