Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity Market Based Restricted Stock (Details)

v2.4.1.9
Shareholders' Equity Market Based Restricted Stock (Details) (USD $)
3 Months Ended 12 Months Ended 0 Months Ended
Feb. 01, 2014
Jan. 31, 2015
Feb. 01, 2014
Feb. 02, 2013
Nov. 18, 2014
Oct. 03, 2012
tranche
Jun. 18, 2014
tranche
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Risk Free Interest Rate   1.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate          
Granted, weighted average grant date fair value $ 3.96us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue $ 3.92us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue   $ 1.03us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue      
Expected Term   6 years 6 years 6 years      
Restricted Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Non-vested shares outstandings 641,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
704,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
641,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
       
Number of tranches           3evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfTranches
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
7evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfTranches
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
Number of consecutive trading days           20 days  
Risk Free Interest Rate         1.03%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
0.32%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
 
Implied volatility rate         60.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
78.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
 
Granted, weighted average grant date fair value         $ 4.91us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
   
Expected Term           2 years 9 months 18 days  
Market Based Stock Restricted Stock Awards [Member] | Restricted Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Non-vested shares outstandings   133,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_MarketBasedStockRestrictedStockAwardsMember
         
Required holding period           1 year  
Tranche 1 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Granted, weighted average grant date fair value           0.93us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= evlv_Tranche1Member
 
Expected Term           15 months  
Tranche 1 [Member] | Restricted Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Exercise price range, minimum           6.00evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisePriceRangeLowerRangeLimit
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche1Member
 
Award vesting percentage           50.00%evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardVestingPercentage
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche1Member
 
Granted, weighted average grant date fair value           1.48us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche1Member
 
Expected Term           15 months  
Tranche 2 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Granted, weighted average grant date fair value           0.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= evlv_Tranche2Member
 
Expected Term           20 months  
Tranche 2 [Member] | Restricted Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Exercise price range, minimum           8.00evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisePriceRangeLowerRangeLimit
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche2Member
 
Award vesting percentage           25.00%evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardVestingPercentage
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche2Member
 
Granted, weighted average grant date fair value           1.39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche2Member
 
Expected Term           20 months  
Tranche 3 [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Granted, weighted average grant date fair value           0.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= evlv_Tranche3Member
 
Expected Term           24 months  
Tranche 3 [Member] | Restricted Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Exercise price range, minimum           10.00evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisePriceRangeLowerRangeLimit
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche3Member
 
Award vesting percentage           25.00%evlv_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardVestingPercentage
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche3Member
 
Granted, weighted average grant date fair value           1.31us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= evlv_Tranche3Member
 
Expected Term           24 months