Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 36,357,000	$ 31,852,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	69,809,000	59,298,000
Loss (gain) on sale of property and equipment	607,000	(104,000)
Stock-based compensation expense related to stock options and employee stock purchases	7,222,000	7,078,000
Deferred income tax benefit	(3,686,000)	(2,802,000)
Excess tax expense (benefit) from stock-based compensation	$ 370,000	(4,306,000)
Acquired research and development		2,000,000
Change in accounts receivable, net	$ (4,681,000)	(55,700,000)
Change in inventories, net	(20,393,000)	(10,095,000)
Change in prepaid expenses and other, net	17,316,000	4,694,000
Change in trade accounts payable	802,000	5,766,000
(Payments) draws on floor plan notes payable – trade, net	(14,327,000)	19,903,000
Change in customer deposits	(25,183,000)	(26,130,000)
Change in accrued expenses	(1,866,000)	15,161,000
Net cash provided by operating activities	62,347,000	46,615,000
Cash flows from investing activities:
Acquisition of property and equipment	(164,203,000)	(116,204,000)
Proceeds from the sale of property and equipment	2,272,000	299,000
Business acquisitions	(57,906,000)	(147,269,000)
Proceeds from the sale of available for sale securities	275,000	150,000
Change in other assets	(2,349,000)	1,733,000
Net cash used in investing activities	(221,911,000)	(261,291,000)
Cash flows from financing activities:
Draws on floor plan notes payable – non-trade, net	39,768,000	73,344,000
Proceeds from long-term debt	84,968,000	114,210,000
Principal payments on long-term debt	(77,663,000)	(56,897,000)
Principal payments on capital lease obligations	(6,147,000)	(7,187,000)
Proceeds from issuance of shares relating to employee stock options and employee stock purchases	1,957,000	9,256,000
Excess tax benefits (expense) from stock-based compensation	(370,000)	4,306,000
Common stock repurchased	(1,464,000)	(8,698,000)
Net cash provided by financing activities	41,049,000	128,334,000
Net decrease in cash and cash equivalents	(118,515,000)	(86,342,000)
Cash and cash equivalents, beginning of period	191,463,000	217,305,000
Cash and cash equivalents, end of period	72,948,000	130,963,000
Supplemental disclosure of cash flow information:
Interest	16,967,000	14,460,000
Income taxes, net of refunds	$ 2,370,000	5,425,000
Noncash investing activities:
Common stock issued related to business acquisition		2,000,000
Assets acquired under capital leases	$ 10,261,000	$ 6,415,000