v3.26.1
Employee Benefits - Changes in Present Value of Defined Benefit Obligations and Fair Value of Plan Assets (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Remeasurements:    
Net defined benefit liabilities (assets) ¥ (187,988) ¥ (185,835)
Japanese plans [member]    
Remeasurements:    
Effects of asset ceiling 345,141 195,916
Net defined benefit liabilities (assets) (26,001) (23,099)
Foreign plans [member]    
Remeasurements:    
Effects of asset ceiling 70,054 37,807
Net defined benefit liabilities (assets) 109,918 86,075
Present value of defined benefit obligations [member] | Japanese plans [member]    
Disclosure of net defined benefit liability (asset) [line items]    
Balance at beginning of year 980,252 1,081,392
Current service cost 21,419 24,203
Interest cost 21,486 16,392
Plan participants' contributions
Remeasurements:    
Changes in demographic assumptions (3,235) 980
Changes in financial assumptions (79,242) (83,744)
Other (2,132) 3,325
Benefits paid (58,011) (62,296)
Exchange differences on translating foreign operations
Balance at end of year 880,537 980,252
Present value of defined benefit obligations [member] | Foreign plans [member]    
Disclosure of net defined benefit liability (asset) [line items]    
Balance at beginning of year 1,006,596 1,037,123
Current service cost 19,615 19,077
Interest cost 50,632 50,717
Plan participants' contributions 3,841 4,022
Remeasurements:    
Changes in demographic assumptions 3,344 1,982
Changes in financial assumptions (19,047) (28,838)
Other 14,447 8,516
Benefits paid (72,880) (63,038)
Exchange differences on translating foreign operations 79,598 (22,965)
Balance at end of year 1,086,146 1,006,596
Fair value of plan assets [member] | Japanese plans [member]    
Disclosure of net defined benefit liability (asset) [line items]    
Balance at beginning of year 1,199,267 1,247,059
Interest income 26,657 19,164
Actual return on plan assets, excluding interest income 63,950 (27,278)
Employer contributions 16,896 19,349
Plan participants' contributions
Remeasurements:    
Benefits paid (55,091) (59,027)
Exchange differences on translating foreign operations
Balance at end of year 1,251,679 1,199,267
Fair value of plan assets [member] | Foreign plans [member]    
Disclosure of net defined benefit liability (asset) [line items]    
Balance at beginning of year 958,328 993,401
Interest income 48,176 52,338
Actual return on plan assets, excluding interest income 7,757 (19,496)
Employer contributions 21,944 15,683
Plan participants' contributions 3,841 4,022
Remeasurements:    
Benefits paid (72,880) (63,038)
Exchange differences on translating foreign operations 79,116 (24,582)
Balance at end of year ¥ 1,046,282 ¥ 958,328