Goodwill - Schedule of Goodwill Activity (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Beginning balance	$ 23,532vdsi_GoodwillNet	$ 13,176vdsi_GoodwillNet
Additions	919us-gaap_GoodwillAcquiredDuringPeriod
Net foreign currency translation	(2,243)us-gaap_GoodwillTranslationAdjustments	1,133us-gaap_GoodwillTranslationAdjustments
Ending balance	22,208vdsi_GoodwillNet	23,532vdsi_GoodwillNet
December 31, 2014 balance at cost	23,130vdsi_GoodwillGross1
Accumulated amortization	(922)vdsi_AccumulatedAmortizationGoodwill
Ending balance	22,208vdsi_GoodwillNet	23,532vdsi_GoodwillNet
Cronto [Member]
Goodwill [Line Items]
Additions		$ 9,223

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Definition

Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillTranslationAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Accumulated amortization goodwill.

+ References

No definition available.

+ Details

Name:	vdsi_AccumulatedAmortizationGoodwill
Namespace Prefix:	vdsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Gross amount of goodwill, as of balance sheet date, before amortization.

+ References

No definition available.

+ Details

Name:	vdsi_GoodwillGross1
Namespace Prefix:	vdsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after accumulated amortization of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

No definition available.

+ Details

Name:	vdsi_GoodwillNet
Namespace Prefix:	vdsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionAxis=vdsi_CrontoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: