Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 36,478,000	$ 13,212,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	77,653,000	78,539,000
(Loss) gain on sale of property and equipment	31,000	(5,000)
Loss on impairment of assets		8,236,000
Stock-based compensation expense related to stock options and employee stock purchases	8,660,000	6,749,000
Deferred income tax expense	2,594,000	159,000
Excess tax expense from stock-based compensation		1,007,000
Change in accounts receivable, net	7,067,000	27,612,000
Change in inventories, net	(52,425,000)	58,015,000
Change in prepaid expenses and other, net	(1,143,000)	21,836,000
Change in trade accounts payable	14,506,000	(1,356,000)
Draws on floor plan notes payable – trade, net	20,994,000	10,984,000
Change in customer deposits	11,330,000	(1,227,000)
Change in accrued expenses	4,977,000	(805,000)
Net cash provided by operating activities	130,722,000	222,956,000
Cash flows from investing activities:
Acquisition of property and equipment	(79,572,000)	(115,268,000)
Proceeds from the sale of property and equipment	3,192,000	327,000
Business acquisitions		(681,000)
Proceeds from the sale of available for sale securities	325,000	250,000
Change in other assets	4,887,000	(334,000)
Net cash used in investing activities	(71,168,000)	(115,706,000)
Cash flows from financing activities:
Draws (payments) on floor plan notes payable – non-trade, net	24,186,000	(35,650,000)
Proceeds from long-term debt	51,108,000	68,490,000
Principal payments on long-term debt	(74,326,000)	(83,561,000)
Principal payments on capital lease obligations	(6,647,000)	(9,851,000)
Proceeds from issuance of shares relating to employee stock options and employee stock purchases	12,840,000	2,445,000
Excess tax expense from stock-based compensation		(1,007,000)
Common stock repurchased	(24,411,000)	(20,299,000)
Debt issuance costs	(523,000)
Net cash (used in) financing activities	(17,773,000)	(79,433,000)
Net increase in cash and cash equivalents	41,781,000	27,817,000
Cash and cash equivalents, beginning of period	82,026,000	64,847,000
Cash and cash equivalents, end of period	123,807,000	92,664,000
Supplemental disclosure of cash flow information:
Interest	16,565,000	19,757,000
Income taxes, net of refunds	17,012,000	(13,129,000)
Noncash activities:
Assets acquired under capital leases	5,513,000	10,017,000
Common stock repurchased	$ 1,798,000