QUARTERLY RESULTS (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 848,728	$ 838,561	$ 771,132	$ 772,512	$ 830,754	$ 782,231	$ 756,315	$ 740,247	$ 3,230,933	$ 3,109,547	$ 3,022,987
Cost of revenue	214,084	199,377	177,963	186,737	233,712	218,452	205,295	202,745	778,161	860,204	977,357
Operating income	(5,430)	87,130	62,769	35,119	110,372	100,953	95,690	71,712	179,588	378,727	426,203
Earnings (loss) from continuing operations	(31,417)	65,026	57,885	21,863	67,986	150,261	(17,995)	34,305	113,357	234,557	281,799
(Loss) earnings from discontinued operations, net of tax	28	17	(153)	125	625	175,730	(868)	(814)	17	174,673	1,926
Net earnings	(31,389)	65,043	57,732	21,988	68,611	325,991	(18,863)	33,491	113,374	409,230	283,725
Net earnings (loss) attributable to IAC shareholders	$ (31,849)	$ 65,611	$ 59,305	$ 26,405	$ 70,172	$ 326,812	$ (17,996)	$ 35,885	$ 119,472	$ 414,873	$ 285,784
Per share information attributable to IAC shareholders:
Basic earnings per share from continuing operations (in usd per share)	$ (0.38)	$ 0.79	$ 0.72	$ 0.31	$ 0.83	$ 1.81	$ (0.21)	$ 0.44	$ 1.44	$ 2.88	$ 3.40
Diluted earnings per share from continuing operations (in usd per share)	(0.38)	0.74	0.68	0.30	0.78	1.70	(0.21)	0.42	1.33	2.71	3.27
Basic earnings per share (in usd per share)	(0.38)	0.79	0.72	0.32	0.84	3.91	(0.22)	0.44	1.44	4.98	3.42
Diluted earnings per share (in usd per share)	$ (0.38)	$ 0.74	$ 0.68	$ 0.30	$ 0.78	$ 3.68	$ (0.22)	$ 0.41	$ 1.33	$ 4.68	$ 3.29
Intangible Assets and Goodwill
Goodwill impairment									$ 14,056	$ 0	$ 0
After tax other-than-temporary impairment charge			$ 63,600
Operating Segments
Intangible Assets and Goodwill
Goodwill impairment									14,056
Publishing | Operating Segments
Quarterly Financial Information Disclosure [Abstract]
Revenue									691,686	791,549	803,141
Operating income									(26,692)	110,523	119,484
Intangible Assets and Goodwill
Write-down of indefinite-lived intangible assets	$ 55,300
Goodwill impairment									0
Other | Operating Segments
Quarterly Financial Information Disclosure [Abstract]
Revenue									184,095	187,834	182,615
Operating income									(9,186)	$ 8,108	$ (344)
Intangible Assets and Goodwill
Goodwill impairment	$ 14,100								$ 14,056