v3.25.2
RESTRUCTURING - Schedule of Restructuring Reserve Activity (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2024
 [1]
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Dec. 31, 2023
Restructuring Reserve [Roll Forward]              
Beginning of period $ 20 $ 42   $ 42 $ 712 $ 712 $ 0
Restructuring charges 0 1       408 781
Change in estimate (2) (4)       (149) 0
Net restructuring charges (2) [1] (3) $ 36 (5) [1] 261 [1] 259 781
Payments and utilization (8) (13)       (936) (69)
Foreign exchange 1 (6)       7 0
End of period 11 20   11   42 712
Personnel costs              
Restructuring Reserve [Roll Forward]              
Beginning of period 20 42   42 687 687 0
Restructuring charges 0 1       354 687
Change in estimate (2) (4)       (146) 0
Net restructuring charges (2) (3)       208 687
Payments and utilization (8) (13)       (860) 0
Foreign exchange 1 (6)       7 0
End of period 11 20   11   42 687
Other              
Restructuring Reserve [Roll Forward]              
Beginning of period 0 0   0 $ 25 25 0
Restructuring charges 0 0       54 94
Change in estimate 0 0       (3) 0
Net restructuring charges 0 0       51 94
Payments and utilization 0 0       (76) (69)
Foreign exchange 0 0       0 0
End of period $ 0 $ 0   $ 0   $ 0 $ 25
[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.