v3.25.2
Loans and Allowance for Credit Losses (Total Outstanding Loans and Past Due Analysis) (Detail) - JPY (¥)
Mar. 31, 2025
Mar. 31, 2024
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans ¥ 131,881,305,000,000 ¥ 128,397,012,000,000
Loans Held for Sale 887,263,000,000 971,514,000,000
Past Due 90 Days and Accruing 10,243,000,000 20,148,000,000
Unearned income, unamortized premiums—net and deferred loan fees—net (442,790,000,000) (486,709,000,000)
Total 131,438,515,000,000 127,910,303,000,000
1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 312,271,000,000 328,332,000,000
Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 350,566,000,000 294,285,000,000
Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 662,837,000,000 622,617,000,000
Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 130,331,205,000,000 126,802,881,000,000
Residential    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 12,561,780,000,000 12,497,378,000,000
Loans Held for Sale 0 0
Past Due 90 Days and Accruing 3,157,000,000 3,837,000,000
Residential | 1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 32,739,000,000 33,943,000,000
Residential | Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 10,711,000,000 11,980,000,000
Residential | Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 43,450,000,000 45,923,000,000
Residential | Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 12,518,330,000,000 12,451,455,000,000
Card    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 498,773,000,000 484,850,000,000
Loans Held for Sale 0 0
Past Due 90 Days and Accruing 0 0
Card | 1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 15,737,000,000 15,790,000,000
Card | Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 30,221,000,000 28,388,000,000
Card | Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 45,958,000,000 44,178,000,000
Card | Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 452,815,000,000 440,672,000,000
Krungsri    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 8,846,908,000,000 8,805,112,000,000
Loans Held for Sale 0 17,930,000,000
Past Due 90 Days and Accruing 0 0
Krungsri | 1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 228,655,000,000 247,919,000,000
Krungsri | Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 252,745,000,000 189,558,000,000
Krungsri | Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 481,400,000,000 437,477,000,000
Krungsri | Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 8,365,508,000,000 8,349,705,000,000
Other    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 2,056,692,000,000 1,758,167,000,000
Loans Held for Sale 0 0
Past Due 90 Days and Accruing 0 0
Other | 1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 21,555,000,000 23,125,000,000
Other | Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 28,744,000,000 28,553,000,000
Other | Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 50,299,000,000 51,678,000,000
Other | Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 2,006,393,000,000 1,706,489,000,000
Domestic | Commercial    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 61,669,333,000,000 57,498,290,000,000
Loans Held for Sale 130,854,000,000 112,496,000,000
Past Due 90 Days and Accruing 2,419,000,000 3,004,000,000
Domestic | Commercial | 1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 9,275,000,000 6,108,000,000
Domestic | Commercial | Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 6,127,000,000 8,289,000,000
Domestic | Commercial | Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 15,402,000,000 14,397,000,000
Domestic | Commercial | Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 61,523,077,000,000 57,371,397,000,000
Foreign    
Loans and Leases Receivable Disclosure [Line Items]    
Total 56,713,215,000,000 57,430,845,000,000
Foreign | Commercial    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 46,247,819,000,000 47,353,215,000,000
Loans Held for Sale 756,409,000,000 841,088,000,000
Past Due 90 Days and Accruing 4,667,000,000 13,307,000,000
Foreign | Commercial | 1-3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 4,310,000,000 1,447,000,000
Foreign | Commercial | Greater Than 3 months    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 22,018,000,000 27,517,000,000
Foreign | Commercial | Total Past Due    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans 26,328,000,000 28,964,000,000
Foreign | Commercial | Current    
Loans and Leases Receivable Disclosure [Line Items]    
Total Loans ¥ 45,465,082,000,000 ¥ 46,483,163,000,000