EARNINGS PER SHARE - COMPUTATION OF BASIC AND DILUTED EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Numerator:
Earnings 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
Net loss attributable to noncontrolling interests									6,098	5,643	2,059
Impact from Match Group's dilutive securities									(1,799)	0	0
Earnings from continuing operations attributable to IAC shareholders									119,455	240,200	283,858
Earnings from continuing operations attributable to IAC shareholders									117,656	240,200	283,858
Less: earnings from discontinued operations, net of tax	28	17	(153)	125	625	175,730	(868)	(814)	17	174,673	1,926
Net earnings 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
Net earnings attributable to IAC shareholders									$ 117,673	$ 414,873	$ 285,784
Denominator:
Weighted average basic shares outstanding									82,944	83,292	83,480
Dilutive securities including stock options, warrants and RSUs (in shares)									5,323	5,266	3,262
Denominator for earnings per share-weighted average shares (in shares)									88,267	88,558	86,742
Earnings per share 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
Discontinued operations, net of tax (in dollars per share)									0.00	2.10	0.02
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
Earnings (loss) per share attributable to IAC shareholders: 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
Discontinued operations, net of tax (in dollars per share)									0.00	1.97	0.02
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
RSUs
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (in shares)									1,500	300	400
PSUs
Anti-dilutive weighted average common shares
Potentially dilutive securities excluded from calculation of diluted earnings per share (in shares)									100	100