Employee Benefit Plans - Change in Projected Benefit Obligations and Change in Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Change in Plan Assets:
Fair value of plan assets at beginning of year	$ 346
Fair value of plan assets at end of year	300	$ 346
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	157	143
Service cost	1	1	$ 1
Interest cost	4	5	5
Loss from changes in actuarial assumptions and plan experience	2	21
Benefits paid	(7)	(11)
Settlements or curtailments	(57)	(1)
Other	(1)	(1)
Benefit obligation at end of year	99	157	143
Change in Plan Assets:
Fair value of plan assets at beginning of year	151	149
Actual return on plan assets	9	14
Employer contribution	1	1
Benefits paid	(7)	(11)
Settlements	(57)	(1)
Expenses paid from assets	(1)	(1)
Fair value of plan assets at end of year	96	151	149
Funded status	(3)	(6)
Recognized asset (liability)	(3)	(6)
Pension Benefits [Member] | Foreign Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	220	373
Service cost	5	7	9
Interest cost	3	5	7
Plan participants’ contribution	1	1
Foreign currency exchange rate changes	7	(13)
Loss from changes in actuarial assumptions and plan experience	5
Benefits paid	(8)	(7)
Settlements or curtailments	(2)	(134)
Divestiture of Specialty Fluids		(13)
Other		1
Benefit obligation at end of year	231	220	373
Change in Plan Assets:
Fair value of plan assets at beginning of year	195	323
Actual return on plan assets	7	17
Employer contribution	6	7
Plan participants’ contribution	1	1
Foreign currency exchange rate changes	5	(11)
Benefits paid	(8)	(7)
Settlements	(2)	(124)
Divestiture		(10)
Expenses paid from assets		(1)
Fair value of plan assets at end of year	204	195	323
Funded status	(27)	(25)
Recognized asset (liability)	(27)	(25)
Postretirement Benefits [Member] | U.S. Defined Benefit Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	28	29
Interest cost	1	1	1
Loss from changes in actuarial assumptions and plan experience	1	1
Benefits paid	(3)	(3)
Benefit obligation at end of year	27	28	29
Change in Plan Assets:
Employer contribution	3	3
Benefits paid	(3)	(3)
Funded status	(27)	(28)
Recognized asset (liability)	(27)	(28)
Postretirement Benefits [Member] | Foreign Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	20	19
Interest cost		1	1
Foreign currency exchange rate changes		(1)
Loss from changes in actuarial assumptions and plan experience		2
Benefits paid		(1)
Benefit obligation at end of year	20	20	$ 19
Change in Plan Assets:
Employer contribution		1
Benefits paid		(1)
Funded status	(20)	(20)
Recognized asset (liability)	$ (20)	$ (20)