Employee Benefit Plans and Other Postretirement Benefits - Summary of Changes in Pension Plans' Level 3 Assets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Level 3 fair value of pension plans' assets [Roll Forward]
Plan assets at fair value at beginning of period	$ 1,200.0
Fair value of plan assets at plan year end	1,300.0
Pension Plans
Level 3 fair value of pension plans' assets [Roll Forward]
Plan assets at fair value at beginning of period	1,300.7
Fair value of plan assets at plan year end	1,382.7
Significant unobservable input (Level 3) | Private Equity Securities | Pension Plans
Level 3 fair value of pension plans' assets [Roll Forward]
Plan assets at fair value at beginning of period	2.0
Purchases	0.4
Sales	(0.9)
Fair value of plan assets at plan year end	$ 1.5