Name:	c_DeferredCompensationArrangementsAwardVestingPeriod
Namespace Prefix:	c_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the holdback period on awards vested under the deferred compensation arrangement.

No definition available.

Name:	c_DeferredCompensationArrangementsHoldbackPeriod
Namespace Prefix:	c_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the period of the sale or transfer restriction on shares received under the deferred compensation arrangement.

No definition available.

Name:	c_DeferredCompensationArrangementsPeriodOfSaleOrTransferRestrictionOnSharesReceived
Namespace Prefix:	c_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the threshold value of awards to be paid entirely in the form of an immediate cash bonus.

No definition available.

Name:	c_IncentiveCompensationThresholdValueOfAwardsPaidAsImmediateCashBonus
Namespace Prefix:	c_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Represents the percentage of incentive pay required to be deferred.

No definition available.

Name:	c_IncentivePayRequiredToBeDeferredPercentage
Namespace Prefix:	c_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of immediate incentive awards required to be delivered in the form of stock payments.

No definition available.

Name:	c_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfIncentiveAwardsDeliveredAsStockPayment
Namespace Prefix:	c_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	c_IncentiveCompensationArrangementsByTypeAxis=c_AnnualIncentiveAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=c_CapitalAccumulationProgramAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_TitleOfIndividualAxis=c_HighlyCompensatedEmployeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_TitleOfIndividualAxis=c_IdentifiedStaffInTheEuropeanUnionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: