Name:	nmr_AssetManagementFeesAndCustodyFee
Namespace Prefix:	nmr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Other revenue from contract with customer, excluding assessed tax

No definition available.

Name:	nmr_OtherRevenueFromContractWithCustomer
Namespace Prefix:	nmr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of commission revenue from buying and selling securities on behalf of customers.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
-Section 05
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=68070981&loc=d3e40544-110947

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(a),(b))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Name:	us-gaap_BrokerageCommissionsRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

Name:	us-gaap_DisaggregationOfRevenueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Includes (1) underwriting revenue (the spread between the resale price received and the cost of the securities and related expenses) generated through the purchasing, distributing and reselling of new issues of securities (alternatively, could be a secondary offering of a large block of previously issued securities); and (2) fees earned for mergers, acquisitions, divestitures, restructurings, and other types of financial advisory services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(b),(d))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Name:	us-gaap_InvestmentBankingRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045