Location and Fair Values of Derivative Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Asset Derivatives Fair Value	$ 24.5	$ 81.6
Liability Derivatives Fair Value	142.9	170.5
Designated as Hedging Instrument | Other Long-term Investments
Derivative [Line Items]
Asset Derivatives Fair Value	24.5	81.6
Designated as Hedging Instrument | Other Liability
Derivative [Line Items]
Liability Derivatives Fair Value	141.4	170.5
Designated as Hedging Instrument | Interest Rate Swaps | Other Long-term Investments
Derivative [Line Items]
Asset Derivatives Fair Value	22.5	76.5
Designated as Hedging Instrument | Interest Rate Swaps | Other Liability
Derivative [Line Items]
Liability Derivatives Fair Value	33.8	31.7
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Long-term Investments
Derivative [Line Items]
Asset Derivatives Fair Value	2.0	5.1
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Liability
Derivative [Line Items]
Liability Derivatives Fair Value	107.6	138.8
Not Designated as Hedging Instrument | Other Liability
Derivative [Line Items]
Liability Derivatives Fair Value	66.9
Not Designated as Hedging Instrument | Credit Default Swaps | Other Liability
Derivative [Line Items]
Liability Derivatives Fair Value	1.5
Not Designated as Hedging Instrument | Embedded Derivative in Modified Coinsurance Arrangement | Other Liability
Derivative [Line Items]
Liability Derivatives Fair Value	$ 65.4	$ 83.9