Employee Benefit Plans (Fair Value Measurements) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 230.1	$ 256.9	$ 245.3
Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.0	3.0
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	226.1	253.9
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Money market accounts
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.0	3.0
Money market accounts | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.0	3.0
Money market accounts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Money market accounts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	226.1	253.9
Mutual funds | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	226.1	253.9
Mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0.0	$ 0.0