v3.26.1
Critical Accounting Estimates and Judgments - Additional Information (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Critical accounting estimates and judgments [line items]      
Impairment losses on goodwill ¥ 0 ¥ 8,032 ¥ 0
Provision 355,063 333,301 231,319
Net assets of retirement benefits 593,472 478,072  
Deferred tax assets 94,526 63,176  
Net total of deferred tax liabilities 203,397 202,591  
Allowance for loan losses 1,236,839 1,102,522  
Impairment losses on other intangible assets 2,389 1,551 9,648
Impairment losses on property, plant and equipment 3,815 5,461 4,168
Credit risk exposure on borrowings 413,940,083 387,253,951  
Russian Borrowers [member]      
Critical accounting estimates and judgments [line items]      
Credit risk exposure on borrowings 64,088    
Middle East Borrowers [Member]      
Critical accounting estimates and judgments [line items]      
Credit risk exposure on borrowings 30,849    
High interest rates in foreign countries [member] | Foreign countries [member]      
Critical accounting estimates and judgments [line items]      
Additional allowance for credit losses due to changes in interest rate 45,300    
Provision for interest repayment [member]      
Critical accounting estimates and judgments [line items]      
Provision ¥ 177,420 ¥ 209,659 ¥ 120,864
Interest Rate Restriction Act [member] | Minimum [member]      
Critical accounting estimates and judgments [line items]      
Interest rates on loans 15.00%    
Interest Rate Restriction Act [member] | Maximum [member]      
Critical accounting estimates and judgments [line items]      
Interest rates on loans 20.00%    
Act regulating the receipt of contributions, receipt of deposits and interest rates [member] | Maximum [member]      
Critical accounting estimates and judgments [line items]      
Interest rates on loans 29.20%