Retirement Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 49.8	$ 59.1	$ 67.5
United States | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.8	8.6
United States | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	45.0	50.5
United States | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	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	0.5
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	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	11.5	10.2
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	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	0.0	4.6
United States | Equity securities | International growth fund | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.4	2.9
United States | Equity securities | International growth fund | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	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	4.3	3.2
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	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	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	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	30.1	36.7
United States | Equity securities | Commingled trust funds | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	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		0.8
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		0.7
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	15.2	18.6	$ 23.6
International | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.2	18.6
International | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	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		0.1
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 | Other investments | Commingled trust funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2.7
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	0.0
International | Other investments | Insurance contracts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.2	15.8
International | Other investments | Insurance contracts | Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Estimate of Fair Value | United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49.8	59.1
Estimate of Fair Value | United States | Short-term investments | Money market securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	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	11.5	10.2
Estimate of Fair Value | United States | Equity securities | International growth fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3.4	7.5
Estimate of Fair Value | United States | Equity securities | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.3	3.2
Estimate of Fair Value | United States | Equity securities | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.1	36.7
Estimate of Fair Value | United States | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.8
Estimate of Fair Value | United States | Other investments | Absolute return strategy equity funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.7
Estimate of Fair Value | International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15.2	18.6
Estimate of Fair Value | International | Short-term investments | Short-term Investments - Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.1
Estimate of Fair Value | International | Other investments | Commingled trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2.7
Estimate of Fair Value | International | Other investments | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 15.2	$ 15.8