CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Redeemable Noncontrolling Interests	Total IAC Shareholders' Equity	Common Stock Common Stock $.001 Par Value	Common Stock Class B Convertible Common Stock $.001 Par Value	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Noncontrolling Interests	Match Group	Match Group Total IAC Shareholders' Equity	Match Group Additional Paid-in Capital	Match Group Accumulated Other Comprehensive Loss	Match Group Noncontrolling Interests	ANGI Homeservices	ANGI Homeservices Total IAC Shareholders' Equity	ANGI Homeservices Additional Paid-in Capital	ANGI Homeservices Accumulated Other Comprehensive Loss	ANGI Homeservices Noncontrolling Interests
Balance at beginning of period at Dec. 31, 2017		$ 42,867
Increase (Decrease) in Redeemable Noncontrolling Interests
Net earnings		34,756
Other comprehensive (loss) income, net of income taxes		(286)
Stock-based compensation expense		800
Purchase of redeemable noncontrolling interests		(59)
Adjustment of redeemable noncontrolling interests to fair value		1,849
Noncontrolling interests created in acquisitions	$ 14,246	2,261								$ 14,246
Other		(6,469)
Balance at end of period at Jun. 30, 2018		75,719
Balance at beginning of period at Dec. 31, 2017	2,946,823		$ 2,430,028	$ 261	$ 16	$ 12,165,002	$ 595,038	$ (103,568)	$ (10,226,721)	516,795
Balance at beginning of period (shares) at Dec. 31, 2017				260,624,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net earnings	333,937		289,435				289,435			44,502
Other comprehensive (loss) income, net of income taxes	(10,884)		(9,087)					(9,087)		(1,797)
Stock-based compensation expense	115,843		36,015			36,015				79,828
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	25,891		25,891	$ 1		25,890
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				1,133,000
Purchase of treasury stock	(14,713)		(14,713)						(14,713)
Purchase of redeemable noncontrolling interests	(818)									(818)
Adjustment of redeemable noncontrolling interests to fair value	(1,849)		(1,849)			(1,849)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											$ (195,094)	$ (194,809)	$ (194,764)	$ (45)	$ (285)	$ (19,290)	$ (24,019)	$ (24,002)	$ (17)	$ 4,729
Noncontrolling interests created in acquisitions	14,246	2,261								14,246
Other	2,651		2,392			2,392				259
Balance at end of period at Jun. 30, 2018	3,236,948		2,576,079	$ 262	$ 16	12,008,684	921,268	(112,717)	(10,241,434)	660,869
Balance at end of period (shares) at Jun. 30, 2018				261,757,000	16,157,000
Balance at beginning of period at Mar. 31, 2018		47,099
Increase (Decrease) in Redeemable Noncontrolling Interests
Net earnings		35,715
Other comprehensive (loss) income, net of income taxes		(865)
Stock-based compensation expense		390
Purchase of redeemable noncontrolling interests		(59)
Adjustment of redeemable noncontrolling interests to fair value		(1,554)
Noncontrolling interests created in acquisitions	14,246	1,474								14,246
Other		(6,481)
Balance at end of period at Jun. 30, 2018		75,719
Balance at beginning of period at Mar. 31, 2018	3,082,391		2,494,527	$ 261	$ 16	12,093,006	702,915	(74,950)	(10,226,721)	587,864
Balance at beginning of period (shares) at Mar. 31, 2018				261,396,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net earnings	245,139		218,353				218,353			26,786
Other comprehensive (loss) income, net of income taxes	(45,698)		(37,444)					(37,444)		(8,254)
Stock-based compensation expense	57,171		18,801			18,801				38,370
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	616		616	$ 1		615
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				361,000
Purchase of treasury stock	(14,713)		(14,713)						(14,713)
Purchase of redeemable noncontrolling interests	(549)									(549)
Adjustment of redeemable noncontrolling interests to fair value	1,554		1,554			1,554
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											(85,051)	(83,352)	(83,043)	(309)	(1,699)	(18,147)	(22,078)	(22,064)	(14)	3,931
Noncontrolling interests created in acquisitions	14,246	1,474								14,246
Other	(11)		(185)			(185)				174
