Credit Facilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Outstanding balances under financing arrangements
Floorplan notes payable - credit facility	$ 1,068,832	$ 856,698
Other floorplan notes payable	18,074	0
Total floorplan notes payable - credit facility and other net	1,086,906	856,698
Offset account related to floorplan notes payable - credit facility	(56,198)	(112,261)
Floorplan notes payable - manufacturer affiliates	346,572	211,965
New Vehicle [Member]
Outstanding balances under financing arrangements
Floorplan notes payable - credit facility	970,780	837,436
Used Vehicle [Member]
Outstanding balances under financing arrangements
Floorplan notes payable - credit facility	127,808	112,261
Rental Vehicle [Member]
Outstanding balances under financing arrangements
Floorplan notes payable - credit facility	26,442	19,262
FMCC Facility [Member]
Outstanding balances under financing arrangements
Floorplan notes payable - manufacturer affiliates	190,954	143,028
Other and Rental Vehicles [Member]
Outstanding balances under financing arrangements
Floorplan notes payable - manufacturer affiliates	$ 155,618	$ 68,937