v3.26.1
Fair value measurements - Gains (losses) due to changes in fair value for financial instruments measured at fair value using fair value option (Detail) - JPY (¥)
¥ in Billions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Short-term borrowings [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[2] ¥ 83 ¥ 153 ¥ 13
Payables and deposits [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1] 38 6 8
Collateralized financing [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[3] (17) (23) (17)
Long-term borrowings [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[2],[4] 12 (48) (110)
Other liabilities [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[5] (11) (1) (1)
Total [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1] 105 87 (107)
Trading assets [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[6] 16 4 0
Private equity and debt investments [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[6] 1 2 2
Loans and receivables [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1] 52 45 54
Collateralized agreements [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[3] 12 20 6
Other assets [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1],[6],[7] 37 15 22
Total [Member]      
Fair Value, Option, Quantitative Disclosures [Line Items]      
Gains/(Losses) [1] ¥ 118 ¥ 86 ¥ 84
[1] Includes gains and losses reported primarily within Revenue – Net gain on trading and Revenue—Other in the consolidated statements of income.
[2] Includes structured notes and other financial liabilities.
[3] Includes reverse repurchase and repurchase agreements.
[4] Includes secured financing transactions arising from transfers of financial assets which did not meet the criteria for sales accounting.
[5] Includes unfunded written loan commitments.
[6] Includes equity investments that would have been accounted for under the equity method had Nomura not chosen to elect the FVO.
[7] Includes non-trading debt securities.