Debt and Other Obligations - Schedule of Long-Term Obligations (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014	Jul. 31, 2012	Sep. 30, 2009
Debt Instrument [Line Items]
Total variable rate debt		$ 28
Total Medium Term Notes	$ 53	53
Total debt	958	984
Capital lease obligations, due through 2031	14	17
Unamortized debt discount	(1)	(1)
Total debt	971	1,028
Less current portion of long-term debt	(1)	(24)
Total long-term debt	970	1,004
Chinese Renminbi Notes, Due Through 2016, 6.15%-6.77% [Member]
Debt Instrument [Line Items]
Notes		28
5% Notes Due 2017 [Member]
Debt Instrument [Line Items]
Notes	300	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)
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 Notes, Due Through 2017, 4.63%-6.15% [Member]
Debt Instrument [Line Items]
Notes	$ 5	$ 31