v2.4.1.9

Segment Information and Information about Geographic Area (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 segment	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of operating segments									1us-gaap_NumberOfOperatingSegments
Revenues	$ 36,573us-gaap_Revenues	$ 34,348us-gaap_Revenues	$ 32,302us-gaap_Revenues	$ 30,356us-gaap_Revenues	$ 29,039us-gaap_Revenues	$ 27,749us-gaap_Revenues	$ 26,291us-gaap_Revenues	$ 24,883us-gaap_Revenues	$ 133,579us-gaap_Revenues	$ 107,962us-gaap_Revenues	$ 91,420us-gaap_Revenues
Property and equipment, net	26,618us-gaap_PropertyPlantAndEquipmentNet				23,075us-gaap_PropertyPlantAndEquipmentNet				26,618us-gaap_PropertyPlantAndEquipmentNet	23,075us-gaap_PropertyPlantAndEquipmentNet
United States
Segment Reporting Information [Line Items]
Revenues									93,425us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_US	75,485us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_US	62,616us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_US
Property and equipment, net	23,650us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US				19,909us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US				23,650us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US	19,909us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = country_US
Other
Segment Reporting Information [Line Items]
Revenues									40,154us-gaap_Revenues / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember	32,477us-gaap_Revenues / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember	28,804us-gaap_Revenues / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember
Property and equipment, net	$ 2,968us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember				$ 3,166us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember				$ 2,968us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember	$ 3,166us-gaap_PropertyPlantAndEquipmentNet / us-gaap_StatementGeographicalAxis = qlys_OtherGeographicAreasMember

X

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

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X

- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



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