Location and Fair Values of Derivative Financial Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Derivative
Asset Derivatives Fair Value	$ 40.4	$ 49.8
Designated as Hedging Instrument | Other Long-term Investments
Derivative
Asset Derivatives Fair Value	40.4	49.8
Designated as Hedging Instrument | Other Liabilities
Derivative
Liability Derivatives Fair Value	23.1	18.3
Designated as Hedging Instrument | Interest Rate Swaps | Other Long-term Investments
Derivative
Asset Derivatives Fair Value	6.3	2.4
Designated as Hedging Instrument | Interest Rate Swaps | Other Liabilities
Derivative
Liability Derivatives Fair Value	6.7	12.3
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Long-term Investments
Derivative
Asset Derivatives Fair Value	34.1	47.4
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Liabilities
Derivative
Liability Derivatives Fair Value	16.4	6.0
Not Designated as Hedging Instrument | Other Liabilities
Derivative
Liability Derivatives Fair Value	116.9	119.5
Not Designated as Hedging Instrument | Foreign Exchange Contracts | Other Liabilities
Derivative
Liability Derivatives Fair Value	33.5	31.6
Not Designated as Hedging Instrument | Credit Risk Contract | Other Liabilities
Derivative
Liability Derivatives Fair Value	0.4	0.3
Not Designated as Hedging Instrument | Embedded Derivative in Modified Coinsurance Arrangement | Other Liabilities
Derivative
Liability Derivatives Fair Value	$ 83.0	$ 87.6