Derivative Financial Instruments (Narrative) (Detail) - JPY (¥)
¥ in Billions
 12 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]    
Carrying value of credit protection, offsetting with purchased protection with identical underlying referenced entities, in approximate ¥ 70 ¥ 66
Notional amounts of credit protection, offsetting with purchased protection with identical underlying referenced entities, in approximate 4,083 4,097
Aggregate fair value of derivative instruments with credit-risk-related contingent features in a liability position, in approximate 500 700
Aggregate fair value of derivative instruments with credit-risk-related contingent features in a liability position, posted collateral, in approximate 349 227
Additional collateral amount which could be requested if the MUFG Group's debt falls below investment grade 53 63
Early termination amount which could be requested if the MUFG Group's debt falls below investment grade ¥ 60 ¥ 92