Note 2 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Total financial assets (liabilities)		$ 86,738
Foreign Exchange Forward [Member]
Derivative assets
Derivative liabilities
Money Market Funds [Member]
Cash equivalents		6,870
US Treasury Securities Included in Cash and Cash Equivalents [Member]
Cash equivalents		39,731
Term Bank Deposits [Member]
Cash equivalents		40,137
Fair Value, Inputs, Level 1 [Member]
Total financial assets (liabilities)	$ 91,921	163
Fair Value, Inputs, Level 1 [Member] \| Foreign Exchange Forward [Member]
Derivative assets		163
Derivative liabilities
Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Cash equivalents	9,029
Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities Included in Cash and Cash Equivalents [Member]
Cash equivalents	37,717
Fair Value, Inputs, Level 1 [Member] \| Term Bank Deposits [Member]
Cash equivalents	45,175
Fair Value, Inputs, Level 2 [Member]
Total financial assets (liabilities)	(2,029)	86,901
Fair Value, Inputs, Level 2 [Member] \| Foreign Exchange Forward [Member]
Derivative assets		163
Derivative liabilities	(2,029)
Fair Value, Inputs, Level 2 [Member] \| Money Market Funds [Member]
Cash equivalents		6,870
Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities Included in Cash and Cash Equivalents [Member]
Cash equivalents		39,731
Fair Value, Inputs, Level 2 [Member] \| Term Bank Deposits [Member]
Cash equivalents		$ 40,137
Fair Value, Inputs, Level 3 [Member]
Total financial assets (liabilities)	89,892
Fair Value, Inputs, Level 3 [Member] \| Foreign Exchange Forward [Member]
Derivative assets
Derivative liabilities	(2,029)
Fair Value, Inputs, Level 3 [Member] \| Money Market Funds [Member]
Cash equivalents	9,029
Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities Included in Cash and Cash Equivalents [Member]
Cash equivalents	37,717
Fair Value, Inputs, Level 3 [Member] \| Term Bank Deposits [Member]
Cash equivalents	$ 45,175

Fair value, after the effects of master netting arrangements, of a financial asset or other 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 assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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 (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

Name:	us-gaap_DerivativeAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

+ Details

Name:	us-gaap_DerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the total fair value of financial assets (liabilities).

+ References

No definition available.

+ Details

Name:	vrns_FinancialAssetsLiabilitiesFairValueDisclosure
Namespace Prefix:	vrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeForwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=vrns_USTreasurySecuritiesIncludedInCashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=vrns_TermBankDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: