v3.26.1
Income Taxes (Reconciliation of Combined Normal Effective Income Tax Rates) (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Reconciliation of effective income tax rate:      
Combined normal effective statutory tax rate   30.60% 30.60%
Nondeductible expenses   0.40% 0.40%
Impairment of goodwill   2.40% 0.00%
Foreign tax credit and payments   0.20% 0.90%
Lower tax rates applicable to income of subsidiaries   (2.50%) (1.50%)
Change in valuation allowance   0.30% (1.40%)
Nontaxable dividends received   (5.30%) (4.10%)
Undistributed earnings of subsidiaries   1.80% 0.90%
Tax and interest expense for uncertainty in income taxes   1.70% 0.00%
Tax penalty and tax refund   (0.029) 0
Noncontrolling interest income   0.10% 0.60%
Effect of changes in tax laws   1.20% 0.00%
Expiration of loss carryforward 0.50% 1.40% 0.10%
Other—net   0.00% 0.20%
Effective income tax rate 24.90% 29.40% 26.70%
Income tax expense ¥ 625,591 ¥ 527,938 ¥ 500,657
CALIFORNIA      
Reconciliation of effective income tax rate:      
Income tax expense   ¥ (52,129)