v3.25.2
Fair Value (Carrying Value of Assets Measured at Fair Value on Nonrecurring Basis by Level) (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2023
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Goodwill ¥ 558,164 ¥ 493,758 ¥ 296,772
Fair Value, Measurements, Nonrecurring      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Investment securities 63,871 54,635  
Loans 277,573 637,457  
Loans held for sale 134,371 472,711  
Collateral dependent loans 143,202 164,746  
Premises and equipment 9,557 11,193  
Intangible assets 5,449 5,174  
Goodwill 161,758 0  
Other assets 53,438 51,048  
Investments in equity method investees 29,802 29,503  
Other 23,636 21,545  
Total 571,646 759,507  
Investment securities valued at net asset value 39,541 18,037  
Unfunded commitments related to investment securities valued at net asset value 34,847 24,208  
Fair Value, Measurements, Nonrecurring | Level 1      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Investment securities 0 0  
Loans 2,466 2,271  
Loans held for sale 0 0  
Collateral dependent loans 2,466 2,271  
Premises and equipment 0 0  
Intangible assets 0 0  
Goodwill 0 0  
Other assets 0 0  
Investments in equity method investees 0 0  
Other 0 0  
Total 2,466 2,271  
Fair Value, Measurements, Nonrecurring | Level 2      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Investment securities 14,041 9,460  
Loans 5,254 5,181  
Loans held for sale 0 0  
Collateral dependent loans 5,254 5,181  
Premises and equipment 0 0  
Intangible assets 0 0  
Goodwill 0 0  
Other assets 34,389 32,481  
Investments in equity method investees 27,745 27,801  
Other 6,644 4,680  
Total 53,684 47,122  
Fair Value, Measurements, Nonrecurring | Level 3      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Investment securities 49,830 45,175  
Loans 269,853 630,005  
Loans held for sale 134,371 472,711  
Collateral dependent loans 135,482 157,294  
Premises and equipment 9,557 11,193  
Intangible assets 5,449 5,174  
Goodwill 161,758 0  
Other assets 19,049 18,567  
Investments in equity method investees 2,057 1,702  
Other 16,992 16,865  
Total 515,496 710,114  
Fair value, recurring measurements      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Loans held for sale 28,447 31,542  
Total 96,224,960 88,967,756  
Fair value, recurring measurements | Marketable equity securities      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Contractual sale restriction equity security ¥ 43,654    
Fair value, recurring measurements | Marketable equity securities | Minimum      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Contractual sale restriction equity security, remaining period 0 years    
Fair value, recurring measurements | Marketable equity securities | Maximum      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Contractual sale restriction equity security, remaining period 3 years    
Fair value, recurring measurements | Level 1      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Loans held for sale ¥ 0 0  
Total 49,087,498 48,862,335  
Fair value, recurring measurements | Level 2      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Loans held for sale 28,447 31,542  
Total 44,006,257 37,540,452  
Fair value, recurring measurements | Level 3      
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]      
Loans held for sale 0 0  
Total ¥ 3,131,205 ¥ 2,564,969