Shareholders' Equity - Accumulated Other Comprehensive (Loss) Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	$ (1,738)	$ (1,001)	$ (516)
Other comprehensive loss before reclassifications, net of taxes	(251)	(787)	(524)
Amounts reclassified into income, net of taxes	60	50	38
Accumulated other comprehensive (loss) income, ending balance	(1,929)	(1,738)	(1,001)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	(961)	(270)	74
Other comprehensive loss before reclassifications, net of taxes	(50)	(692)	(344)
Amounts reclassified into income, net of taxes	0	0	0
Accumulated other comprehensive (loss) income, ending balance	(1,011)	(961)	(270)
Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	(741)	(705)	(558)
Other comprehensive loss before reclassifications, net of taxes	(190)	(80)	(180)
Amounts reclassified into income, net of taxes	48	44	33
Accumulated other comprehensive (loss) income, ending balance	(883)	(741)	(705)
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	(36)	(26)	(31)
Other comprehensive loss before reclassifications, net of taxes	(11)	(16)	0
Amounts reclassified into income, net of taxes	12	6	5
Accumulated other comprehensive (loss) income, ending balance	$ (35)	$ (36)	$ (26)