Intangible Assets, Net and Goodwill

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets, Net and Goodwill

Intangible assets, net consisted of the following:

	December 31,
(in thousands)	2019		2018
Intangible assets subject to amortization:
Patents and purchased technology	$	14,198	$	14,198
Customer relationships	23,000		23,000
Gross carrying amount	37,198		37,198
Accumulated amortization:
Patents and purchased technology	(13,311)		(11,981)
Customer relationships	(15,713)		(14,063)
Accumulated amortization	(29,024)		(26,044)
Net carrying amount	8,174		11,154
Intangible assets not subject to amortization	115,421		115,421
Intangible assets, net	$	123,595	$	126,575

Amortization expense for intangible assets subject to amortization was $3.0 million for the years ended December 31, 2019 and 2018, respectively, and $3.9 million for the year ended December 31, 2017. At December 31, 2019 and 2018, the Company determined that its goodwill and intangible assets were not impaired.

The following table presents the estimated annual amortization expense for the years 2020 through 2024:

(in thousands)
2020	$	2,537
2021	1,650
2022	1,650
2023	1,650
2024	688