There were no changes to the goodwill valued at $3.3 million during the three and nine months ended September 30, 2020. The Company performs an annual impairment test of goodwill as of the end of the first month of the fourth fiscal quarter (October 31), or at an interim date if an event occurs or if circumstances change that would indicate that an impairment loss may have been incurred. In performing the annual impairment test, the Company may consider qualitative factors that would indicate possible impairment. A quantitative fair value assessment is also performed at the reporting unit level. If the fair value exceeds the carrying value, then goodwill is not impaired, and no further testing is performed. If the carrying value exceeds the fair value, the implied fair value of goodwill is then compared against the carrying value of goodwill to determine the amount of impairment. In addition to the annual impairment test, the Company is required to regularly assess whether a triggering event has occurred which would require interim impairment testing. The Company considered the current and expected future economic and market conditions surrounding the COVID-19 pandemic and its impact on each of the reporting units. Further, the Company assessed the current market capitalization, forecasts and the amount of headroom in the 2019 impairment test. There were no triggering events during the nine months ended September 30, 2020. The Company will continue to monitor goodwill for impairment going forward.

The Company amortizes intangible assets with finite lives on a straight-line basis over the estimated useful lives, which range from one to six years. The summary of amortization expense in the condensed consolidated statement of operations is as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Cost of revenues	$	0	$	167	$	111	$	500
Operating expenses		0		48		33		170
Total	$	0	$	215	$	144	$	670

	September 30, 2020						December 31, 2019
			Accumulated		Net Book				Accumulated		Net Book
	Cost		Amortization		Value		Cost		Amortization		Value
Customer contracts and relationships	$	16,880	$	16,880	$	0	$	16,880	$	16,880	$	0
Patents and technology		10,114		10,114		0		10,114		10,003		111
Trademarks and trade names		4,834		4,834		0		4,834		4,801		33
Other		2,506		2,506		0		2,506		2,506		0
Total	$	34,334	$	34,334	$	0	$	34,334	$	34,190	$	144

The $0.1 million decrease in the net book value of intangible assets at September 30, 2020 compared to December 31, 2019 relates to amortization expense for the nine months ended September 30, 2020.

The assigned lives and weighted average amortization periods by intangible asset category are summarized below:

The Company’s intangible assets were fully amortized as of February 2020. The amortization expense for 2020 is as follows: