CONSOLIDATED STATEMENT OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Jan. 01, 2023	Jan. 31, 2023	Dec. 31, 2023	[1],[2],[3]	Dec. 31, 2022	[1],[2],[3]	Dec. 31, 2021	[1],[2],[3]
Statement of Cash Flows [Abstract]
Transfer of investment securities from HTM to AFS	$ 3,300	$ 3,300	$ 3,324		$ 0		$ 0
Transfer of securities from HTM to AFS, unrealized gain		$ 100

[1] In January 2023, Citi adopted ASU 2022-01. Upon adoption, Citi transferred $3.3 billion of mortgage-backed securities from HTM classification to AFS classification as allowed under the ASU. At the time of transfer, the securities were in an unrealized gain position of $0.1 billion, which was recorded in AOCI upon transfer.

[2] Operating and finance lease right-of-use assets and lease liabilities represent non-cash investing and financing activities, respectively, and are not included in the non-cash investing activities presented here. See Note 29 for more information and balances as of December 31, 2023 and 2022.

[3] See Note 2.