DEBT - Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Instrument
Long-term debt, at fair value	$ 279,684	$ 271,606
Trust preferred securities	1,600
Citigroup Inc.
Debt Instrument
Long-term debt, at fair value	166,826	166,257
Bank
Debt Instrument
Long-term debt, at fair value	19,930	21,113
Bank \| Senior notes
Debt Instrument
Collateralized long-term advances from Federal Home Loan Bank	7,300	7,300
Broker-dealer and other
Debt Instrument
Long-term debt, at fair value	$ 92,928	$ 84,236

Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant