Pension Benefits - Changes in Fair Value of Plan Assets and Changes in Accumulated Benefit Obligations (Details) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plans’ Assets at Beginning of Year	$ 16.3	$ 315.8
Actual Return on Plan Assets	(1.1)	7.1
Benefits Paid	0.0	(100.9)
Settlement Benefits	2.6	(205.7)
Assets contributed to 401(k) Plan	(4.7)	0.0
Assets reverted to the Company	(13.1)	0.0
Fair Value of Plan Assets at End of Year	0.0	16.3	$ 315.8
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accumulated Postretirement Benefit Obligation at Beginning of Year	0.0	292.2
Interest Cost	0.0	8.4	8.7
Benefits Paid	0.0	(100.9)
Settlement Benefits	0.0	(205.7)
Actuarial Gains	0.0	6.0
Projected Benefit Obligation at End of Year	0.0	0.0	$ 292.2
Funded Status—Plan Assets in Excess of Projected Benefit Obligation	0.0	16.3
Unamortized Amount Reported in AOCI at End of Year	0.0	0.0
Accumulated Benefit Obligation at End of Year	$ 0.0	$ 0.0