Intangible Assets

9 Months Ended

Sep. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

(5) Intangible Assets

Intangible assets, net, other than goodwill, at September 30, 2020 and December 31, 2019 are summarized as follows:


	2020						2019
(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	$	106,098	$	(86,068)	$	20,030	$	103,661	$	(77,021)	$	26,640	4
Acquired technology	54,795		(53,329)		1,466		54,378		(51,875)		2,503		1
Trade names	23,754		(20,224)		3,530		23,907		(19,133)		4,774		4
Patent costs	19,112		(10,345)		8,767		11,760		(9,535)		2,225		15
Trade secrets	19,857		(17,535)		2,322		19,494		(15,714)		3,780		2
Acquired patents	16,266		(15,498)		768		16,215		(14,706)		1,509		7
Other	19,707		(19,702)		5		26,256		(19,349)		6,907		1
Total intangible assets	$	259,589	$	(222,701)	$	36,888	$	255,671	$	(207,333)	$	48,338	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 $4,260 and $12,806 for the quarter and nine months ended September 30, 2020, respectively, compared to $5,287 and $16,525 for the quarter and nine months ended September 30, 2019, respectively.