INTANGIBLE ASSETS AND GOODWILL

The Company's intangible assets at December 31, 2019 and 2018 consisted of the following (in thousands):



December 31, 2019	Weighted average amortization period (years)	Cost		Accumulated amortization		Net carrying value
In-process research and development	*	$	5,600	$	—	$	5,600
Developed technology	6.79	188,880		100,760		88,120
Customer relationships	9.46	152,140		33,350		118,790
Trade names	5.20	2,000		1,144		856
Internal use software	3.00	730		730		—
	7.82	$	349,350	$	135,984	$	213,366



December 31, 2018	Weighted average amortization period (years)	Cost		Accumulated amortization		Net carrying value
In-process research and development	*	$	5,600	$	—	$	5,600
Developed technology	6.91	182,880		63,187		119,693
Customer relationships	9.44	146,940		22,218		124,722
Trade names	5.20	2,000		624		1,376
Internal use software	3.00	730		730		—
	7.88	$	338,150	$	86,759	$	251,391

* An in-process research and development intangible asset has an indefinite life until the product is generally available, at which time such asset is typically reclassified to developed technology.

Amortization expense for intangible assets for the years ended December 31, 2019, 2018 and 2017 was as follows (in thousands):



	Year ended December 31,						Statement of operations classification
	2019		2018		2017		Statement of operations classification
Developed technology	$	37,573	$	38,976	$	18,358	Cost of revenue - product
Customer relationships	11,132		10,203		4,145		Sales and marketing
Trade names	520		544		80		Sales and marketing
	$	49,225	$	49,723	$	22,583

In connection with the preparation of its financial statements for the fourth quarter of 2017, the Company reviewed its intangible assets and other long-lived assets for impairment indicators. The Company determined that a triggering event had occurred relative to one of its developed technology intangible assets that had been previously acquired. During 2017, the Company discontinued its ongoing development of this technology and determined that there were no alternative uses of the technology within either its existing or future product lines. As a result, the Company recorded an impairment charge of $5.5 million to write down the carrying value of the asset to zero. This expense is included as a component of Cost of revenue - product in the table above and in the Company's consolidated statement of operations for the year ended December 31, 2017.

Estimated future amortization expense for the Company's intangible assets at December 31, 2019 was as follows (in thousands):



Years ending December 31,
2020	$	48,952
2021	43,495
2022	35,092
2023	27,271
2024	20,201
Thereafter	38,355
	$	213,366

Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. The Company's annual testing for impairment of goodwill is completed as of November 30. The Company operates as a single operating segment with one reporting unit and consequently evaluates goodwill for impairment based on an evaluation of the fair value of the Company as a whole. Based on the results of the Company's 2019 annual impairment test, the Company determined that its carrying value exceeded its fair value and accordingly, the Company recorded an impairment charge of $164.3 million.

The changes in the carrying value of the Company's goodwill in the years ended December 31, 2019 and 2018 were as follows (in thousands):



	Year ended December 31,
	2019			2018
Balance at January 1
Goodwill	$	386,761		$	338,822
Accumulated impairment losses	(3,106		)	(3,106		)
	383,655			335,716
Acquisition of Anova	5,541			—
Acquisition of Edgewater	—			48,053
Write-off of goodwill attributable to dissolved subsidiary	—			(114		)
Impairment of goodwill	(164,300		)	—
Balance at December 31	$	224,896		$	383,655

The components of goodwill at December 31, 2019 and 2018 were as follows (in thousands):




	December 31,
	2019			2018
Goodwill	$	392,302		$	386,761
Accumulated impairment losses	(167,406		)	(3,106		)
	$	224,896		$	383,655