Name:	nmr_ScheduleOfShareBasedCompensationEquityLinkedAwardPlansActivityTableTextBlock
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Tabular disclosure of the number of shares for stock unit plans that were outstanding, weighted-average grant date fair value per share and weighted-average remaining life at the beginning and end of the year, exercisable at the end of the year, granted, exercised, repurchased, forfeited, and expired during the year.

No definition available.

Name:	nmr_ScheduleOfShareBasedCompensationStockUnitPlansActivityTableTextBlock
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Tabular disclosure of the number of units and index price for world stock index linked award plans that were outstanding at the beginning and end of the year, granted, vested, and forfeited during the year.

No definition available.

Name:	nmr_ScheduleOfStockBasedCompensationWorldStockIndexLinkedAwardPlansActivityTableTextBlock
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- References

No definition available.

Name:	us-gaap_DeferredCompensationArrangementsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Name:	us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
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Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.

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Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year.

No definition available.