SHAREHOLDERS' EQUITY - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) vote / shares vote shares	Dec. 31, 2018 USD ($) shares	Feb. 06, 2019 shares
Class of Stock [Line Items]
Purchase of treasury stock | $	$ 57,949
Remaining stock authorized for repurchase (shares)	7,700,000
Class A Common Stock
Class of Stock [Line Items]
Votes per each share of stock | vote	1
Common stock outstanding (shares)	79,681,000	80,515,000
Common stock reserved (shares)	55,900,000
Stock authorized for repurchase (shares)			15,000,000
Treasury stock acquired during period (shares)	7,300,000
Purchase of treasury stock | $		$ 57,900
Class B Convertible Common Stock
Class of Stock [Line Items]
Votes per each share of stock | vote	10
Common stock outstanding (shares)	421,570,000	421,118,000
Class C Common Stock
Class of Stock [Line Items]
Common stock outstanding (shares)	0	0
Common stock, voting rights	1.00%
Delaware | Class C Common Stock
Class of Stock [Line Items]
Fractional votes for each share of common stock | vote / shares	0.01
IAC | Class B Convertible Common Stock
Class of Stock [Line Items]
Common stock outstanding (shares)	421,600,000
ANGI Homeservices | IAC | Class B Convertible Common Stock
Class of Stock [Line Items]
Ownership interest (as a percent)	84.10%
Voting interest (as a percent)	98.10%
Minimum proportion of non-voting capital stock that parent is enabled to maintain upon issuance of new stock (as a percent)	80.10%