Segment Information - Summary of Reportable Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total consolidated revenues	$ 2,287,822	$ 2,234,626
Total segment income (loss)	28,062	35,869
Interest expense, other, net	(13,409)	(12,339)
Other income (expense), net	(14,501)	104
Income (loss) from continuing operations before taxes	152	23,634
Franchised Dealerships [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues	2,246,025	2,210,586
Total segment income (loss)	33,470	39,292
Echo Park [Member]
Segment Reporting Information [Line Items]
Total consolidated revenues	41,797	24,040
Total segment income (loss)	$ (5,408)	$ (3,423)