v3.26.1
Accumulated Other Comprehensive Income (Loss) (Changes in Components of Accumulated Other Comprehensive Income (Loss)) (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Beginning Balance ¥ 4,171,783 ¥ 4,021,965 ¥ 3,614,322
Total other comprehensive income (loss) 271,265 (16,139) 206,038
Ending Balance 4,573,068 4,171,783 4,021,965
Net unrealized gains (losses) on investment in securities      
Beginning Balance (403,914) [1] (250,806) (183,034)
Net unrealized gains (losses) (199,534) (152,264) (69,102)
Reclassification adjustment included in net income, net of tax (14,915) (844) 1,340
Total other comprehensive income (loss) (214,449) (153,108) (67,762)
Transaction with noncontrolling interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests (12) 0 10
Ending Balance (618,351) [2] (403,914) [1] (250,806)
Impact of changes in policy liability discount rate      
Beginning Balance 416,124 [1] 257,785 164,516
Net unrealized gains (losses) 299,258 158,339 93,269
Total other comprehensive income (loss) 299,258 158,339 93,269
Transaction with noncontrolling interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests 0 0 0
Ending Balance 715,382 [2] 416,124 [1] 257,785
Debt Valuation Adjustments      
Beginning Balance 49 [1] 84 275
Net unrealized gains (losses) 202 (32) (177)
Reclassification adjustment included in net income, net of tax (9) (3) (14)
Total other comprehensive income (loss) 193 (35) (191)
Transaction with noncontrolling interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests 0 0 0
Ending Balance 242 [2] 49 [1] 84
Defined benefit pension plans      
Beginning Balance 14,791 [1] 9,670 (3,617)
Net unrealized gains (losses) 17,501 5,572 13,559
Reclassification adjustment included in net income, net of tax (334) (444) (266)
Total other comprehensive income (loss) 17,167 5,128 13,293
Transaction with noncontrolling interests 0 0 0
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 5 7 6
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests 0 0 0
Ending Balance 31,953 [2] 14,791 [1] 9,670
Foreign currency translation adjustments      
Beginning Balance 304,657 [1] 324,208 155,912
Net unrealized gains (losses) 177,786 (37,786) 163,062
Reclassification adjustment included in net income, net of tax (5,850) 17,726 10,242
Total other comprehensive income (loss) 171,936 (20,060) 173,304
Transaction with noncontrolling interests 28 136 11
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 3,816 (323) 4,816
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests 3,543 (50) 203
Ending Balance 469,262 [2] 304,657 [1] 324,208
Net unrealized gains (losses) on derivative instruments      
Beginning Balance 9,591 [1] 16,207 22,083
Net unrealized gains (losses) (778) (15,269) (2,928)
Reclassification adjustment included in net income, net of tax (2,062) 8,866 (2,947)
Total other comprehensive income (loss) (2,840) (6,403) (5,875)
Transaction with noncontrolling interests 0 0 (176)
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 129 213 (175)
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests 0 0 0
Ending Balance 6,622 [2] 9,591 [1] 16,207
AOCI Attributable to Parent      
Beginning Balance 341,298 [1] 357,148 156,135
Total other comprehensive income (loss) 271,265 (16,139) 206,038
Transaction with noncontrolling interests 28 136 (165)
Less: Other Comprehensive Income (Loss) Attributable to the Noncontrolling Interests 3,950 (103) 4,647
Less: Other Comprehensive Income (Loss) Attributable to the Redeemable Noncontrolling Interests 3,531 (50) 213
Ending Balance ¥ 605,110 [2] ¥ 341,298 [1] ¥ 357,148
[1] As of March 31, 2025, net unrealized gains (losses) on investment in securities contained ¥(61) million (net of tax of ¥16 million) of net unrealized gains (losses) in investment in securities related to available-for-sale debt securities with allowance for credit losses.
[2] As of March 31, 2026, net unrealized gains (losses) on investment in securities contained ¥(171) million (net of tax of ¥53 million) of net unrealized gains (losses) in investment in securities related to available-for-sale debt securities with allowance for credit losses.