Debt Instrument, Amount of Debt Discount and Increase to Additional Paid in capital

No definition available.

Name:	iac_DebtInstrumentAmountofDebtDiscountandIncreasetoAdditionalPaidincapital
Namespace Prefix:	iac_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt Instrument, Covenant Terms, Interest Coverage Ratio

+ References

No definition available.

+ Details

Name:	iac_DebtInstrumentCovenantTermsInterestCoverageRatio
Namespace Prefix:	iac_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Covenant Terms, Leverage Ratio

+ References

No definition available.

+ Details

Name:	iac_DebtInstrumentCovenantTermsLeverageRatio
Namespace Prefix:	iac_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Exchange Price Per Share

+ References

No definition available.

+ Details

Name:	iac_DebtInstrumentExchangePricePerShare
Namespace Prefix:	iac_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Percentage of Exchange Price on Applicable Trading day

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Percentage of Product of Last Reported Price

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Period of Consecutive Reported Sale Price of Common Stock

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Period of Reported Sale Price of Common Stock

+ References

No definition available.

+ Details

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

- Definition

Dent Instrument, Exchangeable Shares

+ References

No definition available.

+ Details

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

- Definition

Repayment Of Net Premium On Exchangeable Note Hedge And Warrants

+ References

No definition available.

+ Details

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

- Definition

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

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

- Definition

Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(8))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

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

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of warrants or rights outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount by which the convertible debt's if-converted value exceeds its principle amount at the balance sheet date, regardless of whether the instrument is currently convertible. This element applies to public companies only.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031898-161870

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Amount, after accumulated amortization, of debt discount (premium).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28567-108399

