Pension and Other Postretirement Benefits - Fair Value Hierarchy (Details) - Pension - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 216.6	$ 329.7	$ 318.8
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	216.6	329.7
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1.3	2.5
Cash | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Cash | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Cash | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Cash | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1.3	2.5
Global equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	99.0	167.8
Global equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Global equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Global equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Global equity | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	99.0	167.8
Diversified credit
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	40.1	49.2
Diversified credit | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Diversified credit | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Diversified credit | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Diversified credit | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	40.1	49.2
Real assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	30.4	28.6
Real assets | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Real assets | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0
Real assets | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Real assets | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	30.4	28.6
Liability hedging assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	45.8	81.6
Liability hedging assets | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Liability hedging assets | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Liability hedging assets | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0.0	0.0
Liability hedging assets | Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 45.8	$ 81.6