Cash Flows - Actual Employer Contributions (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
U.S. Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual employer contributions	$ 1	$ 16
Expected employer contributions
Expected employer contributions 2017	9
Expected benefit payments
Expected benefit payments 2017	165
Expected benefit payments 2018	88
Expected benefit payments 2019	85
Expected benefit payments 2020	84
Expected benefit payments 2021	81
Expected benefit payments 2022-2026	350
U.S. Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual employer contributions	3	3
Expected employer contributions
Expected employer contributions 2017	3
Expected benefit payments
Expected benefit payments 2017	3
Expected benefit payments 2018	3
Expected benefit payments 2019	2
Expected benefit payments 2020	2
Expected benefit payments 2021	2
Expected benefit payments 2022-2026	2
Non-U.S. Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual employer contributions	102	$ 0
Expected employer contributions
Expected employer contributions 2017	6
Expected benefit payments
Expected benefit payments 2017	4
Expected benefit payments 2018	4
Expected benefit payments 2019	5
Expected benefit payments 2020	5
Expected benefit payments 2021	5
Expected benefit payments 2022-2026	$ 27