Segments and Geographic Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Internet services	$ 1,370,695qihu_InternetServicesRevenue	$ 671,088qihu_InternetServicesRevenue	$ 328,882qihu_InternetServicesRevenue
Others	19,965us-gaap_OtherSalesRevenueNet	0us-gaap_OtherSalesRevenueNet	150us-gaap_OtherSalesRevenueNet
Total revenues	1,390,660us-gaap_Revenues	671,088us-gaap_Revenues	329,032us-gaap_Revenues
Cost of revenues:
Internet services	(297,645)qihu_InternetServicesCost	(87,838)qihu_InternetServicesCost	(32,762)qihu_InternetServicesCost
Others	(7,817)us-gaap_OtherCostOfOperatingRevenue	0us-gaap_OtherCostOfOperatingRevenue	(40)us-gaap_OtherCostOfOperatingRevenue
Total cost of revenues	(305,462)us-gaap_CostOfRevenue	(87,838)us-gaap_CostOfRevenue	(32,802)us-gaap_CostOfRevenue
Gross profit:
Internet services	1,073,050qihu_GrossProfitFromInternetServices	583,250qihu_GrossProfitFromInternetServices	296,120qihu_GrossProfitFromInternetServices
Others	12,148	0	110
Total gross profit	1,085,198us-gaap_GrossProfit	583,250us-gaap_GrossProfit	296,230us-gaap_GrossProfit
Operating expenses:
Product development	(406,250)qihu_ProductDevelopmentExpense	(255,248)qihu_ProductDevelopmentExpense	(156,269)qihu_ProductDevelopmentExpense
Selling and marketing	(333,701)us-gaap_SellingAndMarketingExpense	(110,104)us-gaap_SellingAndMarketingExpense	(58,178)us-gaap_SellingAndMarketingExpense
General and administrative	(94,260)us-gaap_GeneralAndAdministrativeExpense	(117,148)us-gaap_GeneralAndAdministrativeExpense	(35,643)us-gaap_GeneralAndAdministrativeExpense
Total operating expenses	(834,211)us-gaap_OperatingExpenses	(482,500)us-gaap_OperatingExpenses	(250,090)us-gaap_OperatingExpenses
Subsidy income	8,506qihu_SubsidyIncome	2,349qihu_SubsidyIncome	2,570qihu_SubsidyIncome
Income from operations	$ 259,493us-gaap_OperatingIncomeLoss	$ 103,099us-gaap_OperatingIncomeLoss	$ 48,710us-gaap_OperatingIncomeLoss

Gross profit from internet services.

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Gross profit from other operating segments.

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No definition available.

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- Definition

Internet Services Cost

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No definition available.

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- Definition

Internet Services Revenue

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No definition available.

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- Definition

The aggregate total of expenses relate to the research, development and strengthening of existing products which are security products, cloud-based services, search engine related products, mobile Internet products and other Internet products and service.

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No definition available.

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- 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.

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No definition available.

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- Definition

The aggregate cost of goods produced and sold and services rendered during the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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No definition available.

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The net result for the period of deducting operating expenses from operating revenues.

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No definition available.

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Other costs incurred during the reporting period related to other revenue generating activities.

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- Definition

Revenues from the sale of other goods or rendering of other services, not elsewhere specified in the taxonomy; net of (reduced by) sales adjustments, returns, allowances, and discounts.

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

-Publisher FASB

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-Topic 225

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-Subparagraph (SX 210.5-03.1(a),(d))

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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).

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

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The aggregate total amount of expenses directly related to the marketing or selling of products or services.

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No definition available.

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