Pension & Postretirement Expenses (Summary Of Net Periodic Pension And Net Postretirement Plan Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension And Postretirement Plan Expenses [Line Items]
Service cost	$ 21	$ 22	$ 63	$ 67
Interest cost	42	50	126	149
Expected return on plan assets	(86)	(88)	(258)	(264)
Net amortization	53	40	159	121
Total	$ 30	$ 24	$ 90	$ 73