SHAREHOLDER’S EQUITY - Summary of Activity of Common Stock Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		12 Months Ended
	Jun. 20, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Accelerated Share Repurchases [Line Items]
Number of shares repurchased (in shares)		5.7	1.4	1.6
Average price per share (in dollars per share)		$ 75.36	$ 97.34	$ 81.43
Amount			$ 134.0	$ 125.8
Treasury Stock
Accelerated Share Repurchases [Line Items]
Amount		$ 434.7	$ 134.0	$ 125.8
Open Market Purchases
Accelerated Share Repurchases [Line Items]
Number of shares repurchased (in shares)		0.4	1.4	0.9
Average price per share (in dollars per share)		$ 81.60	$ 97.34	$ 93.13
Open Market Purchases | Treasury Stock
Accelerated Share Repurchases [Line Items]
Amount		$ 34.7	$ 134.0	$ 80.3
Private Purchases
Accelerated Share Repurchases [Line Items]
Number of shares repurchased (in shares)		0.0	0.0	0.7
Average price per share (in dollars per share)		$ 0	$ 0	$ 66.63
Private Purchases | Treasury Stock
Accelerated Share Repurchases [Line Items]
Amount		$ 0.0	$ 0.0	$ 45.5
ASR
Accelerated Share Repurchases [Line Items]
Number of shares repurchased (in shares)	5.3	5.3	0.0	0.0
Average price per share (in dollars per share)		$ 74.86	$ 0	$ 0
Amount		$ 500.0
ASR | Treasury Stock
Accelerated Share Repurchases [Line Items]
Amount	$ 400.0	$ 400.0	$ 0.0	$ 0.0