Pension and Savings Plans - Fair Value of Assets in the Master Trust by Asset (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	$ 0.0	$ 430.4	$ 0.3	$ 1.2
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	116.0	583.3	$ 772.4
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	95.9	536.2
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	66.7	67.2
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	23.4	26.1
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| International government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	1.5	2.0
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.5	0.7
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Cash funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	3.8	9.8
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Real estate interests
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		0.3
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Group annuity contract
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		430.1
Pension Plan \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	23.1	33.1
Pension Plan \| Level 1 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 1 \| U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	19.3	23.3
Pension Plan \| Level 1 \| International government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 1 \| Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 1 \| Cash funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	3.8	9.8
Pension Plan \| Level 1 \| Real estate interests
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		0.0
Pension Plan \| Level 1 \| Group annuity contract
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		0.0
Pension Plan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	72.8	72.7
Pension Plan \| Level 2 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	66.7	67.2
Pension Plan \| Level 2 \| U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	4.1	2.8
Pension Plan \| Level 2 \| International government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	1.5	2.0
Pension Plan \| Level 2 \| Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.5	0.7
Pension Plan \| Level 2 \| Cash funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 2 \| Real estate interests
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		0.0
Pension Plan \| Level 2 \| Group annuity contract
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		0.0
Pension Plan \| Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	430.4
Pension Plan \| Level 3 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 3 \| U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 3 \| International government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 3 \| Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 3 \| Cash funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 3 \| Real estate interests
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		0.3
Pension Plan \| Level 3 \| Group annuity contract
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets		430.1
Pension Plan \| Fair Value Measured at Net Asset Value Per Share \| Private mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	$ 20.1	$ 47.1