Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Valuation and Qualifying Accounts [Abstract]
Balance at Beginning of Period		$ 21,109	$ 29,029	$ 31,811
Additions Charged to Costs and Expenses		6,301	6,819	9,316
Additions Charged to Other Accounts	[1]	1,774	1,521	2,585
Deductions	[2]	6,658	16,260	14,683
Balance at End of Period		$ 22,526	$ 21,109	$ 29,029

[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.