Income Taxes (Narrative) (Details) (USD $)	Mar. 31, 2012	Sep. 30, 2011
Income Taxes [Line Items]
Taxes refundable to customers	$ 65,550,000	$ 65,543,000
Recoverable future taxes	146,561,000	144,377,000
Tax Benefit Total Not Realized Due To Tax Loss Carryforwards	32,600,000	19,500,000
Deferred Income Taxes [Member]
Income Taxes [Line Items]
Taxes refundable to customers	65,600,000	65,500,000
Recoverable future taxes	$ 146,600,000	$ 144,400,000