Pension and Other Post Retirement Plans (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Collective Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 78.0	$ 57.5
Commingled Equity Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,149.0	1,027.2
Temporary Cash Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.8	0.2
Total [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Ending Fair Value	1,227.8	1,084.9
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Temporary Cash Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.8	0.2
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Total [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Ending Fair Value	0.8	0.2
Significant Other Observable Inputs (Level 2) [Member] | Collective Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	74.1	54.4
Significant Other Observable Inputs (Level 2) [Member] | Commingled Equity Bond Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,149.0	1,027.2
Significant Other Observable Inputs (Level 2) [Member] | Total [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Ending Fair Value	1,223.1	1,081.6
Significant Unobservable Inputs (Level 3) [Member] | Collective Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3.9	3.1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Fair Value	3.1	2.7
Purchases	0.6	0.9
Gain (loss)	0.2	(0.5)
Ending Fair Value		3.1
Significant Unobservable Inputs (Level 3) [Member] | Total [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Fair Value	3.1	2.7
Purchases	0.6	0.9
Gain (loss)	0.2	(0.5)
Ending Fair Value	$ 3.9	$ 3.1