Condensed Consolidated Financial Information Condensed Consolidated Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Cash and Cash Equivalents, at Carrying Value	$ 26,279	$ 40,975	$ 17,687	$ 20,215
Contracts In Transit And Vehicle Receivables Net	225,048	237,448
Accounts, Notes, Loans and Financing Receivable, Net, Current	137,373	151,330
Intercompany accounts receivable current		0
Inventories, net	1,547,436	1,556,705
Deferred Tax Assets, Net, Current	13,316	11,062
Prepaid Expense and Other Assets, Current	33,037	37,699
Total current assets	1,982,489	2,035,219
Property, Plant and Equipment, Net	944,485	950,388
Goodwill	847,672	830,377
Indefinite-Lived Franchise Rights	305,750	303,947
Investment in Subsidiaries	0	0
Other Assets, Noncurrent	18,071	21,561
Total assets	4,098,467	4,141,492
Floorplan notes payable - credit facility	1,138,495	1,143,246
Offset account related to floorplan notes payable - credit facility	(79,795)	(39,616)
Floorplan notes payable - manufacturer affiliates	290,038	307,656
FMCC Offset	(21,000)	(22,500)
Long-term Debt and Capital Lease Obligations, Current	69,275	72,630
Accounts Payable, Current	250,526	288,320
Intercompany accounts payable current	0	0
Accrued Liabilities, Current	169,567	172,463
Total current liabilities	1,817,106	1,922,199
LONG-TERM DEBT, net of current maturities	1,077,964	1,008,837
Derivative Liability, Noncurrent	33,793	25,311
Deferred income taxes and other liabilities	209,777	207,135
Stockholders' Equity Attributable to Parent	959,827	978,010
Intercompany note receivable	0	0
Stockholders' Equity Attributable to Parent Excluding Intercompany Receivables	959,827	978,010
Total liabilities and stockholders’ equity	4,098,467	4,141,492
Parent Company [Member]
Cash and Cash Equivalents, at Carrying Value	0	0	0	0
Contracts In Transit And Vehicle Receivables Net	0	0
Accounts, Notes, Loans and Financing Receivable, Net, Current	0	0
Intercompany accounts receivable current	0	0
Inventories, net	0	0
Deferred Tax Assets, Net, Current	240	196
Prepaid Expense and Other Assets, Current	743	590
Total current assets	983	786
Property, Plant and Equipment, Net	0	0
Goodwill	0	0
Indefinite-Lived Franchise Rights	0	0
Investment in Subsidiaries	2,039,365	1,964,442
Other Assets, Noncurrent	0	0
Total assets	2,040,348	1,965,228
Floorplan notes payable - credit facility	0	0
Offset account related to floorplan notes payable - credit facility	0	0
Floorplan notes payable - manufacturer affiliates	0	0
FMCC Offset	0	0
Long-term Debt and Capital Lease Obligations, Current	0	0
Accounts Payable, Current	0	0
Intercompany accounts payable current	299,275	295,421
Accrued Liabilities, Current	0	0
Total current liabilities	299,275	295,421
LONG-TERM DEBT, net of current maturities	664,120	609,812
Derivative Liability, Noncurrent	0	0
Deferred income taxes and other liabilities	0	0
Stockholders' Equity Attributable to Parent	1,076,953	1,059,995
Intercompany note receivable	0	0
Stockholders' Equity Attributable to Parent Excluding Intercompany Receivables	1,076,953	1,059,995
Total liabilities and stockholders’ equity	2,040,348	1,965,228
Guarantor Subsidiaries [Member]
Cash and Cash Equivalents, at Carrying Value	4,449	25,379	3,441	4,306
Contracts In Transit And Vehicle Receivables Net	196,674	218,361
Accounts, Notes, Loans and Financing Receivable, Net, Current	105,570	117,427
Intercompany accounts receivable current	257,147	276,217
Inventories, net	1,346,561	1,342,022
Deferred Tax Assets, Net, Current	13,076	10,866
Prepaid Expense and Other Assets, Current	17,297	22,039
Total current assets	1,940,774	2,012,311
Property, Plant and Equipment, Net	835,370	839,063
Goodwill	734,367	700,642
Indefinite-Lived Franchise Rights	266,345	257,502
Investment in Subsidiaries	0	0
Other Assets, Noncurrent	9,277	10,120
Total assets	3,786,133	3,819,638
Floorplan notes payable - credit facility	1,133,884	1,137,743
