Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Sales revenue	$ 3,316,487	$ 2,632,746	$ 2,036,622
Cost of revenue	2,777,187	2,187,462	1,673,676
Gross profit	539,300	445,284	362,946
Asset impairments	115	1,376	15,301
Selling, general and administrative	373,688	316,663	284,163
Operating income	148,369	110,818	46,470
Floor plan interest expense	(12,816)	(10,364)	(10,155)
Other interest expense	(9,621)	(12,878)	(14,523)
Other income, net	2,525	694	420
Income from continuing operations before income taxes	128,457	88,270	22,212
Income tax provision	(49,062)	(33,060)	(8,625)
Income from continuing operations, net of income tax	79,395	55,210	13,587
Income from discontinued operations, net of income tax	967	3,650	132
Net income	80,362	58,860	13,719
Basic income per share from continuing operations (in Dollars per share)	$ 3.09	$ 2.10	$ 0.52
Basic income per share from discontinued operations (in Dollars per share)	$ 0.04	$ 0.14	$ 0.01
Basic net income per share (in Dollars per share)	$ 3.13	$ 2.24	$ 0.53
Shares used in basic per share calculations (in Shares)	25,696	26,230	26,062
Diluted income per share from continuing operations (in Dollars per share)	$ 3.03	$ 2.07	$ 0.52
Diluted income per share from discontinued operations (in Dollars per share)	$ 0.04	$ 0.14
Diluted net income per share (in Dollars per share)	$ 3.07	$ 2.21	$ 0.52
Shares used in diluted per share calculations (in Shares)	26,170	26,664	26,279
New Vehicle [Member]
Sales revenue	1,847,603	1,391,375	1,020,883
Cost of revenue	1,713,156	1,284,225	937,237
Used Retail Vehicle [Member]
Sales revenue	833,484	678,571	558,105
Cost of revenue	711,763	580,357	479,310
Used Wholesale Vehicle [Member]
Sales revenue	139,237	128,329	103,817
Cost of revenue	137,823	127,732	103,114
Finance and Insurance [Member]
Sales revenue	112,234	84,130	64,217
Service, Body and Parts [Member]
Sales revenue	347,703	315,958	277,945
Cost of revenue	179,633	163,738	144,003
Fleet and Other [Member]
Sales revenue	36,226	34,383	11,655
Cost of revenue	34,812	31,410	10,012
Segment, Continuing Operations [Member]
Depreciation and amortization	17,128	16,427	17,012
Income tax provision	$ (49,062)	$ (33,060)	$ (8,625)