v3.26.1
Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Parenthetical) (Detail) - Mizuho Financial Group, Inc. - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Short-term Debt [Line Items]    
Commercial paper ¥ 1,921,799 ¥ 2,138,133
Short-term notes ¥ 353,500 ¥ 567,000