Name:	iac_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfActivePlans
Namespace Prefix:	iac_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of shares of the entity's common stock that would be required to settle equity instruments denominated in the shares of certain subsidiaries held by members of subsidiaries' management.

No definition available.

Name:	iac_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesRequiredToSettleInterestHeldBySubsidiariesManagement
Namespace Prefix:	iac_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The weighted average exercise price of options granted during the reporting period, related to grants with exercise prices greater than the market price of the entity's common stock on date of grant.

No definition available.

Name:	iac_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePriceWithExercisePriceGreaterThanMarketPrice
Namespace Prefix:	iac_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

The weighted average grant-date fair value of options granted during the reporting period, as calculated by applying the disclosed option pricing methodology, related to grants with exercise prices equal to the market price of the entity's common stock on the date of grant.

No definition available.

Name:	iac_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValueWithExercisePriceEqualToMarketPrice
Namespace Prefix:	iac_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

The weighted average grant-date fair value of options granted during the reporting period, as calculated by applying the disclosed option pricing methodology, related to grants with exercise prices greater than the market price of the entity's common stock on the date of grant.

No definition available.

Name:	iac_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValueWithExercisePriceGreaterThanMarketPrice
Namespace Prefix:	iac_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Share Based Compensation Arrangement by Share Based Payment Award, Assumed Withholding Rate In Settlement Of Subsidiary Denominated Awards

No definition available.

Name:	iac_ShareBasedCompensationArrangementbyShareBasedPaymentAwardAssumedWithholdingRateInSettlementOfSubsidiaryDenominatedAwards
Namespace Prefix:	iac_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Estimated Number of Shares Required to Settle Subsidiary Denominated Awards

No definition available.

Name:	iac_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEstimatedNumberofSharesRequiredtoSettleSubsidiaryDenominatedAwards
Namespace Prefix:	iac_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Estimated Payment Related to Tax Withholding For Settlement Of Interest Held By Subsidiaries Management

No definition available.

Name:	iac_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEstimatedPaymentRelatedtoTaxWithholdingForSettlementOfInterestHeldBySubsidiariesManagement
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Estimated Payment Related to Tax Withholding For Settlement Of Subsidiary Denominated Awards

No definition available.

Name:	iac_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEstimatedPaymentRelatedtoTaxWithholdingForSettlementOfSubsidiaryDenominatedAwards
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Including Effect of Tax Withholding, Estimated Number of Shares Required to Settle Subsidiary Denominated Awards

No definition available.

Name:	iac_ShareBasedCompensationArrangementbyShareBasedPaymentAwardIncludingEffectofTaxWithholdingEstimatedNumberofSharesRequiredtoSettleSubsidiaryDenominatedAwards
Namespace Prefix:	iac_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Including Effect of Tax Withholding, Number of Shares Required to Settle Interest Held by Subsidiaries Management

No definition available.

Name:	iac_ShareBasedCompensationArrangementbyShareBasedPaymentAwardIncludingEffectofTaxWithholdingNumberofSharesRequiredtoSettleInterestHeldbySubsidiariesManagement
Namespace Prefix:	iac_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation, Effect Of Each Incremental Ten Percentage Point Increase In Fair Value Of Subsidiaries, Incremental Aggregate Shares Required To Settle Award

No definition available.

Name:	iac_ShareBasedCompensationEffectOfEachIncrementalTenPercentagePointIncreaseInFairValueOfSubsidiariesIncrementalAggregateSharesRequiredToSettleAward
Namespace Prefix:	iac_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement By Share-based Payment Award, Award Vesting Rights, Number of Annual Vesting Installments

No definition available.

Name:	iac_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsNumberofAnnualVestingInstallments
Namespace Prefix:	iac_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Equity Award to Non-Employee, Fair Value

No definition available.

Name:	iac_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityAwardtoNonEmployeeFairValue
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Market Based Options, Consecutive Days Of Price Over Threshold For Vesting Requirement

No definition available.

Name:	iac_SharebasedCompensationArrangementbySharebasedPaymentAwardMarketBasedOptionsConsecutiveDaysOfPriceOverThresholdForVestingRequirement
Namespace Prefix:	iac_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Incremental Compensation Cost Recognized From Prior Period Modification

No definition available.

Name:	iac_SharebasedCompensationArrangementbySharebasedPaymentAwardPlanModificationIncrementalCompensationCostRecognizedFromPriorPeriodModification
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Incremental Compensation Cost Recognized In Current Period

No definition available.

Name:	iac_SharebasedCompensationArrangementbySharebasedPaymentAwardPlanModificationIncrementalCompensationCostRecognizedInCurrentPeriod
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Incremental Compensation Cost Recognized Over Remaining Life

No definition available.

Name:	iac_SharebasedCompensationArrangementbySharebasedPaymentAwardPlanModificationIncrementalCompensationCostRecognizedOverRemainingLife
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Repurchased Equity Awards, Incremental Compensation Cost

No definition available.

Name:	iac_SharebasedCompensationArrangementbySharebasedPaymentAwardRepurchasedEquityAwardsIncrementalCompensationCost
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

Name:	iac_TermOfShareBasedCompensationPlan
Namespace Prefix:	iac_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of deferred tax expense from write-off of the deferred tax asset related to deductible stock options at exercise.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 20
-Section 55
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=65896087&loc=d3e11283-113907

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

Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements.

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

Unrecognized cost of unvested share-based compensation awards.

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

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

Name:	us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The risk-free interest rate assumption that is used in valuing an option on its own shares.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

Net number of share options (or share units) granted during the period.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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

Percentage of vesting of share-based compensation awards.

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_PlanNameAxis=iac_A2008PlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PlanNameAxis=iac_A2013PlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementBusinessSegmentsAxis=iac_TheMatchGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=iac_FormerChiefExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=iac_MarketBasedStockOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=iac_RestrictedStockUnitsandPerformanceStockUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: