v3.26.1
Segment Information - Sales Revenue and Carrying Amounts of Non-current Assets Other Than Financial Instruments and Deferred Tax Assets Based on Location (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of geographical areas [line items]      
Sales revenue ¥ 21,796,610 ¥ 21,688,767 ¥ 20,428,802
Non-current assets other than financial instruments, deferred tax assets and net defined benefit assets 10,769,635 10,469,881 9,790,648
External customers [member]      
Disclosure of geographical areas [line items]      
Sales revenue 21,796,610 21,688,767 20,428,802
Japan [member]      
Disclosure of geographical areas [line items]      
Non-current assets other than financial instruments, deferred tax assets and net defined benefit assets 3,212,461 3,329,692 3,054,330
Japan [member] | External customers [member]      
Disclosure of geographical areas [line items]      
Sales revenue 2,882,484 2,845,609 2,634,505
United States [member]      
Disclosure of geographical areas [line items]      
Non-current assets other than financial instruments, deferred tax assets and net defined benefit assets 5,834,391 5,441,006 4,914,193
United States [member] | External customers [member]      
Disclosure of geographical areas [line items]      
Sales revenue 11,160,904 11,388,564 10,343,985
Other Countries [member]      
Disclosure of geographical areas [line items]      
Non-current assets other than financial instruments, deferred tax assets and net defined benefit assets 1,722,783 1,699,183 1,822,125
Other Countries [member] | External customers [member]      
Disclosure of geographical areas [line items]      
Sales revenue ¥ 7,753,222 ¥ 7,454,594 ¥ 7,450,312