UK Pension Assets, Fair Value Measurements by Input Level (Detail) (Pension Benefits UK Plans [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Diversified Growth Assets	$ 154.7	$ 123.7
Fixed Interest and Index-linked Securities	43.5	63.5
Cash Equivalents	7.4	0.8
Total	205.6	188.0
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Diversified Growth Assets	0	0
Fixed Interest and Index-linked Securities	0	0
Cash Equivalents	7.4	0.8
Total	7.4	0.8
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Diversified Growth Assets	154.7
Fixed Interest and Index-linked Securities	43.5	63.5
Cash Equivalents	0	0
Total	198.2	187.2
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Diversified Growth Assets	0	0
Fixed Interest and Index-linked Securities	0	0
Cash Equivalents	0	0
Total	$ 0	$ 0

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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