Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 24,734	$ 22,055
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	5,507	4,721
Stock-based compensation	1,538	1,140
Loss (gain) on disposal of other assets	20	(19)
Deferred income taxes	1,866	(206)
Excess tax benefit from share-based payment arrangements	(5,846)	(2,937)
(Increase) decrease (net of acquisitions and dispositions):
Trade receivables, net	(12,259)	(960)
Inventories	(56,748)	7,890
Other current assets	1,660	5,757
Other non-current assets	(3,950)	(424)
Increase (decrease) (net of acquisitions and dispositions):
Floor plan notes payable, net	1,675	2,257
Trade payables	1,774	(410)
Accrued liabilities	12,521	6,188
Other long-term liabilities and deferred revenue	5,121	4,705
Net cash provided by (used in) operating activities	(22,387)	49,757
Cash flows from investing activities:
Principal payments received on notes receivable		319
Capital expenditures	(12,630)	(6,585)
Proceeds from sales of assets	27	440
Payments for life insurance policies	(3,530)	(2,641)
Cash paid for acquisitions	(31,689)
Net cash used in investing activities	(47,822)	(8,467)
Cash flows from financing activities:
Borrowings on floor plan notes payable: non-trade, net	51,783	953
Borrowings on lines of credit	233,000	118,000
Repayments on lines of credit	(209,725)	(156,303)
Proceeds from issuance of common stock	1,168	966
Excess tax benefit from share-based payment arrangements	5,846	2,937
Dividends paid	(3,378)
Net cash (used in) provided by financing activities	68,863	(69,123)
Decrease in cash and cash equivalents	(1,346)	(27,833)
Cash and cash equivalents at beginning of period	23,686	42,839
Cash and cash equivalents at end of period	22,340	15,006
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	5,102	5,837
Cash paid during the period for income taxes, net	3,706	(964)
Supplemental schedule of non-cash activities:
Debt issued in connection with acquisitions	3,161
Scheduled Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt	(1,890)	(2,003)
Other Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt		(25,770)
Common Class A [Member]
Cash flows from financing activities:
Repurchase of common stock	$ (7,941)	$ (7,903)