Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 62,455	$ 55,213	$ 31,282
Adjustments to reconcile net income to net cash provided by (used in) operating activities-
Depreciation and amortization	73,289	56,934	45,920
Gain on sale of property and equipment, net	(176)	(418)	(36)
Gain on disposition of equipment centers			(10,091)
Stock-based compensation expense related to employee stock options and employee stock purchases	7,332	5,683	4,468
Provision for deferred income tax expense	28,164	28,680	10,215
Excess tax benefits from stock-based compensation	(1,668)	(1,628)	(885)
Change in accounts receivable, net	14,184	(49,986)	(217)
Change in inventories	32,579	(268,178)	(48,548)
Change in prepaid expenses and other, net	558	1,999	(10,252)
Change in trade accounts payable	(29)	24,366	15,331
Draws on floor plan notes payable – trade, net	34,504
Change in accrued expenses	(31,856)	65,966	29,246
Net cash provided by (used in) operating activities	219,336	(81,369)	66,433
Cash flows from investing activities:
Acquisition of property and equipment	(170,951)	(148,543)	(84,303)
Proceeds from the sale of property and equipment	1,249	10,692	305
Business acquisitions	(104,571)	(94,630)	(39,268)
Proceeds from disposition of equipment centers			26,234
Other	(24)	655	325
Net cash used in investing activities	(274,297)	(231,826)	(96,707)
Cash flows from financing activities:
Draws (payments) on floor plan notes payable - non-trade, net	(20,677)	282,883	43,724
Proceeds from long-term debt	144,639	144,457	66,614
Principal payments on long-term debt	(73,151)	(68,299)	(55,575)
Principal payments on capital lease obligations	(11,584)	(14,048)	(7,595)
Proceeds from issuance of shares relating to employee stock options and employee stock purchases	5,064	5,518	2,281
Excess tax benefits (provision) from stock-based compensation	1,668	1,628	885
Debt issuance costs		(145)	(179)
Net cash provided by financing activities	45,959	351,994	50,155
Net (decrease) increase in cash and cash equivalents	(9,002)	38,799	19,881
Cash and cash equivalents, beginning of year	207,775	168,976	149,095
Cash and cash equivalents, end of year	198,773	207,775	168,976
Supplemental disclosure of cash flow information:
Interest	23,275	15,237	13,264
Income taxes, net of refunds	7,122	2,032	7,544
Note receivable related to disposition of equipment centers			4,453
Assets acquired under capital leases	$ 15,892	$ 17,400	$ 15,353