v3.26.3
Accumulated Other Comprehensive Income (Loss) (Amounts Reclassified to Net Income from Accumulated Other Comprehensive Income (loss)) (Detail) - JPY (¥)
¥ in Millions
 6 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]    
Life insurance costs ¥ (226,760) ¥ (220,628)
Interest expense 91,389 85,029
Income (Loss) from Discontinued Operations before Income Taxes 125,372 12,531
Income tax (expense) or benefit (345,649) (112,662)
Net Income 861,773 274,860
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 11,497 6,481
Income tax (expense) or benefit (3,290) (1,767)
Net Income 8,207 4,714
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 570 189
Life insurance premiums and related investment income 1,534 571
Income (Loss) from Discontinued Operations before Income Taxes   (4,068)
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 8,460 3,731
Life insurance premiums and related investment income 8,760 6,240
Income (Loss) from Discontinued Operations before Income Taxes (25) (65)
Reclassification adjustment included in net income | Net unrealized gains (losses) on investment in securities | Sales or liquidation    
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]    
Income (Loss) from Discontinued Operations before Income Taxes (7,802)  
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   (117)
Reclassification adjustment included in net income | Debt valuation adjustments    
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]    
Life insurance costs 6 5
Total before income tax 6 5
Income tax (expense) or benefit (2) (1)
Net Income 4 4
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 139 169
Amortization of net actuarial loss 187 71
Amortization of transition obligation   0
Settlements 48  
Gains on sales of subsidiaries and equity method investments and liquidation losses, net 181  
Total before income tax 555 240
Income tax (expense) or benefit (178) (69)
Net Income 377 171
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 (675) 7,042
Total before income tax (2,757) 9,823
Income tax (expense) or benefit 599 (3,134)
Net Income (2,158) 6,689
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/Other (income) and expense   2,781
Interest expense (2,082)  
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 (6,724) 4,925
Income tax (expense) or benefit 1,590 (1,417)
Net Income (5,134) 3,508
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 286 121
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 /Other (income) and expense   3,072
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 (6,858) 1,782
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 ¥ (152) ¥ (50)