v3.26.1
Employee benefits - Summary of Changes in the Defined Benefit Obligations Present Value of Defined Benefit Obligations (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Japanese Defined Benefit Plans [Member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year ¥ 59,022  
Remeasurements:    
Ending balance of the fiscal year (31,021) ¥ 59,022
Japanese Defined Benefit Plans [Member] | Present value of defined benefit obligation [member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year 488,818 543,292
Current service cost 6,565 11,561
Interest cost 9,373 7,861
Remeasurements:    
Change in demographic assumptions 1,509 2,005
Change in financial assumptions (33,628) (32,255)
Other (294) 1,514
Benefits paid (32,318) (45,135)
Other 0 (25)
Impact from loss of control of the Financial Services business (52,593)  
Ending balance of the fiscal year 387,432 488,818
Foreign Defined Benefit Plan [Member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year 83,836  
Remeasurements:    
Ending balance of the fiscal year 61,826 83,836
Foreign Defined Benefit Plan [Member] | Present value of defined benefit obligation [member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year 130,259 126,987
Current service cost 1,995 2,049
Past service cost 980 216
Interest cost 5,477 5,155
Remeasurements:    
Change in demographic assumptions 489 14
Change in financial assumptions (5,272) (3,707)
Other 639 8,894
Translation adjustments 14,217 (1,382)
Plan participants' contributions 276 231
Benefits paid (8,741) (8,198)
Curtailments and settlements (551)  
Ending balance of the fiscal year ¥ 139,768 ¥ 130,259