Change in noncontrolling interest during the period as a result of transfers to redeemable noncontrolling interest.

No definition available.

Name:	iaci_NoncontrollingInterestTransferToRedeemableNoncontrollingInterest
Namespace Prefix:	iaci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents Other Comprehensive Income or Loss, Net of Tax, for the period. Includes deferred gains or losses on qualifying hedges, unrealized holding gains or losses on available-for-sale securities, minimum pension liability, and cumulative translation adjustment. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label. This is including the portion attributable to the noncontrolling interest and excluding the portion attributable to Redeemable Noncontrolling Interests.

+ References

No definition available.

+ Details

Name:	iaci_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseExcludingRedeemableNonControllingInterest
Namespace Prefix:	iaci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest and excluding the portion attributable to Redeemable Noncontrolling Interests.

+ References

No definition available.

+ Details

Name:	iaci_ProfitLossExcludingRedeemableNonControllingInterest
Namespace Prefix:	iaci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The portion of net income or loss attributable to redeemable noncontrolling interest.

+ References

No definition available.

+ Details

Name:	iaci_RedeemableNoncontrollingInterestNetIncome
Namespace Prefix:	iaci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents other activity associated with redeemable noncontrolling interests that is not separately disclosed.

+ References

No definition available.

+ Details

Name:	iaci_RedeemableNoncontrollingInterestOtherCharges
Namespace Prefix:	iaci_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents other comprehensive income (loss), net of tax, for the period for redeemable noncontrolling interests.

+ References

No definition available.

+ Details

Name:	iaci_RedeemableNoncontrollingInterestOtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease
Namespace Prefix:	iaci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415241&loc=d3e4534-113899

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 20

-Section 55

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=32706628&loc=d3e11149-113907

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=32706628&loc=d3e11178-113907

+ Details

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

- Definition

Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 740

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6419406&loc=d3e23524-113945

+ Details

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

- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

+ Details

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

- Details

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

- 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

- Definition

Decrease in noncontrolling interest (for example, but not limited to, redeeming or purchasing the interests of noncontrolling shareholders, issuance of shares (interests) by the non-wholly owned subsidiary to the parent entity for other than cash, and a buyback of shares (interest) by the non-wholly owned subsidiary from the noncontrolling interests).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569655-111683

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4616395-111683

+ Details

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

- Definition

Increase in noncontrolling interest balance because of a business combination that occurred during the period.

+ References

No definition available.

+ Details

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

- Definition

As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section S99

-Paragraph 3A

-Subparagraph 14

-URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section S99

-Paragraph 3A

-Subparagraph (16)(c)

-URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section S99

-Paragraph 3A

-Subparagraph 15

-URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section S99

-Paragraph 3A

-Subparagraph (12)(c)

-URI http://asc.fasb.org/extlink&oid=27011957&loc=SL6540498-122764

+ Details

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

- Definition

Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury.

+ References

+ Details

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

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4568447-111683

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4568740-111683

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4I

-URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4590271-111686

+ Details

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

- Definition

This element represents movements included in the statement of changes in stockholders' equity which are not separately disclosed or provided for elsewhere in the taxonomy.

+ References

No definition available.

+ Details

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

- Definition

Number of new stock issued during the period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

