Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Intangible Assets by Major Class [Line Items]
Total estimated life	16 years
Gross amortized other intangible assets	$ 472.7	$ 472.8
Accumulated Amortization	(129.3)	(120.7)
Net	343.4	352.1
Intangible Assets, Net (Excluding Goodwill)	$ 677.1	686.4
Non-compete agreements
Intangible Assets by Major Class [Line Items]
Total estimated life	4 years
Gross amortized other intangible assets	$ 2.6	2.6
Dealer/customer related
Intangible Assets by Major Class [Line Items]
Total estimated life	17 years
Gross amortized other intangible assets	$ 460.3	460.3
Developed technology
Intangible Assets by Major Class [Line Items]
Total estimated life	5 years
Gross amortized other intangible assets	$ 9.8	9.9
Brand/trade names
Intangible Assets by Major Class [Line Items]
Non-amortizable—brand/trade names	333.7	334.3
Non-amortizable, Net	$ 333.7	$ 334.3