Balance at end of period at Jun. 30, 2018	3,236,948		2,576,079	$ 262	$ 16	12,008,684	921,268	(112,717)	(10,241,434)	660,869
Balance at end of period (shares) at Jun. 30, 2018				261,757,000	16,157,000
Balance at beginning of period at Dec. 31, 2018	65,687	65,687
Increase (Decrease) in Redeemable Noncontrolling Interests
Net earnings		5,895
Other comprehensive (loss) income, net of income taxes		(149)
Stock-based compensation expense		77
Purchase of redeemable noncontrolling interests		(6,121)
Adjustment of redeemable noncontrolling interests to fair value		10,138
Noncontrolling interests created in acquisitions	0	5,009	0			0				0
Other		(34)
Balance at end of period at Jun. 30, 2019	80,502	80,502
Balance at beginning of period at Dec. 31, 2018	3,551,801		2,843,125	$ 262	$ 16	12,022,387	1,258,794	(128,722)	(10,309,612)	708,676
Balance at beginning of period (shares) at Dec. 31, 2018				262,303,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net earnings	253,881		202,162				202,162			51,719
Other comprehensive (loss) income, net of income taxes	2,550		2,086					2,086		464
Stock-based compensation expense	129,786		43,055			43,055				86,731
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(23,022)		(23,022)	$ 1		(23,023)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				486,000
Purchase of redeemable noncontrolling interests	0									0
Adjustment of redeemable noncontrolling interests to fair value	(10,138)		(10,138)			(10,138)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											(219,227)	(220,108)	(221,030)	922	881	(26,238)	(37,730)	(37,739)	9	11,492
Noncontrolling interests created in acquisitions	0	5,009	0			0				0
Purchase of exchangeable note hedges	(303,428)		(303,428)			(303,428)
Equity component of exchangeable senior notes, net of deferred financing costs and deferred tax liabilities	321,128		321,128			321,128
Issuance of warrants	166,520		166,520			166,520
Other	(16)		(189)			(189)				173
Balance at end of period at Jun. 30, 2019	3,843,597		2,983,461	$ 263	$ 16	11,957,543	1,460,956	(125,705)	(10,309,612)	860,136
Balance at end of period (shares) at Jun. 30, 2019				262,789,000	16,157,000
Balance at beginning of period at Mar. 31, 2019		71,914
Increase (Decrease) in Redeemable Noncontrolling Interests
Net earnings		6,946
Other comprehensive (loss) income, net of income taxes		(335)
Stock-based compensation expense		35
Purchase of redeemable noncontrolling interests		(2,939)
Adjustment of redeemable noncontrolling interests to fair value		(104)
Noncontrolling interests created in acquisitions		5,009
Other		(24)
Balance at end of period at Jun. 30, 2019	80,502	80,502
Balance at beginning of period at Mar. 31, 2019	3,571,336		2,779,861	$ 263	$ 16	11,868,424	1,347,489	(126,719)	(10,309,612)	791,475
Balance at beginning of period (shares) at Mar. 31, 2019				262,629,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net earnings	139,845		113,467				113,467			26,378
Other comprehensive (loss) income, net of income taxes	1,426		1,091					1,091		335
Stock-based compensation expense	62,384		22,890			22,890				39,494
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(18,112)		(18,112)	$ 0		(18,112)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				160,000
Purchase of redeemable noncontrolling interests	0									0
Adjustment of redeemable noncontrolling interests to fair value	104		104			104
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											$ (87,351)	$ (87,248)	$ (87,169)	$ (79)	$ (103)	$ (10,256)	$ (12,640)	$ (12,642)	$ 2	$ 2,384
Noncontrolling interests created in acquisitions		$ 5,009
Purchase of exchangeable note hedges	(303,428)		(303,428)			(303,428)
Equity component of exchangeable senior notes, net of deferred financing costs and deferred tax liabilities	321,128		321,128			321,128
Issuance of warrants	166,520		166,520			166,520
Other	1		(172)			(172)				173
Balance at end of period at Jun. 30, 2019	$ 3,843,597		$ 2,983,461	$ 263	$ 16	$ 11,957,543	$ 1,460,956	$ (125,705)	$ (10,309,612)	$ 860,136
Balance at end of period (shares) at Jun. 30, 2019				262,789,000	16,157,000