Retirement Plans - Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Change in Projected Benefit Obligation:
Service cost	$ 6	$ 5	$ 7
Interest cost	19	18	10
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated Benefit Obligation	366	331
Change in Projected Benefit Obligation:
Projected benefit obligation at beginning of year	349	340
Service cost	5	5
Interest cost	19	18
Actuarial loss (gain)	28	(15)
Benefits paid	(28)	(20)
Curtailments, settlements and other	(6)	(6)
Currency translation adjustment	17	27
Projected benefit obligation at end of year	384	349	340
Change in Plan Assets:
Fair value of plan assets at beginning of year	263	283
Actual return on plan assets	26	(23)
Employer contributions, net	20	17
Benefits paid	(28)	(20)
Curtailments, settlements and other	(6)	(14)
Currency translation adjustment	18	20
Fair value of plan assets at end of year	293	263	$ 283
Funded status	(91)	(86)
Pension plan assets (other noncurrent assets) | Pension plan
Change in Plan Assets:
Funded status	19	22
Pension benefits (of which $5 million and $16 million are included in accrued compensation and benefits, respectively) | Pension plan
Change in Plan Assets:
Funded status	(110)	(108)
Pension and postretirement benefits | Pension plan
Change in Plan Assets:
Funded status	$ 5	$ 16