v3.26.1
Long-Duration Insurance Contracts Relating to Life Insurance Operations - Schedule of Deferred Policy Acquisition Costs (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Deferred Policy Acquisition Cost [Line Items]    
Beginning balance ¥ 315,840 ¥ 305,734
Capitalization 39,269 35,871
Amortization (20,692) (19,215)
Effect of changes in foreign exchange rate 5,195 (742)
Others [1] (6,720) (5,808)
Ending balance 332,892 315,840
Yen-denominated insurance (First Sector)    
Deferred Policy Acquisition Cost [Line Items]    
Beginning balance 89,361 82,341
Capitalization 17,649 13,431
Amortization (7,120) (6,411)
Effect of changes in foreign exchange rate 0 0
Others [1] 0 0
Ending balance 99,890 89,361
Yen-denominated insurance (Third Sector)    
Deferred Policy Acquisition Cost [Line Items]    
Beginning balance 168,689 169,581
Capitalization 7,784 9,180
Amortization (10,006) (10,072)
Effect of changes in foreign exchange rate 0 0
Others [1] 0 0
Ending balance 166,467 168,689
Foreign currency denominated insurance    
Deferred Policy Acquisition Cost [Line Items]    
Beginning balance 57,151 53,812
Capitalization 6,504 6,633
Amortization (3,018) (2,689)
Effect of changes in foreign exchange rate 4,278 (605)
Others [1] 0 0
Ending balance 64,915 57,151
Single- payment whole life insurance    
Deferred Policy Acquisition Cost [Line Items]    
Beginning balance 639 0
Capitalization 7,332 6,627
Amortization (548) (43)
Effect of changes in foreign exchange rate 917 (137)
Others [1] (6,720) (5,808)
Ending balance ¥ 1,620 ¥ 639
[1] Others include adjustments of reinsurance.