v3.26.1
Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recorded in income ¥ (713,441) ¥ 518,972 ¥ 560,806
Interest rate contracts      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recorded in income (709,941) (10,636) (22,003)
Foreign exchange contracts      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recorded in income 332,489 464,463 387,591
Equity-related contracts      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recorded in income (317,436) 64,292 240,277
Credit-related contracts      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recorded in income [1] (22,718) 6,531 (3,053)
Other contracts      
Derivative Instruments, Gain (Loss) [Line Items]      
Gains (losses) recorded in income ¥ 4,166 ¥ (5,678) ¥ (42,005)
[1] Amounts include the net gains (losses) of ¥(952) million, ¥(964) million and ¥(809) million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2024, 2025 and 2026, respectively.