v3.25.2
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Obligations by Remaining Contractual Maturity and 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
Overnight and open    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 10,579 8,846
Payables under securities lending transactions 717 1,015
Obligations to return securities received as collateral 5,185 6,076
Total 16,481 15,937
30 days or less    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 29,902 20,010
Payables under securities lending transactions 3 1
Obligations to return securities received as collateral 399 610
Total 30,304 20,621
31 to 90 days    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 4,754 7,209
Payables under securities lending transactions 0 0
Obligations to return securities received as collateral 155 135
Total 4,909 7,344
Over 90 days    
Repurchase Agreements, and Securities Lending Transactions Accounted for as Secured Borrowings [Line Items]    
Payables under repurchase agreements 1,146 1,706
Payables under securities lending transactions 17 76
Obligations to return securities received as collateral 308 402
Total ¥ 1,471 ¥ 2,184