v3.26.1
Equity - Changes in Other Components of Equity (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of reserves within equity [line items]      
Beginning balance ¥ 12,627,822 ¥ 13,005,872 ¥ 11,502,291
Ending balance 12,148,072 12,627,822 13,005,872
Remeasurements of defined benefit plans [member]      
Disclosure of reserves within equity [line items]      
Beginning balance
Adjustment during the year (14,637) 26,874 (18,194)
Reclassification to retained earnings 14,637 (26,874) 18,194
Ending balance
Net changes in revaluation of financial assets measured at fair value through other comprehensive income [member]      
Disclosure of reserves within equity [line items]      
Beginning balance 125,516 108,537 126,940
Adjustment during the year 134,224 (19,953) (17,924)
Reclassification to retained earnings (22,225) 36,932 (479)
Ending balance 237,515 125,516 108,537
Exchange differences on translating foreign operations [member]      
Disclosure of reserves within equity [line items]      
Beginning balance 2,060,305 2,203,913 1,290,457
Adjustment during the year 738,648 (143,608) 913,456
Reclassification to retained earnings
Ending balance 2,798,953 2,060,305 2,203,913
Cash flow hedge [Member]      
Disclosure of reserves within equity [line items]      
Beginning balance
Adjustment during the year 11,021
Reclassification to retained earnings  
Ending balance 11,021
Other components of equity [member]      
Disclosure of reserves within equity [line items]      
Beginning balance 2,185,821 2,312,450 1,417,397
Adjustment during the year 869,256 (136,687) 877,338
Reclassification to retained earnings (7,588) 10,058 17,715
Ending balance ¥ 3,047,489 ¥ 2,185,821 ¥ 2,312,450