Retirement Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Total accumulated benefit obligation		$ 3,719	$ 3,910
Defined benefit plan, pension plan with projected benefit obligation in excess of plan assets, projected benefit obligation		519	527
Defined benefit plan, pension plan with projected benefit obligation in excess of plan assets, accumulated benefit obligation		435	444
Defined benefit plan, pension plan with projected benefit obligation in excess of plan assets, plan assets		118	102
Defined benefit plan, pension plan with accumulated benefit obligation in excess of plan assets, projected benefit obligation		469	477
Defined benefit plan, plan with accumulated benefit obligation in excess of plan assets, accumulated benefit obligation		413	421
Defined benefit plan, plan with accumulated benefit obligation in excess of plan assets, plan assets		77	63
Pension contribution		43	43	$ 41
Discontinued Operations
Defined Benefit Plan Disclosure [Line Items]
Pension expense (income)		7	16	21
Defined contribution plan, expense		14	32	30
Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Future benefit payments, 2024		8
Future benefit payments, 2025		8
Future benefit payments, 2026		8
Future benefit payments, 2027		8
Future benefit payments, 2028		8
Total future benefit payments, 2029 - 2033		29
Benefit obligation, ending (recognized in balance sheet)		72	83
Deferred actuarial gains in accumulated other comprehensive income		95	112
Pension income		19	12	15
Benefits paid		9	10
Private Equity Funds | Measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Unfunded commitments for private equity funds		$ 115
Period distributions of underlying assets are expected to occur		10 years
Forecast
Defined Benefit Plan Disclosure [Line Items]
Pension contribution	$ 45
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Pension expense (income)		$ (2)	$ 121	$ 141
Discount rate		6.03%	5.64%	2.92%
Over (Under) funded plans		$ 656
Unfunded plans		159
Future benefit payments, 2024		222
Future benefit payments, 2025		226
Future benefit payments, 2026		229
Future benefit payments, 2027		230
Future benefit payments, 2028		231
Total future benefit payments, 2029 - 2033		1,142
Benefit obligation, ending (recognized in balance sheet)		656	$ 513
Pension income		113	3	$ (27)
Benefits paid		204	204
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Pension expense (income)		$ 98	$ 57	$ 53
Discount rate		5.20%	4.90%	2.20%
Over (Under) funded plans		$ (62)
Unfunded plans		213
Future benefit payments, 2024		62
Future benefit payments, 2025		58
Future benefit payments, 2026		61
Future benefit payments, 2027		63
Future benefit payments, 2028		69
Total future benefit payments, 2029 - 2033		358
Benefit obligation, ending (recognized in balance sheet)		(62)	$ (57)
Pension income		(49)	(5)	$ (1)
Benefits paid		$ 42	$ 40