SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment reporting information
Revenue	$ 485,404	$ 394,244	$ 945,617	$ 772,422
Operating Income (Loss)	58,231	24,633	95,567	33,558
Operating Income Before Amortization	83,438	50,437	143,392	84,081
Depreciation	12,450	16,625	25,889	32,418
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments and to net earnings (loss) attributable to IAC shareholders
Operating Income Before Amortization	83,438	50,437	143,392	84,081
Non-Cash Compensation Expense	(23,007)	(21,048)	(43,168)	(42,593)
Amortization of Intangibles	(2,200)	(4,756)	(4,657)	(7,930)
Operating Income (Loss)	58,231	24,633	95,567	33,558
Equity in losses of unconsolidated affiliates	(8,720)	(4,002)	(10,599)	(26,615)
Other income, net	5,637	103	6,389	5,339
Earnings from continuing operations before income taxes	55,148	20,734	91,357	12,282
Income tax provision	(9,518)	(5,313)	(25,559)	(11,458)
Earnings from continuing operations	45,630	15,421	65,798	824
Loss from discontinued operations, net of tax	(2,488)	(2,586)	(4,436)	(7,313)
Net earnings (loss)	43,142	12,835	61,362	(6,489)
Net (earnings) loss attributable to noncontrolling interests	(718)	756	(868)	1,375
Net earnings (loss) attributable to IAC shareholders	42,424	13,591	60,494	(5,114)
Search
Segment reporting information
Revenue	252,436	197,194	501,040	396,155
Operating Income (Loss)	50,309	31,617	99,397	62,674
Operating Income Before Amortization	50,568	32,043	99,954	63,584
Depreciation	6,367	9,952	13,348	19,015
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments and to net earnings (loss) attributable to IAC shareholders
Operating Income Before Amortization	50,568	32,043	99,954	63,584
Non-Cash Compensation Expense		(89)		(236)
Amortization of Intangibles	(259)	(337)	(557)	(674)
Operating Income (Loss)	50,309	31,617	99,397	62,674
Match
Segment reporting information
Revenue	116,429	96,961	228,026	186,236
Operating Income (Loss)	40,999	25,490	64,428	39,192
Operating Income Before Amortization	42,335	29,104	67,323	43,910
Depreciation	2,278	2,878	4,578	5,906
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments and to net earnings (loss) attributable to IAC shareholders
Operating Income Before Amortization	42,335	29,104	67,323	43,910
Non-Cash Compensation Expense		179		153
Amortization of Intangibles	(1,336)	(3,793)	(2,895)	(4,871)
Operating Income (Loss)	40,999	25,490	64,428	39,192
ServiceMagic
Segment reporting information
Revenue	56,104	49,519	102,397	91,731
Operating Income (Loss)	8,239	5,748	12,047	8,144
Operating Income Before Amortization	8,622	6,125	12,799	8,984
Depreciation	1,114	1,078	2,184	1,996
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments and to net earnings (loss) attributable to IAC shareholders
Operating Income Before Amortization	8,622	6,125	12,799	8,984
Amortization of Intangibles	(383)	(377)	(752)	(840)
Operating Income (Loss)	8,239	5,748	12,047	8,144
Media and Other
Segment reporting information
Revenue	60,767	51,014	115,047	99,129
Operating Income (Loss)	(3,239)	(3,026)	(6,963)	(6,838)
Operating Income Before Amortization	(3,137)	(2,618)	(6,503)	(5,014)
Depreciation	618	566	1,427	1,106
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments and to net earnings (loss) attributable to IAC shareholders
Operating Income Before Amortization	(3,137)	(2,618)	(6,503)	(5,014)
Non-Cash Compensation Expense	120	(159)	(7)	(279)
Amortization of Intangibles	(222)	(249)	(453)	(1,545)
Operating Income (Loss)	(3,239)	(3,026)	(6,963)	(6,838)
Inter-segment elimination
Segment reporting information
Revenue	(332)	(444)	(893)	(829)
Corporate
Segment reporting information
Operating Income (Loss)	(38,077)	(35,196)	(73,342)	(69,614)
Operating Income Before Amortization	(14,950)	(14,217)	(30,181)	(27,383)
Depreciation	2,073	2,151	4,352	4,395
Reconciliation of Operating Income Before Amortization to operating income (loss) for the entity's reportable segments and to net earnings (loss) attributable to IAC shareholders
Operating Income Before Amortization	(14,950)	(14,217)	(30,181)	(27,383)
Non-Cash Compensation Expense	(23,127)	(20,979)	(43,161)	(42,231)
Operating Income (Loss)	$ (38,077)	$ (35,196)	$ (73,342)	$ (69,614)