INTANGIBLE ASSETS AND GOODWILL (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 25,728	$ 50,045
Accumulated Amortization	(7,913)	(17,434)
Total amortization	17,815	32,611
Business relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	9,919	17,400
Accumulated Amortization	(655)	(2,741)
Total amortization	$ 9,264	$ 14,659
Weighted Average Remaining Life (in years)	10 years 6 months 6 days	10 years 1 month 6 days
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 7,834	$ 9,280
Accumulated Amortization	(1,752)	(4,122)
Total amortization	$ 6,082	$ 5,158
Weighted Average Remaining Life (in years)	4 years 3 months 18 days	3 years 1 month 6 days
Domains and data licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,869	$ 2,804
Accumulated Amortization	(1,719)	(1,340)
Total amortization	$ 1,150	$ 1,464
Weighted Average Remaining Life (in years)	2 years 6 months	3 years
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 999	$ 3,338
Accumulated Amortization	(285)	(1,861)
Total amortization	$ 714	$ 1,477
Weighted Average Remaining Life (in years)	2 years 4 months 24 days	2 years 1 month 6 days
Content
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,961	$ 3,674
Accumulated Amortization	(3,476)	(2,581)
Total amortization	$ 485	$ 1,093
Weighted Average Remaining Life (in years)	1 year 10 months 24 days	2 years
User relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 146	$ 12,000
Accumulated Amortization	(26)	(3,240)
Total amortization	$ 120	$ 8,760
Weighted Average Remaining Life (in years)	2 years 6 months	5 years 1 month 6 days
Advertiser relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 1,549
Accumulated Amortization		(1,549)
Total amortization		$ 0
Weighted Average Remaining Life (in years)		0 years