Offset account related to floorplan notes payable - credit facility	(79,795)	(39,616)
Floorplan notes payable - manufacturer affiliates	195,038	207,329
FMCC Offset	(21,000)	(22,500)
Long-term Debt and Capital Lease Obligations, Current	56,439	61,185
Accounts Payable, Current	139,261	176,143
Intercompany accounts payable current	0	0
Accrued Liabilities, Current	146,999	149,700
Total current liabilities	1,570,826	1,669,984
LONG-TERM DEBT, net of current maturities	347,809	347,202
Derivative Liability, Noncurrent	33,793	25,311
Deferred income taxes and other liabilities	197,710	193,077
Stockholders' Equity Attributable to Parent	1,935,270	1,879,485
Intercompany note receivable	(299,275)	(295,421)
Stockholders' Equity Attributable to Parent Excluding Intercompany Receivables	1,635,995	1,584,064
Total liabilities and stockholders’ equity	3,786,133	3,819,638
Non-Guarantor Subsidiaries [Member]
Cash and Cash Equivalents, at Carrying Value	21,830	15,596	14,246	15,909
Contracts In Transit And Vehicle Receivables Net	28,374	19,087
Accounts, Notes, Loans and Financing Receivable, Net, Current	31,803	33,903
Intercompany accounts receivable current	0	0
Inventories, net	200,875	214,683
Deferred Tax Assets, Net, Current	0	0
Prepaid Expense and Other Assets, Current	14,997	15,070
Total current assets	297,879	298,339
Property, Plant and Equipment, Net	109,115	111,325
Goodwill	113,305	129,735
Indefinite-Lived Franchise Rights	39,405	46,445
Investment in Subsidiaries	0	0
Other Assets, Noncurrent	8,794	11,441
Total assets	568,498	597,285
Floorplan notes payable - credit facility	4,611	5,503
Offset account related to floorplan notes payable - credit facility	0	0
Floorplan notes payable - manufacturer affiliates	95,000	100,327
FMCC Offset	0	0
Long-term Debt and Capital Lease Obligations, Current	12,836	11,445
Accounts Payable, Current	111,265	112,177
Intercompany accounts payable current	257,147	276,217
Accrued Liabilities, Current	22,568	22,763
Total current liabilities	503,427	528,432
LONG-TERM DEBT, net of current maturities	66,035	51,823
Derivative Liability, Noncurrent	0	0
Deferred income taxes and other liabilities	12,067	14,058
Stockholders' Equity Attributable to Parent	(13,031)	2,972
Intercompany note receivable	0	0
Stockholders' Equity Attributable to Parent Excluding Intercompany Receivables	(13,031)	2,972
Total liabilities and stockholders’ equity	568,498	597,285
Consolidation, Eliminations [Member]
Cash and Cash Equivalents, at Carrying Value	0	0
Contracts In Transit And Vehicle Receivables Net	0	0
Accounts, Notes, Loans and Financing Receivable, Net, Current	0	0
Intercompany accounts receivable current	(257,147)	(276,217)
Inventories, net	0	0
Deferred Tax Assets, Net, Current	0	0
Prepaid Expense and Other Assets, Current	0	0
Total current assets	(257,147)	(276,217)
Property, Plant and Equipment, Net	0	0
Goodwill	0	0
Indefinite-Lived Franchise Rights	0	0
Investment in Subsidiaries	(2,039,365)	(1,964,442)
Other Assets, Noncurrent	0	0
Total assets	(2,296,512)	(2,240,659)
Floorplan notes payable - credit facility	0	0
Offset account related to floorplan notes payable - credit facility	0	0
Floorplan notes payable - manufacturer affiliates	0	0
FMCC Offset	0	0
Long-term Debt and Capital Lease Obligations, Current	0	0
Accounts Payable, Current	0	0
Intercompany accounts payable current	(556,422)	(571,638)
Accrued Liabilities, Current	0	0
Total current liabilities	(556,422)	(571,638)
LONG-TERM DEBT, net of current maturities	0	0
Derivative Liability, Noncurrent	0	0
Deferred income taxes and other liabilities	0	0
Stockholders' Equity Attributable to Parent	(2,039,365)	(1,964,442)
Intercompany note receivable	299,275	295,421
Stockholders' Equity Attributable to Parent Excluding Intercompany Receivables	(1,740,090)	(1,669,021)
Total liabilities and stockholders’ equity	$ (2,296,512)	$ (2,240,659)