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
Increase (Decrease) in Shareholders' Equity
Cumulative effect of adoption of ASU No. 2014-09	$ 40,205		$ 36,795				$ 36,795			$ 3,410
Balance at beginning of period at Dec. 31, 2017	42,867	$ 42,867
Increase (Decrease) in Redeemable Noncontrolling Interests
Net earnings		34,481
Other comprehensive loss, net of tax		(710)
Stock-based compensation expense		1,084
Purchase of noncontrolling interests		(3,562)
Adjustment of redeemable noncontrolling interests to fair value		(372)
Noncontrolling interests created in acquisitions		2,261														$ 14,246				$ 14,246
Other		(6,519)
Balance at end of period at Sep. 30, 2018	69,530	69,530
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	505,789		435,209				435,209			70,580
Other comprehensive loss, net of tax	(11,538)		(9,616)					(9,616)		(1,922)
Stock-based compensation expense	170,922		52,763			52,763				118,159
Issuance of common stock pursuant to stock-based awards, net of withholding taxes	34,903		34,903	$ 1		34,902
Issuance of common stock pursuant to stock-based awards, net of withholding taxes (in shares)				1,416,000
Purchase of treasury stock	(82,891)		(82,891)						(82,891)
Purchase of noncontrolling interests	(1,236)									(1,236)
Adjustment of redeemable noncontrolling interests to fair value	372		372			372
Issuance of common stock pursuant to stock-based awards, net of withholding taxes, and impact to noncontrolling interests											$ (268,113)	$ (269,802)	$ (270,149)	$ 347	$ 1,689	(23,542)	$ (29,548)	$ (29,530)	$ (18)	6,006
Noncontrolling interests created in acquisitions		$ 2,261														$ 14,246				$ 14,246
Other	2,652		2,269			2,269				383
Balance at end of period at Sep. 30, 2018	$ 3,328,592		$ 2,600,482	$ 262	$ 16	$ 11,955,629	$ 1,067,042	$ (112,855)	$ (10,309,612)	$ 728,110
Balance at end of period (shares) at Sep. 30, 2018				262,040,000	16,157,000