v3.25.2
Fair Value (Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments Not Carried at Fair Value on Recurring Basis on Balance Sheets by Level) (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2025
Mar. 31, 2024
Financial liabilities:    
Carrying amounts of investments in equity method investees ¥ 4,564,269 ¥ 4,115,988
Carrying amount    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and due from banks 4,591,000 4,417,000
Interest-earning deposits in other banks 104,707,000 105,702,000
Call loans and funds sold 1,676,000 1,738,000
Receivables under resale agreements 18,782,000 18,824,000
Receivables under securities borrowing transactions 5,701,000 5,001,000
Investment securities 23,272,000 24,844,000
Loans, net of allowance for credit losses 130,187,000 126,555,000
Other financial assets 9,783,000 11,761,000
Financial liabilities:    
Non-interest-bearing 36,820,000 38,805,000
Interest-bearing 212,633,000 208,360,000
Total deposits 249,453,000 247,165,000
Call money and funds purchased 5,017,000 5,094,000
Payables under repurchase agreements 43,664,000 35,690,000
Payables under securities lending transactions 718,000 1,017,000
Due to trust account and other short-term borrowings 28,229,000 15,747,000
Long-term debt 20,928,000 39,833,000
Other financial liabilities 9,038,000 9,081,000
Carrying amounts of investments in equity method investees 4,116,000 4,564,000
Estimated fair value    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and due from banks 4,591,000 4,417,000
Interest-earning deposits in other banks 104,707,000 105,702,000
Call loans and funds sold 1,676,000 1,738,000
Receivables under resale agreements 18,782,000 18,824,000
Receivables under securities borrowing transactions 5,701,000 5,001,000
Investment securities 22,647,000 24,558,000
Loans, net of allowance for credit losses 129,772,000 126,707,000
Other financial assets 9,783,000 11,761,000
Financial liabilities:    
Non-interest-bearing 36,820,000 38,805,000
Interest-bearing 212,643,000 208,512,000
Total deposits 249,463,000 247,317,000
Call money and funds purchased 5,017,000 5,094,000
Payables under repurchase agreements 43,664,000 35,690,000
Payables under securities lending transactions 718,000 1,017,000
Due to trust account and other short-term borrowings 28,229,000 15,747,000
Long-term debt 20,199,000 39,103,000
Other financial liabilities 9,038,000 9,081,000
Estimated fair value | Level 1    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and due from banks 4,591,000 4,417,000
Interest-earning deposits in other banks 0 0
Call loans and funds sold 0 0
Receivables under resale agreements 0 0
Receivables under securities borrowing transactions 0 0
Investment securities 12,932,000 14,522,000
Loans, net of allowance for credit losses 2,000 2,000
Other financial assets 0 0
Financial liabilities:    
Non-interest-bearing 0 0
Interest-bearing 0 0
Total deposits 0 0
Call money and funds purchased 0 0
Payables under repurchase agreements 0 0
Payables under securities lending transactions 0 0
Due to trust account and other short-term borrowings 0 0
Long-term debt 0 0
Other financial liabilities 0 0
Estimated fair value | Level 2    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and due from banks 0 0
Interest-earning deposits in other banks 104,707,000 105,702,000
Call loans and funds sold 1,676,000 1,738,000
Receivables under resale agreements 18,782,000 18,824,000
Receivables under securities borrowing transactions 5,701,000 5,001,000
Investment securities 8,244,000 7,457,000
Loans, net of allowance for credit losses 70,000 295,000
Other financial assets 9,783,000 11,761,000
Financial liabilities:    
Non-interest-bearing 36,820,000 38,805,000
Interest-bearing 212,643,000 208,512,000
Total deposits 249,463,000 247,317,000
Call money and funds purchased 5,017,000 5,094,000
Payables under repurchase agreements 43,664,000 35,690,000
Payables under securities lending transactions 718,000 1,017,000
Due to trust account and other short-term borrowings 28,229,000 15,747,000
Long-term debt 20,199,000 39,103,000
Other financial liabilities 9,038,000 9,081,000
Estimated fair value | Level 3    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and due from banks 0 0
Interest-earning deposits in other banks 0 0
Call loans and funds sold 0 0
Receivables under resale agreements 0 0
Receivables under securities borrowing transactions 0 0
Investment securities 1,471,000 2,579,000
Loans, net of allowance for credit losses 129,700,000 126,410,000
Other financial assets 0 0
Financial liabilities:    
Non-interest-bearing 0 0
Interest-bearing 0 0
Total deposits 0 0
Call money and funds purchased 0 0
Payables under repurchase agreements 0 0
Payables under securities lending transactions 0 0
Due to trust account and other short-term borrowings 0 0
Long-term debt 0 0
Other financial liabilities ¥ 0 ¥ 0