Financial Instruments (Schedule Of Offset For Derivative Instruments Designated And Qualify As Fair Value Hedge) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) on Derivative	$ 4,107
Operating Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) on Derivative	4,304,103
Gain/(Loss) on Commitment	(4,304,103)
Purchased Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) on Derivative	(196,930)
Gain/(Loss) on Commitment	$ 196,930