v3.26.1
Due to Trust Account, Short-term Borrowings and Long-term Debt (Components of Other Short-term Borrowings) (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Short-term Debt [Line Items]    
Total ¥ 12,859,911 ¥ 24,636,926
Less unamortized discount 1 0
Other short-term borrowings—net ¥ 12,859,910 ¥ 24,636,926
Weighted average interest rate on outstanding balance at end of fiscal year 2.30% 1.58%
Domestic offices:    
Short-term Debt [Line Items]    
Total ¥ 4,954,893 ¥ 17,695,049
Domestic offices: | Commercial paper    
Short-term Debt [Line Items]    
Total 1,238,148 1,527,544
Domestic offices: | Borrowings from the Bank of Japan    
Short-term Debt [Line Items]    
Total 2,782,800 14,995,160
Domestic offices: | Borrowings from other financial institutions    
Short-term Debt [Line Items]    
Total 258,726 175,267
Domestic offices: | Other    
Short-term Debt [Line Items]    
Total 675,219 997,078
Foreign offices:    
Short-term Debt [Line Items]    
Total 7,905,018 6,941,877
Other short-term borrowings—net 7,905,018 6,941,877
Foreign offices: | Commercial paper    
Short-term Debt [Line Items]    
Total 7,445,830 6,707,574
Foreign offices: | Borrowings from other financial institutions    
Short-term Debt [Line Items]    
Total 455,976 219,134
Foreign offices: | Other    
Short-term Debt [Line Items]    
Total ¥ 3,212 ¥ 15,169