Shareholders' Equity - Changes in Certain Components of Shareholders' Equity (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 23,677
Beginning balance (shares)	(80,163,949)
Net Income	$ 1,779	$ 2,092	$ 874
Spin-off of Embecta (See Note 2)	251
Ending balance	$ 25,282	$ 23,677
Ending balance (shares)	(81,283,191)	(80,163,949)
Common Stock  Issued at Par Value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 365	$ 365	347
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments			12
Stock Issued During Period, Value, New Issues			6
Ending balance	365	365	365
Capital in Excess of Par Value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	19,272	19,270	16,270
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments			(9)
Stock Issued During Period, Value, New Issues			2,909
Share-based compensation and other plans, net	(108)	(85)	(143)
Share-based compensation	239	237	244
Treasury Stock, Value, Acquired, Cost Method	150	(150)
Ending balance	19,553	19,272	19,270
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	13,826	12,791	12,913
Net Income	1,779	2,092	874
Cash dividends, common	(992)	(958)	(888)
Dividends, Preferred Stock	(90)	(90)	(107)
Share-based compensation and other plans, net	(1)
Spin-off of Embecta (See Note 2)	634
Ending balance	15,157	13,826	12,791
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Other		(9)
Deferred Compensation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	23	23	23
Ending balance	23	23	23
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ (7,723)	$ (6,138)	$ (6,190)
Beginning balance (shares)	(80,164,000)	(74,623,000)	(76,260,000)
Share-based compensation and other plans, net	$ 44	$ 15	$ 52
Share-based compensation plans, net (shares)	1,271,000	1,068,000	1,597,000
Common stock held in trusts, net (shares)	25,000	33,000	41,000
Treasury Stock, Value, Acquired, Cost Method	$ (650)	$ (1,600)
Treasury Stock, Shares, Acquired	(2,415,000)	(6,643,000)
Ending balance	$ (8,330)	$ (7,723)	$ (6,138)
Ending balance (shares)	(81,283,000)	(80,164,000)	(74,623,000)