Retirement Plans Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Pension Plan | United States
Components of Net Periodic Benefit Cost:
Service cost	$ 0	$ 0	$ 8
Interest cost	47	67	108
Expected return on plan assets	(171)	(180)	(199)
Net actuarial (gain) loss	(214)	244	361
Amortization of prior service cost (credit)	0	0	0
Curtailment gain	0	0	0
Settlement loss	0	6	13
Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits	0	0	0
Net periodic benefit cost (credit)	$ (338)	$ 137	$ 291
Expense Assumptions:
Discount rate	2.25%	2.95%	4.10%
Expected return on plan assets	6.50%	6.90%	7.10%
Rate of compensation increase			3.50%
Pension Plan | Foreign Plan
Components of Net Periodic Benefit Cost:
Service cost	$ 27	$ 25	$ 22
Interest cost	32	36	54
Expected return on plan assets	(112)	(111)	(105)
Net actuarial (gain) loss	(115)	43	236
Amortization of prior service cost (credit)	1	1	0
Curtailment gain	(3)	(8)	0
Settlement loss	(1)	0	4
Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits	2	0	0
Net periodic benefit cost (credit)	$ (169)	$ (14)	$ 211
Expense Assumptions:
Discount rate	1.35%	1.50%	2.45%
Expected return on plan assets	4.90%	5.20%	5.20%
Rate of compensation increase	2.75%	2.80%	2.95%
Interest Crediting Rate	1.50%	1.50%	1.55%
Postretirement Benefits
Components of Net Periodic Benefit Cost:
Service cost	$ 1	$ 1	$ 1
Interest cost	2	4	6
Expected return on plan assets	(8)	(9)	(9)
Net actuarial (gain) loss	(35)	2	17
Amortization of prior service cost (credit)	(4)	(3)	0
Curtailment gain	0	0	0
Settlement loss	0	0	0
Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits	0	0	0
Net periodic benefit cost (credit)	$ (44)	$ (5)	$ 15
Expense Assumptions:
Discount rate	1.90%	2.65%	3.80%
Expected return on plan assets	5.30%	5.70%	5.65%
Discontinued Operations | Pension Plan | United States
Components of Net Periodic Benefit Cost:
Net periodic benefit cost (credit)	$ 0	$ 0	$ (2)
Discontinued Operations | Pension Plan | Foreign Plan
Components of Net Periodic Benefit Cost:
Net periodic benefit cost (credit)	0	0	0
Discontinued Operations | Postretirement Benefits
Components of Net Periodic Benefit Cost:
Net periodic benefit cost (credit)	0	0	0
Continuing Operations [Member] | Pension Plan | United States
Components of Net Periodic Benefit Cost:
Net periodic benefit cost (credit)	(338)	137	289
Continuing Operations [Member] | Pension Plan | Foreign Plan
Components of Net Periodic Benefit Cost:
Service cost	27	25
Interest cost	32	36
Net periodic benefit cost (credit)	(169)	(14)	211
Continuing Operations [Member] | Postretirement Benefits
Components of Net Periodic Benefit Cost:
Net periodic benefit cost (credit)	$ (44)	$ (5)	$ 15