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 (loss) earnings		(959)
Other comprehensive loss, net of tax		579
Stock-based compensation expense		410
Purchase of noncontrolling interests		0
Adjustment of redeemable noncontrolling interests to fair value		3,403
Noncontrolling interests created in acquisitions	$ 0	787								$ 0
Other		12
Balance at end of period at Mar. 31, 2018		47,099
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 (loss) earnings	88,798		71,082				71,082			17,716
Other comprehensive loss, net of tax	34,814		28,357					28,357		6,457
Stock-based compensation expense	58,672		17,214			17,214				41,458
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	25,275		25,275			25,275
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				772,000
Purchase of noncontrolling interests	(269)									(269)
Adjustment of redeemable noncontrolling interests to fair value	(3,403)		(3,403)			(3,403)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											$ (110,043)	$ (111,457)	$ (111,721)	$ 264	$ 1,414	$ (1,143)	$ (1,941)	$ (1,938)	$ (3)	$ 798
Noncontrolling interests created in acquisitions	0	787								0
Other	2,662		2,577			2,577				85
Balance at end 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 end of period (shares) at Mar. 31, 2018				261,396,000	16,157,000
Balance at beginning of period at Dec. 31, 2018	65,687	65,687
Increase (Decrease) in Redeemable Noncontrolling Interests
Net (loss) earnings		(1,051)
Other comprehensive loss, net of tax		186
Stock-based compensation expense		42
Purchase of noncontrolling interests		(3,182)
Adjustment of redeemable noncontrolling interests to fair value		10,242
Other		(10)
Balance at end of period at Mar. 31, 2019	71,914	$ 71,914
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 (loss) earnings	114,036		88,695				88,695			25,341
Other comprehensive loss, net of tax	1,124		995					995		129
Stock-based compensation expense	67,402		20,165			20,165				47,237
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(4,910)		(4,910)	$ 1		(4,911)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				326,000
Purchase of noncontrolling interests	0									0
Adjustment of redeemable noncontrolling interests to fair value	(10,242)		(10,242)			(10,242)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											$ (131,876)	$ (132,860)	$ (133,861)	$ 1,001	$ 984	$ (15,982)	$ (25,090)	$ (25,097)	$ 7	$ 9,108
Other	(17)		(17)			(17)				0
Balance at end 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 end of period (shares) at Mar. 31, 2019				262,629,000	16,157,000