Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Summary Of Significant Accounting Policies [Line Items]
Prepayments	$ 10,472	$ 8,316
Prepaid Property and Other Taxes	10,461	14,455
Fair Values of Firm Commitments	1,384	1,291
Regulatory Assets	22,830	29,726
Other Current Assets	46,205	56,121
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable	0	268
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable	$ 1,058	$ 2,065