5. INTANGIBLE ASSETS

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


		December 31, 2018						December 31, 2017
		Gross		Accumulated		Net Book		Gross		Accumulated		Net Book
	Life	Amount		amortization		Value		Amount		amortization		Value
Customer lists	8 - 17 years	$	64,439	$	(15,343)	$	49,096	$	38,659	$	(12,721)	$	25,938
Trade name	10 - 19 years		12,249		(3,305)		8,944		6,213		(2,798)		3,415
Design and technologies	10 - 15 years		13,023		(2,723)		10,300		5,147		(2,443)		2,704
Patents	17 years		24		(10)		14		24		(8)		16
Total		$	89,735	$	(21,381)	$	68,354	$	50,043	$	(17,970)	$	32,073

Intangible assets resulting from the acquisition of TCI were approximately $36,400 (Note 2). The intangible assets acquired consist of customer lists, a trade name and technology. The valuation and useful life of the purchased intangibles has not been finalized.

Intangible assets resulting from the acquisition of the Maval OE Steering business were approximately $3,870 (Note 2). The intangible assets acquired consist of customer lists.

Total amortization expense for intangible assets for the years 2018, 2017 and 2016 was $3,655, $3,219 and $3,204, respectively.

Estimated amortization expense for intangible assets is as follows (in thousands):


Year ending December 31,	Total
2019	$	5,736
2020		5,736
2021		5,481
2022		5,481
2023		5,400
Thereafter		40,520
	$	68,354