Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 97,580	$ 78,628
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17,399	14,719
Stock-based compensation	5,054	4,161
Loss on disposal of other assets	307	107
Gain from disposal activities within discontinued operations	(5,744)
Deferred income taxes	4,725	8,504
Excess tax benefit from share-based payment arrangements	(6,160)	(5,956)
(Increase) decrease (net of acquisitions and dispositions):
Trade receivables, net	(11,336)	(6,937)
Inventories, net	(44,349)	(18,187)
Other assets	(13,700)	1,660
Increase (decrease) (net of acquisitions and dispositions):
Floor plan notes payable, net	1,132	5,721
Trade payables	4,246	4,848
Accrued liabilities	21,913	13,099
Other long-term liabilities and deferred revenue	16,635	12,307
Net cash provided by operating activities	87,702	112,674
Cash flows from investing activities:
Principal payments received on notes receivable	2,882	88
Capital expenditures	(54,149)	(33,803)
Proceeds from sales of assets	3,243	474
Payments for life insurance policies	(3,385)	(2,508)
Cash paid for acquisitions	(81,558)	(31,786)
Proceeds from sales of stores	10,617
Net cash used in investing activities	(122,350)	(67,535)
Cash flows from financing activities:
Borrowings on floor plan notes payable: non-trade, net	30,375	2,685
Borrowings on lines of credit	836,156	499,000
Repayments on lines of credit	(891,000)	(542,446)
Proceeds from issuance of long-term debt	76,530	4,720
Proceeds from issuance of common stock	3,411	3,967
Excess tax benefit from share-based payment arrangements	6,160	5,956
Dividends paid	(11,731)	(6,719)
Net cash provided by (used in) financing activities	32,628	(71,885)
Decrease in cash and cash equivalents	(2,020)	(26,746)
Cash and cash equivalents at beginning of period	23,686	42,839
Cash and cash equivalents at end of period	21,666	16,093
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	15,556	15,988
Cash paid during the period for income taxes, net	44,918	25,880
Supplemental schedule of non-cash activities:
Debt issued in connection with acquisitions	3,161
Floorplan debt paid in connection with dealership disposals	3,311
Common Class A [Member]
Cash flows from financing activities:
Repurchase of common stock	(11,745)	(7,903)
Scheduled Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt	(5,528)	(5,375)
Other Payments [Member]
Cash flows from financing activities:
Principal payments on long-term debt		$ (25,770)