Employee Benefit Plans and Other Postretirement Benefits - Change in Benefit Obligations and Change in Fair Value of Plan Assets Related to Pension and Postretirement Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in Fair Value of Plan 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	$ 1,200.0
Amounts Recognized on Consolidated Balance Sheets:
Noncurrent liabilities		(157.4)	(298.3)
Pension Plans
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		1,565.6	1,420.1
Service cost		21.4	23.0	$ 24.5
Interest cost		29.6	39.8	47.0
Plan amendments		2.1	1.3
Actuarial (gain) loss	[1]	(61.1)	132.0
Participant contributions
Benefits paid		(53.8)	(50.6)
Benefit obligation at plan year end		1,503.8	1,565.6	1,420.1
Accumulated benefit obligation portion of above		1,464.8	1,520.4
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		1,300.7	1,073.8
Actual return on plan assets		84.7	193.8
Company contributions		51.1	83.7
Participant contributions		0.0	0.0
Benefits paid		(53.8)	(50.6)
Fair value of plan assets at plan year end		1,382.7	1,300.7	1,073.8
Underfunded status		(121.1)	(264.9)
Amounts Recognized on Consolidated Balance Sheets:
Current liabilities		(1.9)	(1.2)
Noncurrent liabilities		(119.2)	(263.7)
Accrued obligation recognized at December 31		(121.1)	(264.9)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax):
Prior service cost (credit)		20.0	21.7
Actuarial loss (gain)		130.4	223.5
Total		150.4	245.2
Postretirement Plans
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		13.1	14.5
Service cost		0.2	0.3	0.3
Interest cost		0.3	0.4	0.5
Plan amendments		(0.1)	0.0
Actuarial (gain) loss	[1]	1.3	(1.5)
Participant contributions		0.6	0.9
Benefits paid		(1.8)	(1.5)
Benefit obligation at plan year end		13.6	13.1	$ 14.5
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		0.0
Actual return on plan assets		0.0	0.0
Company contributions		1.2	0.6
Participant contributions		0.6	0.9
Benefits paid		(1.8)	(1.5)
Fair value of plan assets at plan year end		0.0	0.0
Underfunded status		(13.6)	(13.1)
Amounts Recognized on Consolidated Balance Sheets:
Current liabilities		(0.6)	(0.6)
Noncurrent liabilities		(13.0)	(12.5)
Accrued obligation recognized at December 31		(13.6)	(13.1)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax):
Prior service cost (credit)		(4.7)	(4.9)
Actuarial loss (gain)		(3.6)	(5.5)
Total		$ (8.3)	$ (10.4)

[1] For the year ended December 31, 2021, the most significant driver of the decrease in benefit obligations for the pension plans was the actuarial gains due to an increase in the discount rate assumption. The OPEB plans experienced an actuarial loss primarily due to adverse medical claims experience that was partially offset by the effect of the change in the discount rate assumption. For the year ended December 31, 2020, the most significant driver of the increase in benefit obligations for the plans was the actuarial losses due to the decrease in the discount rate assumption. The OPEB plans experienced a net actuarial gain primarily due to changes in demographic assumptions that were partially offset by the effect of the change in the discount rate assumption.