v2.4.1.9

Business Combination (Details) (Nemean Networks, LLC, USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended
	Aug. 31, 2010	Sep. 30, 2012
Nemean Networks, LLC
Business Acquisition [Line Items]
Consideration for acquisition	$ 3.7us-gaap_BusinessCombinationConsiderationTransferred1 / us-gaap_BusinessAcquisitionAxis = qlys_NemeanNetworksLlcMember
Non-contingent payment		$ 1.0us-gaap_PaymentsToAcquireBusinessesGross / us-gaap_BusinessAcquisitionAxis = qlys_NemeanNetworksLlcMember
Non-contingent payment, number of shares		6,250us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued / us-gaap_BusinessAcquisitionAxis = qlys_NemeanNetworksLlcMember

X

- Definition

Number of shares of equity interests issued or issuable to acquire entity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)(4)

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X

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

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

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-Name Accounting Standards Codification

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

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-Section 50

-Paragraph 1

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-URI http://asc.fasb.org/extlink&oid=7488404&loc=d3e6927-128479

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X

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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