v3.26.1
Insurance contracts in the financial services business - Summary of remaining coverage and liabilities for incurred claims (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Insurance service expenses    
Insurance finance expenses (income)   ¥ 30,155
Other   (1,334)
Insurance contracts issued remaining coverage and incurred claim [member]    
Disclosure of reconciliation of changes in insurance contracts by remaining coverage and incurred claims [line items]    
Insurance contract assets, Beginning ¥ (47,715) (56,975)
Insurance contract liabilities, Beginning 12,870,638 13,094,339
Net amounts, Beginning 12,822,923 13,037,364
Insurance revenue (332,024) (622,959)
Insurance service expenses    
Incurred claims and other insurance service expenses 149,255 298,177
Amortization of insurance acquisition cash flows 70,418 134,818
Changes in liabilities for incurred claims 1,327 5,661
Losses and reversals of losses on onerous contracts 10,950 14,276
Total insurance service expenses 231,950 452,932
Insurance service result (100,074) (170,027)
Insurance finance expenses (income) (141,516) (634,805)
Total amounts recognized in comprehensive income (241,590) (804,832)
Premiums received 976,117 2,056,493
Insurance acquisition cash flows (85,130) (167,299)
Claims and other insurance service expenses paid (596,808) (1,298,150)
Total cash flows 294,179 591,044
Other (1,108) (653)
Impact from loss of control of the Financial Service business (12,874,404)  
Insurance contract assets, Ending   (47,715)
Insurance contracts liabilities, Ending   12,870,638
Net amounts, Ending   12,822,923
Net liabilities or assets for remaining coverage excluding loss component [member] | Insurance contracts issued remaining coverage and incurred claim [member]    
Disclosure of reconciliation of changes in insurance contracts by remaining coverage and incurred claims [line items]    
Insurance contract assets, Beginning (81,537) (90,377)
Insurance contract liabilities, Beginning 12,667,310 12,900,023
Net amounts, Beginning 12,585,773 12,809,646
Insurance revenue (332,024) (622,959)
Insurance service expenses    
Amortization of insurance acquisition cash flows 70,418 134,818
Total insurance service expenses 70,418 134,818
Insurance service result (261,606) (488,141)
Insurance finance expenses (income) (141,098) (631,892)
Total amounts recognized in comprehensive income (402,704) (1,120,033)
Investment component excluded from insurance revenue and insurance service expenses (444,430) (992,966)
Premiums received 976,117 2,056,493
Insurance acquisition cash flows (85,130) (167,299)
Total cash flows 890,987 1,889,194
Other (2,186) (68)
Impact from loss of control of the Financial Service business (12,627,440)  
Insurance contract assets, Ending   (81,537)
Insurance contracts liabilities, Ending   12,667,310
Net amounts, Ending   12,585,773
Loss component [member] | Insurance contracts issued remaining coverage and incurred claim [member]    
Disclosure of reconciliation of changes in insurance contracts by remaining coverage and incurred claims [line items]    
Insurance contract assets, Beginning 2  
Insurance contract liabilities, Beginning 63,181 55,333
Net amounts, Beginning 63,183 55,333
Insurance service expenses    
Incurred claims and other insurance service expenses (3,215) (5,882)
Losses and reversals of losses on onerous contracts 10,950 14,276
Total insurance service expenses 7,735 8,394
Insurance service result 7,735 8,394
Insurance finance expenses (income) (300) (498)
Total amounts recognized in comprehensive income 7,435 7,896
Other 1,159 (46)
Impact from loss of control of the Financial Service business (71,777)  
Insurance contract assets, Ending   2
Insurance contracts liabilities, Ending   63,181
Net amounts, Ending   63,183
Liabilities for incurred claims [member] | Insurance contracts issued remaining coverage and incurred claim [member]    
Disclosure of reconciliation of changes in insurance contracts by remaining coverage and incurred claims [line items]    
Insurance contract assets, Beginning 33,820 33,402
Insurance contract liabilities, Beginning 140,147 138,983
Net amounts, Beginning 173,967 172,385
Insurance service expenses    
Incurred claims and other insurance service expenses 152,470 304,059
Changes in liabilities for incurred claims 1,327 5,661
Total insurance service expenses 153,797 309,720
Insurance service result 153,797 309,720
Insurance finance expenses (income) (118) (2,415)
Total amounts recognized in comprehensive income 153,679 307,305
Investment component excluded from insurance revenue and insurance service expenses 444,430 992,966
Claims and other insurance service expenses paid (596,808) (1,298,150)
Total cash flows (596,808) (1,298,150)
Other (81) (539)
Impact from loss of control of the Financial Service business ¥ (175,187)  
Insurance contract assets, Ending   33,820
Insurance contracts liabilities, Ending   140,147
Net amounts, Ending   ¥ 173,967