Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Prepayments	$ 11,963	$ 10,743
Prepaid Property and Other Taxes	10,574	13,709
Fair Values of Firm Commitments	3,227	15,775
Regulatory Assets	13,287	20,438
Other Current Assets	47,118	60,665
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable	5,830	0
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable	$ 2,237	$ 0