v3.25.2
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings (Secured Borrowing by the Class of Collateral Pledged) (Detail) - JPY (¥)
¥ in Billions
Mar. 31, 2025
Mar. 31, 2024
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements ¥ 46,381 ¥ 37,771
Payables under securities lending transactions 737 1,092
Obligations to return securities received as collateral 6,047 7,223
Total 53,165 46,086
Japanese national government and Japanese government agency bonds    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 16,652 13,001
Payables under securities lending transactions 165 359
Obligations to return securities received as collateral 3,438 4,229
Total 20,255 17,589
Foreign government and official institution bonds    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 16,955 14,172
Payables under securities lending transactions 30 0
Obligations to return securities received as collateral 917 1,033
Total 17,902 15,205
Corporate bonds    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 1,012 773
Payables under securities lending transactions 0 76
Obligations to return securities received as collateral 358 400
Total 1,370 1,249
Residential mortgage-backed securities    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 10,695 8,819
Payables under securities lending transactions 0 0
Obligations to return securities received as collateral 0 0
Total 10,695 8,819
Other debt securities    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 190 346
Payables under securities lending transactions 0 0
Obligations to return securities received as collateral 2 38
Total 192 384
Marketable equity securities    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 846 636
Payables under securities lending transactions 531 657
Obligations to return securities received as collateral 1,332 1,523
Total 2,709 2,816
Other    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 31 24
Payables under securities lending transactions 11 0
Obligations to return securities received as collateral 0 0
Total ¥ 42 ¥ 24