GOODWILL AND INTANGIBLE ASSETS (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 25,729	$ 25,647
Accumulated Amortization	(9,720)	(8,754)
Total amortization	16,009	16,893
Business relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9,918	9,918
Accumulated Amortization	(1,139)	(896)
Total amortization	$ 8,779	$ 9,022
Weighted Average Remaining Life (in years)	10 years 1 month 6 days	10 years 3 months 6 days
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 7,832	$ 7,832
Accumulated Amortization	(2,443)	(2,071)
Total amortization	$ 5,389	$ 5,761
Weighted Average Remaining Life (in years)	3 years 9 months 18 days	4 years 1 month 6 days
Content
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,087	$ 4,005
Accumulated Amortization	(3,747)	(3,610)
Total amortization	$ 340	$ 395
Weighted Average Remaining Life (in years)	1 year 7 months	1 year 10 months
Domains and data licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,869	$ 2,869
Accumulated Amortization	(1,976)	(1,847)
Total amortization	$ 893	$ 1,022
Weighted Average Remaining Life (in years)	2 years	2 years 2 months 6 days
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 877	$ 877
Accumulated Amortization	(360)	(287)
Total amortization	$ 517	$ 590
Weighted Average Remaining Life (in years)	1 year 10 months 24 days	2 years 2 months
User relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 146	$ 146
Accumulated Amortization	(55)	(43)
Total amortization	$ 91	$ 103
Weighted Average Remaining Life (in years)	2 years	2 years 2 months 6 days