Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans, expenses not related to ESOP				$ 17	$ 20	$ 14
Compensation expense related to the ESOP						1
Net losses on curtailments and settlements					(17)
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Net losses on curtailments and settlements				$ (1)		$ (1)
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to multi-employer plan				80.00%
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss amortized from accumulated other comprehensive income to net periodic benefit cost			$ 5
Amortization of estimated prior service credits			$ 3
U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation				$ 175	170
Weighted-average assumed health care cost trend rate				6.50%
U.S. Defined Benefit Plans [Member] | Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of weighted-average target asset allocation				50.00%
U.S. Defined Benefit Plans [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of weighted-average target asset allocation				50.00%
Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation				$ 373	326
Weighted-average assumed health care cost trend rate				6.80%
Foreign Plans [Member] | Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of weighted-average target asset allocation				38.00%
Foreign Plans [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of weighted-average target asset allocation				54.00%
Foreign Plans [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of weighted-average target asset allocation				3.00%
Foreign Plans [Member] | Cash and Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of weighted-average target asset allocation				5.00%
Foreign Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contribution				$ 8
Net losses on curtailments and settlements	[1]			(4)	$ (85)
Pre-tax charge due to transfer of defined benefit plan assets		$ 18
Reduction in plan assets and plan obligations				$ (85)

[1] The $10 million settlements and curtailments amount in 2016 was a result of global restructuring activities. The $85 million settlements amount in 2015 primarily reflects the transfer of certain plan assets and obligations to a third party, as discussed under Curtailments and Settlements of Employee Benefit Plans.