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

- Definition

Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

+ Details

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

- Definition

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

+ References

+ Details

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

- Definition

Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30, 31

-Article 5

+ Details

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

- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

+ Details

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

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Redeemable Noncontrolling Interests	IAC	Common Stock	Common Stock Class B convertible common stock	Additional Paid-in Capital	(Accumulated Deficit) Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock	Noncontrolling Interests
Redeemable noncontrolling interests, balance at the beginning of the period at Dec. 31, 2011		$ 50,349
Balance at the beginning of the period at Dec. 31, 2011	1,960,140		1,905,049	234	16	11,280,173	(477,785)	(12,443)	(8,885,146)	55,091
Balance at the beginning of the period (in shares) at Dec. 31, 2011				234,101	16,157
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings for the year	161,914		159,266				159,266			2,648
Redeemable noncontrolling interests, net (loss) earnings for the year		(1,118)
Other comprehensive (loss) income, net of tax	(19,322)		(19,726)					(19,726)		404
Redeemable noncontrolling interests, other comprehensive (loss) income, net of tax		207
Non-cash compensation expense	85,625		82,807	0	0	82,807	0	0	0	2,818
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	(16,498)		(16,498)	5		(16,503)			0
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes (in shares)				5,153
Income tax benefit related to the exercise of stock options, vesting of restricted stock units and other	49,967		49,967			49,967
Issuance of common stock upon exercise of warrants	284,111		284,111	12		284,099
Issuance of common stock upon exercise of warrants (in shares)				11,728
Dividends	(68,901)us-gaap_DividendsCommonStockCash		(68,901)			(68,901)	0
Purchase of treasury stock	(716,072)		(716,072)						(716,072)
Purchase of redeemable noncontrolling interests		(2,955)
Adjustment of redeemable noncontrolling interests and noncontrolling interests to fair value	(4,275)	4,275	(4,275)			(4,275)				0
Transfer from noncontrolling interests to redeemable noncontrolling interests	(10,049)	10,049								(10,049)
Other	995us-gaap_StockholdersEquityOther									995
Redeemable noncontrolling interests, other		(2,681)
Redeemable noncontrolling interests, balance at the end of the period at Dec. 31, 2012		58,126
Balance at the end of the period at Dec. 31, 2012	1,707,635		1,655,728	251	16	11,607,367	(318,519)	(32,169)	(9,601,218)	51,907
Balance at the end of the period (in shares) at Dec. 31, 2012				250,982	16,157
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings for the year	286,989		285,784				285,784			1,205
Redeemable noncontrolling interests, net (loss) earnings for the year		(3,264)
Other comprehensive (loss) income, net of tax	20,490		19,123					19,123		1,367
Redeemable noncontrolling interests, other comprehensive (loss) income, net of tax		2,305
Non-cash compensation expense	53,005		51,883			51,883				1,122
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	(9,897)		(9,897)			(9,899)			2
Income tax benefit related to the exercise of stock options, vesting of restricted stock units and other	30,986		30,986			30,986
Dividends	(77,830)us-gaap_DividendsCommonStockCash		(77,830)			(77,830)	0
Purchase of treasury stock	(229,101)	0	(229,101)		0				(229,101)
Purchase of redeemable noncontrolling interests	(12,371)	(55,576)								(12,371)
Adjustment of redeemable noncontrolling interests and noncontrolling interests to fair value	(40,638)	40,638	(42,947)			(42,947)				2,309
Transfer from noncontrolling interests to redeemable noncontrolling interests	(2,874)	2,874								(2,874)
Other	(3,007)us-gaap_StockholdersEquityOther		(3,007)			(3,007)				0
Redeemable noncontrolling interests, other		(2,242)
Redeemable noncontrolling interests, balance at the end of the period at Dec. 31, 2013	42,861	42,861
Balance at the end of the period at Dec. 31, 2013	1,729,401		1,686,736	251	16	11,562,567	(32,735)	(13,046)	(9,830,317)	42,665
Balance at the end of the period (in shares) at Dec. 31, 2013				250,982	16,157
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings for the year	414,873		414,873				414,873			0
Redeemable noncontrolling interests, net (loss) earnings for the year		(5,643)
Other comprehensive (loss) income, net of tax	(74,551)		(74,654)					(74,654)		103
Redeemable noncontrolling interests, other comprehensive (loss) income, net of tax		(914)
Non-cash compensation expense	59,076	558	59,362			59,362				(286)
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	1,628		1,628	1		(167,340)			168,967
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes (in shares)				1,188
Income tax benefit related to the exercise of stock options, vesting of restricted stock units and other	37,451		37,451			37,451
Dividends	(96,577)us-gaap_DividendsCommonStockCash		(96,577)			(39,557)	(57,020)
Noncontrolling interests related to acquisitions		17,886
Purchase of redeemable noncontrolling interests	(50,662)	(41,743)								(50,662)
Adjustment of redeemable noncontrolling interests and noncontrolling interests to fair value	(27,750)	27,750	(37,119)			(37,119)				9,369
Other	(253)us-gaap_StockholdersEquityOther		(253)			(253)
Redeemable noncontrolling interests, other		(328)
Redeemable noncontrolling interests, balance at the end of the period at Dec. 31, 2014	40,427	40,427
Balance at the end of the period at Dec. 31, 2014	$ 1,993,142		$ 1,991,953	$ 252	$ 16	$ 11,415,617	$ 325,118	$ (87,700)	$ (9,661,350)	$ 1,189
Balance at the end of the period (in shares) at Dec. 31, 2014				252,170	16,157