Pension and Savings Plans - Fair Value of Assets in the Master Trust by Asset (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	$ 0.3	$ 1.2	$ 4.1	$ 6.2
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	772.4	847.5	$ 855.2
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	735.0	805.4
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	537.5	623.3
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	147.7	142.6
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| International government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	15.5	18.7
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	3.3	4.7
Pension Plan \| Fair Value, Inputs, Level 1, 2 and 3 \| Cash funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	30.7	14.9
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	1.2
Pension Plan \| Level 1
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	155.9	136.3
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	125.2	121.4
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	30.7	14.9
Pension Plan \| Level 1 \| Real estate interests
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.0	0.0
Pension Plan \| Level 2
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	578.8	667.9
Pension Plan \| Level 2 \| Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	537.5	623.3
Pension Plan \| Level 2 \| U.S. government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	22.5	21.2
Pension Plan \| Level 2 \| International government securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	15.5	18.7
Pension Plan \| Level 2 \| Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	3.3	4.7
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	0.0
Pension Plan \| Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	0.3	1.2
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	1.2
Pension Plan \| Fair Value Measured at Net Asset Value Per Share \| Private mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, assets	$ 37.4	$ 42.1