Accumulated Other Comprehensive Income (Loss) - Changes in Each Component of Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 1,338	$ 2,064
Other comprehensive income (loss) before reclassifications	(31)	(263)
Amounts reclassified from accumulated other comprehensive income		24
Net other comprehensive items	(330)	(303)
Less: Noncontrolling interest	(5)	(4)
Ending Balance	1,372	1,338
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(239)	27
Other comprehensive income (loss) before reclassifications	7	(270)
Net other comprehensive items	(232)	(243)
Less: Noncontrolling interest	(5)	(4)
Ending Balance	(227)	(239)
Unrealized Gains on Investment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	2	2
Net other comprehensive items	2	2
Ending Balance	2	2
Pension and Other Postretirement Benefit Liability Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(62)	(93)
Other comprehensive income (loss) before reclassifications	(38)	7
Amounts reclassified from accumulated other comprehensive income		24
Net other comprehensive items	(100)	(62)
Ending Balance	(100)	(62)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(299)	(64)
Ending Balance	$ (325)	$ (299)