Credit Facilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Floorplan Notes Payable Credit Facility	$ 1,150,847	$ 1,098,126
Floorplan Offset	110,759	39,616
Other floorplan notes payable	4,113	5,504
Total floorplan notes payable - credit facility and other net	1,154,960	1,103,630
FMCC Offset	25,500	22,500
Floorplan notes payable - manufacturer affiliates	389,071	307,656
Floorplan Notes Payable Manufacturer Affiliates Net	363,571	285,156
New Vehicles [Member]
Line of Credit Facility [Line Items]
Floorplan Notes Payable Credit Facility	1,094,130	970,075
Used Vehicles [Member]
Line of Credit Facility [Line Items]
Floorplan Notes Payable Credit Facility	142,703	125,085
Rental Vehicle Credit Facility [Member]
Line of Credit Facility [Line Items]
Floorplan Notes Payable Credit Facility	24,773	42,582
FMCC Facility [Member]
Line of Credit Facility [Line Items]
Floorplan Notes Payable Manufacturer Affiliates Gross	196,807	150,183
Floorplan notes payable - manufacturer affiliates	171,307	127,683
Other and Rental Vehicles [Member]
Line of Credit Facility [Line Items]
Floorplan notes payable - manufacturer affiliates	$ 192,264	$ 157,473