Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of Significant Accounting Policies [Abstract]
Construction-in-progress	$ 0us-gaap_ConstructionInProgressGross
Impairment loss on goodwill	0	107,000	1,151,000
Maximum ownership percentage of limited partnerships accounted for using cost method	5.00%
Significant influence existence criteria, minimum ownership interest	20.00%
Significant influence existence criteria, maximum ownership interest	50.00%
VAT and related surcharges rate, minimum	3.21%qihu_VatAndRelatedSurchargesRateMinimum
VAT and related surcharges rate, maximum	19.04%qihu_VatAndRelatedSurchargesRateMaximum
Business tax and VAT included in revenues and cost of revenues	80,514,000us-gaap_ExciseAndSalesTaxes	39,909,000us-gaap_ExciseAndSalesTaxes	18,434,000us-gaap_ExciseAndSalesTaxes
Advertising costs	231,198,000us-gaap_AdvertisingExpense	62,301,000us-gaap_AdvertisingExpense	21,082,000us-gaap_AdvertisingExpense
Subsidy income	$ 8,506,000qihu_SubsidyIncome	$ 2,349,000qihu_SubsidyIncome	$ 2,570,000qihu_SubsidyIncome
Minimum likelihood of uncertain being sustained for uncertain income tax position being recognized	50.00%

This element represents maximum ownership percentage of limited partnerships accounted for using cost method.

No definition available.

Name:	qihu_MaximumOwnershipPercentageOfLimitedPartnershipsAccountedForUsingCostMethod
Namespace Prefix:	qihu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum likelihood of uncertain being sustained for uncertain income tax position being recognized.

+ References

No definition available.

+ Details

Name:	qihu_MinimumLikelihoodOfUncertainBeingSustainedForUncertainIncomeTaxPositionBeingRecognized
Namespace Prefix:	qihu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the upper ownership percentage of the voting stock of the investee's company, below which the entity use equity method to account for an investments.

+ References

No definition available.

+ Details

Name:	qihu_SignificantInfluenceExistenceCriteriaMaximumOwnershipInterest
Namespace Prefix:	qihu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the lower ownership percentage of the voting stock of the investee's company, equal to or more than which the entity use equity method to account for an investments.

+ References

No definition available.

+ Details

Name:	qihu_SignificantInfluenceExistenceCriteriaMinimumOwnershipInterest
Namespace Prefix:	qihu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Government subsidy is recorded as a liability in deferred revenue when received, and recognized as subsidy income when the project is inspected and confirmed by the government, or it is not subject to future return or reimbursement.

+ References

No definition available.

+ Details

Name:	qihu_SubsidyIncome
Namespace Prefix:	qihu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

VAT and Related Surcharges Rate, Maximum

+ References

No definition available.

+ Details

Name:	qihu_VatAndRelatedSurchargesRateMaximum
Namespace Prefix:	qihu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

VAT and Related Surcharges Rate, Minimum

+ References

No definition available.

+ Details

Name:	qihu_VatAndRelatedSurchargesRateMinimum
Namespace Prefix:	qihu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 720

-SubTopic 35

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

+ Details

Name:	us-gaap_AdvertisingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

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

+ Details

Name:	us-gaap_ConstructionInProgressGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of excise and sales taxes included in sales and revenues, which are then deducted as a cost of sales. Includes excise taxes, which are applied to specific types of transactions or items (such as gasoline or alcohol); and sales, use and value added taxes, which are applied to a broad class of revenue-producing transactions involving a wide range of goods and services.

+ 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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 45

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6408196&loc=d3e61097-111654

+ Details

Name:	us-gaap_ExciseAndSalesTaxes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16373-109275

+ Details

Name:	us-gaap_ImpairmentOfIntangibleAssetsFinitelived
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration