GOODWILL AND INTANGIBLE ASSETS (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 25,554	$ 25,647
Accumulated Amortization	(11,312)	(8,754)
Total amortization	14,242	16,893
Business relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9,918	9,918
Accumulated Amortization	(1,625)	(896)
Total amortization	$ 8,293	$ 9,022
Weighted Average Remaining Life (in years)	9 years 8 months 12 days	10 years 3 months 19 days
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 7,832	$ 7,832
Accumulated Amortization	(3,189)	(2,071)
Total amortization	$ 4,643	$ 5,761
Weighted Average Remaining Life (in years)	3 years 4 months 24 days	4 years 1 month 6 days
Content
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,912	$ 4,005
Accumulated Amortization	(3,681)	(3,610)
Total amortization	$ 231	$ 395
Weighted Average Remaining Life (in years)	1 year	1 year 9 months 18 days
Domains and data licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,869	$ 2,869
Accumulated Amortization	(2,231)	(1,847)
Total amortization	$ 638	$ 1,022
Weighted Average Remaining Life (in years)	1 year 7 months 6 days	2 years 2 months 12 days
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 877	$ 877
Accumulated Amortization	(506)	(287)
Total amortization	$ 371	$ 590
Weighted Average Remaining Life (in years)	1 year 4 months 24 days	2 years 2 months 12 days
User relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 146	$ 146
Accumulated Amortization	(80)	(43)
Total amortization	$ 66	$ 103
Weighted Average Remaining Life (in years)	1 year 6 months	2 years 2 months 12 days