Intangible Assets

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets, net, other than goodwill, at June 30, 2018 and December 31, 2017 are summarized as follows:



	2018							2017
(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	$	104,015	$	(62,349	)	$	41,666	$	105,505	$	(57,796	)	$	47,709	6
Acquired technology	48,973		(39,803		)	9,170		54,716		(39,644		)	15,072		2
Trade names	25,284		(16,503		)	8,781		25,813		(15,552		)	10,261		6
Patent costs	17,972		(7,825		)	10,147		17,909		(7,338		)	10,571		15
Trade secrets	19,331		(12,522		)	6,809		19,431		(11,530		)	7,901		4
Acquired patents	16,217		(12,355		)	3,862		16,661		(11,969		)	4,692		8
Other	19,628		(17,922		)	1,706		20,012		(17,435		)	2,577		2
Total intangible assets	$	251,420	$	(169,279	)	$	82,141	$	260,047	$	(161,264	)	$	98,783	6

^(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 $7,836 and $15,903 for the quarter and six months ended June 30, 2018, respectively, compared to $8,984 and $17,816 for the quarter and six months ended June 30, 2017, respectively.