- Components of Other Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	$ 193,137	$ 191,425
Accumulated Amortization	(76,634)	(49,130)	$ (33,728)
Net	116,503	142,295
Total other intangible assets, Gross Carrying Amount	423,846	420,546	$ 138,831
Total other intangible assets, net	$ 347,212	$ 371,416
Non-compete agreements
Intangible Assets by Major Class [Line Items]
Estimated Life (Years)	5 years	5 years
Gross Carrying Amount	$ 540	$ 540
Accumulated Amortization	(540)	(485)
Net	0	55
Dealer/customer related
Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	169,694	164,837
Accumulated Amortization	(60,638)	(35,907)
Net	$ 109,056	$ 128,930
Dealer/customer related | Minimum
Intangible Assets by Major Class [Line Items]
Estimated Life (Years)	5 years	5 years
Dealer/customer related | Maximum
Intangible Assets by Major Class [Line Items]
Estimated Life (Years)	10 years	10 years
Developed technology
Intangible Assets by Major Class [Line Items]
Gross Carrying Amount	$ 22,903	$ 26,048
Accumulated Amortization	(15,456)	(12,738)
Net	$ 7,447	$ 13,310
Developed technology | Minimum
Intangible Assets by Major Class [Line Items]
Estimated Life (Years)	5 years	5 years
Developed technology | Maximum
Intangible Assets by Major Class [Line Items]
Estimated Life (Years)	7 years	7 years
Non-amortizable—brand/trade names
Intangible Assets by Major Class [Line Items]
Non-amortizable—brand/trade names	$ 230,709	$ 229,121
Non-amortizable, Net	$ 230,709	$ 229,121