v3.26.1
Derivative Financial Instruments (Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period) (Detail) - JPY (¥)
¥ in Billions
Mar. 31, 2026
Mar. 31, 2025
Credit Derivatives [Line Items]    
Maximum payout/Notional amount ¥ 12,592 ¥ 15,750
One year or less    
Credit Derivatives [Line Items]    
Maximum payout/Notional amount 1,844 1,173
After one year through five years    
Credit Derivatives [Line Items]    
Maximum payout/Notional amount 9,008 13,125
After five years    
Credit Derivatives [Line Items]    
Maximum payout/Notional amount ¥ 1,740 ¥ 1,452