Income Taxes - Rollforward of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits – January 1	$ 6.7	$ 7.6	$ 41.5
Additions for:
Current year tax positions	1.4	1.7	0.6
Prior year tax positions	0.5	0.3	0.1
Reductions for:
Prior year tax positions	(0.6)	(0.1)	(5.5)
Expiration of statute of limitations	(2.3)	(2.8)	(19.7)
Settlements	0.0	0.0	(9.4)
Unrecognized tax benefits – December 31	$ 5.7	$ 6.7	$ 7.6