GOODWILL AND INTANGIBLE ASSETS - Components of Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	$ 12,181	$ 11,894
Accumulated amortization of Intangible assets (excluding MSRs)	7,545	7,306
Net carrying amount of intangible assets (excluding MSRs)	4,636	4,588
Gross carrying amount, Mortgage servicing rights (MSRs)	584	558
Mortgage servicing rights (MSRs)	584	558
Gross carrying amount of Intangible assets	12,765	12,452
Accumulated amortization of intangible assets	7,545	7,306
Net carrying amount of intangible assets, balance at end of period	5,220	5,146
Intangible assets amortization expense	557	603	$ 595
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019	533
2020	394
2021	376
2022	915
2023	214
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	218	244
Accumulated amortization of Intangible assets (excluding MSRs)	0	0
Net carrying amount of intangible assets (excluding MSRs)	218	244
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	5,733	5,375
Accumulated amortization of Intangible assets (excluding MSRs)	3,936	3,836
Net carrying amount of intangible assets (excluding MSRs)	1,797	1,539
Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	5,225	5,045
Accumulated amortization of Intangible assets (excluding MSRs)	2,791	2,456
Net carrying amount of intangible assets (excluding MSRs)	2,434	2,589
Core deposit intangibles
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	419	639
Accumulated amortization of Intangible assets (excluding MSRs)	415	628
Net carrying amount of intangible assets (excluding MSRs)	4	11
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	470	459
Accumulated amortization of Intangible assets (excluding MSRs)	299	272
Net carrying amount of intangible assets (excluding MSRs)	171	187
Present value of future profits
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	32	32
Accumulated amortization of Intangible assets (excluding MSRs)	29	28
Net carrying amount of intangible assets (excluding MSRs)	3	4
Other
Finite and Indefinite-lived Intangible Assets
Gross carrying amount of Intangible assets (excluding MSRs)	84	100
Accumulated amortization of Intangible assets (excluding MSRs)	75	86
Net carrying amount of intangible assets (excluding MSRs)	$ 9	$ 14
American Airlines, Sears, The Home Depot and Costco \| Intangible Assets, Excluding Mortgage Servicing Rights \| Customer Concentration Risk \| Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Intangible assets, percent	97.00%

No definition available.

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- Definition

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.

+ References

No definition available.

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This element represents the accumulated amortization of all intangible assets, excluding goodwill and mortgage servicing rights (MSRs), as of the balance sheet date.

+ References

No definition available.

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This element represents the gross carrying amounts of all intangible assets, excluding goodwill and mortgage servicing rights (MSRs), as of the balance sheet date.

+ References

No definition available.

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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.

+ References

No definition available.

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This element represents the accumulated amortization of all intangible assets excluding goodwill but including mortgage servicing rights (MSRs), as of the balance sheet date.

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No definition available.

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This element represents the gross carrying amount of intangible assets excluding goodwill but including mortgage servicing rights (MSRs), as of the balance sheet date.

+ References

No definition available.

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

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This element represents the gross carrying amount of mortgage servicing rights (MSRs) as of the balance sheet date.

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No definition available.

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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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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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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