SHAREHOLDERS' EQUITY, Schedule of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period			$ 10,187
OCI:
OCI before reclassifications and taxes	$ (20)	$ 126	342	$ 254
Amounts reclassified from AOCI, before tax	(9)	(8)	(19)	(13)
Pre-tax net OCI	(29)	118	323	241
Income tax effect	(2)	(25)	(76)	(57)
Total other comprehensive income/(loss), net of tax	(31)	93	247	184
Balance end of period	10,979	9,969	10,979	9,969
Accumulated other comprehensive (loss) income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period	(693)	(891)	(971)	(982)
OCI:
Balance end of period	(724)	(798)	(724)	(798)
Subtotal: net investment hedges and currency translations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period	(44)	(77)	(73)	(123)
OCI:
OCI before reclassifications and taxes	(4)	7	18	48
Amounts reclassified from AOCI, before tax	0	0	0	0
Pre-tax net OCI	(4)	7	18	48
Income tax effect	(7)	0	0	5
Total other comprehensive income/(loss), net of tax	(11)	7	18	53
Balance end of period	(55)	(70)	(55)	(70)
Net investment hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period	121	139	143	153
OCI:
OCI before reclassifications and taxes	29	(4)	0	(23)
Amounts reclassified from AOCI, before tax	0	0	0	0
Pre-tax net OCI	29	(4)	0	(23)
Income tax effect	(7)	1	0	6
Total other comprehensive income/(loss), net of tax	22	(3)	0	(17)
Balance end of period	143	136	143	136
Currency translations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period	(165)	(216)	(216)	(276)
OCI:
OCI before reclassifications and taxes	(33)	11	18	71
Amounts reclassified from AOCI, before tax	0	0	0	0
Pre-tax net OCI	(33)	11	18	71
Income tax effect	0	(1)	0	(1)
Total other comprehensive income/(loss), net of tax	(33)	10	18	70
Balance end of period	(198)	(206)	(198)	(206)
Available- for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period	(672)	(855)	(942)	(902)
OCI:
OCI before reclassifications and taxes	(34)	126	324	211
Amounts reclassified from AOCI, before tax	0	0	0	0
Pre-tax net OCI	(34)	126	324	211
Income tax effect	8	(29)	(80)	(67)
Total other comprehensive income/(loss), net of tax	(26)	97	244	144
Balance end of period	(698)	(758)	(698)	(758)
Cash flow hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance beginning of period	23	41	44	43
OCI:
OCI before reclassifications and taxes	18	(7)	0	(5)
Amounts reclassified from AOCI, before tax	(9)	(8)	(19)	(13)
Pre-tax net OCI	9	(15)	(19)	(18)
Income tax effect	(3)	4	4	5
Total other comprehensive income/(loss), net of tax	6	(11)	(15)	(13)
Balance end of period	$ 29	$ 30	$ 29	$ 30