Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
New vehicles	$ 4,715,924	$ 4,088,098	$ 3,513,842
Used vehicles	2,053,477	1,930,852	1,679,927
Wholesale vehicles	183,326	167,075	142,169
Total vehicles	6,952,727	6,186,025	5,335,938
Parts, service and collision repair	1,162,319	1,125,672	1,068,885
Finance, insurance and other	250,422	209,109	173,313
Total revenues	8,365,468	7,520,806	6,578,136
Cost of Sales:
New vehicles	(4,437,575)	(3,826,739)	(3,284,550)
Used vehicles	(1,910,023)	(1,790,994)	(1,546,979)
Wholesale vehicles	(189,301)	(172,281)	(146,629)
Total vehicles	(6,536,899)	(5,790,014)	(4,978,158)
Parts, service and collision repair	(593,416)	(572,181)	(535,413)
Total cost of sales	(7,130,315)	(6,362,195)	(5,513,571)
Gross profit	1,235,153	1,158,611	1,064,565
Selling, general and administrative expenses	(949,026)	(899,424)	(846,592)
Impairment charges	(440)	(200)	(249)
Depreciation and amortization	(45,285)	(39,446)	(33,687)
Operating income (loss)	240,402	219,541	184,037
Other income (expense):
Interest expense, floor plan	(19,454)	(18,405)	(20,239)
Interest expense, other, net	(60,090)	(66,857)	(73,179)
Other income (expense), net	(19,625)	(1,017)	(7,527)
Total other income (expense)	(99,169)	(86,279)	(100,945)
Income (loss) from continuing operations before taxes	141,233	133,262	83,092
Provision for income taxes - benefit (expense)	(49,972)	(51,731)	15,770
Income (loss) from continuing operations	91,261	81,531	98,862
Discontinued operations:
Income (loss) from operations and the sale of dealerships	(4,484)	(10,101)	(12,908)
Income tax benefit (expense)	2,324	4,824	3,975
Income (loss) from discontinued operations	(2,160)	(5,277)	(8,933)
Net income (loss)	$ 89,101	$ 76,254	$ 89,929
Basic earnings (loss) per common share:
Earnings (loss) per share from continuing operations	$ 1.68	$ 1.54	$ 1.88
Earnings (loss) per share from discontinued operations	$ (0.04)	$ (0.10)	$ (0.18)
Earnings (loss) per common share	$ 1.64	$ 1.44	$ 1.70
Weighted average common shares outstanding	53,550	52,358	52,214
Diluted earnings (loss) per common share:
Earnings (loss) per share from continuing operations	$ 1.56	$ 1.37	$ 1.62
Earnings (loss) per share from discontinued operations	$ (0.03)	$ (0.08)	$ (0.13)
Earnings (loss) per common share	$ 1.53	$ 1.29	$ 1.49
Weighted average common shares outstanding	60,406	65,464	65,794
Dividends declared per common share	$ 0.10	$ 0.10	$ 0.025