Pension, Health Care and Other Postretirement Benefits - Summary of the Components of Net Periodic Benefit Cost and Cumulative Other Comprehensive Loss Related to Postretirement Benefits Other than Pensions (Details) - Postretirement Benefits Other than Pensions - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net periodic benefit cost:
Service cost	$ 0.6	$ 1.2	$ 1.4
Interest cost	7.4	6.0	4.9
Amortization of actuarial (gains) losses	0.1	4.2	4.7
Amortization of prior service (credit) cost	(23.9)	(0.4)	0.3
Net periodic benefit cost	(15.8)	11.0	11.3
Other changes in projected benefit obligation recognized in AOCI (before taxes):
Net actuarial gain arising during the year	(8.0)	(54.5)	(4.1)
Prior service (credit) arising during the year		(62.8)	(2.2)
Amortization of actuarial gains (losses)	(0.1)	(4.2)	(4.7)
Amortization of prior service credit (cost)	23.9	0.4	(0.3)
Total recognized in AOCI	15.8	(121.1)	(11.3)
Total recognized in net pension cost and AOCI	$ 0.0	$ (110.1)	$ 0.0