Debt and Other Obligations - Schedule of Long-Term Obligations (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015	Jul. 31, 2012	Sep. 30, 2009
Debt Instrument [Line Items]
Total Medium Term Notes	$ 53	$ 53
Debt	907
Total debt	907	958
Capital lease obligations, due through 2031	13	14
Unamortized debt discount	(1)	(1)
Total debt	919	971
Less current portion of long-term debt	(1)	(1)
Total long-term debt	918	970
5% Notes [Member]
Debt Instrument [Line Items]
Notes		300
Unamortized debt discount				$ (2)
2.55% Notes Due 2018 [Member]
Debt Instrument [Line Items]
Notes	250	250
Unamortized debt discount			$ (1)
3.7% Notes Due 2022 [Member]
Debt Instrument [Line Items]
Notes	350	350
Unamortized debt discount			$ (1)
3.4% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Notes	250
Unamortized debt discount	(1)
Notes Due 2019, 7.42% [Member]
Debt Instrument [Line Items]
Total Medium Term Notes	30	30
Notes Due 2022, 8.35% - 8.47% [Member]
Debt Instrument [Line Items]
Total Medium Term Notes	15	15
Notes Due 2028, 6.57%-7.28% [Member]
Debt Instrument [Line Items]
Total Medium Term Notes	8	8
Chinese Renminbi Debt, Due 2017, 6.15% [Member]
Debt Instrument [Line Items]
Debt	$ 4	$ 5