Credit Facilities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
FMCC Offset	$ 23,300	$ 22,500
Outstanding balances under financing arrangements
Floorplan Offset	(22,466)	(39,616)
Floorplan notes payable - manufacturer affiliates	$ 308,710	$ 307,656