GOODWILL AND INTANGIBLE ASSETS - Changes in Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Finite and Indefinite-lived Intangible Assets
Beginning balance	$ 3,763
Acquisitions/ renewals/ divestitures	321
Amortization	(370)
Impairments	0
FX translation and other	16
Ending balance	3,730
Mortgage servicing rights (MSRs)	691	$ 665
Total intangible assets	4,421	$ 4,428
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	1,087
Acquisitions/ renewals/ divestitures	0
Amortization	(150)
Impairments	0
FX translation and other	0
Ending balance	937
Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Beginning balance	2,385
Acquisitions/ renewals/ divestitures	290
Amortization	(188)
Impairments	0
FX translation and other	(8)
Ending balance	2,479
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	90
Acquisitions/ renewals/ divestitures	11
Amortization	(24)
Impairments	0
FX translation and other	(4)
Ending balance	73
Present value of future profits
Finite and Indefinite-lived Intangible Assets
Beginning balance	1
Acquisitions/ renewals/ divestitures	0
Amortization	0
Impairments	0
FX translation and other	0
Ending balance	1
Other
Finite and Indefinite-lived Intangible Assets
Beginning balance	8
Acquisitions/ renewals/ divestitures	0
Amortization	(8)
Impairments	0
FX translation and other	0
Ending balance	0
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Beginning balance	192
Acquisitions/ renewals/ divestitures	20
Amortization	0
Impairments	0
FX translation and other	28
Ending balance	$ 240