GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - STATEMENT OF OPERATIONS (Details2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Revenue	$ 745,439	$ 771,132	$ 1,564,618	$ 1,543,644
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	170,397	177,963	364,131	364,700
Selling and marketing expense	295,525	324,710	677,866	687,192
General and administrative expense	152,135	129,349	288,377	244,143
Product development expense	49,911	46,430	105,741	91,687
Depreciation	17,575	15,500	33,370	31,068
Amortization of intangibles	36,975	14,411	50,795	26,966
Goodwill impairment	275,367	0	275,367	0
Total operating costs and expenses	997,885	708,363	1,795,647	1,445,756
Operating (loss) income	(252,446)	62,769	(231,029)	97,888
Equity in earnings (losses) of unconsolidated affiliates	0	0	0	0
Interest expense	(27,644)	(15,214)	(55,504)	(29,278)
Other (expense) income, net	(7,192)	(1,638)	8,705	5,350
(Loss) earnings from continuing operations before income taxes	(287,282)	45,917	(277,828)	73,960
Income tax benefit (provision)	96,740	11,968	95,220	5,788
(Loss) earnings from continuing operations	(190,542)	57,885	(182,608)	79,748
(Loss) earnings from discontinued operations, net of tax	0	(153)	0	(28)
Net (loss) earnings	(190,542)	57,732	(182,608)	79,720
Net (earnings) loss attributable to noncontrolling interests	(4,233)	1,573	(3,885)	5,990
Net (loss) earnings attributable to IAC shareholders	(194,775)	59,305	(186,493)	85,710
Comprehensive (loss) income attributable to IAC shareholders	(201,218)	72,283	(172,928)	43,115
Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenue	(3,885)	(2,888)	(6,763)	(5,219)
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	(632)	(193)	(1,243)	(440)
Selling and marketing expense	(3,261)	(2,702)	(5,536)	(4,793)
General and administrative expense	8	7	16	14
Product development expense	0	0	0	0
Depreciation	0	0	0	0
Amortization of intangibles	0	0	0	0
Goodwill impairment	0		0
Total operating costs and expenses	(3,885)	(2,888)	(6,763)	(5,219)
Operating (loss) income	0	0	0	0
Equity in earnings (losses) of unconsolidated affiliates	169,031	(89,612)	127,628	(140,799)
Interest expense	0	0	0	0
Other (expense) income, net	0	0	0	0
(Loss) earnings from continuing operations before income taxes	169,031	(89,612)	127,628	(140,799)
Income tax benefit (provision)	0	0	0	0
(Loss) earnings from continuing operations	169,031	(89,612)	127,628	(140,799)
(Loss) earnings from discontinued operations, net of tax	0	(3)	0	(3)
Net (loss) earnings	169,031	(89,615)	127,628	(140,802)
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net (loss) earnings attributable to IAC shareholders	169,031	(89,615)	127,628	(140,802)
Comprehensive (loss) income attributable to IAC shareholders	162,939	(99,971)	99,318	(88,629)
IAC
Condensed Financial Statements, Captions [Line Items]
Revenue	0	0	0	0
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	381	294	592	539
Selling and marketing expense	871	1,010	1,760	2,065
General and administrative expense	24,860	33,942	43,833	58,006
Product development expense	1,739	2,330	3,118	4,507
Depreciation	415	426	852	827
Amortization of intangibles	0	0	0	0
Goodwill impairment	0		0
Total operating costs and expenses	28,266	38,002	50,155	65,944
Operating (loss) income	(28,266)	(38,002)	(50,155)	(65,944)
Equity in earnings (losses) of unconsolidated affiliates	(150,210)	75,197	(116,667)	137,931
Interest expense	(6,996)	(12,992)	(14,414)	(25,982)
Other (expense) income, net	(18,989)	(7,506)	(28,972)	(16,859)
(Loss) earnings from continuing operations before income taxes	(204,461)	16,697	(210,208)	29,146
Income tax benefit (provision)	9,686	42,761	23,715	56,592
(Loss) earnings from continuing operations	(194,775)	59,458	(186,493)	85,738
(Loss) earnings from discontinued operations, net of tax	0	(153)	0	(28)
Net (loss) earnings	(194,775)	59,305	(186,493)	85,710
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net (loss) earnings attributable to IAC shareholders	(194,775)	59,305	(186,493)	85,710
Comprehensive (loss) income attributable to IAC shareholders	(201,218)	72,283	(172,928)	43,115
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue	322,969	397,941	707,479	812,355
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	69,374	81,348	142,191	166,787
Selling and marketing expense	162,835	204,791	371,606	418,156
General and administrative expense	43,842	39,149	83,714	74,083
Product development expense	20,098	20,974	44,516	41,572
Depreciation	7,215	6,755	14,188	13,380
Amortization of intangibles	27,098	4,182	29,083	8,363
Goodwill impairment	253,245		253,245
Total operating costs and expenses	583,707	357,199	938,543	722,341
Operating (loss) income	(260,738)	40,742	(231,064)	90,014
Equity in earnings (losses) of unconsolidated affiliates	(18,821)	14,415	(10,961)	2,868
Interest expense	0	(2,160)	0	(3,198)
Other (expense) income, net	1,874	16,177	5,978	25,633
(Loss) earnings from continuing operations before income taxes	(277,685)	69,174	(236,047)	115,317
Income tax benefit (provision)	93,393	(21,597)	80,177	(44,375)
(Loss) earnings from continuing operations	(184,292)	47,577	(155,870)	70,942
(Loss) earnings from discontinued operations, net of tax	0	0	0	0
Net (loss) earnings	(184,292)	47,577	(155,870)	70,942
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net (loss) earnings attributable to IAC shareholders	(184,292)	47,577	(155,870)	70,942
Comprehensive (loss) income attributable to IAC shareholders	(171,896)	48,886	(136,977)	66,457
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenue	426,355	376,079	863,902	736,508
Operating costs and expenses:
Cost of revenue (exclusive of depreciation shown separately below)	101,274	96,514	222,591	197,814
Selling and marketing expense	135,080	121,611	310,036	271,764
General and administrative expense	83,425	56,251	160,814	112,040
Product development expense	28,074	23,126	58,107	45,608
Depreciation	9,945	8,319	18,330	16,861
Amortization of intangibles	9,877	10,229	21,712	18,603
Goodwill impairment	22,122		22,122
Total operating costs and expenses	389,797	316,050	813,712	662,690
Operating (loss) income	36,558	60,029	50,190	73,818
Equity in earnings (losses) of unconsolidated affiliates	0	0	0	0
Interest expense	(20,648)	(62)	(41,090)	(98)
Other (expense) income, net	9,923	(10,309)	31,699	(3,424)
(Loss) earnings from continuing operations before income taxes	25,833	49,658	40,799	70,296
Income tax benefit (provision)	(6,339)	(9,196)	(8,672)	(6,429)
(Loss) earnings from continuing operations	19,494	40,462	32,127	63,867
(Loss) earnings from discontinued operations, net of tax	0	3	0	3
Net (loss) earnings	19,494	40,465	32,127	63,870
Net (earnings) loss attributable to noncontrolling interests	(4,233)	1,573	(3,885)	5,990
Net (loss) earnings attributable to IAC shareholders	15,261	42,038	28,242	69,860
Comprehensive (loss) income attributable to IAC shareholders	$ 8,957	$ 51,085	$ 37,659	$ 22,172