DISCONTINUED OPERATIONS, SIGNIFICANT DISPOSALS AND OTHER BUSINESS EXITS - Summarized Reserve Charges (Details) - Citibank Korea Inc. - Severance costs - USD ($) $ in Millions	2 Months Ended	3 Months Ended
Dec. 31, 2021	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Employee termination costs
Beginning of period	$ 1,052	$ 0	$ 714	$ 1,054
Additional charges (releases)		0	(3)	31
Utilization	(1)	0	(670)	(347)
Foreign exchange	3	0	(41)	(24)
End of period	$ 1,054	$ 0	$ 0	$ 714

Restructuring and Related Charges, Charges to Reserve

No definition available.

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Period Type:	duration

- Definition

Restructuring and Related Charges, Utilization

+ References

No definition available.

+ Details

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

- Definition

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI https://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b)(2))
-URI https://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

Amount of foreign currency translation gain (loss) which decreases (increases) the restructuring reserve.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI https://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4(b)(2))
-URI https://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747

+ Details

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Balance Type:	credit
Period Type:	duration

- Details

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- Details

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