Goodwill and Intangible Assets

3 Months Ended

Mar. 31, 2020

Goodwill

The following table represents changes in the carrying amount of goodwill:


	December 31, 2019		Additions		Foreign currency exchange rate fluctuations		March 31, 2020

	(In thousands)
Goodwill	$	336,539	$	—	$	(1,697)	$	334,842

Intangible Assets, Net

The carrying amounts and useful lives of intangible assets as of March 31, 2020 and December 31, 2019 were as follows:


	March 31, 2020
	Gross carrying amount ⁽¹⁾		Accumulated amortization		Foreign currency exchange rate fluctuations		Net carrying amount		Useful life (years)

	(In thousands, except for years)
Customer relationships	$	134,889	$	(56,727)	$	(1,398)	$	76,764	10 - 30
Acquired technology	77,029		(38,058)		4		38,975		5 - 20
Backlog	1,150		(863)		—		287		4
Trade names	7,650		(5,206)		9		2,453		6 - 12
Patents	3,217		(1,633)		—		1,584		2 - 20


Total intangibles assets, net	$	223,935	$	(102,487)	$	(1,385)	$	120,063


	December 31, 2019
	Gross carrying amount ⁽¹⁾		Accumulated amortization		Foreign currency exchange rate fluctuations		Net carrying amount		Useful life (years)

	(In thousands, except for years)
Customer relationships	$	135,234	$	(54,860)	$	(1,058)	$	79,316	10 - 30
Acquired technology	77,142		(36,194)		5		40,953		3 - 20
Backlog	1,150		(791)		—		359		4
Trade names	7,650		(5,037)		11		2,624		6 - 12
Patents	3,217		(1,603)		1		1,615		2 - 20


Total intangibles assets, net	$	224,393	$	(98,485)	$	(1,041)	$	124,867

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⁽¹⁾The differences in gross carrying amounts between periods are primarily due to the write-off of certain fully amortized intangible assets.

Amortization expense of intangible assets was $4.5 million and $4.8 million for the three months ended March 31, 2020 and 2019, respectively.

The estimated future amortization expenses for amortizable intangible assets were as follows: