Debt and Other Obligations - Schedule of Long-Term Obligations (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Total variable rate debt	$ 90
Total Medium Term Notes	53	$ 53
Debt	747
Total debt	657	908
Capital lease obligations, due through fiscal 2033	11	13
Unamortized debt issuance costs and debt discount	(4)	(4)
Total debt	754	917
Less current portion of long-term debt	(35)	(256)
Total long-term debt	719	661
Revolving Credit Facility - Canada, expires fiscal 2021 [Member]
Debt Instrument [Line Items]
Line of credit	90
2.55% Notes matured fiscal 2018 [Member]
Debt Instrument [Line Items]
Notes		250
3.7% Notes due fiscal 2022 [Member]
Debt Instrument [Line Items]
Notes	350	350
3.4% Notes due fiscal 2026 [Member]
Debt Instrument [Line Items]
Notes	250	250
Notes due fiscal 2019, 7.42% [Member]
Debt Instrument [Line Items]
Total Medium Term Notes	30	30
Notes due fiscal 2022, 8.34% - 8.47% [Member]
Debt Instrument [Line Items]
Total Medium Term Notes	15	15
Notes due fiscal 2028, 6.57% - 7.28% [Member]
Debt Instrument [Line Items]
Total Medium Term Notes	8	8
Chinese Renminbi Debt, Due Fiscal 2018, 4.75% [Member]
Debt Instrument [Line Items]
Debt		$ 5
Chinese Renminbi Debt, Due Fiscal 2019, 4.35% [Member]
Debt Instrument [Line Items]
Debt	$ 4

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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