Goodwill and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill
Goodwill, beginning balance	$ 176.5	$ 142.3
Acquisitions of businesses	0.0	59.5
Dispositions of businesses	(6.7)	0.0
Attribution of acquisition date fair value estimates between goodwill and other intangible assets	0.0	(22.9)
Measurement period adjustments	(1.0)	(2.4)
Goodwill, ending balance	168.8	176.5	$ 142.3
Other Intangible Assets
Other intangible assets (excluding goodwill), beginning balance	215.9	198.2
Acquisition of businesses	0.0	0.0
Dispositions of businesses	(6.9)	0.0
Attribution of acquisition date fair value estimates between goodwill and other intangible assets	0.0	22.9
Amortization	(7.2)	(5.2)	(4.6)
Other intangible assets (excluding goodwill), ending balance	201.8	215.9	198.2
Total Goodwill and Other Intangible Assets
Total Goodwill and Other Intangible Assets, beginning balance	392.4	340.5
Acquisition of businesses	0.0	59.5
Disposition of businesses	(13.6)	0.0
Attribution of acquisition date fair value estimates between goodwill and other intangible assets	0.0	0.0
Measurement period adjustments	(1.0)	(2.4)
Amortization	(7.2)	(5.2)	(4.6)
Total Goodwill and Other Intangible Assets, ending balance	$ 370.6	$ 392.4	$ 340.5