Employee Benefit Plans (Fair Values of Pension Plan Assets by Category) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 179.7	$ 154.3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.2
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	179.3	154.1
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.2
Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.2
Cash and Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Cash and Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Equity [Member] | Commingled Pools / Collective Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47.0	50.8
U.S. Equity [Member] | Commingled Pools / Collective Trusts [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
U.S. Equity [Member] | Commingled Pools / Collective Trusts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47.0	50.8
U.S. Equity [Member] | Commingled Pools / Collective Trusts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Equity [Member] | Commingled Pools / Collective Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.0	8.3
International Equity [Member] | Commingled Pools / Collective Trusts [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Equity [Member] | Commingled Pools / Collective Trusts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23.0	8.3
International Equity [Member] | Commingled Pools / Collective Trusts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Equity [Member] | Trust for Benefit of Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.1	4.8
International Equity [Member] | Trust for Benefit of Employees [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
International Equity [Member] | Trust for Benefit of Employees [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.1	4.8
International Equity [Member] | Trust for Benefit of Employees [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income [Member] | Commingled Pools / Collective Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64.9	54.6
Fixed Income [Member] | Commingled Pools / Collective Trusts [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income [Member] | Commingled Pools / Collective Trusts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64.9	54.6
Fixed Income [Member] | Commingled Pools / Collective Trusts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income [Member] | Trust for Benefit of Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14.1	13.6
Fixed Income [Member] | Trust for Benefit of Employees [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income [Member] | Trust for Benefit of Employees [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14.1	13.6
Fixed Income [Member] | Trust for Benefit of Employees [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income [Member] | Pension Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25.2	22.0
Fixed Income [Member] | Pension Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Fixed Income [Member] | Pension Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25.2	22.0
Fixed Income [Member] | Pension Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0.0	$ 0.0