Retirement Plan And Other Post-Retirement Benefits (Schedule Of Health Care Cost Trend Rates) (Details)	12 Months Ended
	Sep. 30, 2021		Sep. 30, 2020		Sep. 30, 2019
Retirement Benefits [Abstract]
Rate of Medical Cost Increase for Pre Age 65 Participants	5.38%	[1]	5.42%	[2]	5.50%	[2]
Rate of Medical Cost Increase for Post Age 65 Participants	4.84%	[1]	4.75%	[2]	4.75%	[2]
Annual Rate of Increase in the Per Capita Cost of Covered Prescription Drug Benefits	6.53%	[1]	6.80%	[2]	7.35%	[2]
Annual Rate of Increase in the Per Capita Medicare Part B Reimbursement	4.84%	[1]	4.75%	[2]	4.75%	[2]
Annual Rate of Increase in the Per Capita Medicare Part D Subsidy	6.15%	[1]	6.20%	[2]	6.84%	[2]
Ultimate Health Care Trend Rate	4.00%		4.50%		4.50%

[1] It was assumed that this rate would gradually decline to 4% by 2046.

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