v3.26.1
Loans - Delinquent Status of Modified Loans to Borrowers Experiencing Financial Difficulty (Detail) - JPY (¥)
¥ in Billions
Mar. 31, 2026
Mar. 31, 2025
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount ¥ 240 ¥ 454
Domestic | Corporate | Large companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 193 412
Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 29 28
Domestic | Retail    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 225 445
Domestic | Retail | Housing Loan    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Domestic | Retail | Other    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 4 5
Foreign    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 15 9
30-59 Days Past Due    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
30-59 Days Past Due | Domestic | Corporate | Large companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
30-59 Days Past Due | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
30-59 Days Past Due | Domestic | Retail    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
30-59 Days Past Due | Domestic | Retail | Housing Loan    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
30-59 Days Past Due | Domestic | Retail | Other    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
30-59 Days Past Due | Foreign    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due | Domestic | Corporate | Large companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due | Domestic | Retail    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due | Domestic | Retail | Housing Loan    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due | Domestic | Retail | Other    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
60-89 Days Past Due | Foreign    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
90 Days or More Past Due    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 3 10
90 Days or More Past Due | Domestic | Corporate | Large companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 3 3
90 Days or More Past Due | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
90 Days or More Past Due | Domestic | Retail    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 3 3
90 Days or More Past Due | Domestic | Retail | Housing Loan    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
90 Days or More Past Due | Domestic | Retail | Other    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
90 Days or More Past Due | Foreign    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 7
Total Past Due    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 3 11
Total Past Due | Domestic | Corporate | Large companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 3 4
Total Past Due | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Total Past Due | Domestic | Retail    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 3 4
Total Past Due | Domestic | Retail | Housing Loan    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Total Past Due | Domestic | Retail | Other    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Total Past Due | Foreign    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 7
Current    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 236 443
Current | Domestic | Corporate | Large companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 189 408
Current | Domestic | Corporate | Small and medium-sized companies    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 29 28
Current | Domestic | Retail    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 222 441
Current | Domestic | Retail | Housing Loan    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 0 0
Current | Domestic | Retail | Other    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount 4 5
Current | Foreign    
Financing Receivable, Modified, Past Due [Line Items]    
Financing Receivable, Modified in Period, Amount ¥ 15 ¥ 2