Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Scheduled Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt, scheduled	$ (3,979,000)	$ (3,619,000)
Other Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt, scheduled	(2,303,000)	(9,189,000)
Common Class A [Member]
Cash flows from financing activities:
Excess tax benefit from share-based payment arrangements	4,379,000	4,733,000
Net income	40,270,000	40,653,000
Asset impairments	3,498,000	4,130,000
Depreciation and amortization	11,663,000	9,726,000
Stock-based compensation	3,149,000	2,727,000
(Gain) loss on disposal of other assets	(3,391,000)	8,000
Gain on disposal of franchise	(1,087,000)	(3,349,000)
Deferred income taxes	10,261,000	3,863,000
Excess tax benefit from share-based payment arrangements	(4,379,000)	(4,733,000)
Trade receivables, net	25,564,000	7,569,000
Inventories	(73,744,000)	(39,460,000)
Other assets	(4,705,000)	(2,078,000)
Floor plan notes payable	7,753,000	1,092,000
Trade payables	920,000	6,799,000
Accrued liabilities	13,425,000	4,444,000
Other long-term liabilities and deferred revenue	5,396,000	6,838,000
Net cash provided by operating activities	34,593,000	38,229,000
Capital expenditures	(15,900,000)	(24,917,000)
Proceeds from sales of assets	92,000	103,000
Cash paid for other investments	(11,449,000)	$ (9,804,000)
Cash paid for acquisitions, net of cash acquired	(13,799,000)
Proceeds from sales of stores	11,822,000	$ 3,680,000
Net cash used in investing activities	(29,234,000)	(30,938,000)
Borrowings on floor plan notes payable, net: non-trade	38,626,000	(21,984,000)
Borrowings on lines of credit	213,123,000	271,023,000
Repayments on lines of credit	(229,311,000)	(293,960,000)
Proceeds from issuance of long-term debt	12,080,000	50,350,000
Proceeds from issuance of common stock	1,464,000	1,039,000
Repurchase of common stock	(57,736,000)	(10,343,000)
Dividends paid	(5,151,000)	(4,216,000)
Net cash used in financing activities	(28,808,000)	(16,166,000)
Decrease in cash and cash equivalents	(23,449,000)	(8,875,000)
Cash and cash equivalents at beginning of period	45,008,000	29,898,000
Cash and cash equivalents at end of period	21,559,000	21,023,000
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	12,990,000	12,494,000
Cash paid during the period for income taxes, net	497,000	6,542,000
Supplemental schedule of non-cash activities:
Floor plan debt paid in connection with store disposals	$ 5,284,000	$ 2,208,000