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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
 3 Months Ended
Mar. 31, 2015
Country
Mar. 31, 2014
Schedule Of Accounting Policies [Line Items]    
Number of Countries in which Entity Operates 14us-gaap_NumberOfCountriesInWhichEntityOperates  
Gain or loss from foreign currency transactions $ 617,000us-gaap_ForeignCurrencyTransactionGainLossBeforeTax $ 159,000us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Percent of renewals within median VSOE range 80.00%vdsi_PercentageOfRenewal  
Range within median renewal percentage rate 15.00%vdsi_MedianRenewalPercentageRate  
VSOE transaction agreement initial, Term years 2 years  
Cash equivalents maturity, Term Cash equivalents are high-quality short term money market instruments, with original maturities of three months or less.  
Software development costs were capitalized $ 0us-gaap_CapitalizedComputerSoftwareAdditions  
Patents [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated useful lives of assets 20 years  
Minimum [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated useful lives of assets 3 years  
Warranty for hardware purchase 1 year  
Extended product warranty period 1 year  
Minimum [Member] | Software Development Costs [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated economic life of product 2 years  
Minimum [Member] | Proprietary Technology [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated useful lives of assets 3 years  
Maximum [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated useful lives of assets 7 years  
Warranty for hardware purchase 2 years  
Extended product warranty period 4 years  
Maximum [Member] | Software Development Costs [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated economic life of product 5 years  
Maximum [Member] | Proprietary Technology [Member]    
Schedule Of Accounting Policies [Line Items]    
Estimated useful lives of assets 7 years