v3.26.1
Financial Risk Management - Maximum Exposure to Credit Risk before Collateral Held or Other Credit Enhancements (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements ¥ 413,940,083 ¥ 387,253,951
Deposits with banks [Member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 73,623,887 75,754,246
Call loans and bills bought [Member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 7,885,057 5,200,789
Reverse repurchase agreements and cash collateral on securities borrowed [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 25,468,742 22,076,009
Trading assets [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 6,476,194 5,511,465
Derivatives [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 10,093,100 8,313,016
Financial assets at fair value through profit or loss [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 2,620,759 2,820,665
Debt investment securities at amortized cost [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 4,763,716 366,997
Debt investment securities at FVOCI [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 23,268,702 28,008,280
Loans and advances [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 130,516,241 125,190,819
Other financial asset [Member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements 11,876,173 7,061,639
Loan commitments [member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements [1] 100,314,339 91,810,227
Financial guarantees and other credit-related contingent liabilities [Member]    
Disclosure of credit risk exposure [line items]    
Maximum exposure to credit risk before collateral held or other credit enhancements [1] ¥ 17,033,173 ¥ 15,139,799
[1] Under the group aggregation system, the Company and its wholly-owned domestic subsidiaries recognized deferred tax assets relating to deductible temporary differences and tax losses carried forward on a consolidated basis for Japanese national corporation tax purposes and on a stand-alone basis for Japanese local corporation tax purposes. There are deductible temporary differences and tax losses carried forward on which deferred tax assets are recognized for Japanese national corporation tax purposes, but on which no deferred tax assets are recognized for Japanese local corporation tax purposes. These deductible temporary differences and tax losses carried forward amounted to ¥0 million and ¥304,322 million at March 31, 2026 and 2025, respectively.