Credit Facilities (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Credit Facility (Textual) [Abstract]
Offset account related to floorplan notes payable - credit facility	$ (110,759)	$ (39,616)
Maximum Limit of Restricted Payment	125
Floorplan notes payable - manufacturer affiliates	$ 389,071	307,656
FMCC Offset	25,500	$ 22,500
Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Line of Credit Facility, Amount Outstanding	0
Letters of credit outstanding	41,900
Revolving Credit Facility [Member]
Credit Facility (Textual) [Abstract]
Maximum borrowing capacity under line of credit facility	$ 1,700,000
Number of financial institutions	24
Number of Manufacturer-affiliated finance companies	6
Number of tranches	2
Line of credit facility, maximum borrowing capacity can be extended, amount	$ 1,950,000
Line of credit facility, unamortized cost	3,700
Restricted Payment Basket	144,700
FMCC Facility [Member]
Credit Facility (Textual) [Abstract]
Maximum borrowing capacity under line of credit facility	$ 300,000
Basis spread on interest rate	1.50%	1.50%
Available amount under borrowing capacity	$ 128,700
Cancellation of agreement	30 days
Floorplan notes payable - manufacturer affiliates	$ 171,307	$ 127,683
Debt interest rate	4.75%	4.75%
UK Credit Facilities [Member]
Credit Facility (Textual) [Abstract]
Interest rate, minimum	1.15%
Interest rate, maximum	3.95%
Brazil credit facilities [Member]
Credit Facility (Textual) [Abstract]
Interest rate, minimum	16.80%
Interest rate, maximum	25.20%
Rental Vehicle [Member]
Credit Facility (Textual) [Abstract]
Interest rate, maximum	5.00%
Floorplan Line [Member]
Credit Facility (Textual) [Abstract]
Maximum borrowing capacity under line of credit facility	$ 1,600,000
Maximum period for outstanding borrowing	1 year
Commitment fees, Percentage	0.20%
Line of Credit Facility, Amount Outstanding	$ 1,150,847
Available amount under borrowing capacity	$ 229,200
Weighted average interest rate	1.70%	1.40%
Floorplan Line [Member] | New Vehicles [Member]
Credit Facility (Textual) [Abstract]
Basis spread on interest rate	1.25%	1.25%
Floorplan Line [Member] | Used vehicles [Member]
Credit Facility (Textual) [Abstract]
Basis spread on interest rate	1.50%	1.50%
Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Maximum borrowing capacity under line of credit facility	$ 320,000
Line of credit facility minimum borrowing capacity	$ 100,000
Basis spread on interest rate	1.50%	1.50%
Restricted payment maximum	$ 100,000
Line of Credit Facility, Amount Outstanding	0
Available amount under borrowing capacity	$ 278,200
Maximum [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Commitment fees, Percentage	0.45%
Minimum [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Commitment fees, Percentage	0.25%
United States of America, Dollars | Maximum [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Basis spread on interest rate	1.00%	1.00%
United States of America, Dollars | Minimum [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Basis spread on interest rate	0.00%	0.00%
Euros or Pound Sterling [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Maximum borrowing capacity under line of credit facility	$ 125,000
Euros or Pound Sterling [Member] | Maximum [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Basis spread on interest rate	2.50%	2.50%
Euros or Pound Sterling [Member] | Minimum [Member] | Acquisition Line [Member]
Credit Facility (Textual) [Abstract]
Basis spread on interest rate	1.50%	1.50%