Pension and 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, 2025	Sep. 30, 2024	Sep. 30, 2023
Pension Plan \| United States
Retirement Plans [Line Items]
Accumulated Benefit Obligation	$ 1,473	$ 1,603
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	1,603	1,564
Service cost	0	0	$ 0
Interest cost	65	79	78
Plan participant contributions	0	0
Actuarial loss (gain)	(62)	104
Benefits and settlements paid	(133)	(144)
Divestitures	0	0
Other	0	0
Currency translation adjustment	0	0
Projected benefit obligation at end of year	1,473	1,603	1,564
Change in Plan Assets
Fair value of plan assets at beginning of year	1,591	1,499
Actual return on plan assets	(12)	234
Employer and employee contributions	2	2
Divestitures	0	0
Other	0	0
Currency translation adjustment	0	0
Fair value of plan assets at end of year	1,448	1,591	1,499
Funded status	(25)	(12)
Net amount recognized	$ (25)	$ (12)
Weighted Average Assumptions
Discount rate	4.98%	4.60%
Pension Plan \| United States \| Other noncurrent assets
Change in Plan Assets
Assets	$ 1	$ 2
Pension Plan \| United States \| Noncurrent assets held for sale
Change in Plan Assets
Assets	0	0
Pension Plan \| United States \| Accrued compensation and benefits
Change in Plan Assets
Liabilities	(2)	(2)
Pension Plan \| United States \| Pension and postretirement benefit obligations
Change in Plan Assets
Liabilities	(24)	(12)
Pension Plan \| United States \| Noncurrent liabilities held for sale
Change in Plan Assets
Liabilities	0	0
Pension Plan \| Foreign Plan
Retirement Plans [Line Items]
Accumulated Benefit Obligation	1,335	1,563
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	1,617	1,473
Service cost	17	17	16
Interest cost	64	69	68
Plan participant contributions	3	3
Actuarial loss (gain)	(111)	84
Benefits and settlements paid	(96)	(132)
Divestitures	(131)	(5)
Other	(3)	2
Currency translation adjustment	14	(106)
Projected benefit obligation at end of year	1,374	1,617	1,473
Change in Plan Assets
Fair value of plan assets at beginning of year	1,525	1,388
Actual return on plan assets	(25)	137
Employer and employee contributions	32	26
Divestitures	(168)	0
Other	(2)	1
Currency translation adjustment	8	105
Fair value of plan assets at end of year	1,274	1,525	1,388
Funded status	(100)	(92)
Net amount recognized	$ (100)	$ (92)
Weighted Average Assumptions
Discount rate	5.17%	4.35%
Rate of compensation increase	2.91%	3.01%
Interest crediting rate	1.75%	1.58%
Pension Plan \| Foreign Plan \| Other noncurrent assets
Change in Plan Assets
Assets	$ 72	$ 62
Pension Plan \| Foreign Plan \| Noncurrent assets held for sale
Change in Plan Assets
Assets	0	52
Pension Plan \| Foreign Plan \| Accrued compensation and benefits
Change in Plan Assets
Liabilities	(12)	(12)
Pension Plan \| Foreign Plan \| Pension and postretirement benefit obligations
Change in Plan Assets
Liabilities	(157)	(166)
Pension Plan \| Foreign Plan \| Noncurrent liabilities held for sale
Change in Plan Assets
Liabilities	(3)	(28)
Postretirement Benefits
Retirement Plans [Line Items]
Accumulated Benefit Obligation	63	73
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	73	77
Service cost	0	0	0
Interest cost	3	4	4
Plan participant contributions	1	2
Actuarial loss (gain)	(5)	4
Benefits and settlements paid	(9)	(13)
Divestitures	0	0
Other	0	(1)
Currency translation adjustment	0	0
Projected benefit obligation at end of year	63	73	77
Change in Plan Assets
Fair value of plan assets at beginning of year	161	144
Actual return on plan assets	20	26
Employer and employee contributions	3	4
Divestitures	0	0
Other	0	0
Currency translation adjustment	0	0
Fair value of plan assets at end of year	175	161	$ 144
Funded status	112	88
Net amount recognized	$ 112	$ 88
Weighted Average Assumptions
Discount rate	4.77%	4.50%
Postretirement Benefits \| Other noncurrent assets
Change in Plan Assets
Assets	$ 136	$ 118
Postretirement Benefits \| Noncurrent assets held for sale
Change in Plan Assets
Assets	0	0
Postretirement Benefits \| Accrued compensation and benefits
Change in Plan Assets
Liabilities	(2)	(2)
Postretirement Benefits \| Pension and postretirement benefit obligations
Change in Plan Assets
Liabilities	(22)	(28)
Postretirement Benefits \| Noncurrent liabilities held for sale
Change in Plan Assets
Liabilities	$ 0	$ 0

Pension and Retirement Plans - Accumulated Benefit Obligations and Reconciliations of Changes in Projected Benefit Obligation, Changes in Plan Assets and Funded Status (Details) - USD ($)
$ in Millions