GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Revenue	$ 799,411	$ 680,612	$ 1,541,660	$ 1,321,212
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	272,822	237,304	528,671	460,604
Selling and marketing expense	247,153	211,252	490,067	430,038
General and administrative expense	103,515	89,639	199,239	178,111
Product development expense	34,052	26,911	69,169	55,032
Depreciation	17,036	12,225	31,052	24,340
Amortization of intangibles	18,137	5,805	32,215	12,846
Total costs and expenses	692,715	583,136	1,350,413	1,160,971
Operating income	106,696	97,476	191,247	160,241
Equity in losses of unconsolidated affiliates	(1,078)	(19,009)	(1,169)	(24,910)
Interest expense	(7,658)	(1,364)	(15,321)	(2,711)
Other (expense) income, net	(4)	(368)	1,654	2,388
Earnings from continuing operations before income taxes	97,956	76,735	176,411	135,008
Income tax provision	(39,416)	(28,634)	(65,162)	(55,754)
Earnings from continuing operations	58,540	48,101	111,249	79,254
Loss from discontinued operations, net of tax	(1,068)	(4,641)	(2,012)	(957)
Net earnings	57,472	43,460	109,237	78,297
Net loss (earnings) attributable to noncontrolling interests	818	(128)	2,690	(487)
Net earnings attributable to IAC shareholders	58,290	43,332	111,927	77,810
Comprehensive income attributable to IAC shareholders	70,199	9,319	111,909	74,693
IAC
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0	0	0
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	549	1,299	1,226	2,693
Selling and marketing expense	710	869	1,141	1,772
General and administrative expense	23,582	28,721	45,827	58,060
Product development expense	867	1,447	1,766	2,823
Depreciation	344	145	711	292
Amortization of intangibles	0	0	0	0
Total costs and expenses	26,052	32,481	50,671	65,640
Operating income	(26,052)	(32,481)	(50,671)	(65,640)
Equity in losses of unconsolidated affiliates	75,927	108,333	190,477	206,198
Interest expense	(6,515)	(277)	(13,072)	(555)
Other (expense) income, net	3,109	(104,077)	(52,339)	(208,564)
Earnings from continuing operations before income taxes	46,469	(28,502)	74,395	(68,561)
Income tax provision	12,889	76,475	39,544	147,328
Earnings from continuing operations	59,358	47,973	113,939	78,767
Loss from discontinued operations, net of tax	(1,068)	(4,641)	(2,012)	(957)
Net earnings	58,290	43,332	111,927	77,810
Net loss (earnings) attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to IAC shareholders	58,290	43,332	111,927	77,810
Comprehensive income attributable to IAC shareholders	70,199	9,319	111,909	74,693
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue	553,406	473,580	1,069,190	933,251
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	156,703	136,869	310,375	278,845
Selling and marketing expense	187,543	160,409	358,210	319,751
General and administrative expense	44,015	35,333	84,167	71,117
Product development expense	23,284	18,514	46,098	38,965
Depreciation	11,380	8,673	20,381	17,643
Amortization of intangibles	12,157	596	21,067	1,226
Total costs and expenses	435,082	360,394	840,298	727,547
Operating income	118,324	113,186	228,892	205,704
Equity in losses of unconsolidated affiliates	8,540	14,025	11,311	18,185
Interest expense	(1,078)	(1,065)	(2,143)	(2,130)
Other (expense) income, net	(9,627)	(3,072)	(28,357)	(1,791)
Earnings from continuing operations before income taxes	116,159	123,074	209,703	219,968
Income tax provision	(41,871)	(38,459)	(75,454)	(75,075)
Earnings from continuing operations	74,288	84,615	134,249	144,893
Loss from discontinued operations, net of tax	0	0	0	0
Net earnings	74,288	84,615	134,249	144,893
Net loss (earnings) attributable to noncontrolling interests	404	21	412	37
Net earnings attributable to IAC shareholders	74,692	84,636	134,661	144,930
Comprehensive income attributable to IAC shareholders	74,628	84,400	134,523	144,720
