Retirement Plans - Fair Value of Plan Assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 67.5	$ 71.0	$ 71.7
United States | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.5	29.3
United States | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37.0	41.7
United States | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Short-term investments | Money market securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.5
United States | Short-term investments | Money market securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Short-term investments | Money market securities | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | Large-cap growth funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | Large-cap growth funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14.6	16.1
United States | Equity securities | Large-cap growth funds | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | International growth fund | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.3	7.5
United States | Equity securities | International growth fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.5	3.6
United States | Equity securities | International growth fund | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | Common Stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.3	8.3
United States | Equity securities | Common Stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | Common Stock | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | Commingled trust funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Equity securities | Commingled trust funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.7	9.2
United States | Equity securities | Commingled trust funds | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.5	13.0
United States | Fixed income securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Fixed income securities | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Other investments | Absolute return strategy equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Other investments | Absolute return strategy equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13.2	12.8
United States | Other investments | Absolute return strategy equity funds | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.6	26.1	58.0
International | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.6	26.1
International | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Short-term investments | Short-term Investments - Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Short-term investments | Short-term Investments - Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.3
International | Short-term investments | Short-term Investments - Other | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Equity securities | Blended mutual funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
International | Equity securities | Blended mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
International | Equity securities | Blended mutual funds | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
International | Fixed income securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Fixed income securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.7	6.1
International | Fixed income securities | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Other investments | Insurance contracts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Other investments | Insurance contracts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.6	19.7
International | Other investments | Insurance contracts | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Estimate of Fair Value | United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	67.5	71.0
Estimate of Fair Value | United States | Short-term investments | Money market securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.5
Estimate of Fair Value | United States | Equity securities | Large-cap growth funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14.6	16.1
Estimate of Fair Value | United States | Equity securities | International growth fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.8	11.1
Estimate of Fair Value | United States | Equity securities | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.3	8.3
Estimate of Fair Value | United States | Equity securities | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.7	9.2
Estimate of Fair Value | United States | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.5	13.0
Estimate of Fair Value | United States | Other investments | Absolute return strategy equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13.2	12.8
Estimate of Fair Value | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.6	26.1
Estimate of Fair Value | International | Short-term investments | Short-term Investments - Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.3
Estimate of Fair Value | International | Equity securities | Blended mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Estimate of Fair Value | International | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.7	6.1
Estimate of Fair Value | International | Other investments | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 17.6	$ 19.7