v3.26.1
Business Developments (Acquisition of WealthNavi Inc) (Details) - JPY (¥)
¥ in Millions
1 Months Ended 12 Months Ended
Mar. 06, 2025
Jan. 27, 2025
Apr. 30, 2025
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2026
Dec. 01, 2024
Business Developments [Line Items]              
Goodwill       ¥ 558,164 ¥ 493,758 ¥ 566,536  
Marketable equity securities included in investment in equity method investees, aggregated market values       7,461,707   ¥ 11,034,755  
WealthNavi Inc              
Business Developments [Line Items]              
Payments to acquire businesses   ¥ 90,026 ¥ 8,809        
Assets acquired ¥ 88,038            
Cash and bank deposits acquired 34,424            
Liabilities acquired 43,294            
Other liabilities acquired 33,722            
Acquisition related costs 451            
Goodwill 63,730            
Intangible assets ¥ 22,869            
Weighted average amortization period, in years 9 years            
Marketable equity securities included in investment in equity method investees, aggregated market values ¥ 9,638            
Equity interest remeasurement loss ¥ 6,035            
Finite-lived intangible assets, purchase accounting adjustments       ¥ 2,541 ¥ 2,541    
Business Combination, Achieved in Stages, Preacquisition Equity Interest in Acquiree, Remeasurement, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration] Other non-interest income            
WealthNavi Inc              
Business Developments [Line Items]              
Ownership percentage             15.13%