v3.26.3
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
 6 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Liability for Future Policy Benefit, Activity [Line Items]    
Liability for Future Policy Benefit, Gross Premium Income ¥ 242,693 ¥ 233,136
Liability for Future Policy Benefit, Interest Expense 19,364 16,824
Yen-denominated insurance (First Sector)    
Liability for Future Policy Benefit, Activity [Line Items]    
Liability for Future Policy Benefit, Gross Premium Income 96,709 89,337
Liability for Future Policy Benefit, Interest Expense 7,852 7,289
Yen-denominated insurance (Third Sector)    
Liability for Future Policy Benefit, Activity [Line Items]    
Liability for Future Policy Benefit, Gross Premium Income 93,340 96,721
Liability for Future Policy Benefit, Interest Expense 6,191 5,543
Foreign currency denominated insurance    
Liability for Future Policy Benefit, Activity [Line Items]    
Liability for Future Policy Benefit, Gross Premium Income 52,644 47,078
Liability for Future Policy Benefit, Interest Expense ¥ 5,321 ¥ 3,992