Share-Based Compensation - Compensation Cost Relating to Share-Based Payments (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	$ 177	$ 196	$ 166
Income tax benefit recognized	61	69	59
Cost of products sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	30	29	23
Selling and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	113	106	82
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	24	22	17
Acquisition And Other Restructuring
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost relating to share-based payments	$ 10	$ 39	$ 44