Pensions and Other Postretirement Benefits - Fair Value of Plan Assets (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,038,900,000	$ 1,092,800,000
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	343,800,000	311,900,000
Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	659,200,000	780,900,000
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35,900,000	0
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,400,000	28,800,000
Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,000,000	2,300,000
Cash | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,400,000	26,500,000
Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity Securities, Domestic
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	397,100,000	379,800,000
Equity Securities, Domestic | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	79,800,000	77,700,000
Equity Securities, Domestic | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	317,300,000	302,100,000
Equity Securities, Domestic | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity Securities, Foreign
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	140,100,000	177,700,000
Equity Securities, Foreign | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63,500,000	62,800,000
Equity Securities, Foreign | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	76,600,000	114,900,000
Equity Securities, Foreign | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	431,800,000	436,300,000
Fixed Income Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	172,900,000	169,100,000
Fixed Income Securities | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	258,900,000	267,200,000
Fixed Income Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,600,000	21,800,000
Real Estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22,600,000	0
Real Estate | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	21,800,000
Real Estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Diversified Growth Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35,900,000	48,400,000
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	0
Diversified Growth Fund | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	48,400,000
Diversified Growth Fund | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 35,900,000	$ 0