v3.26.1
CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (AOCI) - Schedule of Pre-Tax and After-Tax (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period $ 213,822  
Balance, end of period 212,572 $ 213,258
Citigroup's accumulated other comprehensive income (loss)    
Change in accumulated other comprehensive income (loss), pretax    
Balance, beginning of period, pretax (48,156) (54,439)
Other comprehensive income (loss), pretax 1,382 2,506
Balance, end of period, pretax (46,774) (51,933)
Change in accumulated other comprehensive income (loss), tax effect    
Balance, beginning of period, tax effect 6,259 6,587
Other comprehensive income (loss), tax effect (100) (376)
Balance, end of period, tax effect 6,159 6,211
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period (41,897) (47,852)
Total other comprehensive income 1,282 2,130
Balance, end of period (40,615) (45,722)
Net unrealized gains (losses) on debt securities    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax (1,150) 744
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect 331 (229)
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period (1,240) (2,837)
Total other comprehensive income (819) 515
Balance, end of period (2,059) (2,322)
Debt valuation adjustment (DVA)    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax 1,832 1,000
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect (427) (221)
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period (2,143) (1,121)
Total other comprehensive income 1,405 779
Balance, end of period (738) (342)
Excluded component of fair value hedges    
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period (34) (52)
Total other comprehensive income 13 7
Balance, end of period (21) (45)
Benefit plans    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax 96 (18)
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect (58) (8)
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period (5,504) (5,627)
Total other comprehensive income 38 (26)
Balance, end of period (5,466) (5,653)
Foreign currency translation adjustment (CTA)    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax 907 764
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect (18) 85
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period (33,016) (38,047)
Total other comprehensive income 889 849
Balance, end of period (32,127) (37,198)
Long-duration insurance contracts    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax 8 (2)
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect (3) 1
Change in accumulated other comprehensive income (loss), after-tax    
Balance, beginning of period 30 52
Total other comprehensive income 5 (1)
Balance, end of period 35 51
Cash flow hedges | Excluded component of fair value hedges    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax (330) 8
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect 81 (1)
Change in accumulated other comprehensive income (loss), after-tax    
Total other comprehensive income (249) 7
Excluded component of fair value hedges | Excluded component of fair value hedges    
Change in accumulated other comprehensive income (loss), pretax    
Other comprehensive income (loss), pretax 19 10
Change in accumulated other comprehensive income (loss), tax effect    
Other comprehensive income (loss), tax effect (6) (3)
Change in accumulated other comprehensive income (loss), after-tax    
Total other comprehensive income $ 13 $ 7