Retirement Plan And Other Post-Retirement Benefits (Schedule Of Benefit Obligations, Plan Assets And Funded Status) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Non-Current Assets		$ 17,649	$ 24,459
Amortization period		10 years
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Obligation at Beginning of Period		$ 1,026,190	999,499	$ 946,305
Service Cost		11,710	12,047	11,987
Interest Cost		42,315	41,217	43,574
Plan Participants' Contributions		0	0	0
Retiree Drug Subsidy Receipts		0	0	0
Amendments	[1]	0	7,752	0
Actuarial (Gain) Loss		76,309	23,426	53,887
Benefits Paid		(59,103)	(57,751)	(56,254)
Benefit Obligation at End of Period		1,097,421	1,026,190	999,499
Fair Value of Assets at Beginning of Period		834,870	869,791	799,307
Actual Return on Plan Assets		87,008	(13,370)	93,238
Employer Contributions		7,000	36,200	33,500
Fair Value of Assets at End of Period		869,775	834,870	869,791
Net Amount Recognized at End of Period (Funded Status)		(227,646)	(191,320)	(129,708)
Non-Current Liabilities		(227,646)	(191,320)	(129,708)
Non-Current Assets		0	0	0
Accumulated Benefit Obligation		$ 1,039,408	$ 968,984	$ 940,068
Discount Rate		3.60%	4.25%	4.25%
Rate of Compensation Increase		4.70%	4.75%	4.75%
Expected Return on Plan Assets		$ (59,369)	$ (59,615)	$ (59,974)
Amortization of Prior Service Cost (Credit)		1,234	183	210
Recognition of Actuarial Loss	[2]	32,248	36,129	36,007
Net Amortization and Deferral for Regulatory Purposes		3,957	7,739	8,151
Net Periodic Benefit Cost		$ 32,095	$ 37,700	$ 39,955
Discount Rate		4.25%	4.25%	4.75%
Expected Return on Plan Assets		7.25%	7.50%	8.00%
Rate of Compensation Increase		4.75%	4.75%	4.75%
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit Obligation at Beginning of Period		$ 464,987	$ 465,583	$ 460,634
Service Cost		2,331	2,693	2,939
Interest Cost		20,386	19,285	21,308
Plan Participants' Contributions		2,558	2,242	2,265
Retiree Drug Subsidy Receipts		1,925	1,338	1,419
Amendments	[1]	0	0	0
Actuarial (Gain) Loss		60,402	(1,575)	1,087
Benefits Paid		(26,451)	(24,579)	(24,069)
Benefit Obligation at End of Period		526,138	464,987	465,583
Fair Value of Assets at Beginning of Period		477,959	497,601	472,392
Actual Return on Plan Assets		37,415	534	44,898
Employer Contributions		2,839	2,161	2,115
Fair Value of Assets at End of Period		494,320	477,959	497,601
Net Amount Recognized at End of Period (Funded Status)		(31,818)	12,972	32,018
Non-Current Liabilities		(49,467)	(11,487)	(4,494)
Non-Current Assets		$ 17,649	$ 24,459	$ 36,512
Discount Rate		3.70%	4.50%	4.25%
Rate of Compensation Increase		4.70%	4.75%	4.75%
Expected Return on Plan Assets		$ (31,535)	$ (34,089)	$ (37,424)
Amortization of Prior Service Cost (Credit)		(912)	(1,913)	(2,138)
Recognition of Actuarial Loss	[2]	5,530	4,148	2,645
Net Amortization and Deferral for Regulatory Purposes		17,123	20,322	23,263
Net Periodic Benefit Cost		$ 12,923	$ 10,446	$ 10,593
Discount Rate		4.50%	4.25%	4.75%
Expected Return on Plan Assets		6.75%	7.00%	8.00%
Rate of Compensation Increase		4.75%	4.75%	4.75%

[1] In fiscal 2015, the Company passed an amendment which updated the mortality table used in the Retirement Plan's definition of "actuarially equivalent" effective July 1, 2015. This increased the benefit obligation of the Retirement Plan.

[2] Distribution Corporation’s New York jurisdiction calculates the amortization of the actuarial loss on a vintage year basis over 10 years, as mandated by the NYPSC. All the other subsidiaries of the Company utilize the corridor approach.