Retirement Plans Accumulated Benefit Obligations and Reconciliations of Changes in Projected Benefit Obligation, Changes in Plan Assets and Funded Status (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Pension Plan | Foreign Plan
Retirement Plans [Line Items]
Accumulated Benefit Obligation		$ 2,627	$ 2,549
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year		2,652	2,542
Service cost		25	22	$ 23
Interest cost		36	54	57
Plan participant contributions		3	2
Actuarial (gain) loss		7	337
Amendments made during the year		0	26
Estimated subsidy received		0	0
Curtailment		(8)	0
Other		4	(2)
Currency translation adjustment		118	(109)
Projected benefit obligation at end of year		2,726	2,652	2,542
Change in Plan Assets
Fair value of plan assets at beginning of year		2,098	2,117
Actual return on plan assets		75	203
Employer and employee contributions		56	50
Benefits paid		(73)	(76)
Settlement payments		(36)	(50)
Other		0	(2)
Currency translation adjustment		93	(95)
Fair value of plan assets at end of year		2,213	2,098	2,117
Funded status		(513)	(554)
Net amount recognized		$ (513)	$ (554)
Weighted Average Assumptions
Discount rate	[1]	1.35%	1.50%
Rate of compensation increase		2.75%	2.80%
Defined Benefit Plan, Total Plan Assets		$ 2,213	$ 2,098
Pension Plan | United States
Retirement Plans [Line Items]
Accumulated Benefit Obligation		3,217	3,115
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year		3,115	3,191
Service cost		0	8	15
Interest cost		67	108	105
Plan participant contributions		0	0
Actuarial (gain) loss		298	441
Amendments made during the year		0	0
Estimated subsidy received		0	0
Curtailment		0	0
Other		0	0
Currency translation adjustment		0	0
Projected benefit obligation at end of year		3,217	3,115	3,191
Change in Plan Assets
Fair value of plan assets at beginning of year		2,736	3,046
Actual return on plan assets		228	266
Employer and employee contributions		5	38
Benefits paid		(112)	(136)
Settlement payments		(151)	(107)
Other		0	0
Currency translation adjustment		0	0
Fair value of plan assets at end of year		2,706	2,736	3,046
Funded status		(511)	(379)
Net amount recognized		$ (511)	$ (379)
Weighted Average Assumptions
Discount rate	[1]	2.25%	2.95%
Defined Benefit Plan, Total Plan Assets		$ 2,706	$ 2,736
Pension Plan | Fair Value, Inputs, Level 1 | Foreign Plan
Change in Plan Assets
Fair value of plan assets at beginning of year		641
Fair value of plan assets at end of year		665	641
Pension Plan | Fair Value, Inputs, Level 1 | United States
Change in Plan Assets
Fair value of plan assets at beginning of year		2,175
Fair value of plan assets at end of year		2,251	2,175
Pension Plan | Fair Value, Inputs, Level 2 [Member] | Foreign Plan
Change in Plan Assets
Fair value of plan assets at beginning of year		1,443
Fair value of plan assets at end of year		1,532	1,443
Pension Plan | Fair Value, Inputs, Level 2 [Member] | United States
Change in Plan Assets
Fair value of plan assets at beginning of year		359
Fair value of plan assets at end of year		259	359
Postretirement Benefits
Retirement Plans [Line Items]
Accumulated Benefit Obligation		0	0
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year		174	196
Service cost		1	1	2
Interest cost		4	6	7
Plan participant contributions		4	6
Actuarial (gain) loss		(3)	15
Amendments made during the year		(13)	(19)
Estimated subsidy received		1	1
Curtailment		0	0
Other		0	0
Currency translation adjustment		(1)	0
Projected benefit obligation at end of year		146	174	196
Change in Plan Assets
Fair value of plan assets at beginning of year		163	174
Actual return on plan assets		4	7
Employer and employee contributions		7	9
Benefits paid		(21)	(23)
Settlement payments		0	0
Other		0	0
Currency translation adjustment		0	0
Fair value of plan assets at end of year		153	163	$ 174
Funded status		7	(11)
Net amount recognized		$ 7	$ (11)
Weighted Average Assumptions
Discount rate	[1]	1.90%	2.65%
Defined Benefit Plan, Total Plan Assets		$ 153	$ 163
Postretirement Benefits | Fair Value, Inputs, Level 1
Change in Plan Assets
Fair value of plan assets at beginning of year		6
Fair value of plan assets at end of year		5	6
Postretirement Benefits | Fair Value, Inputs, Level 2 [Member]
Change in Plan Assets
Fair value of plan assets at beginning of year		157
Fair value of plan assets at end of year		148	157
Other noncurrent assets | Pension Plan | Foreign Plan
Change in Projected Benefit Obligation
Benefits and settlements paid		(109)	(126)
Other noncurrent assets | Pension Plan | United States
Change in Projected Benefit Obligation
Benefits and settlements paid		(263)	(243)
Other noncurrent assets | Postretirement Benefits
Change in Projected Benefit Obligation
Benefits and settlements paid		(21)	(23)
Power Solutions | Pension Plan | Foreign Plan
Change in Projected Benefit Obligation
Power Solutions divestiture		0	(86)
Change in Plan Assets
Power Solutions divestiture		0	(45)
