SEGMENT INFORMATION - Segmented Revenue Disaggregated by Service (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenue from contracts with customers	$ 375,061	$ 343,896	$ 718,711	$ 647,339
North America
Segment Reporting Information [Line Items]
Revenue from contracts with customers	357,417	324,400	681,549	606,394
North America | Marketplace revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	293,173	261,291	551,949	481,791
North America | Consumer connection revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	272,649	241,236	512,479	442,818
North America | Service professional membership subscription revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	13,017	16,302	26,794	32,702
North America | Other revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	7,507	3,753	12,676	6,271
North America | Advertising and other revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	64,244	63,109	129,600	124,603
Europe
Segment Reporting Information [Line Items]
Revenue from contracts with customers	17,644	19,496	37,162	40,945
Europe | Advertising and other revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	484	651	1,014	1,235
Europe | Consumer connection revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	13,945	15,232	29,634	32,355
Europe | Service professional membership subscription revenue
Segment Reporting Information [Line Items]
Revenue from contracts with customers	$ 3,215	$ 3,613	$ 6,514	$ 7,355