Changes in Fair Value of Level Three Assets (Detail) (Fair Value, Inputs, Level 3, Private Equity Funds, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Fair Value, Inputs, Level 3 \| Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 38.9	$ 30.1
Unrealized gains/losses—net	8.7	5.8
Purchases, sales and settlements	(4.2)	3.0
Fair value of plan assets at end of year	$ 43.4	$ 38.9

Amount before tax, after reclassification adjustments, of actuarial gain (loss) that has not been recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-SubTopic 20

-Section 50

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- Definition

Amount of increase (decrease) in plan assets from purchases, sales and settlement of plan obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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