4.    Goodwill and Intangible Assets

There were no changes to the goodwill carrying value from December 31, 2020 through March 31, 2021. The foreign exchange impact on Goodwill was immaterial for the period.

The following table summarizes the Company’s intangible assets and related accumulated amortization:

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Amortization expense for each of the three months ended March 31, 2021 and March 31, 2020 is $4.5 million.

Estimated future expected amortization expense of intangible assets as of March 31, 2021, is as follows:

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The weighted-average remaining useful life by major asset classes as of March 31, 2021 is as follows:

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There were no impairments identified during the three months ended March 31, 2021 and March 31, 2020.