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

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

- Definition

Number of shares issued which are neither cancelled nor held in the treasury.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_IACCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=iac_MatchGroupInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_MatchGroupCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_SixPointThreeSevenFivePercentSeniorNotesDueJuneFirstTwentyTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_SeniorNotes0.875dueOctober12022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_SeniorNotes4.75DueDecember152022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_MatchGroupSeniorNotes5.00December152027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_MatchGroupSeniorNotes6.75dueDecemberFifteenTwentyTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_TermLoandueNovember162022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_MatchGroupTermLoandueNovemberSixteenthTwentyTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=iac_ANGIHomeservicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=iac_TermLoandueNovember012022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	iac_DebtCovenantPeriodAxis=iac_QuarterlyPaymentsforFirstThreeYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	iac_DebtCovenantPeriodAxis=iac_QuarterlyPaymentsinFourthYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	iac_DebtCovenantPeriodAxis=iac_QuarterlyPaymentsinFifthYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LONG-TERM DEBT - Narrative (Details)		3 Months Ended	9 Months Ended	12 Months Ended
LONG-TERM DEBT - Narrative (Details)	Oct. 02, 2017 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)	Dec. 04, 2017 USD ($)	Jun. 01, 2016 USD ($)
Debt Instrument [Line Items]
Exchange price per share (USD per share) \| $ / shares		$ 152.18
IAC Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 300,000,000	$ 300,000,000
Borrowings outstanding of credit facility		0	$ 0	$ 0
Annual commitment fee on undrawn funds, basis points (as a percent)			0.25%
IAC Credit Facility \| Maximum \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum leverage ratio			3.25
Match Group
Debt Instrument [Line Items]
Outstanding balance of debt instrument		1,275,000,000	$ 1,275,000,000	1,275,000,000
Net unamortized discount (premium)		7,681,000	7,681,000	8,668,000
Match Group \| Match Group Credit Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		500,000,000.0	500,000,000.0
Borrowings outstanding of credit facility		0	$ 0	$ 0
Annual commitment fee on undrawn funds, basis points (as a percent)			0.25%
Match Group \| Match Group Credit Agreement \| Maximum \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum leverage ratio			5.0
Match Group \| Match Group Credit Agreement \| Minimum \| Revolving Credit Facility
Debt Instrument [Line Items]
Minimum interest coverage ratio			2.5
Senior Notes \| IAC
Debt Instrument [Line Items]
Outstanding balance of debt instrument	$ 517,500,000.0	$ 460,100,000	$ 460,100,000
Exchangeable stock (shares) \| shares	6.5713
Exchange price per share (USD per share) \| $ / shares	$ 152.18		$ 152.18
Period of reported sale price of common stock (trading days)	20 days
Period of consecutive reported sale price of common stock (trading days)	30 days
Exchange price on applicable trading day (as a percent)	130.00%
Amount of product relative to last reported price (as a percent)	98.00%
Proceeds from issuance of debt	$ 499,500,000
Repayment of net premium on exchangeable note hedge and warrants	50,700,000
Amount of debt discount and increase to additional paid in capital	$ 70,400,000
Outstanding stock (shares) \| shares		3,400,000	3,400,000
Outstanding warrants (shares) \| shares		3,400,000	3,400,000
Exercise price of warrants (USD per share) \| $ / shares		$ 229.70	$ 229.70
If-converted value in excess of principal			$ 219,500,000
Interest expense		$ 5,300,000	15,800,000
Amortization of debt discount (premium)		3,300,000	9,800,000
Amortization of debt issuance costs		900,000	2,600,000
Net unamortized discount (premium)		$ 57,400,000	$ 57,400,000
Senior Notes \| 6.375% Senior Notes \| Maximum
Debt Instrument [Line Items]
Maximum leverage ratio			5.0
Senior Notes \| Exchangeable Senior Notes, 0.875% \| IAC
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.875%
Senior Notes \| Exchangeable Senior Notes, 0.875% \| Maximum \| IAC
Debt Instrument [Line Items]
Stated interest rate (as a percent)		3.88%	3.88%
Senior Notes \| Exchangeable Senior Notes, 0.875% \| Minimum \| IAC
Debt Instrument [Line Items]
Stated interest rate (as a percent)		0.875%	0.875%
Senior Notes \| Senior Notes, 4.75% \| IAC
Debt Instrument [Line Items]
Stated interest rate (as a percent)		4.75%	4.75%
Senior Notes \| Match Group \| 6.375% Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)		6.375%	6.375%	6.375%		6.375%
Face amount of debt instrument						$ 400,000,000.0
Outstanding balance of debt instrument		$ 400,000,000	$ 400,000,000	$ 400,000,000
Senior Notes \| Match Group \| Match Group Senior Notes, 5.00%
Debt Instrument [Line Items]
Stated interest rate (as a percent)		5.00%	5.00%		5.00%
Outstanding balance of debt instrument		$ 450,000,000	$ 450,000,000	450,000,000	$ 450,000,000
Senior Notes \| Match Group \| 6.75% Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)					6.75%
Outstanding balance of debt instrument					$ 445,200,000
Term Loan \| Match Group \| Term Loan
Debt Instrument [Line Items]
Outstanding balance of debt instrument		425,000,000	$ 425,000,000	$ 425,000,000
Term Loan \| Match Group \| Match Group Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			4.67%	3.85%
Term Loan \| Match Group \| Match Group Term Loan \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			2.50%
Term Loan \| ANGI Homeservices \| Term Loan
Debt Instrument [Line Items]
Outstanding balance of debt instrument		$ 264,688,000	$ 264,688,000	$ 275,000,000
Basis spread on variable rate (as a percent)			4.10%	3.38%
Term Loan \| ANGI Homeservices \| Term Loan \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.75%	2.00%
Term Loan \| ANGI Homeservices \| Term Loan \| Maximum
Debt Instrument [Line Items]
Maximum leverage ratio			4.5
Term Loan \| ANGI Homeservices \| Term Loan \| Minimum
Debt Instrument [Line Items]
Minimum interest coverage ratio			2.5
Quarterly Payments for First Three Years \| Term Loan \| ANGI Homeservices \| Term Loan \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.25%
Quarterly Payments in Fourth Year \| Term Loan \| ANGI Homeservices \| Term Loan \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			2.50%
Quarterly Payments in Fifth Year \| Term Loan \| ANGI Homeservices \| Term Loan \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			3.75%