Power Solutions | Pension Plan | United States
Change in Projected Benefit Obligation
Power Solutions divestiture		0	(390)
Change in Plan Assets
Power Solutions divestiture		0	(371)
Power Solutions | Postretirement Benefits
Change in Projected Benefit Obligation
Power Solutions divestiture		0	(9)
Change in Plan Assets
Power Solutions divestiture		0	(4)
Business Divestitures, Not Specific | Pension Plan | Foreign Plan
Change in Projected Benefit Obligation
Power Solutions divestiture		(2)	(8)
Change in Plan Assets
Power Solutions divestiture		0	(4)
Business Divestitures, Not Specific | Pension Plan | United States
Change in Projected Benefit Obligation
Power Solutions divestiture		0	0
Change in Plan Assets
Power Solutions divestiture		0	0
Business Divestitures, Not Specific | Postretirement Benefits
Change in Projected Benefit Obligation
Power Solutions divestiture		0	0
Change in Plan Assets
Power Solutions divestiture		0	0
Hedge Funds | Pension Plan | Fair Value, Inputs, Level 1 | Foreign Plan
Change in Plan Assets
Fair value of plan assets at beginning of year		0
Fair value of plan assets at end of year		0	0
Hedge Funds | Pension Plan | Fair Value, Inputs, Level 2 [Member] | Foreign Plan
Change in Plan Assets
Fair value of plan assets at beginning of year		69
Fair value of plan assets at end of year		49	69
Cash and cash equivalents | Pension Plan | Fair Value, Inputs, Level 1 | Foreign Plan
Change in Plan Assets
Fair value of plan assets at beginning of year		174
Fair value of plan assets at end of year		178	174
Cash and cash equivalents | Pension Plan | Fair Value, Inputs, Level 1 | United States
Change in Plan Assets
Fair value of plan assets at beginning of year		24
Fair value of plan assets at end of year		0	24
Cash and cash equivalents | Pension Plan | Fair Value, Inputs, Level 2 [Member] | Foreign Plan
Change in Plan Assets
Fair value of plan assets at beginning of year		0
Fair value of plan assets at end of year		0	0
Cash and cash equivalents | Pension Plan | Fair Value, Inputs, Level 2 [Member] | United States
Change in Plan Assets
Fair value of plan assets at beginning of year		31
Fair value of plan assets at end of year		36	31
Cash and cash equivalents | Postretirement Benefits
Change in Plan Assets
Fair value of plan assets at beginning of year		6
Fair value of plan assets at end of year		5	6
Cash and cash equivalents | Postretirement Benefits | Fair Value, Inputs, Level 1
Change in Plan Assets
Fair value of plan assets at beginning of year		6
Fair value of plan assets at end of year		5	6
Cash and cash equivalents | Postretirement Benefits | Fair Value, Inputs, Level 2 [Member]
Change in Plan Assets
Fair value of plan assets at beginning of year		0
Fair value of plan assets at end of year		0	0
Commodities | Postretirement Benefits
Change in Plan Assets
Fair value of plan assets at beginning of year		13
Fair value of plan assets at end of year		12	13
Commodities | Postretirement Benefits | Fair Value, Inputs, Level 1
Change in Plan Assets
Fair value of plan assets at beginning of year		0
Fair value of plan assets at end of year		0	0
Commodities | Postretirement Benefits | Fair Value, Inputs, Level 2 [Member]
Change in Plan Assets
Fair value of plan assets at beginning of year		13
Fair value of plan assets at end of year		12	13
Continuing Operations [Member] | Pension Plan | Foreign Plan
Change in Projected Benefit Obligation
Service cost		25	22
Interest cost		36	54
Change in Plan Assets
Prepaid benefit cost		29	25
Accrued benefit liability		(542)	(579)
Continuing Operations [Member] | Pension Plan | United States
Change in Plan Assets
Prepaid benefit cost		32	30
Accrued benefit liability		(543)	(409)
Continuing Operations [Member] | Postretirement Benefits
Change in Plan Assets
Prepaid benefit cost		78	66
Accrued benefit liability		$ (71)	$ (77)

[1] The Company considers the expected benefit payments on a plan-by-plan basis when setting assumed discount rates. As a result, the Company uses different discount rates for each plan depending on the plan jurisdiction, the demographics of participants and the expected timing of benefit payments. For the U.S. pension and postretirement plans, the Company uses a discount rate provided by an independent third party calculated based on an appropriate mix of high quality bonds. For the non-U.S. pension and postretirement plans, the Company consistently uses the relevant country specific benchmark indices for determining the various discount rates. The Company has elected to utilize a full yield curve approach in the estimation of service and interest components of net periodic benefit cost (credit) for pension and other postretirement for plans that utilize a yield curve approach. The full yield curve approach applies the specific spot rates along the yield curve used in the determination of the benefit obligation to the relevant projected cash flows.