Derivative Instruments and Risk Management Activities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Floor Plan Interest Expense	$ (10,913)	$ (9,364)
Derivatives in cash flow hedging relationship
Interest rate swap contracts	(2,520)	(14)
Floorplan Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Floor Plan Interest Expense	(2,429)	(2,420)
Other Interest Expense [Member]
Location of Loss Reclassified from OCI into Statements of Operations
Interest Expense	(355)	(313)
Interest Rate Swap Contracts [Member]
Derivatives in cash flow hedging relationship
Interest rate swap contracts	$ (2,520)	$ (14)