Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended			36 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2017	Sep. 30, 2014
Income Taxes [Line Items]
Net discrete tax (benefits) charges related to tax settlements	$ (25)	$ 1	$ (13)
Net tax benefits from excess foreign tax credits upon repatriation of prior foreign earnings and accrual on certain foreign earnings	16
Net tax benefits from change in valuation allowance	6
Net tax benefits for return to provision adjustments related to tax return filings	(4)
Other miscellaneous tax items	1
Foreign currency transaction gain (loss), before tax		(3)
Cost of renewal of the U.S. research and experimentation credit		1	2
Foreign currency charge related to tax settlements			7
Tax benefits from repatriation of high taxed income			4
Net operating loss carryforwards	798			$ 798
Other tax credit carryforwards	212			212
Undistributed earnings	1,900			1,900
Tax credits profit	210
Tax credits				89
Required future taxable operating income	$ 629
Expected term to realize deferred tax asset, years	20 years
Increased/(decreased) valuation allowance	$ (9)	16
Unrecognized tax benefits	36	30	30	36	$ 41
Unrecognized tax benefits, recorded	25			25
Unrecognized tax benefits, not recorded	11			11
Accruals for penalties	1	1		1
Accruals for interest	8	8		8
Total penalties and interest	2	2	$ 2
Favorable impact on tax provision	$ 34
Earliest Tax Year [Member] | State Tax Authorities [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2005
Earliest Tax Year [Member] | Non-U.S. Jurisdictions [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2002
Earliest Tax Year [Member] | United States Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2013
Latest Tax Year [Member] | State Tax Authorities [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2015
Latest Tax Year [Member] | Non-U.S. Jurisdictions [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2015
Latest Tax Year [Member] | United States Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2015
U.S. Management [Member]
Income Taxes [Line Items]
Net deferred tax assets	$ 220			$ 220
Deferred Income Tax Charge [Member]
Income Taxes [Line Items]
Charge for valuation allowance on deferred tax assets in foreign jurisdiction		$ 5