GOODWILL AND INTANGIBLE ASSETS - Changes in Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Finite and Indefinite-lived Intangible Assets
Beginning balance	$ 3,734
Acquisitions/renewals/ divestitures	0
Amortization	(121)
Impairments	0
FX translation and other	26
Ending balance	3,639
Mortgage servicing rights (MSRs)	770	$ 760
Total intangible assets	4,409	$ 4,494
Indefinite-lived intangible assets
Finite and Indefinite-lived Intangible Assets
Beginning balance	197
Acquisitions/renewals/ divestitures	0
Amortization	0
Impairments	0
FX translation and other	21
Ending balance	218
Purchased credit card relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	808
Acquisitions/renewals/ divestitures	0
Amortization	(66)
Impairments	0
FX translation and other	0
Ending balance	742
Credit card contract related intangibles
Finite and Indefinite-lived Intangible Assets
Beginning balance	2,681
Acquisitions/renewals/ divestitures	0
Amortization	(45)
Impairments	0
FX translation and other	2
Ending balance	2,638
Other customer relationships
Finite and Indefinite-lived Intangible Assets
Beginning balance	47
Acquisitions/renewals/ divestitures	0
Amortization	(10)
Impairments	0
FX translation and other	3
Ending balance	40
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

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.

+ Details

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- Definition

Intangible Assets, Excluding Mortgage Servicing Rights Acquisitions (Divestitures)

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

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

+ References

No definition available.

+ Details

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Balance Type:	credit
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

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.

+ 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

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	c_MortgageServicingRightsMSR
Namespace Prefix:	c_
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Period Type:	instant

- Details

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- Details

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- Details

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