v3.26.1
Fair Value (Summary of Fair Value of Financial Instruments) (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Assets:      
Equity securities (without readily determinable fair values) ¥ 686,545 ¥ 601,621 ¥ 357,938
Fair Value, Measurements, Nonrecurring      
Assets:      
Loans 116,000 84,000  
Loans held-for-sale 70,000 54,000  
Equity securities (without readily determinable fair values) 5,000 10,000  
Other investments   68,000  
Premises and equipment—net 2,000 0  
Other assets   3,000  
Total assets measured at fair value 193,000 219,000  
Fair Value, Measurements, Nonrecurring | Aggregate cost      
Assets:      
Loans 172,000 345,000  
Loans held-for-sale 92,000 57,000  
Equity securities (without readily determinable fair values) 9,000 23,000  
Other investments   106,000  
Premises and equipment—net 3,000 2,000  
Other assets   10,000  
Total assets measured at fair value 276,000 543,000  
Fair Value, Measurements, Nonrecurring | Level 1      
Assets:      
Loans 0 0  
Loans held-for-sale 0 0  
Equity securities (without readily determinable fair values) 0 0  
Other investments   66,000  
Premises and equipment—net 0 0  
Other assets   0  
Total assets measured at fair value 0 66,000  
Fair Value, Measurements, Nonrecurring | Level 2      
Assets:      
Loans 0 0  
Loans held-for-sale 47,000 48,000  
Equity securities (without readily determinable fair values) 2,000 1,000  
Other investments   0  
Premises and equipment—net 0 0  
Other assets   0  
Total assets measured at fair value 49,000 49,000  
Fair Value, Measurements, Nonrecurring | Level 3      
Assets:      
Loans 116,000 84,000  
Loans held-for-sale 23,000 5,000  
Equity securities (without readily determinable fair values) 3,000 9,000  
Other investments   2,000  
Premises and equipment—net 2,000 0  
Other assets   3,000  
Total assets measured at fair value ¥ 144,000 ¥ 104,000