Goodwill and Intangible Assets, Net

Goodwill

Changes in the carrying amount of goodwill were as follows:



(In thousands)
Balance at December 31, 2017	$	48,651
Foreign exchange effects	(166		)
Balance at December 31, 2018	48,485
Foreign exchange effects	(38		)
Balance at December 31, 2019	$	48,447

We conducted annual goodwill impairment reviews on December 31, 2019, 2018, and 2017. Based on the analysis performed, we determined that our goodwill was not impaired.

Intangible Assets, Net

The components of intangible assets, net were as follows:



	December 31,
	2019							2018
(In thousands)	Gross ⁽¹⁾		Accumulated Amortization ⁽¹⁾			Net ⁽¹⁾		Gross ⁽¹⁾		Accumulated Amortization ⁽¹⁾			Net ⁽¹⁾
Distribution rights (10 years)	$	322	$	(210	)	$	112	$	329	$	(188	)	$	141
Patents (10 years)	16,587		(6,491		)	10,096		14,560		(5,704		)	8,856
Trademarks and trade names (10 years)	2,785		(2,205		)	580		2,786		(1,900		)	886
Developed and core technology (5-15 years)	12,480		(10,016		)	2,464		12,560		(8,087		)	4,473
Capitalized software development costs (2 years)	—		—			—		155		—			155
Customer relationships (10-15 years)	32,534		(25,956		)	6,578		32,534		(22,675		)	9,859
Total intangible assets, net	$	64,708	$	(44,878	)	$	19,830	$	62,924	$	(38,554	)	$	24,370


⁽¹⁾	This table excludes the gross value of fully amortized intangible assets totaling $7.4 million and $7.1 million on December 31, 2019 and 2018, respectively.

Amortization expense is recorded in selling, general and administrative expenses, except amortization expense related to capitalized software development costs, which is recorded in cost of sales. Amortization expense by statement of operations caption was as follows:



	Year Ended December 31,
(In thousands)	2019		2018		2017
Cost of sales	$	—	$	103	$	184
Selling, general and administrative expenses	7,192		7,081		6,772
Total amortization expense	$	7,192	$	7,184	$	6,956

Estimated future annual amortization expense related to our intangible assets at December 31, 2019, is as follows:



(In thousands)
2020	$	6,101
2021	2,531
2022	2,500
2023	2,354
2024	1,774
Thereafter	4,570
Total	$	19,830

The remaining weighted average amortization period of our intangible assets is 5.3 years.