v3.26.1
Parent Company Only Financial Information (Narrative) (Detail) - BK and TB - JPY (¥)
¥ in Billions
Mar. 31, 2026
Mar. 31, 2025
Companies Act    
Parent Company Only Financial Information [Line Items]    
Unrestricted amount of retained earnings that are in excess of the level required under the statutory reserve requirements ¥ 6,702 ¥ 6,225
Banking Law and Related Regulations    
Parent Company Only Financial Information [Line Items]    
Percentage limitation of loans or credits to the parent company over the banking subsidiary's consolidated total capital 15.00%  
Restricted amount of net assets of consolidated subsidiaries as to payment of cash dividends and loans to the parent company ¥ 6,742 ¥ 6,265