Purchased intangible assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Purchased Intangible Assets

Purchased intangible assets consist of the following (in thousands): 

	December 31, 2019							December 31, 2018
	Gross Assets		Accumulated Amortization			Net Assets		Gross Assets		Accumulated Amortization			Net Assets
Technology and patents	$	36,880	$	(35,555	)	$	1,325	$	37,029	$	(34,995	)	$	2,034
Customer relationships	15,089		(15,089		)	—		15,146		(15,026		)	120
Leasehold interest	1,222		(396		)	826		1,238		(374		)	864
	$	53,191	$	(51,040	)	$	2,151	$	53,413	$	(50,395	)	$	3,018

Amortization Expense of Purchased Intangible Assets

The following table presents details of the amortization expense of the Company’s purchased intangible assets as reported in the consolidated statements of operations (in thousands): 

	Years ended December 31,
	2019		2018		2017
Cost of goods sold	$	737	$	756	$	869
Operating expenses	119		475		472
Total	$	856	$	1,231	$	1,341

 

Estimated Future Amortization Expense of Purchased Intangible Assets

The estimated future amortization expense of purchased intangible assets as of December 31, 2019, is as follows (in thousands): 

2020	$	736
2021	644
2022	27
2023	27
2024	27
Thereafter	690
	$	2,151