v3.26.1
Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified to Net Income from Accumulated Other Comprehensive Income (loss)) (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Life insurance costs ¥ (479,937) ¥ (384,753) ¥ (433,863)
Interest expense (193,889) (169,051) (188,328)
Income tax (expense) or benefit (233,103) (128,828) (131,388)
Net Income 458,328 351,635 338,587
Reclassification adjustment included in net income | Net unrealized gains (losses) on investment in securities      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Total before income tax 20,987 497 (2,089)
Income tax (expense) or benefit (6,072) 347 749
Net Income 14,915 844 (1,340)
Reclassification adjustment included in net income | Net unrealized gains (losses) on investment in securities | Sales of debt securities      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Gains on investment securities and dividend (3,943) 1,004 231
Life insurance premiums and related investment income 140 (9,010) (7,184)
Reclassification adjustment included in net income | Net unrealized gains (losses) on investment in securities | Amortization of debt securities      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Finance revenues 11,487 1,732 756
Life insurance premiums and related investment income 13,508 6,771 4,108
Reclassification adjustment included in net income | Net unrealized gains (losses) on investment in securities | Others      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Write-downs of securities and other (205)    
Reclassification adjustment included in net income | Debt valuation adjustments      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Life insurance costs 13 4 19
Total before income tax 13 4 19
Income tax (expense) or benefit (4) (1) (5)
Net Income 9 3 14
Reclassification adjustment included in net income | Defined benefit pension plans      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Amortization of prior service credit 335 394 438
Amortization of net actuarial loss 134 84 (70)
Amortization of transition obligation   (1) (1)
Settlements   148  
Total before income tax 469 625 367
Income tax (expense) or benefit (135) (181) (101)
Net Income 334 444 266
Reclassification adjustment included in net income | Foreign currency translation adjustments      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Gains on sales of subsidiaries and equity method investments and liquidation losses, net 7,376 903 109
Total before income tax 8,591 (25,689) (14,843)
Income tax (expense) or benefit (2,741) 7,963 4,601
Net Income 5,850 (17,726) (10,242)
Reclassification adjustment included in net income | Foreign currency translation adjustments | Foreign exchange contracts      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Gains on sales of subsidiaries and equity method investments and liquidation losses, net/Interest expense 1,215 (26,592) (14,952)
Reclassification adjustment included in net income | Net unrealized gains (losses) on derivative instruments      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Total before income tax 3,176 (11,501) 3,892
Income tax (expense) or benefit (1,114) 2,635 (945)
Net Income 2,062 (8,866) 2,947
Reclassification adjustment included in net income | Net unrealized gains (losses) on derivative instruments | Interest rate swap agreements      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Interest expense 1,186 446 114
Reclassification adjustment included in net income | Net unrealized gains (losses) on derivative instruments | Foreign exchange contracts      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Interest expense   (694)  
Interest expense /Other (income) and expense 3,071    
Reclassification adjustment included in net income | Net unrealized gains (losses) on derivative instruments | Foreign currency swap agreements      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Interest expense /Other (income) and expense (956) (11,239) ¥ 3,778
Reclassification adjustment included in net income | Net unrealized gains (losses) on derivative instruments | Options held/written and other      
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]      
Life insurance premiums and related investment income ¥ (125) ¥ (14)