v3.26.1
Parent Company Only Condensed Financial Information - Condensed Statements of Income (Detail) - JPY (¥)
¥ in Millions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Income Statement [Abstract]      
Net gain on trading ¥ 696,894 ¥ 580,099 ¥ 491,611
Gain on private equity and debt investments 12,604 7,634 11,877
Interest and dividends 2,669,640 2,927,861 2,620,856
Gain on investments in equity securities 13,066 444 9,612
Other 241,845 223,264 175,824
Total revenue 4,758,486 4,736,743 4,157,294
Interest expense 2,590,773 2,844,258 2,595,294
Net revenue [1] 2,167,713 1,892,485 1,562,000
Noninterest Expense [Abstract]      
Compensation and benefits 829,502 732,390 673,523
Commissions and floor brokerage 221,857 177,452 137,328
Information processing and communications 248,439 227,018 217,126
Occupancy and related depreciation 71,523 70,166 68,698
Business development expenses 33,679 27,055 24,236
Other 222,892 186,440 167,239
Total non-interest expenses [2] 1,627,892 1,420,521 1,288,150
Income before income taxes 539,821 471,964 273,850
Income tax expense 165,439 124,709 96,630
Net income before undistributed earnings of subsidiaries 374,382 347,255 177,220
Net Income (Loss) 362,129 340,736 165,863
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]      
Change in cumulative translation adjustments 149,812 (35,768) 204,507
Defined benefit pension plans (6,983) (12,407) (12,662)
Non-trading debt securities (2,215) (1,147)
Total Other comprehensive income (loss), net of tax 105,627 (13,419) 143,572
Comprehensive income attributable to NHI shareholders 462,542 328,560 307,393
Parent Company [Member]      
Income Statement [Abstract]      
Net gain on trading 8,532 13,202 977
Gain on private equity and debt investments 770 2,458 1,033
Dividends from subsidiaries and affiliates 264,304 215,342 156,742
Interest income from loans to subsidiaries and affiliates 270,803 274,818 239,682
Interest and dividends 18,435 20,427 20,368
Gain on investments in equity securities 13,066 444 9,335
Property and equipment fee revenue from subsidiaries 123,896 110,475 110,856
Rent revenue from subsidiaries 26,728 27,627 27,823
Royalty on trademark from subsidiaries 60,952 53,505 45,920
Other 8,346 7,876 8,474
Total revenue 795,832 726,174 621,210
Interest expense 305,121 306,232 267,724
Net revenue 490,711 419,942 353,486
Noninterest Expense [Abstract]      
Compensation and benefits 59,755 54,743 51,444
Commissions and floor brokerage 537 790 690
Information processing and communications 124,343 111,961 110,320
Occupancy and related depreciation 27,415 27,056 27,389
Business development expenses 3,470 2,566 1,735
Other 50,256 32,084 26,246
Total non-interest expenses 265,776 229,200 217,824
Income before income taxes 224,935 190,742 135,662
Income tax expense 9,931 6,133 5,965
Net income before undistributed earnings of subsidiaries 215,004 184,609 129,697
Undistributed earnings of subsidiaries 147,125 156,127 36,166
Net Income (Loss) 362,129 340,736 165,863
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]      
Change in cumulative translation adjustments 142,524 (36,094) 201,304
Defined benefit pension plans 6,983 12,407 12,662
Non-trading debt securities (2,215) (1,147)
Own credit adjustments (46,879) 12,658 (72,436)
Total Other comprehensive income (loss), net of tax 100,413 (12,176) 141,530
Comprehensive income attributable to NHI shareholders ¥ 462,542 ¥ 328,560 ¥ 307,393
[1] There is no revenue derived from transactions with a single major external customer.
[2] Includes primarily personnel expenses, occupancy, technology, and professional fees.