Pensions and Postretirement Benefits (Summary of Pension Plan Asset Allocation By Level) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 144.4	$ 128.2
Common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	40.0	34.2
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	43.9	37.9
Foreign stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	7.0	5.7
U.S. Government obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	8.6	4.8
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	11.5	13.1
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	14.2	12.0
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	2.7	6.3
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	127.9	114.0
Level 1 | Common stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	40.0	34.2
Level 1 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	43.9	37.9
Level 1 | Foreign stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	7.0	5.7
Level 1 | U.S. Government obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	8.6	4.8
Level 1 | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	11.5	13.1
Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	14.2	12.0
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	2.7	6.3
Investments measured at net asset value | Common collective trusts
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	0.0	0.1
Investments measured at net asset value | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 16.5	$ 14.1