v3.26.1
Income Taxes - Additional Information (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of income taxes [Line Items]      
Statutory income tax rate 30.20% 30.20% 30.20%
Deferred tax assets recognized by entities that have suffered a loss in either the preceding or current period ¥ 103,123 ¥ 637  
Aggregate amounts of temporary differences relating to investments in subsidiaries and interests in joint ventures for which deferred tax liabilities are not recognized ¥ 9,268,070 ¥ 8,127,532  
Japan [member]      
Disclosure of income taxes [Line Items]      
Statutory income tax rate 30.20%