INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 19, 2018	Dec. 31, 2017
Intangible assets subject to amortization
Gross Amount	$ 53,426		$ 53,426			$ 50,043
Accumulated amortization	(19,598)		(19,598)			(17,970)
Net Book Value	33,828		33,828			32,073
Intangible assets resulting from acquisition					$ 3,700
Amortization expense for intangible assets	878	$ 799	1,762	$ 1,592
Estimated amortization expense
Remainder of 2018	1,747		1,747
2019	3,493		3,493
2020	3,493		3,493
2021	3,234		3,234
2022	3,234		3,234
2023	3,152		3,152
Thereafter	15,475		15,475
Total estimated amortization expense	33,828		33,828
Customer lists
Intangible assets subject to amortization
Gross Amount	42,200		42,200			38,659
Accumulated amortization	(13,982)		(13,982)			(12,721)
Net Book Value	28,218		$ 28,218			25,938
Customer lists | Minimum
Intangible assets subject to amortization
Estimated Life			8 years
Customer lists | Maximum
Intangible assets subject to amortization
Estimated Life			17 years
Trade name
Intangible assets subject to amortization
Gross Amount	6,178		$ 6,178			6,213
Accumulated amortization	(3,042)		(3,042)			(2,798)
Net Book Value	3,136		$ 3,136			3,415
Trade name | Minimum
Intangible assets subject to amortization
Estimated Life			10 years
Trade name | Maximum
Intangible assets subject to amortization
Estimated Life			12 years
Design and technologies
Intangible assets subject to amortization
Gross Amount	5,024		$ 5,024			5,147
Accumulated amortization	(2,565)		(2,565)			(2,443)
Net Book Value	2,459		$ 2,459			2,704
Design and technologies | Minimum
Intangible assets subject to amortization
Estimated Life			10 years
Design and technologies | Maximum
Intangible assets subject to amortization
Estimated Life			12 years
Patents
Intangible assets subject to amortization
Gross Amount	24		$ 24			24
Accumulated amortization	(9)		(9)			(8)
Net Book Value	$ 15		$ 15			$ 16
Estimated Life			17 years