Disclosures About Derivative Instruments and Hedging Activities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Derivatives, Fair Value [Line Items]
Total Derivatives Assets	$ 5,468	$ 68
Total Derivatives Liability	39,959	30,321
Interest rate contracts [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total Derivatives Assets	0	0
Interest rate contracts [Member] | Designated as Hedging Instrument [Member] | Derivative Financial Instruments and Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total Derivatives Liability	30,522	18,585
Commodity contracts [Member] | Accounted for Under ASC 980 [Member] | Derivative Financial Instruments [Member]
Derivatives, Fair Value [Line Items]
Total Derivatives Assets	5,303	41
Commodity contracts [Member] | Accounted for Under ASC 980 [Member] | Derivative Financial Instruments and Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total Derivatives Liability	9,437	11,736
Commodity contracts [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Total Derivatives Liability	0	0
Commodity contracts [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Derivative Financial Instruments [Member]
Derivatives, Fair Value [Line Items]
Total Derivatives Assets	$ 165	$ 27