Credit Facilities (Details Textual) (USD $)					3 Months Ended
	Jun. 30, 2013 loan	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2013 Floorplan Line [Member]	Jun. 30, 2013 Floorplan Line [Member]	Jun. 30, 2013 Brazilian Credit Facility [Member] Maximum [Member]	Jun. 30, 2013 Brazilian Credit Facility [Member] Minimum [Member]	Jun. 30, 2013 Fmcc Facility [Member]	Jun. 30, 2013 Revolving Credit Facility [Member]	Jun. 30, 2013 Revolving Credit Facility [Member] Maximum [Member]	Jun. 30, 2013 Revolving Credit Facility [Member] Minimum [Member]	Jun. 30, 2013 New Vehicle [Member]	Jun. 30, 2013 New Vehicle [Member] Maximum [Member]	Jun. 30, 2013 New Vehicle [Member] Minimum [Member]	Jun. 30, 2013 Used Vehicle [Member]	Jun. 30, 2013 Acquisition Line [Member]	Jun. 30, 2013 Acquisition Line [Member] Maximum [Member]	Jun. 30, 2013 Acquisition Line [Member] Maximum [Member] Available to Borrow in Pounds or Euros	Jun. 30, 2013 Acquisition Line [Member] Minimum [Member]	Jun. 30, 2013 Acquisition Line [Member] Minimum [Member] Available to Borrow in Pounds or Euros	Jun. 30, 2013 Rental Vehicle Credit Facility [Member]	Jun. 30, 2013 Immediate [Member] Floorplan Line [Member]
Credit Facility (Textual) [Abstract]
Debt Instrument, Basis Spread on Variable Rate								1.50%				1.25%			1.50%		1.50%	2.50%	0.00%	1.00%
Maximum borrowing capacity under line of credit facility	$ 1,700,000,000	$ 1,350,000,000						$ 200,000,000	$ 1,600,000,000								$ 320,000,000	$ 125,000,000	$ 100,000,000
Number of financial institution	25
Number of Manufacturer-affiliated finance companies	6
Expiry date of Revolving Credit Facility									Jun. 20, 2018
Line of credit facility, maximum borrowing capacity can be extended, amount									1,950,000,000
Commitment fees, Percentage									0.20%	0.45%	0.25%
Acquisition Line Minimum Commitment									100,000,000
Line of credit facility, unamortized cost									7,600,000
Line of Credit Facility, Amount Outstanding					929,300,000			150,200,000								0
Available amount under borrowing capacity					450,700,000			49,800,000								263,600,000						82,000,000
Floorplan Offset	(81,996,000)		(112,261,000)
Weighted average interest rate				1.70%
Maximum period for outstanding borrowing					1 year 0 months 0 days
Letters of credit outstanding																29,300,000
Restricted payment									$ 146,300,000
Maximum Limit of Restricted Payment									$125.0 million plus (or minus if negative) (a) one-half of the aggregate consolidated net income of the Company for the period beginning on January 1, 2013 and ending on the date of determination and (b) the amount of net cash proceeds received from the sale of capital stock on or after January 1, 2013 and ending on the date of determination less (c) cash dividends and share repurchases (“Restricted Payment Basket”)
Cancellation of agreement								0 years 0 months 30 days
Prime interest rate, minimum								3.50%
Debt interest rate						16.76%	12.00%						3.95%	1.37%							5.00%
Debt Instrument Maturity Date Period						12 months	1 month
Interest rate, maximum								5.00%