v2.4.1.9
Employee Stock and Benefit Plans (Options Outstanding and Vested) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Number of shares, outstanding 7,605,407us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions    
Weighted average exercise price per share, outstanding (in dollar per share) $ 12.93us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1    
Weighted average remaining contractual life, outstanding 6 years 6 months    
Number of shares, vested 4,379,624qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions    
Weighted average exercise price per share, vested (in dollar per share) $ 5.58qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice    
Stock Options      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Weighted average grant date fair value (in dollars per share) $ 12.07us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 7.62us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 4.27us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Grant date fair value $ 33.1qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 15.2qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 6.3qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Intrinsic value of options exercised $ 25.7us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 11.1us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 4.0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$1.00 - $1.50      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 1.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeOneMember
   
Exercise price range, upper limit (in dollar per share) $ 1.50us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeOneMember
   
Number of shares, outstanding 238,559us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeOneMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 1.40us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeOneMember
   
Weighted average remaining contractual life, outstanding 1 year 6 months 7 days    
Number of shares, vested 238,559qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeOneMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 1.40qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeOneMember
   
$1.90 - $1.90      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 1.90us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTwoMember
   
Exercise price range, upper limit (in dollar per share) $ 1.90us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTwoMember
   
Number of shares, outstanding 941,482us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTwoMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 1.90us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTwoMember
   
Weighted average remaining contractual life, outstanding 2 years 1 month 7 days    
Number of shares, vested 941,482qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTwoMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 1.90qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTwoMember
   
$2.10 - $2.80      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 2.10us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeThreeMember
   
Exercise price range, upper limit (in dollar per share) $ 2.80us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeThreeMember
   
Number of shares, outstanding 461,758us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeThreeMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 2.62us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeThreeMember
   
Weighted average remaining contractual life, outstanding 3 years 10 months 7 days    
Number of shares, vested 461,758qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeThreeMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 2.62qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeThreeMember
   
$3.80 - $3.80      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 3.80us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFourMember
   
Exercise price range, upper limit (in dollar per share) $ 3.80us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFourMember
   
Number of shares, outstanding 1,148,568us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFourMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 3.80us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFourMember
   
Weighted average remaining contractual life, outstanding 4 years 9 months 7 days    
Number of shares, vested 1,126,625qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFourMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 3.80qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFourMember
   
$4.10 - $8.40      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 4.10us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFiveMember
   
Exercise price range, upper limit (in dollar per share) $ 8.40us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFiveMember
   
Number of shares, outstanding 924,121us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFiveMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 5.55us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFiveMember
   
Weighted average remaining contractual life, outstanding 6 years 0 months 7 days    
Number of shares, vested 826,292qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFiveMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 5.35qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeFiveMember
   
$8.90 - $12.68      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 8.90us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSixMember
   
Exercise price range, upper limit (in dollar per share) $ 12.68us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSixMember
   
Number of shares, outstanding 846,930us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSixMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 11.20us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSixMember
   
Weighted average remaining contractual life, outstanding 7 years 10 months 7 days    
Number of shares, vested 392,645qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSixMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 10.93qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSixMember
   
$13.50 - $20.80      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 13.50us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSevenMember
   
Exercise price range, upper limit (in dollar per share) $ 20.80us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSevenMember
   
Number of shares, outstanding 962,889us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSevenMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 18.50us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSevenMember
   
Weighted average remaining contractual life, outstanding 8 years 6 months 7 days    
Number of shares, vested 250,599qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSevenMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 17.03qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeSevenMember
   
$22.31 - $23.51      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 22.31us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeEightMember
   
Exercise price range, upper limit (in dollar per share) $ 23.51us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeEightMember
   
Number of shares, outstanding 383,050us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeEightMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 23.28us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeEightMember
   
Weighted average remaining contractual life, outstanding 9 years 7 months 7 days    
Number of shares, vested 45,009qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeEightMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 22.55qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeEightMember
   
$26.86 - $26.86      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 26.86us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeNineMember
   
Exercise price range, upper limit (in dollar per share) $ 26.86us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeNineMember
   
Number of shares, outstanding 701,350us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeNineMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 26.86us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeNineMember
   
Weighted average remaining contractual life, outstanding 9 years 0 months 7 days    
Number of shares, vested 29,728qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeNineMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 26.86qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeNineMember
   
$30.58 - $30.58      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Exercise price range, lower limit (in dollar per share) $ 30.58us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTenMember
   
Exercise price range, upper limit (in dollar per share) $ 30.58us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTenMember
   
Number of shares, outstanding 996,700us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTenMember
   
Weighted average exercise price per share, outstanding (in dollar per share) $ 30.58us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTenMember
   
Weighted average remaining contractual life, outstanding 9 years 4 months 7 days    
Number of shares, vested 66,927qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfVestedOptions
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTenMember
   
Weighted average exercise price per share, vested (in dollar per share) $ 30.58qlys_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeVestedOptionsWeightedAverageExercisePrice
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= qlys_ExercisePriceRangeTenMember