Segement Information Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 2,335,110,000	$ 1,895,826,000	$ 4,298,942,000	$ 3,560,571,000
Gross profit	341,274,000	285,344,000	641,763,000	545,768,000
Selling, general and administrative expense	251,159,000	214,327,000	484,592,000	413,439,000
Floorplan interest expense	10,873,000	7,863,000	20,237,000	15,482,000
Interest Expense, Other	9,570,000	9,190,000	18,812,000	18,230,000
Net Income (Loss) Attributable to Parent	37,388,000	28,625,000	59,506,000	51,742,000
Payments for (Proceeds from) Other Investing Activities			(574,000)	(396,000)
Assets	3,409,318,000		3,409,318,000		3,023,015,000
U.S. [Member]
Segment Reporting Information [Line Items]
Gain (Loss) on Sale of Business	8,400,000		9,000,000
Revenues	1,881,654,000	1,757,634,000	3,603,440,000	3,343,854,000
Gross profit	290,476,000	269,567,000	563,418,000	520,484,000
Selling, general and administrative expense	210,820,000	201,316,000	420,304,000	392,893,000
Floorplan interest expense	8,645,000	7,546,000	16,941,000	15,028,000
Interest Expense, Other	9,301,000	9,070,000	18,341,000	17,989,000
Net Income (Loss) Attributable to Parent	32,209,000	27,300,000	53,674,000	49,477,000
Payments for (Proceeds from) Other Investing Activities	15,420,000	16,416,000	30,695,000	25,999,000
Intangible Assets, Net (Including Goodwill)	754,539,000		754,539,000		752,372,000
Assets	2,886,311,000		2,886,311,000		2,860,771,000
Loss from Catastrophes	11,100,000	2,700,000	11,900,000
Business Combination, Acquisition Related Costs			5,200,000
Gains (Losses) on Sales of Other Real Estate		1,100,000
U.K. [Member]
Segment Reporting Information [Line Items]
Revenues	207,436,000	138,192,000	378,514,000	216,717,000
Gross profit	23,744,000	15,777,000	42,915,000	25,284,000
Selling, general and administrative expense	18,570,000	13,011,000	34,606,000	20,546,000
Floorplan interest expense	421,000	317,000	727,000	454,000
Interest Expense, Other	293,000	120,000	507,000	241,000
Net Income (Loss) Attributable to Parent	2,972,000	1,325,000	4,488,000	2,265,000
Payments for (Proceeds from) Other Investing Activities	675,000	48,000	760,000	160,000
Intangible Assets, Net (Including Goodwill)	26,076,000		26,076,000		26,070,000
Assets	205,034,000		205,034,000		162,244,000
Business Combination, Acquisition Related Costs			100,000
Brazil [Member]
Segment Reporting Information [Line Items]
Revenues	246,020,000	0	316,988,000	0
Gross profit	27,054,000	0	35,430,000	0
Selling, general and administrative expense	21,769,000	0	29,682,000	0
Floorplan interest expense	1,807,000	0	2,569,000	0
Interest Expense, Other	(24,000)	0	(36,000)	0
Net Income (Loss) Attributable to Parent	2,207,000	0	1,344,000	0
Payments for (Proceeds from) Other Investing Activities	684,000	0	929,000	0
Intangible Assets, Net (Including Goodwill)	175,215,000		175,215,000		0
Assets	317,973,000		317,973,000		0
Business Combination, Acquisition Related Costs			1,200,000
Total [Member]
Segment Reporting Information [Line Items]
Revenues	2,335,110,000	1,895,826,000	4,298,942,000	3,560,571,000
Gross profit	341,274,000	285,344,000	641,763,000	545,768,000
Selling, general and administrative expense	251,159,000	214,327,000	484,592,000	413,439,000
Floorplan interest expense	10,873,000	7,863,000	20,237,000	15,482,000
Interest Expense, Other	9,570,000	9,190,000	18,812,000	18,230,000
Net Income (Loss) Attributable to Parent	37,388,000	28,625,000	59,506,000	51,742,000
Payments for (Proceeds from) Other Investing Activities	16,779,000	16,464,000	32,384,000	26,159,000
Intangible Assets, Net (Including Goodwill)	955,830,000		955,830,000		778,442,000
Assets	$ 3,409,318,000		$ 3,409,318,000		$ 3,023,015,000