Saving Plans, Pension and Post Retirement Benefits - Fair Value of Asset Categories (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 520.2		$ 463.8
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.9		15.8
Common and preferred stock [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18.9		15.7
Mutual funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19.4	[1]	23.1	[1]
Mutual funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16.0	[1]	10.1	[1]
Mutual funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63.2	[1]	53.9	[1]
Mutual funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	[1]	1.6	[1]
Mutual funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.0	[1]	3.8	[1]
Mutual funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.6	[1]	3.7	[1]
Fixed income securities [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49.8		86.1
Fixed income securities [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9.9		30.4
Common and collective funds [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.7	[1]	14.5	[1]
Common and collective funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.0	[1]	31.7	[1]
Common and collective funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70.2	[1]	28.5	[1]
Common and collective funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27.0	[1]	18.7	[1]
Common and collective funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74.3	[1]	64.3	[1]
Common and collective funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.7	[1]	15.2	[1]
Common and collective funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.1	[1]	4.5	[1]
Common and collective funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.0	[1]	0.8	[1]
Hedge funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.2	[1]
Hedge funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.9	[1]	23.9	[1]
Hedge funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	[1]	1.9	[1]
Hedge funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.1	[1]	3.5	[1]
Hedge funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.8	[1]	4.3	[1]
Hedge funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.0	[1]	0.7	[1]
Hedge funds [Member] | Foreign Exchange Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]	5.0	[1]
Group annuity contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.3		2.1
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137.6		128.4
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.9		15.8
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and preferred stock [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18.9		15.7
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19.4	[1]	23.1	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16.0	[1]	10.1	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63.2	[1]	53.9	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	[1]	1.6	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.0	[1]	3.8	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.6	[1]	3.7	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed income securities [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed income securities [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common and collective funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]	0.7	[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge funds [Member] | Foreign Exchange Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Group annuity contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	382.0		335.4
Significant Observable Inputs (Level 2) [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Observable Inputs (Level 2) [Member] | Common and preferred stock [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Mutual funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Fixed income securities [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49.2		86.1
Significant Observable Inputs (Level 2) [Member] | Fixed income securities [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9.9		30.4
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.7	[1]	14.5	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.0	[1]	31.7	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70.2	[1]	28.5	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27.0	[1]	18.7	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74.3	[1]	64.3	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.7	[1]	15.2	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.1	[1]	4.5	[1]
Significant Observable Inputs (Level 2) [Member] | Common and collective funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.0	[1]	0.8	[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.2	[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.9	[1]	23.9	[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.6	[1]	1.9	[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.1	[1]	3.5	[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.8	[1]	4.3	[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.0	[1]		[1]
Significant Observable Inputs (Level 2) [Member] | Hedge funds [Member] | Foreign Exchange Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]	5.0	[1]
Significant Observable Inputs (Level 2) [Member] | Group annuity contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.3		2.1
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.6
Significant Unobservable Inputs (Level 3) [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Common and preferred stock [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Mutual funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Fixed income securities [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.6
Significant Unobservable Inputs (Level 3) [Member] | Fixed income securities [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | Emerging markets international equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Common and collective funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Hedge funds [Member] | Foreign Exchange Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		[1]		[1]
Significant Unobservable Inputs (Level 3) [Member] | Group annuity contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets

[1] The investments in mutual funds, common and collective funds and hedge funds are disclosed above within the respective underlying investments' class (i.e., various equities, corporate bonds, government bonds and other investment classes), while the fair value hierarchy levels of the investments are based on the Company's direct ownership unit of account.