Goodwill and Other Intangible Assets - Net Intangible Assets (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible assets with finite lives, Beginning balance	$ 77.8
Intangible assets with finite lives, Ending balance	77.8
Intangible assets with finite lives, Accumulated amortization, Beginning balance	(75.3)
Accumulated amortization	(0.5)
Intangible assets with finite lives, Accumulated amortization, Ending balance	(75.8)
Net intangible assets with finite lives, Beginning balance	2.5
Amortization, intangible assets	(0.5)
Net intangible assets with finite lives, Ending balance	2.0
Indefinite-lived Intangible Assets, Tradename and Other, Beginning Balance	300.3
Indefinite-lived Intangible Assets, Tradename and Other, Ending Balance	300.3
Total intangible assets - net, Beginning balance	302.8
Amortization, Total intangible assets net	(0.5)
Total intangible assets - net, Ending balance	$ 302.3