v3.26.1
Investment Securities - Schedule of Fair Value of Equity Instruments Measured at Fair Value through Other Comprehensive Income at Date of Derecoginititon And Cumulative Gain on Disposal (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disclosure of detailed information about financial instruments [abstract]    
Fair value of the equity instruments at fair value through other comprehensive income at the date of derecognition ¥ 619,772 ¥ 667,657
Cumulative gain on disposal ¥ 482,553 ¥ 490,955