Accumulated Other Comprehensive (Loss) Income - Accumulated Other Comprehensive (Loss) Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive (loss) income, beginning balance	$ (1,001)
Other comprehensive income before reclassifications, net of taxes	(150)
Amounts reclassified into income, net of taxes	13
Accumulated other comprehensive (loss) income, ending balance	(1,139)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive (loss) income, beginning balance	(270)
Other comprehensive income before reclassifications, net of taxes	(141)
Accumulated other comprehensive (loss) income, ending balance	(411)
Benefit Plans Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive (loss) income, beginning balance	(705)
Amounts reclassified into income, net of taxes	11	9
Accumulated other comprehensive (loss) income, ending balance	(694)
Unrealized Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive (loss) income, beginning balance	(26)
Other comprehensive income before reclassifications, net of taxes	(8)
Amounts reclassified into income, net of taxes	1	1
Accumulated other comprehensive (loss) income, ending balance	$ (33)