Benefit Plans - Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Pension benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net actuarial loss (gain)	$ 15.8	$ 16.7
Prior service cost (credit)	(1.1)	(1.1)
Total	14.7	15.6
Other retirement benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net actuarial loss (gain)	(3.6)	(5.2)
Prior service cost (credit)	0.0	0.0
Total	$ (3.6)	$ (5.2)