v3.26.1
Long-Duration Insurance Contracts Relating to Life Insurance Operations - Schedule of Liability For Future Policy Benefit Gross Premiums And Interest Expense (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Liability for Future Policy Benefit, Activity [Line Items]      
Liability for Future Policy Benefit, Gross Premium Income ¥ 486,676 ¥ 471,859 ¥ 456,924
Liability for Future Policy Benefit, Interest Expense 34,979 31,466 28,105
Yen-denominated insurance (First Sector)      
Liability for Future Policy Benefit, Activity [Line Items]      
Liability for Future Policy Benefit, Gross Premium Income 202,621 184,650 168,805
Liability for Future Policy Benefit, Interest Expense 14,801 13,895 13,142
Yen-denominated insurance (Third Sector)      
Liability for Future Policy Benefit, Activity [Line Items]      
Liability for Future Policy Benefit, Gross Premium Income 193,321 199,809 205,787
Liability for Future Policy Benefit, Interest Expense 11,499 10,509 9,720
Foreign currency denominated insurance      
Liability for Future Policy Benefit, Activity [Line Items]      
Liability for Future Policy Benefit, Gross Premium Income 90,734 87,400 82,332
Liability for Future Policy Benefit, Interest Expense ¥ 8,679 ¥ 7,062 ¥ 5,243