v3.25.2
Income Taxes - Summary of Components of Deferred Tax Assets and Liabilities (Detail) - JPY (¥)
¥ in Millions
Mar. 31, 2025
Mar. 31, 2024
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets ¥ 517,869 ¥ 502,230
Deferred tax liabilities (1,659,433) (2,219,638)
Net deferred tax assets and liabilities (1,141,564) (1,717,408)
Deferred tax assets [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 2,129,712 1,983,775
Deferred tax assets [Member] | Defined Benefit Plan [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 156,650 100,770
Deferred tax assets [Member] | Accrued expenses and liabilities for quality assurance [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 821,680 724,325
Deferred tax assets [Member] | Other accrued employees' compensation [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 146,548 138,219
Deferred tax assets [Member] | Operating loss carryforwards for tax purposes [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 44,324 50,214
Deferred tax assets [Member] | Allowance for doubtful accounts and credit losses [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 115,209 103,860
Deferred tax assets [Member] | Property plant equipment and other assets [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 340,410 296,739
Deferred tax assets [Member] | Other [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 504,892 569,648
Deferred tax liabilities [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (3,271,276) (3,701,183)
Deferred tax liabilities [Member] | Changes in fair value of financial instruments measured in other comprehensive income [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (727,581) (1,015,448)
Deferred tax liabilities [Member] | Undistributed earnings of foreign subsidiaries [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (63,179) (42,365)
Deferred tax liabilities [Member] | Undistributed earnings of associates and joint ventures [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (1,223,489) (1,176,045)
Deferred tax liabilities [Member] | Basis difference of acquired assets [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (71,386) (82,852)
Deferred tax liabilities [Member] | Capitalised development costs [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (181,775) (189,496)
Deferred tax liabilities [Member] | Lease transactions [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities (860,487) (897,291)
Deferred tax liabilities [Member] | Other [Member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities ¥ (143,379) ¥ (297,686)