Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Valuation and Qualifying Accounts [Abstract]
Balance at Beginning of Period		$ 29,029	$ 31,811	$ 27,144
Additions Charged to Costs and Expenses		6,819	9,316	10,856
Additions Charged to Other Accounts	[1]	1,521	2,585	3,241
Deductions	[2]	16,260	14,683	9,430
Balance at End of Period		$ 21,109	$ 29,029	$ 31,811

[1] Represents the discount on accounts receivable purchased in accordance with the Utility segment’s 2005 New York rate agreement.

[2] Amounts represent net accounts receivable written-off.