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Employee Benefit Plan - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
United States [Member]
Schedule Of Pension And Other Postretirement Benefits Expected Benefit Payments [Line Items]
Contribution pension plan	$ 116	$ 111	$ 100
Belgium [Member]
Schedule Of Pension And Other Postretirement Benefits Expected Benefit Payments [Line Items]
Contribution pension plan	$ 655	$ 542	$ 515

X

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

+ Details

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

X

- Details

Name:	vdsi_ScheduleOfPensionAndOtherPostretirementBenefitsExpectedBenefitPaymentsLineItems
Namespace Prefix:	vdsi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration