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) Income	Treasury Stock	Noncontrolling Interests	Match Group and ANGI Homeservices	Match Group and ANGI Homeservices Total IAC Shareholders' Equity	Match Group and ANGI Homeservices Additional Paid-in Capital	Match Group and ANGI Homeservices Accumulated Other Comprehensive (Loss) Income	Match Group and ANGI Homeservices Noncontrolling Interests
Balance at beginning of period at Dec. 31, 2018		$ 65,687
Increase (Decrease) in Redeemable Noncontrolling Interests
Net (loss) earnings		(1,051)
Other comprehensive income (loss), net of income taxes		186
Stock-based compensation expense		42
Purchase of redeemable 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
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 income (loss), net of income taxes	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 (shares)				326,000
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(4,910)		(4,910)	$ 1		(4,911)
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											$ (147,858)	$ (157,950)	$ (158,958)	$ 1,008	$ 10,092
Other	(17)		(17)			(17)
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
Balance at beginning of period at Dec. 31, 2019	44,527	44,527
Increase (Decrease) in Redeemable Noncontrolling Interests
Net (loss) earnings		(1,462)
Other comprehensive income (loss), net of income taxes		99
Stock-based compensation expense		15
Purchase of redeemable noncontrolling interests		(3,165)
Adjustment of redeemable noncontrolling interests to fair value		2,418
Other		(1)
Balance at end of period at Mar. 31, 2020	42,431	$ 42,431
Balance at beginning of period at Dec. 31, 2019	3,898,318		2,928,042	$ 263	$ 16	11,683,799	1,689,925	(136,349)	(10,309,612)	970,276
Balance at beginning of period (shares) at Dec. 31, 2019				263,230,000	16,157,000
Increase (Decrease) in Shareholders' Equity
Net (loss) earnings	(181,181)		(211,040)				(211,040)			29,859
Other comprehensive income (loss), net of income taxes	(26,204)		(21,339)					(21,339)		(4,865)
Stock-based compensation expense	56,085		11,499			11,499				44,586
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (shares)				272,000
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	(20,515)		(20,515)	$ 1		(20,516)
Adjustment of redeemable noncontrolling interests to fair value	(2,418)		(2,418)			(2,418)
Issuance of common stock pursuant to stock-based awards, net of withholding taxes											(148,604)	(139,162)	(139,565)	$ 403	$ (9,442)
Purchase of treasury stock											$ (120,658)	$ (120,658)	$ (120,658)
Other	1		1			1
Balance at end of period at Mar. 31, 2020	$ 3,454,824		$ 2,424,410	$ 264	$ 16	$ 11,412,142	$ 1,478,885	$ (157,285)	$ (10,309,612)	$ 1,030,414
Balance at end of period (shares) at Mar. 31, 2020				263,502,000	16,157,000