Income Taxes - Summarizes major tax jurisdictions subject to examination (Detail)

12 Months Ended

Mar. 31, 2026

Income Tax Contingency [Line Items]

Income tax examination, year(s) under examination

2021

^[1]

United Kingdom [Member]

Income Tax Contingency [Line Items]

Income tax examination, year(s) under examination

2016

^[2]

United States [Member]

Income Tax Contingency [Line Items]

Income tax examination, year(s) under examination

2023

Income Tax Contingency [Line Items]

Income tax examination, year(s) under examination

2020

^[3]

Income Tax Contingency [Line Items]

Income tax examination, year(s) under examination

2021

[1]	The earliest year in which Nomura remains subject to examination for transfer pricing issues is the year ended March 31, 2019.
[2]	The earliest year in which Nomura remains subject to examination for transfer pricing issues is the year ended March 31, 2016.
[3]	The earliest year in which Nomura remains subject to examination for transfer pricing issues is the year ended March 31, 2008.