GOODWILL AND INTANGIBLE ASSETS - Components of Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	$ 14,869	$ 15,098
Accumulated amortization of Intangible assets (excluding MSRs)	10,625	10,532
Net carrying amount of Intangible assets (excluding MSRs)	4,244	4,566
Gross carrying amount, Mortgage servicing rights (MSRs)	1,685	1,845
Mortgage servicing rights (MSRs)	1,685c_MortgageServicingRightsMSR	1,845c_MortgageServicingRightsMSR
Gross carrying amount of Intangible assets	16,554	16,943
Accumulated amortization of Intangible assets	10,625	10,532
Net carrying amount of Intangible assets, balance at end of period	5,929	6,411
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	281	290
Accumulated amortization of Intangible assets (excluding MSRs)	0	0
Net carrying amount of Intangible assets (excluding MSRs)	281	290
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	7,618	7,626
Accumulated amortization of Intangible assets (excluding MSRs)	6,355	6,294
Net carrying amount of Intangible assets (excluding MSRs)	1,263	1,332
Core deposit intangibles
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	1,122	1,153
Accumulated amortization of Intangible assets (excluding MSRs)	1,006	1,021
Net carrying amount of Intangible assets (excluding MSRs)	116	132
Other customer relationships
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	518	579
Accumulated amortization of Intangible assets (excluding MSRs)	335	331
Net carrying amount of Intangible assets (excluding MSRs)	183	248
Present value of future profits
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	163	233
Accumulated amortization of Intangible assets (excluding MSRs)	156	154
Net carrying amount of Intangible assets (excluding MSRs)	7	79
Other
Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying amount of Intangible assets (excluding MSRs)	5,167	5,217
Accumulated amortization of Intangible assets (excluding MSRs)	2,773	2,732
Net carrying amount of Intangible assets (excluding MSRs)	$ 2,394	$ 2,485

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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.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

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.

+ Details

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- Definition

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.

+ Details

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- Definition

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.

+ Details

Name:	c_IntangibleAssetsIncludingMortgageServicingRights
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Balance Type:	debit
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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- Details

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