GOODWILL AND INTANGIBLE ASSETS - Changes in Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Finite and Indefinite-lived Intangible Assets
Beginning balance	$ 4,411
Acquisitions/renewals/ divestitures	24
Amortization	(271)
Impairments	(1)
FX translation and other	(19)
Ending balance	4,144	$ 4,411
Mortgage servicing rights (MSRs)	409	336
Total intangible assets	4,553	4,747
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Beginning balance	190
Acquisitions/renewals/ divestitures	0
Amortization	0
Impairments	0
FX translation and other	(7)
Ending balance	183	190
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	1,419
Acquisitions/renewals/ divestitures	(15)
Amortization	(129)
Impairments	0
FX translation and other	(2)
Ending balance	1,273	1,419
Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Beginning balance	2,653
Acquisitions/renewals/ divestitures	4
Amortization	(105)
Impairments	(1)
FX translation and other	(1)
Ending balance	2,550	2,653
Core deposit intangibles
Finite and Indefinite-lived Intangible Assets
Beginning balance	1
Acquisitions/renewals/ divestitures	0
Amortization	(1)
Impairments	0
FX translation and other	0
Ending balance	0	1
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	141
Acquisitions/renewals/ divestitures	12
Amortization	(17)
Impairments	0
FX translation and other	(10)
Ending balance	126	141
Present value of future profits
Finite and Indefinite-lived Intangible Assets
Beginning balance	2
Acquisitions/renewals/ divestitures	0
Amortization	0
Impairments	0
FX translation and other	0
Ending balance	2	2
Other
Finite and Indefinite-lived Intangible Assets
Beginning balance	5
Acquisitions/renewals/ divestitures	23
Amortization	(19)
Impairments	0
FX translation and other	1
Ending balance	$ 10	$ 5
American Airlines, Costco, The Home Depot and AT&T \| Customer Concentration Risk \| Intangible Assets, Excluding Mortgage Servicing Rights \| Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Concentration risk, percentage	97.00%	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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No definition available.

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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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No definition available.

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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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No definition available.

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

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- Definition

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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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