Income Taxes - Provision (Benefit) for Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current provision (benefit):
Federal	$ 8.2	$ 17.4	$ (0.4)
State	4.5	2.4	(0.7)
Foreign	2.8	2.3	0.3
Total current provision (benefit)	15.5	22.1	(0.8)
Deferred benefit:
Federal	(3.6)	(18.3)	(0.1)
State	(2.8)	(1.0)	1.1
Foreign	0.0	2.2	(2.3)
Total deferred benefit	(6.4)	(17.1)	(1.3)
Total provision (benefit):
Federal	4.6	(0.9)	(0.5)
State	1.7	1.4	0.4
Foreign	2.8	4.5	(2.0)
Total income tax provision (benefit)	$ 9.1	$ 5.0	$ (2.1)