v2.4.1.9
Employee Stock and Benefit Plans (Plan Information) (Details)
0 Months Ended 12 Months Ended
Sep. 26, 2012
Dec. 31, 2014
Sep. 30, 2014
2012 Equity Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares authorized     4,668,764us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= qlys_A2012EquityIncentivePlanMember
Number of shares available for grant   803,630us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= qlys_A2012EquityIncentivePlanMember
 
2012 Equity Incentive Plan | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expiration period 10 years    
2012 Equity Incentive Plan | Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 4 years    
Term of award 10 years    
2000 Equity Incentive Plan | Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period   4 years  
Term of award   10 years  
Number of shares available for issuance   0qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForIssuance
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= qlys_A2000EquityIncentivePlanMember
 
2000 Equity Incentive Plan | Stock Options | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award strike price as a percentage of market value   85.00%qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardStrikePriceAsPercentageOfMarketValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= qlys_A2000EquityIncentivePlanMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
 
Increase of Number of Shares Option | 2012 Equity Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Equity incentive plan annual increase (in shares) 3,050,000qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseShares
/ qlys_EquityIncentivePlanAnnualIncreaseFeatureAxis
= qlys_IncreaseOfNumberOfSharesOptionMember
/ us-gaap_PlanNameAxis
= qlys_A2012EquityIncentivePlanMember
   
Increase of Percentage of Shares Outstanding Option | 2012 Equity Incentive Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Equity incentive plan, annual increase, percent of shares outstanding 5.00%qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreasePercentOfSharesOutstanding
/ qlys_EquityIncentivePlanAnnualIncreaseFeatureAxis
= qlys_IncreaseOfPercentageOfSharesOutstandingOptionMember
/ us-gaap_PlanNameAxis
= qlys_A2012EquityIncentivePlanMember