Employee Retirement Plans and Postretirement Benefits - Pension Fair Value Hierarchy (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	$ 5,667.5	$ 5,958.4	$ 5,542.1
Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	5,667.5	5,958.4	5,542.1
Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	2,410.1	2,590.2
Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	(276.7)	(322.0)
Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	1,932.3	2,055.9
Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	754.5	856.3	$ 830.2
Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	754.5	856.3
Cash | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	198.4	144.6
Cash | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	198.4	144.6
Cash | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Cash | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Trades awaiting settlement | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	2.1	16.7
Trades awaiting settlement | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	2.1	16.7
Trades awaiting settlement | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Trades awaiting settlement | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Bank deposits, short-term bills and notes | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	25.5	25.0
Bank deposits, short-term bills and notes | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Bank deposits, short-term bills and notes | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	25.5	25.0
Bank deposits, short-term bills and notes | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Government debt securities | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	751.0	869.6
Government debt securities | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Government debt securities | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	751.0	869.6
Government debt securities | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Corporate debt securities | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	142.0	112.7
Corporate debt securities | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Corporate debt securities | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	142.0	112.7
Corporate debt securities | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Interest and inflation linked assets | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	1,029.7	1,059.6
Interest and inflation linked assets | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Interest and inflation linked assets | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	1,013.8	1,048.6
Interest and inflation linked assets | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	15.9	11.0
Annuities | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	708.9	783.9
Annuities | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Annuities | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Annuities | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	708.9	783.9
Repurchase agreements | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	(477.4)	(483.5)
Repurchase agreements | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	(477.4)	(483.5)
Repurchase agreements | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Repurchase agreements | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Recoverable taxes | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.2	0.2
Recoverable taxes | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.2	0.2
Recoverable taxes | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Recoverable taxes | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Private equity | Fair Value, Inputs, Level 1, 2 and 3 | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	29.7	61.4
Private equity | Quoted prices in active markets (Level 1) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Private equity | Significant observable inputs (Level 2) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	0.0	0.0
Private equity | Significant unobservable inputs (Level 3) | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	29.7	61.4
Private equity | Fair Value Measured at Net Asset Value Per Share | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	65.8	77.1
Debt funds | Fair Value Measured at Net Asset Value Per Share | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	2,034.2	1,591.4
Equity funds | Fair Value Measured at Net Asset Value Per Share | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	732.1	1,418.6
Real estate funds | Fair Value Measured at Net Asset Value Per Share | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	285.0	274.4
Hedge funds | Fair Value Measured at Net Asset Value Per Share | Pension
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan assets	$ 140.3	$ 6.7