Postretirement Health Care and Life Insurance Benefits - Net Periodic Postretirement Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2023	Jan. 01, 2022
Retirement Benefits [Abstract]
Average remaining service period (in years)				1 year 10 months 24 days	2 years 10 months 24 days
Postretirement Health Care and Life Insurance Benefits
Retirement Benefits [Abstract]
Average remaining service period (in years)				13 years	14 years
Defined Benefit Plan Disclosure [Line Items]
Service cost for benefits earned	$ 0.8	$ 1.0	$ 3.8
Interest cost on accumulated postretirement benefit obligation	7.0	10.5	20.2
Expected return on plan assets	(0.8)	(1.0)	(1.5)
Amortization of prior service credit	(53.8)	(46.4)	(17.3)
Net actuarial (gain) loss	(51.2)	(54.5)	16.5
Net periodic postretirement benefit (credit) cost	$ (98.0)	$ (90.4)	$ 21.7