v3.26.1
Fair value measurements - Information on investments where net asset value per share is calculated or disclosed (Detail) - JPY (¥)
¥ in Billions
12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Fair value ¥ 119 ¥ 77
Unfunded commitments [1] 13 17
Hedge funds [Member]    
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Fair value 33 11
Unfunded commitments [1] ¥ 2 ¥ 4
Redemption frequency (if currently eligible) [2] Daily-Monthly Daily-Monthly
Hedge funds [Member] | Minimum [Member]    
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Redemption notice [3] 1 day 1 day
Hedge funds [Member] | Maximum [Member]    
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Redemption notice [3] 30 days 30 days
Venture capital funds [Member]    
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Fair value ¥ 20 ¥ 19
Unfunded commitments [1] ¥ 3 ¥ 3
Redemption frequency (if currently eligible) [2]
Redemption notice [3]
Private equity funds and private credit funds [Member]    
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Fair value ¥ 63 ¥ 43
Unfunded commitments [1] ¥ 8 ¥ 10
Redemption frequency (if currently eligible) [2]
Redemption notice [3]
Real estate funds [Member]    
Fair value, balance sheet grouping, financial statement captions [Line Items]    
Fair value ¥ 3 ¥ 4
Unfunded commitments [1] ¥ 0 ¥ 0
Redemption frequency (if currently eligible) [2]
Redemption notice [3]
[1] The contractual amount of any unfunded commitments Nomura is required to make to the entities in which the investment is held.
[2] The frequency with which Nomura is permitted to redeem investments.
[3] The range in prior notice period for redemption.