v2.4.1.9
Property and Equipment, Net (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]      
Property and equipment $ 71,889,000us-gaap_PropertyPlantAndEquipmentGross $ 57,927,000us-gaap_PropertyPlantAndEquipmentGross  
Depreciation, Depletion And Amortization, Excluding Intangible Asset Amortization 11,500,000qlys_DepreciationDepletionAndAmortizationExcludingIntangibleAssetAmortization 9,200,000qlys_DepreciationDepletionAndAmortizationExcludingIntangibleAssetAmortization 6,900,000qlys_DepreciationDepletionAndAmortizationExcludingIntangibleAssetAmortization
Less: accumulated depreciation and amortization (45,271,000)us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment (34,852,000)us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment  
Property and equipment, net 26,618,000us-gaap_PropertyPlantAndEquipmentNet 23,075,000us-gaap_PropertyPlantAndEquipmentNet  
Capital lease   3,100,000us-gaap_CapitalLeasedAssetsGross  
Capital lease, accumulated depreciation   1,200,000us-gaap_CapitalLeasesLesseeBalanceSheetAssetsByMajorClassAccumulatedDeprecation  
Computer equipment      
Property, Plant and Equipment [Line Items]      
Property and equipment 35,576,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerEquipmentMember
27,464,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerEquipmentMember
 
Computer software      
Property, Plant and Equipment [Line Items]      
Property and equipment 10,899,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerSoftwareIntangibleAssetMember
9,277,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_ComputerSoftwareIntangibleAssetMember
 
Furniture, fixtures and equipment      
Property, Plant and Equipment [Line Items]      
Property and equipment 2,931,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_FurnitureAndFixturesMember
2,031,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_FurnitureAndFixturesMember
 
Scanner appliances      
Property, Plant and Equipment [Line Items]      
Property and equipment 19,861,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_ScannerAppliancesMember
17,055,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_ScannerAppliancesMember
 
Scanner appliances and other computer equipment subject to subscription      
Property, Plant and Equipment [Line Items]      
Property and equipment, net 6,000,000us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_ScannerAppliancesAndOtherComputerEquipmentSubjectToSubscriptionMember
4,700,000us-gaap_PropertyPlantAndEquipmentNet
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_ScannerAppliancesAndOtherComputerEquipmentSubjectToSubscriptionMember
 
Scanner appliances and other computer equipment not placed in service      
Property, Plant and Equipment [Line Items]      
Property and equipment 1,400,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_ScannerAppliancesAndOtherComputerEquipmentNotPlacedInServiceMember
600,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_ScannerAppliancesAndOtherComputerEquipmentNotPlacedInServiceMember
 
Leasehold improvements      
Property, Plant and Equipment [Line Items]      
Property and equipment 2,622,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LeaseholdImprovementsMember
2,100,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LeaseholdImprovementsMember
 
Other fixed assets not placed in service      
Property, Plant and Equipment [Line Items]      
Property and equipment $ 2,800,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_OtherFixedAssetsNotPlacedInServiceMember
$ 1,600,000us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= qlys_OtherFixedAssetsNotPlacedInServiceMember