v3.25.2
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, 2025
Mar. 31, 2024
Japanese Defined Benefit Plans [Member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year ¥ 88,753  
Remeasurements:    
Ending balance of the fiscal year 59,022 ¥ 88,753
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 543,292 573,143
Current service cost 11,561 12,078
Past service cost   11
Interest cost 7,861 6,534
Remeasurements:    
Change in demographic assumptions 2,005 4,399
Change in financial assumptions (32,255) (16,568)
Other 1,514 1,677
Benefits paid (45,135) (37,787)
Other (25) (195)
Ending balance of the fiscal year 488,818 543,292
Foreign Defined Benefit Plan [Member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year 82,551  
Remeasurements:    
Ending balance of the fiscal year 83,836 82,551
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 126,987 124,702
Current service cost 2,049 1,783
Past service cost 216 142
Interest cost 5,155 5,349
Remeasurements:    
Change in demographic assumptions 14 (385)
Change in financial assumptions (3,707) 1,170
Other 8,894 632
Translation adjustments (1,382) 16,068
Plan participants' contributions 231 565
Benefits paid (8,198) (11,198)
Curtailments and settlements 0 (11,841)
Ending balance of the fiscal year ¥ 130,259 ¥ 126,987