Credit Facilities (Details Textual) $ in Thousands	3 Months Ended
	Jun. 30, 2016 USD ($) loan	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Floorplan Offset	$ (35,461)		$ (110,759)
FMCC Offset	(27,500)		$ (25,500)
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under line of credit facility	$ 1,800,000	$ 1,700,000
Expiry date of Revolving Credit Facility	Jun. 17, 2021	Jun. 20, 2018
Number of financial institutions | loan	24
Number of Manufacturer-affiliated finance companies | loan	6
Number of tranches	2
Line Of Credit Facility Maximum Borrowing Capacity Can Be Extended Amount	$ 2,100,000
Line of credit facility, Unamortized Cost	5,900
Maximum Limit Of Restricted Payment Basket	208,500
Restricted payment	108,800
Brazil Credit Facilities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding	16,700
FMCC Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under line of credit facility	$ 300,000
Debt Instrument, Basis Spread on Variable Rate	1.50%
Line of Credit Facility, Amount Outstanding	$ 159,000
Available amount under borrowing capacity	$ 141,000
Cancellation of agreement	30 days
Debt interest rate	5.00%
Revolving Credit Facility, Floorplan Line [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under line of credit facility	$ 1,750,000
Commitment fees, Percentage	0.15%
Maximum period for outstanding borrowing	1 year
Line of Credit Facility, Amount Outstanding	$ 1,198,100
Available amount under borrowing capacity	241,900
Floorplan Offset	$ (35,500)
Weighted average interest rate	1.70%		1.70%
Revolving Credit Facility, Floorplan Line, New Vehicles [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Revolving Credit Facility, Floorplan Line, Used Vehicles [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under line of credit facility	$ 360,000
Line Of Credit Facility, Minimum Borrowing Capacity	$ 50,000
Debt Instrument, Basis Spread on Variable Rate	1.50%
Line of Credit Facility, Amount Outstanding	$ 10,000		$ 0
Available amount under borrowing capacity	252,300
Letters of credit outstanding	37,100
Rental Vehicle Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding	116,000
UK Credit Facilities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding	$ 83,800
Minimum [Member] | Brazil Credit Facilities [Member]
Line of Credit Facility [Line Items]
Debt interest rate	16.77%
Debt Instrument Maturity Date Period	1 month
Grace Period for Outstanding Borrowings	0 days
Minimum [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Commitment fees, Percentage	0.20%
Minimum [Member] | UK Credit Facilities [Member]
Line of Credit Facility [Line Items]
Debt interest rate	1.73%
Maximum [Member] | Brazil Credit Facilities [Member]
Line of Credit Facility [Line Items]
Debt interest rate	24.45%
Debt Instrument Maturity Date Period	12 months
Grace Period for Outstanding Borrowings	90 days
Maximum [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Commitment fees, Percentage	0.45%
Maximum [Member] | Rental Vehicle Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt interest rate	5.00%
Debt Instrument Maturity Date Period	2 years
Maximum [Member] | UK Credit Facilities [Member]
Line of Credit Facility [Line Items]
Debt interest rate	3.95%
United States of America, Dollars | Minimum [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
United States of America, Dollars | Maximum [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Euros or Pound Sterling [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under line of credit facility	$ 125,000
Euros or Pound Sterling [Member] | Minimum [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Euros or Pound Sterling [Member] | Maximum [Member] | Revolving Credit Facility, Acquisition Line [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.50%