Retirement Benefits Fair Value Pension Plan Assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 835.7	$ 764.0
Employer stock included in plan assets	37.6	35.0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	381.2	345.3
Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	376.4	286.4
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78.1	132.3
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26.2	23.9
Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	26.2	23.9
Cash and cash equivalents | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and cash equivalents | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
US Large-Cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35.1	75.7
US Large-Cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35.1	75.7
US Large-Cap | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
US Large-Cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
US Mid-Cap and Small-Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41.5	42.0
US Mid-Cap and Small-Cap Growth | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41.5	42.0
US Mid-Cap and Small-Cap Growth | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
US Mid-Cap and Small-Cap Growth | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International Large-cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.4	80.7
International Large-cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.4	80.7
International Large-cap | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International Large-cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.3	28.3
Emerging Markets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.3	28.3
Emerging Markets | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging Markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
US Treasuries
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.7	59.6
US Treasuries | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
US Treasuries | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57.7	59.6
US Treasuries | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	214.1	120.7
Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate Bonds | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	214.1	120.7
Corporate Bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Asset Backed Securities and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	87.9	91.8
Asset Backed Securities and Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	1.1
Asset Backed Securities and Other | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	87.5	90.7
Asset Backed Securities and Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity/Debt Futures
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	150.1	97.5
Equity/Debt Futures | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	149.1	97.5
Equity/Debt Futures | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.0	0
Equity/Debt Futures | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Derivative Liability
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(15.9)	(37.2)
Derivative Liability | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(15.9)	(37.2)
Alternative Investment Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	188.2	165.6
Alternative Investment Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	110.1	33.3
Alternative Investment Funds | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Alternative Investment Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	78.1	132.3	126.2
Common Pooled Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16.1	15.4
Common Pooled Fund | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common Pooled Fund | Quoted Prices in Active Markets for Similar Assets (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16.1	15.4
Common Pooled Fund | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0