v3.25.4
REGULATORY CAPITAL (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
CET1 Capital ratio, stated minimum 4.50%  
Tier 1 Capital ratio, stated minimum 0.060  
Total Capital ratio, stated minimum 0.080  
Tier 1 Leverage ratio, stated minimum 0.040  
Supplementary leverage ratio, stated minimum 3.00%  
Dividends received from Citibank N.A. $ 12,700 $ 5,500
Citibank, N.A.    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
CET1 Capital 158,202 153,483
Tier 1 Capital 160,338 155,613
Quarterly Adjusted Average Total Assets 1,864,383 1,726,312
Total Leverage Exposure $ 2,374,748 $ 2,195,386
CET1 Capital ratio 14.33% 13.83%
CET1 Capital ratio, well capitalized minimum 6.50%  
Tier 1 Capital ratio, well capitalized minimum 0.080  
Tier 1 Capital ratio 0.1452 0.1403
Total Capital ratio, well capitalized minimum 0.100  
Total Capital ratio 0.1522 0.1493
Tier 1 Leverage ratio 0.0860 0.0901
Tier 1 Leverage ratio, well capitalized minimum 0.050  
Supplementary leverage ratio 0.0675 0.0709
Supplementary leverage ratio, well capitalized minimum 6.00%  
Citigroup Inc.    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
CET1 Capital $ 157,099 $ 155,363
Tier 1 Capital 179,675 174,527
Quarterly Adjusted Average Total Assets 2,685,119 2,433,364
Total Leverage Exposure $ 3,276,212 $ 2,985,418
CET1 Capital ratio 13.18% 13.63%
Tier 1 Capital ratio, well capitalized minimum 0.060  
Tier 1 Capital ratio 0.1365 0.1531
Total Capital ratio, well capitalized minimum 0.100  
Total Capital ratio 0.1566 0.1542
Tier 1 Leverage ratio 0.0669 0.0717
Supplementary leverage ratio 0.0548 0.0585
Standardized Approach | Citibank, N.A.    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Total Capital (Tier 1 Capital and Tier 2 Capital) $ 175,949 $ 173,060
Total Risk-Weighted Assets 1,006,961 998,817
Standardized Approach | Citigroup Inc.    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Total Capital (Tier 1 Capital and Tier 2 Capital) 216,468 205,827
Total Risk-Weighted Assets 1,192,174 1,139,988
Advanced Approach | Citibank, N.A.    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Total Capital (Tier 1 Capital and Tier 2 Capital) 168,005 165,581
Total Risk-Weighted Assets 1,104,193 1,109,387
Advanced Approach | Citigroup Inc.    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Total Capital (Tier 1 Capital and Tier 2 Capital) 206,170 197,371
Total Risk-Weighted Assets $ 1,316,371 $ 1,280,190