Retirement Plans - Funded Status (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated Benefit Obligation	$ 552	$ 582
Change in Projected Benefit Obligation:
Projected benefit obligation at beginning of year	606	598
Service cost	8	7	$ 7
Interest cost	9	10	13
Actuarial (gain) loss	(29)	16
Benefits paid	(20)	(22)
Settlements and curtailments	(16)	(11)
Divestitures	(2)	(12)
Currency translation adjustment	18	20
Projected benefit obligation at end of year	574	606	598
Change in Plan Assets:
Fair value of plan assets at beginning of year	486	470
Actual return on plan assets	4	12
Employer contributions/(distributions)	23	19
Benefits paid	(20)	(22)
Settlements and curtailments	(16)	(10)
Divestitures	0	(1)
Currency translation adjustment	16	18
Fair value of plan assets at end of year	493	486	$ 470
Funded status	(81)	(120)
Prepaid benefit cost
Change in Plan Assets:
Funded status	51	26
Accrued benefit liability
Change in Plan Assets:
Funded status	$ (132)	$ (146)