v3.25.2
Pledged Assets and Collateral (Narrative) (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2023
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Investment securities pledged for acting as a collection agent of public funds ¥ 23,264,575    
Reserve funds included in Cash and due from banks and Interest-earning deposits in other banks 2,962,933 ¥ 3,012,095  
Total assets at end of fiscal year 405,940,211 397,820,570 ¥ 382,177,876
Fair value of securities accepted as collateral that is permitted to be sold or repledged 41,438,000 38,353,000  
Fair value of securities accepted as collateral that was sold or repledged 29,714,000 25,795,000  
Cash collateral pledged for derivative transactions included in Other assets 2,566,588 3,182,590  
Cash collateral received for derivative transactions included in Other liabilities 1,415,939 ¥ 1,404,066  
Asset pledged as collateral without right      
Financial Instruments Owned and Pledged as Collateral [Line Items]      
Total assets at end of fiscal year ¥ 37,827,000