Derivative Financial Instruments (Notional Amounts of Derivative Contracts) (Detail) - JPY (¥)
¥ in Trillions
Mar. 31, 2022
Mar. 31, 2021
Derivative [Line Items]    
Total ¥ 1,657.3 ¥ 1,551.8
Interest rate contracts    
Derivative [Line Items]    
Total 1,391.8 1,308.4
Foreign exchange contracts    
Derivative [Line Items]    
Total 245.0 222.0
Equity contracts    
Derivative [Line Items]    
Total 7.4 8.0
Commodity contracts    
Derivative [Line Items]    
Total 0.1 0.1
Credit derivatives    
Derivative [Line Items]    
Total 9.8 9.8
Other    
Derivative [Line Items]    
Total ¥ 3.2 ¥ 3.5