Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 78,628	$ 60,530
Asset impairments		115
Stock-based compensation	4,161	2,329
Loss (gain) on disposal of other assets	107	(378)
Deferred income taxes	8,504	6,851
Excess tax benefit from share-based payment arrangements	(5,956)	(1,629)
Trade receivables, net	(6,937)	(29,160)
Inventories	(18,187)	(158,186)
Other current assets	5,464	3,169
Other non-current assets	(3,804)	(4,346)
Floor plan notes payable, net	5,721	(93,975)
Trade payables	4,848	5,381
Accrued liabilities	13,099	10,164
Other long-term liabilities and deferred revenue	12,307	9,927
Net cash provided by (used in) operating activities	112,674	(176,335)
Cash flows from investing activities:
Principal payments received on notes receivable	88	79
Capital expenditures	(33,803)	(34,966)
Proceeds from sales of assets	474	6,025
Payments for life insurance policies	(2,508)	(1,908)
Cash paid for acquisitions	(31,786)	(31,376)
Proceeds from sales of stores		2,901
Net cash used in investing activities	(67,535)	(59,245)
Cash flows from financing activities:
Borrowings on floor plan notes payable: non-trade, net	2,685	272,760
Borrowings on lines of credit	499,000	365,623
Repayments on lines of credit	(542,446)	(356,791)
Proceeds from issuance of long-term debt	4,720	14,169
Proceeds from issuance of common stock	3,967	4,600
Excess tax benefit from share-based payment arrangements	5,956	1,629
Dividends paid	(6,719)	(6,943)
Change in restricted cash		3,300
Net cash (used in) provided by financing activities	(71,885)	234,486
Decrease in cash and cash equivalents	(26,746)	(1,094)
Cash and cash equivalents at beginning of period	42,839	20,851
Cash and cash equivalents at end of period	16,093	19,757
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	15,988	17,316
Cash paid during the period for income taxes, net	25,880	25,814
Supplemental schedule of non-cash activities:
Floor plan debt paid in connection with store disposals		6,712
Acquisition of assets with capital leases		2,609
Scheduled Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt	(5,375)	(5,889)
Other Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt	(25,770)	(37,366)
Common Class A [Member]
Cash flows from financing activities:
Repurchase of common stock	(7,903)	(20,606)
Continuing Operations [Member]
Cash flows from operating activities:
Depreciation and amortization	14,719	12,687
Discontinued Operations [Member]
Cash flows from operating activities:
Depreciation and amortization		$ 186