Name:	nmr_DerivativeLiabilityPositionWithRelatedCollateralPledged
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The aggregate fair value of all derivative instruments with credit-risk-related contingent features that are in a liability position.

No definition available.

Name:	nmr_FairValueOfDerivativeLiabilityCreditRiskRelatedToContingentFeatures
Namespace Prefix:	nmr_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Transfer of financial assets accounted for as sales amount recognized.

No definition available.

Name:	nmr_TransferOfFinancialAssetsAccountedForAsSalesAmountRecognized
Namespace Prefix:	nmr_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Transfer of financial assets accounted for as sales cash proceeds received for assets recognized amount.

No definition available.

Name:	nmr_TransferOfFinancialAssetsAccountedForAsSalesCashProceedsReceivedForAssetsRecognizedAmount
Namespace Prefix:	nmr_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624258-113959

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Fair value of derecognized financial assets from transactions which comprise an initial transfer and an agreement entered into in contemplation of the initial transfer resulting in retention of substantially all of the exposure to the economic return throughout the term of the transaction.