SUPPLEMENTAL CASH FLOW INFORMATION - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Interest expense—third-party	$ 12,148	$ 0	$ 0
Interest expense—related party	155	6,169	417
Income tax payments, including amounts paid to IAC for ANGI Homeservices' share of IAC's consolidated tax liability	332	1,700	8,820
Income tax refunds	$ (172)	$ (402)	$ (263)