Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values of Long-term Debt and Derivative Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Total debt	$ 2,555.1	$ 2,457.4
Carrying (Reported) Amount, Fair Value Disclosure
Derivative [Line Items]
Variable rate debt	528.9	427.7
Fixed rate debt	2,026.2	2,029.7
Total debt	2,555.1	2,457.4
Estimate of Fair Value, Fair Value Disclosure
Derivative [Line Items]
Variable rate debt	528.9	427.7
Fixed rate debt	2,002.2	2,081.3
Total debt	$ 2,531.1	$ 2,509.0

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

No definition available.

Name:	us-gaap_LongtermDebtPercentageBearingVariableInterestAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant