v3.26.1
Employee benefits - Summary of Changes in the Defined Benefit Obligations Impact of Minimum Funding Requirement and Asset Ceiling (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
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
Effect of asset ceiling [member] | Japanese Defined Benefit Plans [Member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year 10,147 9,837
Interest income 0 139
Remeasurements:    
Change in asset ceiling excluding interest income 0 171
Impact from loss of control of the Financial Services business (10,147)  
Ending balance of the fiscal year 0 10,147
Effect of asset ceiling [member] | Foreign Defined Benefit Plan [Member]    
Disclosure of net defined benefit liability (asset) [line items]    
Beginning balance of the fiscal year 3,225 3,457
Interest income 178 174
Remeasurements:    
Change in asset ceiling excluding interest income (387) (436)
Translation adjustments 303 30
Ending balance of the fiscal year ¥ 3,319 ¥ 3,225