CONSOLIDATED STATEMENT OF COMPREHENSIVE OPERATIONS - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net earnings		$ 146,791	$ 280,854	$ 259,776	$ 368,693
Other comprehensive income (loss), net of income taxes:
Change in foreign currency translation adjustment		1,097	(46,576)	2,406	(11,183)
Change in unrealized gains and losses of available-for-sale debt securities	[1]	(6)	13	(5)	13
Total other comprehensive income (loss), net of income taxes		1,091	(46,563)	2,401	(11,170)
Comprehensive income, net of income taxes		147,882	234,291	262,177	357,523
Components of comprehensive income attributable to noncontrolling interests:
Net earnings attributable to noncontrolling interests		(33,324)	(62,501)	(57,614)	(79,258)
Change in foreign currency translation adjustment attributable to noncontrolling interests		0	9,119	(316)	2,083
Change in unrealized gains and losses of available-for-sale debt securities attributable to noncontrolling interests		0	0	1	0
Comprehensive income attributable to noncontrolling interests		(33,324)	(53,382)	(57,929)	(77,175)
Comprehensive income attributable to IAC shareholders		$ 114,558	$ 180,909	$ 204,248	$ 280,348

[1] Net of income tax provision of $4 for both the three and six months ended June 30, 2018.