Postretirement and Other Benefits Fair Value of Plan Assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 754.5		$ 706.0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	223.0		174.1
Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	531.5		531.9
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14.8	[1]	3.7
Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.6	[1]	1.3
Cash | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14.2	[1]	2.4
Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0
Equity Securities, Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	301.7	[1]	264.4	[1]
Equity Securities, Domestic | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58.2	[1]	52.1	[1]
Equity Securities, Domestic | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	243.5	[1]	212.3	[1]
Equity Securities, Domestic | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[1]
Equity Securities, Foreign
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	93.8	[1]	123.1	[1]
Equity Securities, Foreign | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	43.5	[1]	9.3	[1]
Equity Securities, Foreign | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50.3	[1]	113.8	[1]
Equity Securities, Foreign | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[1]
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	309.3	[1]	280.4	[1]
Fixed Income Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	120.7	[1]	111.4	[1]
Fixed Income Securities | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	188.6	[1]	169.0	[1]
Fixed Income Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[1]
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12.0	[2]	11.6	[2]
Real Estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]	0	[2]
Real Estate | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12.0	[2]	11.6	[2]
Real Estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]	0	[2]
Diversified Growth Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22.9	[3]	22.8	[3]
Diversified Growth Fund | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[3]	0	[3]
Diversified Growth Fund | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22.9	[3]	22.8	[3]
Diversified Growth Fund | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	[3]	$ 0	[3]

[1] The Level 2 investments are held in pooled funds.

[2]

[3] The fund invests in a combination of traditional investments (equities, bonds, and foreign exchange), seeking to achieve returns through active asset allocation over a three to five year horizon.