Interest Rate Swaps (Details Textuals) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2010	Sep. 30, 2011
Derivative [Line Items]
Portion of floating rate floor plan debt fixed by swap agreements		$ 100,000
Interest Rate Swaps (Textuals) [Abstract]
Interest rate swap, fixed		1.55%
Estimated liabilities of swaps designated as hedging instruments, fair value		15,157
Net gain in accumulated other comprehensive income	3,643
Losses reclassified from accumulated other comprehensive income into floor plan interest expense	6,482
Increase in the weighted average interest rate on floor plan borrowings due to the swaps	0.80%
Forward Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Portion of floating rate floor plan debt fixed by swap agreements		300,000
Derivative, Variable Interest Rate		2.135%
Floating Rate Floor Plan Debt [Member]
Derivative [Line Items]
Portion of floating rate floor plan debt fixed by swap agreements		$ 300,000
Derivative, Variable Interest Rate		3.67%

Monetary amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

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Interest Rate Swaps.

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Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph a

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Fixed interest rate related to the interest rate derivative.

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Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.

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The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of short-term debt outstanding by type or by instrument at that time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

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-Publisher FASB

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Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 46

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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