v3.26.1
Employee Benefits - Summary of Changes in Present Value of the Defined Benefit Obligations (Details) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Defined Benefit Plan, Change in Benefit Liability [Roll Forward]    
At beginning of the year ¥ 384,488  
Remeasurement of defined benefit pension plans    
At end of the year 420,153 ¥ 384,488
Japan    
Defined Benefit Plan, Change in Benefit Liability [Roll Forward]    
At beginning of the year 130,864  
Remeasurement of defined benefit pension plans    
At end of the year 116,648 130,864
Foreign    
Defined Benefit Plan, Change in Benefit Liability [Roll Forward]    
At beginning of the year 253,624  
Remeasurement of defined benefit pension plans    
At end of the year 303,505 253,624
Present value of defined benefit obligation    
Defined Benefit Plan, Change in Benefit Liability [Roll Forward]    
At beginning of the year 384,488 444,790
Current service cost 15,486 15,199
Interest cost 10,187 11,618
Remeasurement of defined benefit pension plans    
From changes in demographic assumptions (3,971) 77
From changes in financial assumptions (13,655) (11,574)
Experience adjustments 5,588 7,701
Past service cost   (1,196)
Settlement   (57,537)
Benefits paid (23,807) (29,754)
Contributions by the employees 5,978 5,053
Effect of business combinations and disposals   (256)
Foreign currency translation differences 39,859 366
At end of the year 420,153 384,488
Present value of defined benefit obligation | Japan    
Defined Benefit Plan, Change in Benefit Liability [Roll Forward]    
At beginning of the year 130,864 143,712
Current service cost 2,370 2,918
Interest cost 3,209 2,448
Remeasurement of defined benefit pension plans    
From changes in demographic assumptions 7 40
From changes in financial assumptions (9,507) (7,622)
Experience adjustments (900) 696
Past service cost   1,535
Settlement   0
Benefits paid (9,394) (12,701)
Contributions by the employees 0 0
Effect of business combinations and disposals   (161)
Foreign currency translation differences 0 0
At end of the year 116,648 130,864
Present value of defined benefit obligation | Foreign    
Defined Benefit Plan, Change in Benefit Liability [Roll Forward]    
At beginning of the year 253,624 301,078
Current service cost 13,117 12,281
Interest cost 6,978 9,170
Remeasurement of defined benefit pension plans    
From changes in demographic assumptions (3,977) 37
From changes in financial assumptions (4,149) (3,952)
Experience adjustments 6,488 7,006
Past service cost   (2,731)
Settlement   (57,537)
Benefits paid (14,412) (17,053)
Contributions by the employees 5,978 5,053
Effect of business combinations and disposals   (95)
Foreign currency translation differences 39,859 366
At end of the year ¥ 303,505 ¥ 253,624