v3.26.1
Insurance contracts in the financial services business - Summary of effect of insurance contracts initially recognized (Detail)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
JPY (¥)
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year ¥ 1,768
Claims and other insurance service expenses [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 2,234,025
Insurance acquisition cash flows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 157,870
Estimates of present value of future cash outflows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 2,391,895
Estimates of present value of future cash inflows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year (2,823,696)
Estimates of present value of future cash flows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year (431,801)
Risk adjustment for non-financial risk [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 44,335
CSM [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 389,234
Profitable Contracts Issued [Member] | Claims and other insurance service expenses [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 2,227,649
Profitable Contracts Issued [Member] | Insurance acquisition cash flows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 155,135
Profitable Contracts Issued [Member] | Estimates of present value of future cash outflows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 2,382,784
Profitable Contracts Issued [Member] | Estimates of present value of future cash inflows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year (2,816,078)
Profitable Contracts Issued [Member] | Estimates of present value of future cash flows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year (433,294)
Profitable Contracts Issued [Member] | Risk adjustment for non-financial risk [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 44,060
Profitable Contracts Issued [Member] | CSM [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 389,234
Onerous Contract Issued [Member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 1,768
Onerous Contract Issued [Member] | Claims and other insurance service expenses [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 6,376
Onerous Contract Issued [Member] | Insurance acquisition cash flows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 2,735
Onerous Contract Issued [Member] | Estimates of present value of future cash outflows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 9,111
Onerous Contract Issued [Member] | Estimates of present value of future cash inflows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year (7,618)
Onerous Contract Issued [Member] | Estimates of present value of future cash flows [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year 1,493
Onerous Contract Issued [Member] | Risk adjustment for non-financial risk [member]  
Disclosure of effect of insurance contracts initially recognised [line items]  
Effect of contracts initially recognized in the year ¥ 275