v3.25.2
Insurance contracts in the financial services segment - Summary of effect of insurance contracts initially recognized (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Disclosure of effect of insurance contracts initially recognised [line items]    
Effect of contracts initially recognized in the year ¥ 1,768 ¥ 2,116
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 2,122,195
Insurance acquisition cash flows [member]    
Disclosure of effect of insurance contracts initially recognised [line items]    
Effect of contracts initially recognized in the year 157,870 145,877
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 2,268,072
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) (2,671,196)
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) (403,124)
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 40,912
CSM [member]    
Disclosure of effect of insurance contracts initially recognised [line items]    
Effect of contracts initially recognized in the year 389,234 364,328
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 2,117,351
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 155,135 143,674
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 2,261,025
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) (2,666,256)
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) (405,231)
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 40,903
Profitable Contracts Issued [Member] | CSM [member]    
Disclosure of effect of insurance contracts initially recognised [line items]    
Effect of contracts initially recognized in the year 389,234 364,328
Onerous Contract Issued [Member]    
Disclosure of effect of insurance contracts initially recognised [line items]    
Effect of contracts initially recognized in the year 1,768 2,116
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 4,844
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 2,203
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 7,047
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) (4,940)
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 2,107
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 ¥ 9