Goodwill and Other Intangible Assets Components of Other Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Amortizable:
Gross amortized other intangible assets	$ 472,500	$ 514,800
Accumulated Amortization	(111,800)	(126,500)
Net amortized other intangible assets	360,700	388,300
Total other intangible assets, net	$ 694,400	830,300
Non-compete agreements
Amortizable:
Total estimated life	4 years
Gross amortized other intangible assets	$ 2,600	2,600
Dealer/customer related
Amortizable:
Gross amortized other intangible assets	$ 460,100	499,500
Dealer/customer related | Minimum
Amortizable:
Total estimated life	5 years
Dealer/customer related | Maximum
Amortizable:
Total estimated life	20 years
Developed technology
Amortizable:
Gross amortized other intangible assets	$ 9,800	12,700
Developed technology | Minimum
Amortizable:
Total estimated life	5 years
Developed technology | Maximum
Amortizable:
Total estimated life	7 years
Brand/trade names
Non-amortizable—indefinite lived:
Non-amortizable, Net	$ 333,700	$ 442,000