Benefit Plans Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Other Pension Plan
Retirement Plan Disclosure
Defined benefit plan contributions			$ 225
Pension Benefits
Retirement Plan Disclosure
Service cost	$ 13	$ 14	39	$ 42
Interest cost	94	92	283	276
Expected return on plan assets	108	(123)	326	(369)
Amortization of prior service cost	(23)	(24)	(70)	(73)
Recognized net actuarial loss	(97)	113	(294)	340
Total net periodic benefit cost as actuarially determined	73	72	220	216
Amount capitalized due to actions of regulator	3	5	10	(14)
Total net periodic benefit cost	76	77	230	230
Other Post-retirement Benefits
Retirement Plan Disclosure
Defined benefit plan contributions			21
Service cost	5	5	13	14
Interest cost	4	4	11	12
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(5)	(5)	(13)	(14)
Recognized net actuarial loss	(2)	3	(5)	8
Total net periodic benefit cost as actuarially determined	6	7	16	20
Amount capitalized due to actions of regulator	0		0	0
Total net periodic benefit cost	$ 6	$ 7	$ 16	$ 20