Intangible Assets

12 Months Ended

Dec. 31, 2017

Note 6 Intangible Assets

Intangible assets other than goodwill at December 31, 2017 and December 31, 2016 are summarized as follows:


	2017						2016
(in thousands)	Gross		Accumulated Amortization		Net		Gross		Accumulated Amortization		Net		Useful Life (in years)	Weighted Average Useful Life Remaining (in years)
Intangible assets with finite lives:
Customer relationships	$	105,505	$	(57,796)	$	47,709	$	99,067	$	(46,252)	$	52,815	1-14	6
Acquired technology		54,716		(39,644)		15,072		52,881		(27,543)		25,338	1-16	2
Trade names		25,813		(15,552)		10,261		28,110		(16,015)		12,095	1-8	6
Patent costs		17,909		(7,338)		10,571		16,263		(5,873)		10,390	1-20	15
Trade secrets		19,431		(11,530)		7,901		19,134		(9,383)		9,751	7	4
Acquired patents		16,661		(11,969)		4,692		16,965		(10,674)		6,291	1-6	8
Other		20,012		(17,435)		2,577		23,431		(18,610)		4,821	2-4	2
Total intangible assets	$	260,047	$	(161,264)	$	98,783	$	255,851	$	(134,350)	$	121,501	1-20	6

The Company includes all amortization from assets attributable to the generation of revenue in the Cost of Sales line item in the statement of operations. Amortization related to assets that are not attributable to the generation of revenue are included in the Research and Development and Selling and General Administrative line items in the statement of operations. Amortization expense related to intangible assets was $35,559, $35,124 and $61,066 for the years ended December 31, 2017, 2016 and 2015, respectively. Amortization of these intangible assets is calculated on a straight-line basis.

Annual amortization expense for intangible assets is expected to be $29,448 in 2018, $20,411 in 2019, $17,308 in 2020, $12,859 in 2021 and $7,493 in 2022.

For discussion on intangible asset impairment testing, see Note 2.