PRINCIPAL CLIENTS (Major Customer) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
T-Mobile
Revenue, Major Customer [Line Items]
Revenue	$ 74,686	$ 69,427	$ 76,675
Revenue concentration, percentage	24.30%	24.60%	30.70%
Sprint
Revenue, Major Customer [Line Items]
Revenue	$ 45,137	$ 25,422	$ 0
Revenue concentration, percentage	14.70%	9.00%	0.00%
AT&T
Revenue, Major Customer [Line Items]
Revenue	$ 38,257	$ 35,019	$ 55,265
Revenue concentration, percentage	12.50%	12.40%	22.10%
Comcast
Revenue, Major Customer [Line Items]
Revenue	$ 25,323	$ 31,976	$ 40,868
Revenue concentration, percentage	8.20%	11.30%	16.30%