Location and Fair Values of Derivative Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative
Asset Derivatives Fair Value	$ 11.4	$ 10.8
Liability Derivatives Fair Value	133.2	135.6
Designated as Hedging Instrument | Other Long-term Investments
Derivative
Asset Derivatives Fair Value	11.4	10.8
Designated as Hedging Instrument | Other Liability
Derivative
Liability Derivatives Fair Value	131.0	133.7
Designated as Hedging Instrument | Interest Rate Swaps | Other Long-term Investments
Derivative
Asset Derivatives Fair Value	8.0	9.2
Designated as Hedging Instrument | Interest Rate Swaps | Other Liability
Derivative
Liability Derivatives Fair Value	26.4	35.0
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Long-term Investments
Derivative
Asset Derivatives Fair Value	3.4	1.6
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Liability
Derivative
Liability Derivatives Fair Value	104.6	98.7
Not Designated as Hedging Instrument | Other Liability
Derivative
Liability Derivatives Fair Value	34.5	55.1
Not Designated as Hedging Instrument | Credit Default Swaps | Other Liability
Derivative
Liability Derivatives Fair Value	2.2	1.9
Not Designated as Hedging Instrument | Embedded Derivative in Modified Coinsurance Arrangement | Other Liability
Derivative
Liability Derivatives Fair Value	$ 32.3	$ 53.2