INTEREST INCOME AND EXPENSE (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Interest income
Loan interest, including fees		$ 14,726	$ 15,542
Deposits with banks		3,001	2,647
Securities borrowed and purchased under agreements to resell		6,291	7,822
Investments, including dividends		4,166	4,849
Trading account assets		4,370	4,128
Other interest-earning assets		1,112	1,235
Total interest income	[1]	33,666	36,223
Interest expense
Deposits		8,438	10,411
Securities loaned and sold under agreements to repurchase		6,256	6,966
Trading account liabilities		757	831
Short-term borrowings and other interest-bearing liabilities		1,726	1,956
Long-term debt		2,477	2,552
Total interest expense	[1]	19,654	22,716
Net interest income	[1]	14,012	13,507
Provision for credit losses on loans		2,561	2,422
Net interest income after provision for credit losses on loans		11,451	11,085
Consumer loans
Interest income
Loan interest, including fees		9,758	9,798
Corporate loans
Interest income
Loan interest, including fees		$ 4,968	$ 5,744

[1]     Effective January 1, 2025, certain transaction processing fees paid by Citi, primarily to credit card networks, which were previously presented within Other operating expenses, are presented as contra-revenue within Commissions and fees reported in Non-interest revenue. Prior periods were conformed to reflect this change in presentation.