v2.4.1.9

Commitments and Contingencies (Leases) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Leased Assets [Line Items]
Rent expense	$ 6,200,000us-gaap_LeaseAndRentalExpense	$ 5,400,000us-gaap_LeaseAndRentalExpense	$ 4,300,000us-gaap_LeaseAndRentalExpense
Deferred rent credit, noncurrent	500,000us-gaap_DeferredRentCreditNoncurrent	600,000us-gaap_DeferredRentCreditNoncurrent
Capital Lease Obligations | Minimum
Leased Assets [Line Items]
Debt interest rate		1.80%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_LongtermDebtTypeAxis = us-gaap_CapitalLeaseObligationsMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Capital Addition Purchase Commitments | Capital Lease Obligations
Leased Assets [Line Items]
Debt face amount				3,100,000us-gaap_DebtInstrumentFaceAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_CapitalLeaseObligationsMember / us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Maintenance and Support
Leased Assets [Line Items]
Recorded unconditional purchase obligation	$ 0us-gaap_RecordedUnconditionalPurchaseObligation / us-gaap_RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = qlys_MaintenanceAndSupportMember	$ 300,000us-gaap_RecordedUnconditionalPurchaseObligation / us-gaap_RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = qlys_MaintenanceAndSupportMember

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- Details

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Namespace Prefix:	qlys_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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Balance Type:	credit
Period Type:	instant

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



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 210.5-02.22(a)(1))

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

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- Definition

For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7501430&loc=d3e39927-112707



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 210.5-02.26(c))

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

+ Details

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- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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- Definition

Amount of the recorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25383-109308

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