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, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension And Postretirement Plan Expenses [Line Items]
Service cost	$ 19	$ 21	$ 57	$ 63
Interest cost	46	42	139	126
Expected return on plan assets	(87)	(86)	(262)	(258)
Net amortization	30	53	91	159
Total	$ 8	$ 30	$ 25	$ 90