Intangible Assets

12 Months Ended

Dec. 31, 2018

Intangible Assets [Abstract]

Intangible Assets

6. INTANGIBLE ASSETS

Intangible assets consisted of the following at December 31, 2018 and 2017 (in thousands):

	2018		2017
Patents and copyrights	$	18,350	$	19,324
Less accumulated amortization		(14,448)		(14,248)
	$	3,902	$	5,076

Amortization expense for each of the years ended December 31, 2018 and 2017 was approximately $1.1 million and $1.2 million, respectively.  For each of the years ended December 31, 2018 and 2017, we recorded losses on the disposal of intangible assets of approximately $0.1 million.

Future estimated amortization expense for intangible assets that have remaining unamortized amounts as of December 31, 2018 is as follows (in thousands):

2019	$	713
2020		520
2021		448
2022		406
2023		359
2024 and thereafter		1,456
Total	$	3,902