Goodwill and Intangible Assets

9 Months Ended

Sep. 30, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

The changes in the carrying amount of goodwill for the nine months ended September 30, 2021 are as follows:


	Nine months ended September 30, 2021
	(in thousands)
Balance as of December 31, 2020	$	635,590
Foreign currency translation and other adjustments	45
Balance as of September 30, 2021	$	635,635

As of September 30, 2021 and December 31, 2020, our intangible assets consisted of the following:


	As of September 30, 2021						As of December 31, 2020
	Gross carrying value		Accumulated amortization		Net carrying value		Gross carrying value		Accumulated amortization		Net carrying value
	(in thousands)
Intangible assets:
Customer relationships	$	69,100	$	(8,638)	$	60,462	$	69,100	$	(2,053)	$	67,047
Developed technology	49,500		(9,900)		39,600		49,500		(2,475)		47,025
Trade names	3,300		(1,100)		2,200		3,300		(275)		3,025
Internet protocol addresses	4,984		(848)		4,136		2,891		(578)		2,313
Backlog	2,200		(1,100)		1,100		2,200		(275)		1,925
In-process research and development ("IPR&D")	368		—		368		368		—		368
Domain name	39		—		39		39		—		39
Total intangible assets	$	129,491	$	(21,586)	$	107,905	$	127,398	$	(5,656)	$	121,742

Our intangible assets are comprised of customer relationships, developed technology, trade names, internet protocol addresses, backlog, and IPR&D. Our customer relationships, developed technology, trade names, internet protocol addresses, backlog, domain name intangible assets are subject to amortization. IPR&D intangible and domain name assets are indefinite-lived and not subject to amortization. We purchased $2.1 million and $1.8 million of intangible assets during the nine months ended September 30, 2021 and 2020, respectively. We did not purchase intangible assets during the three months ended September 30, 2021 and 2020.

Amortization expense was $5.3 million and $15.9 million for the three and nine months ended September 30, 2021, respectively. Amortization expense was less than $0.1 million and $0.1 million for the three and nine months ended September 30, 2020, respectively.

We perform tests for impairment of goodwill and long-lived assets on an annual basis as of October 31 or more frequently if events or changes in circumstances indicate that our long-lived assets might be impaired. We did not record any impairment charges during both the three and nine months ended September 30, 2021 and 2020.

The annual expected amortization expense of intangible assets subject to amortization as of September 30, 2021 is as follows:


	As of September 30, 2021
	(in thousands)
Remainder of 2021	$	5,313
2022	20,974
2023	19,874
2024	19,040
2025	16,561
Thereafter	25,771
Total	$	107,533