Pension & Postretirement Expenses (Schedule Of Net Periodic Pension And Net Postretirement Plan Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Pension And Postretirement Plan Expenses [Line Items]
Total			$ 34	$ 0
Other Pension, Postretirement and Supplemental Plans [Member]
Pension And Postretirement Plan Expenses [Line Items]
Service cost	$ 22	$ 18	44	36
Interest cost	40	50	80	100
Expected return on plan assets	(84)	(88)	168	176
Net amortization	38	16	75	33
Total	$ 16	$ (4)	$ 31	$ (7)