v3.25.2
Loans and Allowance for Credit Losses (Aging Analysis) (Details) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Current    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) ¥ 579,550 ¥ 672,988
1-3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 39,562 31,906
Greater Than 3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 30,458 10,966
Commercial | Current | Domestic    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 300,859 324,772
Commercial | Current | Foreign    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 84,672 85,566
Commercial | 1-3 months Past Due | Domestic    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 442 740
Commercial | 1-3 months Past Due | Foreign    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 690 0
Commercial | Greater Than 3 months Past Due | Domestic    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 148 338
Commercial | Greater Than 3 months Past Due | Foreign    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 0 0
Residential | Current    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 8,930 13,770
Residential | 1-3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 742 918
Residential | Greater Than 3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 154 154
Card | Current    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 19,316 17,888
Card | 1-3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 3,562 3,961
Card | Greater Than 3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 1,694 2,066
Krungsri | Current    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 159,909 225,319
Krungsri | 1-3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 31,610 24,839
Krungsri | Greater Than 3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 27,416 8,114
Other | Current    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 5,864 5,673
Other | 1-3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) 2,516 1,448
Other | Greater Than 3 months Past Due    
Financing Receivable, Modifications [Line Items]    
Payment Status (Amortized Cost Basis at the Period End) ¥ 1,046 ¥ 294