Retirement Plan And Other Post-Retirement Benefits (Schedule Of Health Care Cost Trend Rates) (Details)	12 Months Ended
	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]
Rate of Medical Cost Increase for Pre Age 65 Participants	5.75%	[1]	6.93%	[2]	7.10%	[2]
Rate of Medical Cost Increase for Post Age 65 Participants	4.75%	[1]	6.68%	[2]	6.73%	[2]
Annual Rate of Increase in the Per Capita Cost of Covered Prescription Drug Benefits	9.00%	[1]	7.17%	[2]	7.47%	[2]
Annual Rate of Increase in the Per Capita Medicare Part B Reimbursement	4.75%	[1]	6.68%	[2]	6.73%	[2]
Annual Rate of Increase in the Per Capita Medicare Part D Subsidy	7.20%	[1]	6.65%	[2]	6.79%	[2]
Ultimate health care trend rate	4.50%		4.50%		4.50%

[1] It was assumed that this rate would gradually decline to 4.5% by 2039.

[2] It was assumed that this rate would gradually decline to 4.5% by 2028.