Accumulated Other Comprehensive Income - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax provision associated with net gain resulting from remeasurement of benefit plan			$ 16
Income tax provision (benefit)	97	87	261	267
Unrealized gains or losses recognized on cash flow hedges	0		0
Income tax provision (benefit) for cash flow hedges				1
Benefit Plans Adjustments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax provision (benefit)	(4)	(8)	(13)	(23)
Unrealized Losses on Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax provision (benefit)	$ (1)		$ (2)	$ (2)