GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Revenue	$ 756,872	$ 714,470	$ 2,298,532	$ 2,035,682
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	248,856	262,275	777,527	722,879
Selling and marketing expense	248,282	235,130	738,349	665,168
General and administrative expense	75,977	93,074	275,216	271,185
Product development expense	35,232	27,596	104,401	82,628
Depreciation	13,489	13,150	44,541	37,490
Amortization of intangibles	13,032	5,212	45,247	18,058
Total costs and expenses	634,868	636,437	1,985,281	1,797,408
Operating income	122,004	78,033	313,251	238,274
Equity in losses of unconsolidated affiliates	(3,253)	(3,298)	(4,422)	(28,208)
Interest expense	(7,623)	(1,391)	(22,944)	(4,102)
Other income, net	16,719	447	18,373	2,835
Earnings from continuing operations before income taxes	127,847	73,791	304,258	208,799
Income tax provision	(36,126)	(27,606)	(101,288)	(83,360)
Earnings from continuing operations	91,721	46,185	202,970	125,439
Earnings (loss) from discontinued operations, net of tax	3,914	(5,624)	1,902	(6,581)
Net earnings	95,635	40,561	204,872	118,858
Net loss (earnings) attributable to noncontrolling interests	1,305	156	3,995	(331)
Net earnings attributable to IAC shareholders	96,940	40,717	208,867	118,527
Comprehensive income attributable to IAC shareholders	122,502	44,386	234,411	119,079
IAC
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0	0	0
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	578	1,347	1,804	4,040
Selling and marketing expense	743	1,250	1,884	3,022
General and administrative expense	23,334	31,539	69,161	89,599
Product development expense	1,321	1,486	3,087	4,309
Depreciation	340	203	1,051	495
Amortization of intangibles	0	0	0	0
Total costs and expenses	26,316	35,825	76,987	101,465
Operating income	(26,316)	(35,825)	(76,987)	(101,465)
Equity in losses of unconsolidated affiliates	95,701	(9,808)	286,178	196,390
Interest expense	(6,520)	(277)	(19,592)	(832)
Other income, net	20,882	205,214	(31,457)	(3,350)
Earnings from continuing operations before income taxes	83,747	159,304	158,142	90,743
Income tax provision	9,279	(112,963)	48,823	34,365
Earnings from continuing operations	93,026	46,341	206,965	125,108
Earnings (loss) from discontinued operations, net of tax	3,914	(5,624)	1,902	(6,581)
Net earnings	96,940	40,717	208,867	118,527
Net loss (earnings) attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to IAC shareholders	96,940	40,717	208,867	118,527
Comprehensive income attributable to IAC shareholders	122,502	44,386	234,411	119,079
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue	519,972	495,065	1,589,162	1,428,316
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	134,280	143,348	444,655	422,193
Selling and marketing expense	182,195	177,896	540,405	497,647
General and administrative expense	36,715	37,769	120,882	108,886
Product development expense	23,858	18,107	69,956	57,072
Depreciation	8,187	8,508	28,568	26,151
Amortization of intangibles	9,003	468	30,070	1,694
Total costs and expenses	394,238	386,096	1,234,536	1,113,643
Operating income	125,734	108,969	354,626	314,673
Equity in losses of unconsolidated affiliates	19,670	10,572	30,981	28,757
Interest expense	(1,061)	(1,063)	(3,204)	(3,193)
Other income, net	(9,813)	(578)	(38,170)	(2,369)
Earnings from continuing operations before income taxes	134,530	117,900	344,233	337,868
Income tax provision	(40,929)	(35,809)	(116,383)	(110,884)
Earnings from continuing operations	93,601	82,091	227,850	226,984
Earnings (loss) from discontinued operations, net of tax	0	0	0	0
Net earnings	93,601	82,091	227,850	226,984
Net loss (earnings) attributable to noncontrolling interests	0	146	412	183
Net earnings attributable to IAC shareholders	93,601	82,237	228,262	227,167
Comprehensive income attributable to IAC shareholders	94,037	82,188	228,560	226,908
