Property, Plant and Equipment - Summary of Vehicles and Equipment on Operating Leases (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	¥ 17,067,365	¥ 15,333,693
Gross carrying amount [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	36,571,364	33,867,518	¥ 32,359,692
Vehicles and equipment on operating leases, net [Member] \| Gross carrying amount [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	9,705,647	8,051,945	¥ 7,523,911
Property, plant and equipment subject to operating leases [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	9,705,647	8,051,945
Property, plant and equipment subject to operating leases [Member] \| Vehicles [Member] \| Gross carrying amount [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	9,644,572	7,996,894
Property, plant and equipment subject to operating leases [Member] \| Equipment [Member] \| Gross carrying amount [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	61,076	55,051
Property, plant and equipment subject to operating leases [Member] \| Vehicles and equipment on operating leases, net [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	7,855,554	6,553,359
Property, plant and equipment subject to operating leases [Member] \| Vehicles and equipment on operating leases, net [Member] \| Less – Accumulated depreciation [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	¥ (1,850,094)	¥ (1,498,586)