v3.26.1
Transfers of Financial Assets - Carrying Amounts and Fair Values of Transferred Financial Assets that did not Qualify for Derecognition and Associated Financial Liabilities (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Repurchase agreements and securities lending transactions [member]    
Disclosure of transferred financial assets that are not derecognised in their entirety [Line Items]    
Carrying amount of assets ¥ 14,494,575 ¥ 17,619,448
Carrying amount of associated liabilities 11,128,463 14,266,491
For those liabilities that have recourse only to the transferred assets:    
Fair value of assets
Fair value of associated liabilities
Net position
Loans and advances [member] | Residential mortgages [member]    
Disclosure of transferred financial assets that are not derecognised in their entirety [Line Items]    
Carrying amount of assets 1,333,049 1,405,542
Carrying amount of associated liabilities 1,025,112 1,087,079
For those liabilities that have recourse only to the transferred assets:    
Fair value of assets 1,269,430 1,442,378
Fair value of associated liabilities 840,998 1,056,219
Net position 428,432 386,159
Loans and advances [member] | Corporate loans [member]    
Disclosure of transferred financial assets that are not derecognised in their entirety [Line Items]    
Carrying amount of assets 1,132,384 1,044,583
Carrying amount of associated liabilities 1,064,516 988,678
For those liabilities that have recourse only to the transferred assets:    
Fair value of assets 1,140,657 1,051,706
Fair value of associated liabilities 1,064,516 988,678
Net position ¥ 76,141 ¥ 63,028