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue	237,990	220,943	712,656	611,954
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	114,627	118,908	333,476	300,297
Selling and marketing expense	65,691	56,195	196,816	165,453
General and administrative expense	16,042	23,765	85,295	72,683
Product development expense	10,053	8,003	31,358	21,247
Depreciation	4,962	4,439	14,922	10,844
Amortization of intangibles	4,029	4,744	15,177	16,364
Total costs and expenses	215,404	216,054	677,044	586,888
Operating income	22,586	4,889	35,612	25,066
Equity in losses of unconsolidated affiliates	(56)	(3,062)	(279)	(25,774)
Interest expense	(42)	(51)	(148)	(77)
Other income, net	5,650	(204,189)	88,000	8,554
Earnings from continuing operations before income taxes	28,138	(202,413)	123,185	7,769
Income tax provision	(4,476)	121,166	(33,728)	(6,841)
Earnings from continuing operations	23,662	(81,247)	89,457	928
Earnings (loss) from discontinued operations, net of tax	3	598	14	856
Net earnings	23,665	(80,649)	89,471	1,784
Net loss (earnings) attributable to noncontrolling interests	1,305	10	3,583	(514)
Net earnings attributable to IAC shareholders	24,970	(80,639)	93,054	1,270
Comprehensive income attributable to IAC shareholders	37,401	(68,147)	83,895	(2,587)
Total Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenue	(1,090)	(1,538)	(3,286)	(4,588)
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	(629)	(1,328)	(2,408)	(3,651)
Selling and marketing expense	(347)	(211)	(756)	(954)
General and administrative expense	(114)	1	(122)	17
Product development expense	0	0	0	0
Depreciation	0	0	0	0
Amortization of intangibles	0	0	0	0
Total costs and expenses	(1,090)	(1,538)	(3,286)	(4,588)
Operating income	0	0	0	0
Equity in losses of unconsolidated affiliates	(118,568)	(1,000)	(321,302)	(227,581)
Interest expense	0	0	0	0
Other income, net	0	0	0	0
Earnings from continuing operations before income taxes	(118,568)	(1,000)	(321,302)	(227,581)
Income tax provision	0	0	0	0
Earnings from continuing operations	(118,568)	(1,000)	(321,302)	(227,581)
Earnings (loss) from discontinued operations, net of tax	(3)	(598)	(14)	(856)
Net earnings	(118,571)	(1,598)	(321,316)	(228,437)
Net loss (earnings) attributable to noncontrolling interests	0	0	0
Net earnings attributable to IAC shareholders	(118,571)	(1,598)	(321,316)	(228,437)
Comprehensive income attributable to IAC shareholders	(131,438)	(14,041)	(312,455)	(224,321)
IAC Consolidated
Condensed Financial Statements, Captions [Line Items]
Revenue	756,872	714,470	2,298,532	2,035,682
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	248,856	262,275	777,527	722,879
Selling and marketing expense	248,282	235,130	738,349	665,168
General and administrative expense	75,977	93,074	275,216	271,185
Product development expense	35,232	27,596	104,401	82,628
Depreciation	13,489	13,150	44,541	37,490
Amortization of intangibles	13,032	5,212	45,247	18,058
Total costs and expenses	634,868	636,437	1,985,281	1,797,408
Operating income	122,004	78,033	313,251	238,274
Equity in losses of unconsolidated affiliates	(3,253)	(3,298)	(4,422)	(28,208)
Interest expense	(7,623)	(1,391)	(22,944)	(4,102)
Other income, net	16,719	447	18,373	2,835
Earnings from continuing operations before income taxes	127,847	73,791	304,258	208,799
Income tax provision	(36,126)	(27,606)	(101,288)	(83,360)
Earnings from continuing operations	91,721	46,185	202,970	125,439
Earnings (loss) from discontinued operations, net of tax	3,914	(5,624)	1,902	(6,581)
Net earnings	95,635	40,561	204,872	118,858
Net loss (earnings) attributable to noncontrolling interests	1,305	156	3,995	(331)
Net earnings attributable to IAC shareholders	96,940	40,717	208,867	118,527
Comprehensive income attributable to IAC shareholders	$ 122,502	$ 44,386	$ 234,411	$ 119,079