Employee Benefit Plans (Fair Values of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,354.6	$ 315.7
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51.8	3.9
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	613.4	89.3
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	592.0	179.9
Assets held by insurance companies and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	97.4	42.6
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	493.1	176.5
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51.2	3.4
Level 1 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	145.3	33.8
Level 1 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	292.6	138.0
Level 1 | Assets held by insurance companies and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4.0	1.3
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	788.1	111.7
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.6	0.5
Level 2 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	468.1	55.5
Level 2 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	299.4	41.9
Level 2 | Assets held by insurance companies and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20.0	13.8
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	73.4	27.5
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Level 3 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Level 3 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.0	0.0
Level 3 | Assets held by insurance companies and other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 73.4	$ 27.5