Goodwill and Other Intangible Assets Components of Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Amortizable:
Gross amortized other intangible assets	$ 195,205	$ 193,137
Accumulated Amortization	(84,085)	(76,634)
Net amortized other intangible assets	111,120	116,503
Total other intangible assets, net	$ 342,204	347,212
Non-compete agreements
Amortizable:
Total estimated life	5 years
Gross amortized other intangible assets	$ 540	540
Dealer/customer related
Amortizable:
Gross amortized other intangible assets	$ 170,958	169,694
Dealer/customer related | Minimum
Amortizable:
Total estimated life	5 years
Dealer/customer related | Maximum
Amortizable:
Total estimated life	10 years
Developed technology
Amortizable:
Gross amortized other intangible assets	$ 23,707	22,903
Developed technology | Minimum
Amortizable:
Total estimated life	5 years
Developed technology | Maximum
Amortizable:
Total estimated life	7 years
Brand names
Non-amortizable—indefinite lived:
Non-amortizable, Net	$ 231,084	$ 230,709