v3.26.1
Loans - Troubled Debt Restructurings On Financing Receivables (Detail) - JPY (¥)
¥ in Billions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[2] ¥ 240 ¥ 454
Domestic    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[2] 225 445
Domestic | Corporate | Large companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[2] 193 412
Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[2] 29 28
Domestic | Retail | Housing Loan    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[2] 0 0
Domestic | Retail | Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[2] 4 5
Foreign    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [1],[3] 15 [2] 9
Term Extension    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 191 443
Term Extension | Domestic    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 191 441
Term Extension | Domestic | Corporate | Large companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 159 408
Term Extension | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 28 28
Term Extension | Domestic | Retail | Housing Loan    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Term Extension | Domestic | Retail | Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 4 5
Term Extension | Foreign    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [3],[4] 0 2
Interest rate reduction    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 15 0
Interest rate reduction | Domestic    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Interest rate reduction | Domestic | Corporate | Large companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Interest rate reduction | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Interest rate reduction | Domestic | Retail | Housing Loan    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Interest rate reduction | Domestic | Retail | Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Interest rate reduction | Foreign    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [3],[4] 14 0
Term Extension And Interest Rate Reduction    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 20 0
Term Extension And Interest Rate Reduction | Domestic    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 20 0
Term Extension And Interest Rate Reduction | Domestic | Corporate | Large companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 20 0
Term Extension And Interest Rate Reduction | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Term Extension And Interest Rate Reduction | Domestic | Retail | Housing Loan    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Term Extension And Interest Rate Reduction | Domestic | Retail | Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [4] 0 0
Term Extension And Interest Rate Reduction | Foreign    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [3],[4] 0 0
Principal Forgiveness    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 10 0
Principal Forgiveness | Domestic    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 10 0
Principal Forgiveness | Domestic | Corporate | Large companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 10 0
Principal Forgiveness | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Principal Forgiveness | Domestic | Retail | Housing Loan    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Principal Forgiveness | Domestic | Retail | Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Principal Forgiveness | Foreign    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [3] 0 0
Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 3 10
Other | Domestic    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 3 3
Other | Domestic | Corporate | Large companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 3 3
Other | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Other | Domestic | Retail | Housing Loan    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Other | Domestic | Retail | Other    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Other | Foreign    
Financing Receivable, Modifications [Line Items]    
Financing Receivable, Modified in Period, Amount [3] ¥ 0 ¥ 7
[1] Commitments to lend to borrowers experiencing financial difficulty that were granted modifications were immaterial at March 31, 2025 and 2026.
[2] The allowance for credit losses on loans is based on macroeconomic-sensitive models that rely on historical performance and macroeconomic scenarios to forecast expected credit losses. Modifications of loans impact expected credit losses by affecting the likelihood of default.
[3] The majority of total foreign consist of corporate.
[4] The financial effects of loan modifications, which were largely in the form of term extensions and interest rate reductions, included extending the weighted-average life of the loans by 11.0 months and 20.2 months, and reducing the weighted-average contractual interest rate by 0.5% and 1.0% for the fiscal years ended March 31, 2025 and 2026, respectively.