v2.4.1.9

Goodwill and Intangible Assets, Net (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Goodwill and Intangible Assets [Line Items]
Cost	$ 3,469,000us-gaap_FiniteLivedIntangibleAssetsGross
Accumulated Amortization	(1,763,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization	(1,370,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Net Book Value	1,706,000us-gaap_FiniteLivedIntangibleAssetsNet	2,099,000us-gaap_FiniteLivedIntangibleAssetsNet
Intangible assets not subject to amortization	295,000us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill	295,000us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Total intangible assets, net	2,001,000us-gaap_IntangibleAssetsNetExcludingGoodwill	2,394,000us-gaap_IntangibleAssetsNetExcludingGoodwill
Amortization of intangible assets	400,000us-gaap_AmortizationOfIntangibleAssets	400,000us-gaap_AmortizationOfIntangibleAssets	400,000us-gaap_AmortizationOfIntangibleAssets
Goodwill	317,000us-gaap_Goodwill	317,000us-gaap_Goodwill
Existing technology
Schedule of Goodwill and Intangible Assets [Line Items]
Estimated Lives	7 years
Cost	1,910,000us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_DevelopedTechnologyRightsMember
Accumulated Amortization	(1,183,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_DevelopedTechnologyRightsMember	(909,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_DevelopedTechnologyRightsMember
Net Book Value	727,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_DevelopedTechnologyRightsMember	1,001,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_DevelopedTechnologyRightsMember
Patent license
Schedule of Goodwill and Intangible Assets [Line Items]
Estimated Lives	14 years
Cost	1,388,000us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_PatentsMember
Accumulated Amortization	(422,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_PatentsMember	(323,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_PatentsMember
Net Book Value	966,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_PatentsMember	1,065,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_PatentsMember
Non-competition agreements and other
Schedule of Goodwill and Intangible Assets [Line Items]
Estimated Lives	3 years
Cost	171,000us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = qlys_NonCompetitionAgreementsAndOtherIntangibleAssetsMemberMember
Accumulated Amortization	(158,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = qlys_NonCompetitionAgreementsAndOtherIntangibleAssetsMemberMember	(138,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = qlys_NonCompetitionAgreementsAndOtherIntangibleAssetsMemberMember
Net Book Value	$ 13,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = qlys_NonCompetitionAgreementsAndOtherIntangibleAssetsMemberMember	$ 33,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = qlys_NonCompetitionAgreementsAndOtherIntangibleAssetsMemberMember

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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