Intangible Assets

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

(8) Intangible Assets

Intangible assets, net, other than goodwill, at December 31, 2019 and 2018 are summarized as follows:


	2019										2018
(in thousands)	Gross ^a		Accumulated Amortization		Net		Gross ^a		Accumulated Amortization		Net		Weighted Average Useful Life Remaining (in years)
Intangible assets with finite lives:
Customer relationships	$	103,661	$	(77,021)	$	26,640	$	103,332	$	(67,129)	$	36,203	4
Acquired technology	54,378		(51,875)		2,503		52,691		(47,546)		5,145		1
Trade names	23,907		(19,133)		4,774		25,096		(17,669)		7,427		4
Patent costs	11,760		(9,535)		2,225		11,032		(8,382)		2,650		15
Trade secrets	19,494		(15,714)		3,780		19,374		(13,574)		5,800		2
Acquired patents	16,215		(14,706)		1,509		16,212		(13,160)		3,052		7
Other	26,256		(19,349)		6,907		26,551		(18,553)		7,998		1
Total intangible assets	$	255,671	$	(207,333)	$	48,338	$	254,288	$	(186,013)	$	68,275	5

a.Change in gross carrying amounts consists primarily of charges for license and patent costs and foreign currency translation.

Amortization expense related to intangible assets was $20,312, $29,722 and $35,559 for the years ended December 31, 2019 2018 and 2017, respectively.

Annual amortization expense for intangible assets is expected to be $16,936 in 2020, $12,488 in 2021, $7,370 in 2022, $2,418 in 2023 and $1,320 in 2024.