Share-Based Compensation - Compensation Cost Relating to Share-Based Payments (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	$ 238	$ 245	$ 265
Income tax benefit recognized	55	57	62
Cost of products sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	43	40	37
Selling and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	158	150	145
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	36	34	32
Acquisitions and other restructurings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	$ 1	$ 20	$ 50