Employee Retirement Plans and Postretirement Benefits - Projected Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in benefit obligation
Prior year benefit obligation	$ 3,456.3	$ 5,744.5
Service cost, net of expected employee contributions	3.9	6.5
Interest cost	162.9	120.0
Actual employee contributions	0.3	0.3
Actuarial (gain) loss	39.3	(1,325.6)
Plan amendments	0.0	(0.1)
Benefits paid	(263.2)	(302.5)
Curtailment, settlement and special termination	0.0	(460.4)
Foreign currency exchange rate change	89.2	(326.4)
Benefit obligation at end of year	3,488.7	3,456.3	$ 5,744.5
Change in plan assets
Prior year fair value of assets	3,336.8	5,667.5
Actual return on plan assets	188.7	(1,272.9)
Employer contributions	35.3	38.2
Curtailment, settlement and special termination	0.0	(460.6)
Benefits and plan expenses paid	(263.2)	(302.5)
Foreign currency exchange rate change	99.0	(333.2)
Fair value of plan assets at end of year	3,396.9	3,336.8	5,667.5
Funded status	(91.8)	(119.5)
Amounts recognized in the Consolidated Balance Sheets
Other non-current assets	416.9	397.2
Accounts payable and other current liabilities	(42.9)	(43.4)
Pension and postretirement benefits	(465.8)	(473.3)
Net amounts recognized	(91.8)	(119.5)
Amounts in Accumulated Other Comprehensive Loss (Income) not yet recognized as components of net periodic pension cost or (benefit), pre-tax:
Net actuarial (gain) loss	512.9	488.2
Net prior service (benefit) cost	7.7	8.9
Total not yet recognized	520.6	497.1
Pension
Change in benefit obligation
Prior year benefit obligation	2,978.0	5,095.8
Service cost, net of expected employee contributions	0.6	1.0
Interest cost	140.4	103.9	93.9
Actual employee contributions	0.3	0.3
Actuarial (gain) loss	38.0	(1,181.0)
Plan amendments	0.0	0.0
Benefits paid	(226.2)	(263.8)
Curtailment, settlement and special termination	0.0	(460.6)
Foreign currency exchange rate change	87.0	(317.6)
Benefit obligation at end of year	3,018.1	2,978.0	5,095.8
Change in plan assets
Prior year fair value of assets	3,336.8	5,667.5
Actual return on plan assets	188.7	(1,272.9)
Employer contributions	(1.7)	(0.5)
Curtailment, settlement and special termination	0.0	(460.6)
Benefits and plan expenses paid	(226.2)	(263.8)
Foreign currency exchange rate change	99.0	(333.2)
Fair value of plan assets at end of year	3,396.9	3,336.8	5,667.5
Funded status	378.8	358.8
Amounts recognized in the Consolidated Balance Sheets
Other non-current assets	416.9	397.2
Accounts payable and other current liabilities	(3.6)	(3.9)
Pension and postretirement benefits	(34.5)	(34.5)
Net amounts recognized	378.8	358.8
Funded status:
Accumulated benefit obligation	38.1	38.4
Projected benefit obligation	38.1	38.4
Fair value of plan assets	0.0	0.0
Amounts in Accumulated Other Comprehensive Loss (Income) not yet recognized as components of net periodic pension cost or (benefit), pre-tax:
Net actuarial (gain) loss	773.3	766.4
Net prior service (benefit) cost	9.4	9.7
Total not yet recognized	782.7	776.1
OPEB
Change in benefit obligation
Prior year benefit obligation	478.3	648.7
Service cost, net of expected employee contributions	3.3	5.5
Interest cost	22.5	16.1	14.6
Actual employee contributions	0.0	0.0
Actuarial (gain) loss	1.3	(144.6)
Plan amendments	0.0	(0.1)
Benefits paid	(37.0)	(38.7)
Curtailment, settlement and special termination	0.0	0.2
Foreign currency exchange rate change	2.2	(8.8)
Benefit obligation at end of year	470.6	478.3	648.7
Change in plan assets
Prior year fair value of assets	0.0	0.0
Actual return on plan assets	0.0	0.0
Employer contributions	37.0	38.7
Curtailment, settlement and special termination	0.0	0.0
Benefits and plan expenses paid	(37.0)	(38.7)
Foreign currency exchange rate change	0.0	0.0
Fair value of plan assets at end of year	0.0	0.0	$ 0.0
Funded status	(470.6)	(478.3)
Amounts recognized in the Consolidated Balance Sheets
Other non-current assets	0.0	0.0
Accounts payable and other current liabilities	(39.3)	(39.5)
Pension and postretirement benefits	(431.3)	(438.8)
Net amounts recognized	(470.6)	(478.3)
Amounts in Accumulated Other Comprehensive Loss (Income) not yet recognized as components of net periodic pension cost or (benefit), pre-tax:
Net actuarial (gain) loss	(260.4)	(278.2)
Net prior service (benefit) cost	(1.7)	(0.8)
Total not yet recognized	$ (262.1)	$ (279.0)