v3.26.1
Income Taxes (Reconciliation of Effective Income Tax Rates) (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Amount      
National statutory corporate tax rate ¥ 618,841    
Prefectural. and municipal tax, net of national income tax effect 102,873    
Foreign tax effects (10,489)    
Effect of changes in tax laws (12,876) ¥ 20,982  
Change in valuation allowances (20,757)    
Changes in unrecognized tax benefits 147    
Foreign branch tax rate difference 21,110    
Other, effect of cross-border tax laws 22,723    
Tax credits (4,337)    
Nontaxable dividends received (82,603)    
Other, non taxable income (96)    
Impairment of goodwill 1,270    
Other, nondeductible expenses (1,337)    
Tax penalty and tax refund 17    
Expiration of loss carryforward 13,065    
Undistributed earnings of subsidiaries 4,362    
Other-net (26,322)    
Income tax expense ¥ 625,591 ¥ 527,938 ¥ 500,657
Percent      
National statutory corporate tax rate 24.70%    
Prefectural. and municipal tax, net of national income tax effect 4.10%    
Foreign tax effects (0.40%)    
Effect of changes in tax laws (0.50%)    
Change in valuation allowances (0.80%)    
Changes in unrecognized tax benefits 0.00%    
Foreign branch tax rate difference 0.008    
Other, effect of cross-border tax laws 0.90%    
Tax credits (0.20%)    
Nontaxable dividends received (3.30%)    
Other, non taxable income (0.00%)    
Impairment of goodwill 0.10%    
Other, nondeductible expenses (0.10%)    
Tax penalty and tax refund 0.00%    
Expiration of loss carryforward 0.50% 1.40% 0.10%
Undistributed earnings of subsidiaries 0.20%    
Other-net (1.10%)    
Effective income tax rate 24.90% 29.40% 26.70%