GOODWILL AND INTANGIBLE ASSETS - Changes in Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Finite and Indefinite-lived Intangible Assets
Beginning balance	$ 4,327
Acquisitions/ renewals/ divestitures	527
Amortization	(419)
Impairments	(38)
FX translation and other	14
Ending balance	4,411	$ 4,327
Mortgage servicing rights (MSRs)	336	495
Total intangible assets	4,747	4,822
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	1,617
Acquisitions/ renewals/ divestitures	11
Amortization	(200)
Impairments	(10)
FX translation and other	1
Ending balance	1,419	1,617
Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Beginning balance	2,324
Acquisitions/ renewals/ divestitures	509
Amortization	(183)
Impairments	0
FX translation and other	3
Ending balance	2,653	2,324
Core deposit intangibles
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	1
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	149
Acquisitions/ renewals/ divestitures	0
Amortization	(24)
Impairments	0
FX translation and other	16
Ending balance	141	149
Present value of future profits
Finite and Indefinite-lived Intangible Assets
Beginning balance	3
Acquisitions/ renewals/ divestitures	0
Amortization	0
Impairments	0
FX translation and other	(1)
Ending balance	2	3
Other
Finite and Indefinite-lived Intangible Assets
Beginning balance	5
Acquisitions/ renewals/ divestitures	7
Amortization	(12)
Impairments	0
FX translation and other	5
Ending balance	5	5
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Beginning balance	228
Acquisitions/ renewals/ divestitures	0
Amortization	0
Impairments	(28)
FX translation and other	(10)
Ending balance	$ 190	$ 228
Intangible Assets, Excluding Mortgage Servicing Rights \| Customer Concentration Risk \| American Airlines, Sears, The Home Depot and Costco \| Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Intangible assets, percent	96.00%	96.00%

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Sum of the carrying amounts of all intangible assets, excluding goodwill and excluding mortgage servicing rights, as of the balance sheet date, net of accumulated amortization and impairment charges.

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Intangible Assets, Excluding Mortgage Servicing Rights Acquisitions (Divestitures)

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This element represents the aggregate amount of amortization of intangible assets excluding mortgage servicing rights (MSRs) during the period.

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This element represents the aggregate amount of impairment of intangible assets excluding mortgage servicing rights (MSRs) during the period.

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This element represents net changes to the recorded value of intangible assets excluding mortgage servicing rights (MSRs), due to foreign currency translation adjustments and purchase accounting adjustments.

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This element represents the sum of the carrying amounts of all intangible assets excluding goodwill but including mortgage servicing rights, as of the balance sheet date that is net of accumulated amortization and impairment charges.

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The amount of mortgage servicing rights (MSRs) as of the balance sheet date.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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