Employee Benefit Plans - Change in Projected Benefit Obligations and Change in Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Change in Plan Assets:
Fair value of plan assets at beginning of year	$ 472
Fair value of plan assets at end of year	346	$ 472
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	143	160
Service cost	1	1	$ 1
Interest cost	5	5	4
(Gain) Loss from changes in actuarial assumptions and plan experience	21	(10)
Benefits paid	(11)	(7)
Settlements or curtailments	(1)	(5)
Other	(1)	(1)
Benefit obligation at end of year	157	143	160
Change in Plan Assets:
Fair value of plan assets at beginning of year	149	156
Actual return on plan assets	14	4
Employer contribution	1	1
Benefits paid	(11)	(7)
Settlements	(1)	(4)
Expenses paid from assets	(1)	(1)
Fair value of plan assets at end of year	151	149	156
Funded status	(6)	6
Recognized asset (liability)	(6)	6
Pension Benefits [Member] | Foreign Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	373	376
Service cost	7	9	10
Interest cost	5	7	6
Plan participants’ contribution	1	2
Foreign currency exchange rate changes	(13)	(7)
(Gain) Loss from changes in actuarial assumptions and plan experience		2
Benefits paid	(7)	(13)
Settlements or curtailments	(134)	(2)
Divestiture of Specialty Fluids	(13)
Other	1	(1)
Benefit obligation at end of year	220	373	376
Change in Plan Assets:
Fair value of plan assets at beginning of year	323	318
Actual return on plan assets	17	17
Employer contribution	7	9
Plan participants’ contribution	1	2
Foreign currency exchange rate changes	(11)	(7)
Benefits paid	(7)	(13)
Settlements	(124)	(2)
Divestiture	(10)
Expenses paid from assets	(1)	(1)
Fair value of plan assets at end of year	195	323	318
Funded status	(25)	(50)
Recognized asset (liability)	(25)	(50)
Postretirement Benefits [Member] | U.S. Defined Benefit Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	29	33
Interest cost	1	1	1
(Gain) Loss from changes in actuarial assumptions and plan experience	1	(2)
Benefits paid	(3)	(3)
Benefit obligation at end of year	28	29	33
Change in Plan Assets:
Employer contribution	3	3
Benefits paid	(3)	(3)
Funded status	(28)	(29)
Recognized asset (liability)	(28)	(29)
Postretirement Benefits [Member] | Foreign Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	19	20
Interest cost	1	1	1
Foreign currency exchange rate changes	(1)	(1)
(Gain) Loss from changes in actuarial assumptions and plan experience	2
Benefits paid	(1)	(1)
Benefit obligation at end of year	20	19	$ 20
Change in Plan Assets:
Employer contribution	1	1
Benefits paid	(1)	(1)
Funded status	(20)	(19)
Recognized asset (liability)	$ (20)	$ (19)