| **Concentration of Risk (Details) (USD $)In Thousands, unless otherwise specified**                                            | Sep. 30, 2012 |
|--------------------------------------------------------------------------------------------------------------------------------|---------------|
| **Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]**                                               |          |  |
| Fair Value of Derivatice Assets                                                                                                | $ 69,262      |  |
| JPMorgan Chase Bank [Member]                                                                                                   |          |  |
| **Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]**                                               |          |  |
| Fair Value of Derivatice Assets                                                                                                | 42,763        | [1] |
| Wells Fargo Bank [Member]                                                                                                      |          |  |
| **Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]**                                               |          |  |
| Fair Value of Derivatice Assets                                                                                                | 7,831         | [1] |
| Credit Agricole CIB [Member]                                                                                                   |          |  |
| **Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]**                                               |          |  |
| Fair Value of Derivatice Assets                                                                                                | 5,206         | [1] |
| Other Lenders in Our Credit Facility [Member]                                                                                  |          |  |
| **Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]**                                               |          |  |
| Fair Value of Derivatice Assets                                                                                                | 12,112        |  |
| Various [Member]                                                                                                               |          |  |
| **Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]**                                               |          |  |
| Fair Value of Derivatice Assets                                                                                                | $ 1,350       | [2] |
|                                                                                                                                |
| [1](1)Major lender in our revolving credit facility. See Note 7, Long-Term Debt.[2](2)Represents a total of 28 counterparties. |

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| - Definition
This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 6 -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.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 65 -Paragraph 21 -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.Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15A -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.Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15C -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.Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 15 -Paragraph 83 -URI http://asc.fasb.org/extlink&oid=6913464&loc=d3e34841-113949Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 10 -Subparagraph i -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.Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15D -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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