EARNINGS (LOSS) PER SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator: Basic
Net earnings (loss)	$ 80,557	$ (190,542)	$ 109,020	$ (182,608)
Net earnings attributable to noncontrolling interests	(14,289)	(4,233)	(16,543)	(3,885)
Net earnings (loss) attributable to IAC shareholders	66,268	(194,775)	92,477	(186,493)
Numerator: Diluted
Net earnings (loss)	80,557	(190,542)	109,020	(182,608)
Net earnings attributable to noncontrolling interests	(14,289)	(4,233)	(16,543)	(3,885)
Impact from Match Group's dilutive securities	(7,925)	0	(10,355)	0
Net earnings (loss) attributable to IAC shareholders	$ 58,343	$ (194,775)	$ 82,122	$ (186,493)
Denominator: Basic
Weighted average basic shares outstanding (in shares)	79,067	79,523	78,633	80,775
Denominator: Diluted
Weighted average basic shares outstanding (in shares)	79,067	79,523	78,633	80,775
Dilutive securities including subsidiary denominated equity awards, stock options and RSUs (in shares)	4,711	0	4,510	0
Denominator for earnings per share - weighted average shares (in shares)	83,778	79,523	83,143	80,775
Earnings (loss) per share attributable to IAC shareholders: Basic
Basic earnings per share (in dollars per share)	$ 0.84	$ (2.45)	$ 1.18	$ (2.31)
Earnings (loss) per share attributable to IAC shareholders: Diluted
Diluted earnings per share (in dollars per share)	$ 0.70	$ (2.45)	$ 0.99	$ (2.31)