Condensed Consolidated Financial Information Condensed Consolidated Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Income Statements, Captions [Line Items]
REVENUES:	$ 2,782,449	$ 2,726,480	$ 5,390,804	$ 5,159,334
COST OF SALES:	2,372,330	2,334,907	4,591,583	4,403,877
GROSS PROFIT	410,119	391,573	799,221	755,457
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	299,022	280,568	592,687	552,037
DEPRECIATION AND AMORTIZATION EXPENSE	12,713	11,946	25,177	23,630
ASSET IMPAIRMENTS	1,024	1,039	1,956	1,039
INCOME FROM OPERATIONS	97,360	98,020	179,401	178,751
Floorplan interest expense	(11,593)	(10,015)	(22,603)	(19,362)
Interest Expense, Other	(16,705)	(14,228)	(33,634)	(28,139)
INCOME BEFORE INCOME TAXES	69,062	73,777	123,164	131,250
BENEFIT (PROVISION) FOR INCOME TAXES	(22,482)	(27,467)	(42,293)	(49,126)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	46,580	46,310	80,871	82,124
COMPREHENSIVE LOSS	(9,548)	13,783	(16,420)	(21,357)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO PARENT	37,032	60,093	64,451	60,767
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
REVENUES:	0	0	0	0
COST OF SALES:	0	0	0	0
GROSS PROFIT	0	0	0	0
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	605	848	1,808	2,079
DEPRECIATION AND AMORTIZATION EXPENSE	0	0	0	0
ASSET IMPAIRMENTS	0	0	0	0
INCOME FROM OPERATIONS	(605)	(848)	(1,808)	(2,079)
Floorplan interest expense	0	0	0	0
Interest Expense, Other	0	605	0	1,197
INCOME BEFORE INCOME TAXES	(605)	(243)	(1,808)	(882)
BENEFIT (PROVISION) FOR INCOME TAXES	227	92	677	331
EQUITY IN EARNINGS OF SUBSIDIARIES	46,958	46,461	82,002	82,675
NET INCOME	46,580	46,310	80,871	82,124
COMPREHENSIVE LOSS	0	0	0	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO PARENT	46,580	46,310	80,871	82,124
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
REVENUES:	2,207,383	2,287,447	4,289,016	4,285,947
COST OF SALES:	1,862,787	1,945,263	3,611,709	3,629,275
GROSS PROFIT	344,596	342,184	677,307	656,672
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	243,312	237,716	486,327	465,188
DEPRECIATION AND AMORTIZATION EXPENSE	10,642	10,357	21,238	20,475
ASSET IMPAIRMENTS	1,024	498	1,533	498
INCOME FROM OPERATIONS	89,618	93,613	168,209	170,511
Floorplan interest expense	(10,402)	(8,959)	(20,450)	(17,477)
Interest Expense, Other	(16,072)	(13,073)	(32,124)	(25,796)
INCOME BEFORE INCOME TAXES	63,144	71,581	115,635	127,238
BENEFIT (PROVISION) FOR INCOME TAXES	(23,081)	(26,382)	(42,362)	(46,985)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	40,063	45,199	73,273	80,253
COMPREHENSIVE LOSS	(3,480)	3,784	(12,507)	(762)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO PARENT	36,583	48,983	60,766	79,491
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
REVENUES:	575,066	439,033	1,101,788	873,387
COST OF SALES:	509,543	389,644	979,874	774,602
GROSS PROFIT	65,523	49,389	121,914	98,785
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	55,105	42,004	104,552	84,770
DEPRECIATION AND AMORTIZATION EXPENSE	2,071	1,589	3,939	3,155
ASSET IMPAIRMENTS	0	541	423	541
INCOME FROM OPERATIONS	8,347	5,255	13,000	10,319
Floorplan interest expense	(1,191)	(1,056)	(2,153)	(1,885)
Interest Expense, Other	(633)	(1,760)	(1,510)	(3,540)
INCOME BEFORE INCOME TAXES	6,523	2,439	9,337	4,894
BENEFIT (PROVISION) FOR INCOME TAXES	372	(1,177)	(608)	(2,472)
EQUITY IN EARNINGS OF SUBSIDIARIES	0	0	0	0
NET INCOME	6,895	1,262	8,729	2,422
COMPREHENSIVE LOSS	(6,068)	9,999	(3,913)	(20,595)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO PARENT	827	11,261	4,816	(18,173)
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
REVENUES:	0	0	0	0
COST OF SALES:	0	0	0	0
GROSS PROFIT	0	0	0	0
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	0	0	0	0
DEPRECIATION AND AMORTIZATION EXPENSE	0	0	0	0
ASSET IMPAIRMENTS	0	0	0	0
INCOME FROM OPERATIONS	0	0	0	0
Floorplan interest expense	0	0	0	0
Interest Expense, Other	0	0	0	0
INCOME BEFORE INCOME TAXES	0	0	0	0
BENEFIT (PROVISION) FOR INCOME TAXES	0	0	0	0
EQUITY IN EARNINGS OF SUBSIDIARIES	(46,958)	(46,461)	(82,002)	(82,675)
NET INCOME	(46,958)	(46,461)	(82,002)	(82,675)
COMPREHENSIVE LOSS	0	0	0	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO PARENT	$ (46,958)	$ (46,461)	$ (82,002)	$ (82,675)