Goodwill and Other Intangible Assets

On July 6, 2018, we acquired Griswold. For further detail on the goodwill and other intangible assets recorded in connection with the acquisition, see Note 5 - Acquisitions.

Goodwill

The changes in the carrying amount of goodwill for the period ending September 30, 2018, by operating segment, were as follows:



(Dollars in thousands)	Advanced Connectivity Solutions		Elastomeric Material Solutions			Power Electronics Solutions			Other		Total
December 31, 2017	$	51,693	$	111,575		$	71,615		$	2,224	$	237,107
Acquisition	—		32,305			—			—		32,305
Foreign currency translation adjustment	—		(631		)	(2,477		)	—		(3,108		)
September 30, 2018	$	51,693	$	143,249		$	69,138		$	2,224	$	266,304

Other Intangible Assets



	September 30, 2018						December 31, 2017
(Dollars in thousands)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Customer relationships	$	149,933	$	27,985	$	121,948	$	128,907	$	22,514	$	106,393
Technology	81,840		36,974		44,866		73,891		33,491		40,400
Trademarks and trade names	12,024		2,934		9,090		10,213		2,157		8,056
Covenants not to compete	1,340		200		1,140		1,799		1,108		691
Total definite-lived other intangible assets	245,137		68,093		177,044		214,810		59,270		155,540
Indefinite-lived other intangible asset	4,574		—		4,574		4,738		—		4,738
Total other intangible assets	$	249,711	$	68,093	$	181,618	$	219,548	$	59,270	$	160,278

Gross and net carrying amounts and accumulated amortization may differ from prior periods due to foreign exchange rate fluctuations.

Amortization expense for the three and nine months ended September 30, 2018 was approximately $4.4 million and $12.1 million, respectively. Amortization expense for the three and nine months ended September 30, 2017 was approximately $3.8 million and $11.0 million, respectively. The estimated future amortization expense is $4.4 million for the remainder of 2018 and $17.8 million, $14.7 million, $13.9 million and $13.3 million for 2019, 2020, 2021 and 2022, respectively.

The indefinite-lived other intangible asset was acquired as part of the acquisition of Curamik Electronics GmbH. This asset is assessed for impairment annually, and between annual assessments if an event occurs or circumstances change that indicate the carrying value may not be recoverable.

The definite-lived other intangible assets are amortized using a fair value methodology that is based on the projected economic use of the related underlying asset. The weighted average remaining amortization period as of September 30, 2018, by definite-lived other intangible asset class, is presented in the table below:



Definite-Lived Other Intangible Asset Class		Weighted Average Remaining Amortization Period
Customer relationships		7.7
Technology		4.4
Trademarks and trade names		5.1
Covenants not to compete		2.3
Total definite-lived other intangible assets		6.7