v3.26.1
Equity and Other Equity Items - Disclosure of Other Components of Equity (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of detailed information about other components of equity [Line items]      
Beginning balance ¥ 36,878,913 ¥ 35,239,338 ¥ 29,264,213
Other comprehensive income, net of tax 1,529,944 (746,031) 2,117,103
Ending balance 41,020,068 36,878,913 35,239,338
Net changes in revaluation of financial assets measured at fair value through other comprehensive income [Member]      
Disclosure of detailed information about other components of equity [Line items]      
Beginning balance 1,109,439 1,300,855 933,702
Other comprehensive income, net of tax 334,394 44,731 716,048
Reclassification to retained earnings (180,113) (234,994) (341,709)
Other comprehensive income for the period attributable to non-controlling interests (6,178) (1,153) (7,186)
Transfer to other comprehensive income associated with assets held for sale (148,535)    
Ending balance 1,109,007 1,109,439 1,300,855
Remeasurements of defined benefit plans [Member]      
Disclosure of detailed information about other components of equity [Line items]      
Other comprehensive income, net of tax 91,099 (85,084) 56,434
Reclassification to retained earnings (79,403) 94,635 (45,625)
Other comprehensive income for the period attributable to non-controlling interests (11,696) (9,551) (10,809)
Exchange differences on translating foreign operations [Member]      
Disclosure of detailed information about other components of equity [Line items]      
Beginning balance 2,500,693 3,202,901 1,902,493
Other comprehensive income, net of tax 1,104,451 (705,678) 1,344,621
Other comprehensive income for the period attributable to non-controlling interests (52,073) 3,470 (44,213)
Transfer to other comprehensive income associated with assets held for sale (118,061)    
Ending balance 3,435,012 2,500,693 3,202,901
Total other components of equity [Member]      
Disclosure of detailed information about other components of equity [Line items]      
Beginning balance 3,610,133 4,503,756 2,836,195
Other comprehensive income, net of tax 1,529,944 (746,031) 2,117,103
Reclassification to retained earnings (259,516) (140,359) (387,334)
Other comprehensive income for the period attributable to non-controlling interests (69,946) (7,233) (62,208)
Transfer to other comprehensive income associated with assets held for sale (266,596)    
Ending balance ¥ 4,544,019 ¥ 3,610,133 ¥ 4,503,756