SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Property and Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 40,873	$ 40,931
Less accumulated depreciation	29,661	27,863
Property and equipment, net	11,212	13,068
Depreciation expense	2,200	2,300
Cost of Sales [Member]
Property, Plant and Equipment, Net [Abstract]
Depreciation expense	2,100	2,200
General and Administrative Expense [Member]
Property, Plant and Equipment, Net [Abstract]
Depreciation expense	100	100
Land [Member]
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	4,993	4,993
Equipment and vehicles [Member]
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 26,738	26,606
Equipment and vehicles [Member] | Minimum [Member]
Property, Plant and Equipment, Net [Abstract]
Life	1 year
Equipment and vehicles [Member] | Maximum [Member]
Property, Plant and Equipment, Net [Abstract]
Life	10 years
Office equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 1,457	1,624
Office equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Net [Abstract]
Life	1 year
Office equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Net [Abstract]
Life	7 years
Building and leasehold improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property and equipment, gross	$ 7,685	$ 7,708
Building and leasehold improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Net [Abstract]
Life	5 years
Building and leasehold improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Net [Abstract]
Life	40 years