Condensed Consolidated Financial Information Condensed Consolidated Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues	$ 2,726,480	$ 2,511,638	$ 5,159,334	$ 4,772,501
Cost of Goods and Services Sold	2,334,907	2,142,490	4,403,877	4,065,231
GROSS PROFIT	391,573	369,148	755,457	707,270
Selling, General and Administrative Expense	280,568	271,970	552,037	529,528
Depreciation, Depletion and Amortization	11,946	10,753	23,630	20,678
Asset Impairment Charges	1,039	1,721	1,039	1,721
INCOME FROM OPERATIONS	98,020	84,704	178,751	155,343
Floor Plan Interest Expense	(10,015)	(10,329)	(19,362)	(21,242)
Interest Expense, Other	(14,228)	(12,567)	(28,139)	(23,080)
INCOME BEFORE INCOME TAXES	73,777	38,194	131,250	87,407
Income Tax Expense (Benefit)	(27,467)	(21,332)	(49,126)	(39,242)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
NET INCOME	46,310	16,862	82,124	48,165
Other Comprehensive Income (Loss), Net of Tax	13,783	4,315	(21,357)	11,749
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	60,093	21,177	60,767	59,914
Gains (Losses) on Extinguishment of Debt	0	(23,614)	0	(23,614)
Parent Company [Member]
Revenues	0	0	0	0
Cost of Goods and Services Sold	0	0	0	0
GROSS PROFIT	0	0	0	0
Selling, General and Administrative Expense	848	914	2,079	1,756
Depreciation, Depletion and Amortization	0	0	0	0
Asset Impairment Charges	0	0	0	0
INCOME FROM OPERATIONS	(848)	(914)	(2,079)	(1,756)
Floor Plan Interest Expense	0	0	0	0
Interest Expense, Other	605	564	1,197	1,129
INCOME BEFORE INCOME TAXES	(243)	(350)	(882)	(627)
Income Tax Expense (Benefit)	92	132	331	235
Income (Loss) from Subsidiaries, Net of Tax	46,461	17,080	82,675	48,557
NET INCOME	46,310	16,862	82,124	48,165
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	46,310	16,862	82,124	48,165
Gains (Losses) on Extinguishment of Debt		0		0
Guarantor Subsidiaries [Member]
Revenues	2,287,447	2,060,596	4,285,947	3,895,223
Cost of Goods and Services Sold	1,945,263	1,743,819	3,629,275	3,288,714
GROSS PROFIT	342,184	316,777	656,672	606,509
Selling, General and Administrative Expense	237,716	225,521	465,188	440,179
Depreciation, Depletion and Amortization	10,357	9,310	20,475	17,936
Asset Impairment Charges	498	1,721	498	1,721
INCOME FROM OPERATIONS	93,613	80,225	170,511	146,673
Floor Plan Interest Expense	(8,959)	(8,360)	(17,477)	(16,944)
Interest Expense, Other	(13,073)	(11,798)	(25,796)	(22,062)
INCOME BEFORE INCOME TAXES	71,581	36,453	127,238	84,053
Income Tax Expense (Benefit)	(26,382)	(20,369)	(46,985)	(37,300)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
NET INCOME	45,199	16,084	80,253	46,753
Other Comprehensive Income (Loss), Net of Tax	3,784	(2,080)	(762)	(2,860)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	48,983	14,004	79,491	43,893
Gains (Losses) on Extinguishment of Debt		(23,614)		(23,614)
Non-Guarantor Subsidiaries [Member]
Revenues	439,033	451,042	873,387	877,278
Cost of Goods and Services Sold	389,644	398,671	774,602	776,517
GROSS PROFIT	49,389	52,371	98,785	100,761
Selling, General and Administrative Expense	42,004	45,535	84,770	87,593
Depreciation, Depletion and Amortization	1,589	1,443	3,155	2,742
Asset Impairment Charges	541	0	541	0
INCOME FROM OPERATIONS	5,255	5,393	10,319	10,426
Floor Plan Interest Expense	(1,056)	(1,969)	(1,885)	(4,298)
Interest Expense, Other	(1,760)	(1,333)	(3,540)	(2,147)
INCOME BEFORE INCOME TAXES	2,439	2,091	4,894	3,981
Income Tax Expense (Benefit)	(1,177)	(1,095)	(2,472)	(2,177)
Income (Loss) from Subsidiaries, Net of Tax	0	0	0	0
NET INCOME	1,262	996	2,422	1,804
Other Comprehensive Income (Loss), Net of Tax	9,999	6,395	(20,595)	14,609
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	11,261	7,391	(18,173)	16,413
Gains (Losses) on Extinguishment of Debt		0		0
Consolidation, Eliminations [Member]
Revenues	0	0	0	0
Cost of Goods and Services Sold	0	0	0	0
GROSS PROFIT	0	0	0	0
Selling, General and Administrative Expense	0	0	0	0
Depreciation, Depletion and Amortization	0	0	0	0
Asset Impairment Charges	0	0	0	0
INCOME FROM OPERATIONS	0	0	0	0
Floor Plan Interest Expense	0	0	0	0
Interest Expense, Other	0	0	0	0
INCOME BEFORE INCOME TAXES	0	0	0	0
Income Tax Expense (Benefit)	0	0	0	0
Income (Loss) from Subsidiaries, Net of Tax	(46,461)	(17,080)	(82,675)	(48,557)
NET INCOME	(46,461)	(17,080)	(82,675)	(48,557)
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (46,461)	(17,080)	$ (82,675)	(48,557)
Gains (Losses) on Extinguishment of Debt		$ 0		$ 0