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue	247,164	208,759	474,666	391,011
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	116,570	100,489	218,849	181,389
Selling and marketing expense	59,052	50,353	131,125	109,258
General and administrative expense	35,925	25,580	69,253	48,918
Product development expense	9,901	6,950	21,305	13,244
Depreciation	5,312	3,407	9,960	6,405
Amortization of intangibles	5,980	5,209	11,148	11,620
Total costs and expenses	232,740	191,988	461,640	370,834
Operating income	14,424	16,771	13,026	20,177
Equity in losses of unconsolidated affiliates	(132)	(18,659)	(223)	(22,712)
Interest expense	(65)	(22)	(106)	(26)
Other (expense) income, net	6,514	106,781	82,350	212,743
Earnings from continuing operations before income taxes	20,741	104,871	95,047	210,182
Income tax provision	(10,434)	(66,650)	(29,252)	(128,007)
Earnings from continuing operations	10,307	38,221	65,795	82,175
Loss from discontinued operations, net of tax	4	718	11	258
Net earnings	10,311	38,939	65,806	82,433
Net loss (earnings) attributable to noncontrolling interests	414	(149)	2,278	(524)
Net earnings attributable to IAC shareholders	10,725	38,790	68,084	81,909
Comprehensive income attributable to IAC shareholders	5,227	16,287	46,494	65,560
Total Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenue	(1,159)	(1,727)	(2,196)	(3,050)
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	(1,000)	(1,353)	(1,779)	(2,323)
Selling and marketing expense	(152)	(379)	(409)	(743)
General and administrative expense	(7)	5	(8)	16
Product development expense	0	0	0	0
Depreciation	0	0	0	0
Amortization of intangibles	0	0	0	0
Total costs and expenses	(1,159)	(1,727)	(2,196)	(3,050)
Operating income	0	0	0	0
Equity in losses of unconsolidated affiliates	(85,413)	(122,708)	(202,734)	(226,581)
Interest expense	0	0	0	0
Other (expense) income, net	0	0	0	0
Earnings from continuing operations before income taxes	(85,413)	(122,708)	(202,734)	(226,581)
Income tax provision	0	0	0	0
Earnings from continuing operations	(85,413)	(122,708)	(202,734)	(226,581)
Loss from discontinued operations, net of tax	(4)	(718)	(11)	(258)
Net earnings	(85,417)	(123,426)	(202,745)	(226,839)
Net loss (earnings) attributable to noncontrolling interests	0	0	0	0
Net earnings attributable to IAC shareholders	(85,417)	(123,426)	(202,745)	(226,839)
Comprehensive income attributable to IAC shareholders	(79,855)	(100,687)	(181,017)	(210,280)
IAC Consolidated
Condensed Financial Statements, Captions [Line Items]
Revenue	799,411	680,612	1,541,660	1,321,212
Costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	272,822	237,304	528,671	460,604
Selling and marketing expense	247,153	211,252	490,067	430,038
General and administrative expense	103,515	89,639	199,239	178,111
Product development expense	34,052	26,911	69,169	55,032
Depreciation	17,036	12,225	31,052	24,340
Amortization of intangibles	18,137	5,805	32,215	12,846
Total costs and expenses	692,715	583,136	1,350,413	1,160,971
Operating income	106,696	97,476	191,247	160,241
Equity in losses of unconsolidated affiliates	(1,078)	(19,009)	(1,169)	(24,910)
Interest expense	(7,658)	(1,364)	(15,321)	(2,711)
Other (expense) income, net	(4)	(368)	1,654	2,388
Earnings from continuing operations before income taxes	97,956	76,735	176,411	135,008
Income tax provision	(39,416)	(28,634)	(65,162)	(55,754)
Earnings from continuing operations	58,540	48,101	111,249	79,254
Loss from discontinued operations, net of tax	(1,068)	(4,641)	(2,012)	(957)
Net earnings	57,472	43,460	109,237	78,297
Net loss (earnings) attributable to noncontrolling interests	818	(128)	2,690	(487)
Net earnings attributable to IAC shareholders	58,290	43,332	111,927	77,810
Comprehensive income attributable to IAC shareholders	$ 70,199	$ 9,319	$ 111,909	$ 74,693