v3.26.1
Employee Benefits - Summary of Fair Value of Classes of Plan Assets (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Japanese plans [Member]    
Disclosure of fair value of plan assets [line items]    
Stocks ¥ 357,318 ¥ 375,443
Commingled funds 522,785 500,917
Insurance contracts 154,224 224,694
Other 449,619 660,162
Total 1,952,578 2,081,009
Japanese plans [Member] | Government bonds [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 391,927 239,849
Japanese plans [Member] | Bonds (other) [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 76,705 79,944
Japanese plans [Member] | Quoted prices in active markets available [Member]    
Disclosure of fair value of plan assets [line items]    
Stocks 357,318 375,443
Other 219,996 400,852
Total 969,555 1,018,321
Japanese plans [Member] | Quoted prices in active markets available [Member] | Government bonds [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 391,927 239,849
Japanese plans [Member] | Quoted prices in active markets available [Member] | Bonds (other) [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 314 2,177
Japanese plans [Member] | Quoted prices in active markets not available [Member]    
Disclosure of fair value of plan assets [line items]    
Commingled funds 522,785 500,917
Insurance contracts 154,224 224,694
Other 229,623 259,310
Total 983,023 1,062,688
Japanese plans [Member] | Quoted prices in active markets not available [Member] | Government bonds [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets   0
Japanese plans [Member] | Quoted prices in active markets not available [Member] | Bonds (other) [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 76,390 77,768
Foreign plans [Member]    
Disclosure of fair value of plan assets [line items]    
Stocks 161,268 128,908
Commingled funds 470,609 398,380
Other 179,179 195,142
Total 1,410,042 1,271,236
Foreign plans [Member] | Government bonds [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 337,120 301,955
Foreign plans [Member] | Bonds (other) [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 261,867 246,851
Foreign plans [Member] | Quoted prices in active markets available [Member]    
Disclosure of fair value of plan assets [line items]    
Stocks 161,268 128,908
Other 36,022 44,066
Total 505,029 474,929
Foreign plans [Member] | Quoted prices in active markets available [Member] | Government bonds [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 307,740 301,955
Foreign plans [Member] | Quoted prices in active markets not available [Member]    
Disclosure of fair value of plan assets [line items]    
Commingled funds 470,609 398,380
Other 143,157 151,076
Total 905,013 796,306
Foreign plans [Member] | Quoted prices in active markets not available [Member] | Government bonds [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets 29,380  
Foreign plans [Member] | Quoted prices in active markets not available [Member] | Bonds (other) [Member]    
Disclosure of fair value of plan assets [line items]    
Fair value of plan assets ¥ 261,867 ¥ 246,851