EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator: Basic
Earnings from continuing operations	$ 91,721	$ 46,185	$ 202,970	$ 125,439
Net loss (earnings) attributable to noncontrolling interests	1,305	156	3,995	(331)
Earnings from continuing operations attributable to IAC shareholders	93,026	46,341	206,965	125,108
Earnings (loss) from discontinued operations attributable to IAC shareholders	3,914	(5,624)	1,902	(6,581)
Net earnings attributable to IAC shareholders	96,940	40,717	208,867	118,527
Numerator: Diluted
Earnings from continuing operations	91,721	46,185	202,970	125,439
Net loss (earnings) attributable to noncontrolling interests	1,305	156	3,995	(331)
Earnings from continuing operations attributable to IAC shareholders	93,026	46,341	206,965	125,108
Earnings (loss) from discontinued operations attributable to IAC shareholders	3,914	(5,624)	1,902	(6,581)
Net earnings attributable to IAC shareholders	$ 96,940	$ 40,717	$ 208,867	$ 118,527
Denominator: Basic
Weighted average basic shares outstanding	83,094	88,296	83,636	85,766
Denominator: Diluted
Weighted average basic shares outstanding	83,094	88,296	83,636	85,766
Dilutive securities including stock options, warrants and RSUs (in shares)	2,978	6,394	3,032	7,026
Denominator for earnings per share-weighted average shares (in shares)	86,072	94,690	86,668	92,792
Earnings (loss) per share attributable to IAC shareholders: Basic
Earnings per share from continuing operations (in dollars per share)	$ 1.12	$ 0.52	$ 2.47	$ 1.46
Discontinued operations (in dollars per share)	$ 0.05	$ (0.06)	$ 0.03	$ (0.08)
Earnings per share (in dollars per share)	$ 1.17	$ 0.46	$ 2.50	$ 1.38
Earnings (loss) per share attributable to IAC shareholders: Diluted
Earnings per share from continuing operations (in dollars per share)	$ 1.08	$ 0.49	$ 2.39	$ 1.35
Discontinued operations (in dollars per share)	$ 0.05	$ (0.06)	$ 0.02	$ (0.07)
Earnings per share (in dollars per share)	$ 1.13	$ 0.43	$ 2.41	$ 1.28