v2.4.1.9

FAIR VALUE MEASUREMENTS AND FINANCIAL INSTRUMENTS (Details 2)	12 Months Ended					12 Months Ended					12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 Twoo [Member] USD ($)	Dec. 31, 2014 Twoo [Member] EUR (€)	Dec. 31, 2014 Auction rate securities USD ($)	Dec. 31, 2013 Auction rate securities USD ($)	Dec. 31, 2014 Contingent Consideration Arrangement USD ($)	Dec. 31, 2013 Contingent Consideration Arrangement USD ($)	Dec. 31, 2014 Contingent Consideration Without Limit USD ($)	Dec. 31, 2014 Contingent Consideration Liability - Twoo
Changes in assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance at the beginning of the period, assets						$ 8,920,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember	$ 8,100,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember
Included in other comprehensive (loss) income, assets						(2,850,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember	820,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember
Settlements, assets							0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember
Balance at the end of the period, assets						6,070,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember	8,920,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember
Changes in liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3)
Balance at the beginning of the period, liabilities								(45,828,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember	(1,909,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Included in Earnings, liabilities								13,367,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember	(343,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Included in Other Comprehensive (Loss) Income, liabilities								3,025,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember	(2,445,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Fair Value Of Contingent Consideration At Date Of Acquisition	8,800,000iaci_FairValueOfContingentConsiderationAtDateOfAcquisition	41,400,000iaci_FairValueOfContingentConsiderationAtDateOfAcquisition						8,813,000iaci_FairValueOfContingentConsiderationAtDateOfAcquisition / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember	41,387,000iaci_FairValueOfContingentConsiderationAtDateOfAcquisition / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Settlements, liabilities								8,109,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember	256,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Balance at the end of the period, liabilities								(30,140,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember	(45,828,000)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Auction rate securities
Cost Basis	159,418,000us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis					10,000,000us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember	10,000,000us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember
Gross unrealized loss	1,387,000us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	4,784,000us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax				3,900,000us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember	1,100,000us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_AuctionRateSecuritiesMember
Contingent consideration arrangment
Number of contingent consideration arrangements related to business acquisitions	5iaci_NumberofContingentConsiderationArrangementsRelatedtoBusinessAcquisitions
Number of contingent consideration arrangements with payment limit	4iaci_NumberofContingentConsiderationArrangementswithPaymentLimit
Business Acquisition Contingent Consideration Maximum Amount At Balance Sheet Date								166,900,000iaci_BusinessAcquisitionContingentConsiderationMaximumAmountAtBalanceSheetDate / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Business Acquisition Contingent Consideration Fair Value at Balance Sheet Date With A Maximum Limit								29,500,000iaci_BusinessAcquisitionContingentConsiderationFairValueatBalanceSheetDateWithAMaximumLimit / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationArrangementMember
Fair value of one contingent consideration arrangements without a maximum limit										700,000iaci_BusinessAcquisitionContingentConsiderationFairvalueatBalanceSheetDateWithoutaLimit / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationWithoutLimitMember
Acquisition-related contingent consideration payments	8,109,000iaci_BusinessCombinationContingentConsiderationPaymentFinancing	256,000iaci_BusinessCombinationContingentConsiderationPaymentFinancing	10,781,000iaci_BusinessCombinationContingentConsiderationPaymentFinancing	7,400,000iaci_BusinessCombinationContingentConsiderationPaymentFinancing / us-gaap_BusinessAcquisitionAxis = iaci_TwooMember
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High				94,900,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh / us-gaap_BusinessAcquisitionAxis = iaci_TwooMember	77,900,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh / us-gaap_BusinessAcquisitionAxis = iaci_TwooMember
Fair Value, Discount Rate											15.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = iaci_ContingentConsiderationLiabilityTwooMember
Contingent Consideration, Current				10,700,000iaci_BusinessAcquisitionContingentConsiderationFairValueAtBalanceSheetDateCurrent / us-gaap_BusinessAcquisitionAxis = iaci_TwooMember
Contingent Consideration, Noncurrent				$ 19,600,000iaci_BusinessAcquisitionContingentConsiderationFairValueAtBalanceSheetNoncurrent / us-gaap_BusinessAcquisitionAxis = iaci_TwooMember

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Current portion of the fair value as of the Balance Sheet date of potential payments under the contingent consideration arrangement.

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Fair Value, as of the Balance Sheet date, of potential cash payments under the contingent consideration arrangement with a maximum amount limit.

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Fair value, as of the Balance Sheet date, of potential cash payments under the contingent consideration arrangement without a limit.

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Noncurrent portion of the fair value as of the Balance Sheet date of potential payments under the contingent consideration arrangement.

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Maximum amount of potential cash payments under the contingent consideration arrangement as of the Balance Sheet date.

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Business combination contingent consideration cash payment financing.

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Fair Value Of Contingent Consideration At Date Of Acquisition

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Number of Contingent Consideration Arrangements Related to Business Acquisitions

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Number of Contingent Consideration Arrangements with Payment Limit

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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