INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2017

INTANGIBLE ASSETS

INTANGIBLE ASSETS

3.    INTANGIBLE ASSETS

Intangible assets on the Company’s consolidated balance sheets consist of the following (in thousands):

		December 31, 2017							December 31, 2016
	Life	Gross Amount		Accumulated amortization			Net Book Value		Gross Amount		Accumulated amortization			Net Book Value
Customer lists	8 - 17 years	$	38,659	$	(12,721	)	$	25,938	$	37,868	$	(10,087	)	$	27,781
Trade name	10 - 12 years	6,213		(2,798		)	3,415		6,038		(2,281		)	3,757
Design and technologies	10 - 12 years	5,147		(2,443		)	2,704		4,537		(1,840		)	2,697
Patents	17 years	24		(8		)	16		24		(7		)	17
Total		$	50,043	$	(17,970	)	$	32,073	$	48,467	$	(14,215	)	$	34,252

Total amortization expense for intangible assets for the years 2017, 2016 and 2015 was $3,219, $3,204 and $2,644, respectively.

Estimated amortization expense for intangible assets is as follows:

Year ending December 31,	Total
2018	$	3,268
2019	3,268
2020	3,268
2021	3,002
Thereafter	19,267
	$	32,073