Note 6 Intangible Assets

Intangible assets other than goodwill at December 31, 2016 and December 31, 2015 are summarized as follows:



	2016						2015
(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:
Patent costs	$	16,263	$	(5,873)	$	10,390	$	16,251	$	(4,895)	$	11,356	1-20	9
Acquired technology		52,881		(27,543)		25,338		52,809		(16,405)		36,404	1-16	4
Internally developed software		4,730		(3,522)		1,208		4,730		(2,919)		1,811	2	2
Customer relationships		99,067		(46,252)		52,815		101,933		(36,158)		65,775	1-14	6
Non-compete agreements		9,423		(7,277)		2,146		12,163		(8,558)		3,605	1-4	2
Trade names		28,110		(16,015)		12,095		28,108		(12,498)		15,610	1-8	5
Other		45,377		(27,868)		17,509		46,435		(23,530)		22,905	1-6	4
Total intangible assets	$	255,851	$	(134,350)	$	121,501	$	262,429	$	(104,963)	$	157,466	1-20	4

Amortization expense related to intangible assets was $35,124, $61,066 and $39,484 for the years ended December 31, 2016, 2015 and 2014, respectively. Amortization of these intangible assets is calculated on a straight-line basis.

Annual amortization expense for intangible assets is expected to be $33,286 in 2017, $28,287 in 2018, $19,883 in 2019, $16,121 in 2020 and $11,865 in 2021.

No intangible asset impairment charges were recorded by the Company for the year ended December 31, 2016.

For the year ended December 31, 2015, the Company recorded impairment charges of $93,520, reflecting $92,248 of impairment charges related to the Company’s Americas reporting unit and $1,272 of impairment charges related to the Company’s EMEA reporting unit. Further, impairment charges reflected approximately $63,852 of charges to customer relationships, $19,164 of charges to acquired technology, $5,952 of charges to trade names, $3,416 of charges to non-compete agreements, $791 of charges to other intangibles and $345 of charges to internally developed software. The impairment charges were measured as the difference between the carrying amount of the assets and their fair value. The fair value of the assets was determined under the income approach based on a discounted cash flow model using updated future revenue and operating income projections. In addition to impairment charges, gross intangible assets were negatively impacted by foreign currency translation. See Note 2 to the Consolidated Financial Statements.

No intangible asset impairment charges were recorded by the Company for the year ended December 31, 2014.