Shareholders' Equity - Changes in Certain Components of Shareholders' Equity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Components Of Stockholders Equity [Line Items]
Balance	$ 4,136
Balance, Shares	(135,751,039)
Net Income	1,293	1,170	1,271
Balance	5,043	4,136
Balance, Shares	(138,663,113)	(135,751,039)
Common Stock Issued at Par Value [Member]
Components Of Stockholders Equity [Line Items]
Balance	333	333	333
Net Income
Balance	333	333	333
Capital in Excess of Par Value [Member]
Components Of Stockholders Equity [Line Items]
Balance	1,920	1,793	1,625
Net Income
Share-based compensation plans, net	50	39	95
Share-based compensation	98	88	73
Balance	2,068	1,920	1,793
Retained Earnings [Member]
Components Of Stockholders Equity [Line Items]
Balance	10,435	9,634	8,724
Net Income	1,293	1,170	1,271
Common ($1.64, 1.80 and $1.98 per share for the year ended 2011, 2012, 2013 respectively)	(386)	(368)	(362)
Balance	11,342	10,435	9,634
Deferred Compensation [Member]
Components Of Stockholders Equity [Line Items]
Balance	19	19	17
Net Income
Common stock held in trusts, net			2
Balance	19	19	19
Treasury Stock [Member]
Components Of Stockholders Equity [Line Items]
Balance	(7,769)	(6,280)	(4,806)
Balance, Shares	(135,751,000)	(117,844,000)	(102,846,000)
Share-based compensation plans, net	15	11	28
Share-based compensation plans, net, Shares	2,537,000	1,973,000	3,432,000
Common stock held in trusts, net			(2)
Common stock held in trusts, net, Shares	36,000	66,000	3,000
Repurchase of common stock	(450)	(1,500)	(1,500)
Repurchase of common stock, Shares	(5,485,000)	(19,945,000)	(18,434,000)
Balance	$ (8,204)	$ (7,769)	$ (6,280)
Balance, Shares	(138,663,000)	(135,751,000)	(117,844,000)