Goodwill and Intangible Assets, Net

Goodwill

Changes in the carrying amount of goodwill were as follows:



(In thousands)
Balance at December 31, 2018	$	48,485
Foreign exchange effects	(37		)
Balance at March 31, 2019	$	48,448

Intangible Assets, Net

The components of intangible assets, net were as follows:



	March 31, 2019							December 31, 2018
(In thousands)	Gross ⁽¹⁾		Accumulated Amortization ⁽¹⁾			Net		Gross ⁽¹⁾		Accumulated Amortization ⁽¹⁾			Net
Distribution rights	$	322	$	(189	)	$	133	$	329	$	(188	)	$	141
Patents	14,902		(5,837		)	9,065		14,560		(5,704		)	8,856
Trademarks and trade names	2,786		(1,976		)	810		2,786		(1,900		)	886
Developed and core technology	12,560		(8,591		)	3,969		12,560		(8,087		)	4,473
Capitalized software development costs	222		—			222		155		—			155
Customer relationships	32,683		(23,645		)	9,038		32,534		(22,675		)	9,859
Total intangible assets, net	$	63,475	$	(40,238	)	$	23,237	$	62,924	$	(38,554	)	$	24,370


⁽¹⁾	This table excludes the gross value of fully amortized intangible assets totaling $7.1 million and $7.1 million at March 31, 2019 and December 31, 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:



	Three Months Ended March 31,
(In thousands)	2019		2018
Cost of sales	$	—	$	55
Selling, general and administrative expenses	1,784		1,747
Total amortization expense	$	1,784	$	1,802

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



(In thousands)
2019 (remaining 9 months)	$	5,400
2020	6,052
2021	2,459
2022	2,259
2023	2,100
Thereafter	4,967
Total	$	23,237