SHARE-BASED COMPENSATION (Details) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024 USD ($) plan $ / shares shares	Mar. 31, 2023 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) plan $ / shares shares	Mar. 31, 2023 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans | plan	1		1
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs granted during period (in shares) | shares	87	203	1,800	2,100
RSUs granted during period, weighted-average grant-date fair value (in usd per share) | $ / shares	$ 117.55	$ 108.39	$ 107.21	$ 116.75
Compensation expense	$ 53	$ 54	$ 140	$ 130
Total pre-tax compensation costs not yet recognized, net of forfeitures	377		$ 377
Compensation costs not yet recognized, period of recognition (in years)			3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	2	$ 2	$ 4	$ 5
Total pre-tax compensation costs not yet recognized, net of forfeitures	$ 8		$ 8
Compensation costs not yet recognized, period of recognition (in years)			2 years