v2.4.1.9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Advertising Costs (excluding Amortization of Non-Cash Marketing) |  |  |
Advertising expense | $ 971,800,000 us-gaap_AdvertisingExpense | $ 824,100,000 us-gaap_AdvertisingExpense | $ 774,100,000 us-gaap_AdvertisingExpense
Capitalized access fees, estimated useful lives | 18 months |  |
Income Tax Uncertainties [Abstract] |  |  |
Tax Benefits Recognition Basis for Uncertain Tax Position Likelihood Realization Greater than Percentage | 50.00%iaci_TaxBenefitsRecognitionBasisForUncertainTaxPositionLikelihoodRealizationGreaterThanPercentage |  |
Redeemable Noncontrolling Interest |  |  |
Number of years in which put and call arrangements become exercisable | 4 years |  |
Number of put and call arrangements that became exercisable | 0 iaci_NumberofPutandCallArrangementsExercised | 2 iaci_NumberofPutandCallArrangementsExercised | 0 iaci_NumberofPutandCallArrangementsExercised
Adjustment to increase redeemable noncontrolling interests to fair value | (27,750,000)us-gaap_MinorityInterestChangeInRedemptionValue | (40,638,000)us-gaap_MinorityInterestChangeInRedemptionValue | (4,275,000)us-gaap_MinorityInterestChangeInRedemptionValue
Minimum |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Royalty rates used for impairment assessment of indefinite-lived intangible assets (as a percent) | 1.00%iaci_ImpairmentAssessmentofIndefiniteLivedIntangibleAssetsFairValueInputsRoyaltyRate / us-gaap_RangeAxis = us-gaap_MinimumMember | 1.00%iaci_ImpairmentAssessmentofIndefiniteLivedIntangibleAssetsFairValueInputsRoyaltyRate / us-gaap_RangeAxis = us-gaap_MinimumMember |
Maximum |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Royalty rates used for impairment assessment of indefinite-lived intangible assets (as a percent) | 9.00%iaci_ImpairmentAssessmentofIndefiniteLivedIntangibleAssetsFairValueInputsRoyaltyRate / us-gaap_RangeAxis = us-gaap_MaximumMember | 9.00%iaci_ImpairmentAssessmentofIndefiniteLivedIntangibleAssetsFairValueInputsRoyaltyRate / us-gaap_RangeAxis = us-gaap_MaximumMember |
Redeemable Noncontrolling Interest |  |  |
Redeemable Noncontrolling Interest |  |  |
Adjustment to increase redeemable noncontrolling interests to fair value | 27,800,000 us-gaap_MinorityInterestChangeInRedemptionValue / us-gaap_StatementEquityComponentsAxis = iaci_RedeemableNoncontrollingInterestMember | 40,600,000 us-gaap_MinorityInterestChangeInRedemptionValue / us-gaap_StatementEquityComponentsAxis = iaci_RedeemableNoncontrollingInterestMember | 4,300,000 us-gaap_MinorityInterestChangeInRedemptionValue / us-gaap_StatementEquityComponentsAxis = iaci_RedeemableNoncontrollingInterestMember
Search & Applications |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount | 15.00%us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount / us-gaap_StatementBusinessSegmentsAxis = iaci_SearchAndApplicationsMember |  |
Reporting Unit Hypothetical Percentage Lower of Fair Value In Excess of Carrying Amount | 20.00%iaci_HypotheticalPercentageReductionInFairValueOfReportingUnit / us-gaap_StatementBusinessSegmentsAxis = iaci_SearchAndApplicationsMember |  |
Reporting Unit Hypothetical Amount Of Fair Value In Excess Of Carrying Amount | $ 100,000,000 iaci_ReportingUnitHypotheticalAmountOfFairValueInExcessOfCarryingAmount / us-gaap_StatementBusinessSegmentsAxis = iaci_SearchAndApplicationsMember |  |
Goodwill [Member] | Minimum |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Fair Value, Discount Rate | 13.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_GoodwillMember / us-gaap_RangeAxis = us-gaap_MinimumMember | 13.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_GoodwillMember / us-gaap_RangeAxis = us-gaap_MinimumMember |
Goodwill [Member] | Maximum |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Fair Value, Discount Rate | 19.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_GoodwillMember / us-gaap_RangeAxis = us-gaap_MaximumMember | 25.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_GoodwillMember / us-gaap_RangeAxis = us-gaap_MaximumMember |
Indefinite-lived Intangible Assets [Member] | Minimum |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Fair Value, Discount Rate | 10.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_IndefinitelivedIntangibleAssetsMember / us-gaap_RangeAxis = us-gaap_MinimumMember | 10.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_IndefinitelivedIntangibleAssetsMember / us-gaap_RangeAxis = us-gaap_MinimumMember |
Indefinite-lived Intangible Assets [Member] | Maximum |  |  |
Goodwill and Indefinite-Lived Intangible Assets |  |  |
Fair Value, Discount Rate | 20.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_IndefinitelivedIntangibleAssetsMember / us-gaap_RangeAxis = us-gaap_MaximumMember | 18.00%us-gaap_FairValueInputsDiscountRate / iaci_FairValueByAssetAndLiabilityClassAxis = us-gaap_IndefinitelivedIntangibleAssetsMember / us-gaap_RangeAxis = us-gaap_MaximumMember |

X
- Definition The useful life of capitalized costs associated with certain distribution arrangements that require a fee per access point delivered, over which amortization is recognized. + References No definition available. + Details
Name: | iaci_CapitalizeAccessFeesUsefulLife
Namespace Prefix: | iaci_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Hypothetical Percentage Reduction in Fair Value Of Reporting Unit. + References No definition available. + Details
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Namespace Prefix: | iaci_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The royalty rates used in annual indefinite-lived intangible assets impairment assessment. + References No definition available. + Details
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Namespace Prefix: | iaci_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of put and call arrangements that were exercised during the year. + References No definition available. + Details
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Namespace Prefix: | iaci_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of subsequent years in which put and call arrangements become exercisable by the company and the counter-party. + References No definition available. + Details
Name: | iaci_NumberofSubsequentYearsinwhichPutandCallArrangementsbecomeExercisable
Namespace Prefix: | iaci_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of fair value of reporting unit in excess of carrying amount, had the estimated fair value been hypothetically lower by 20%. + References No definition available. + Details
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Namespace Prefix: | iaci_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The percentage of likelihood of realization that the tax position must exceed in order for the amount to be recognized in the financial statements. + References No definition available. + Details
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Namespace Prefix: | iaci_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Change in noncontrolling interest during the period as a result of a change in the redemption value of redeemable noncontrolling interest. + References No definition available. + Details
Name: | us-gaap_MinorityInterestChangeInRedemptionValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of fair value of reporting unit in excess of carrying amount. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | iaci_FairValueByAssetAndLiabilityClassAxis=us-gaap_GoodwillMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
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- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=iaci_SearchAndApplicationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Data Type: | na
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