Goodwill is attributable to the acquisition of the Biopharma business from CGI in July 2019. The carrying value of the intangible assets acquired was $15.6 million, with goodwill of approximately $8.3 million and identifiable intangible assets of approximately $7.3 million. The goodwill balance at December 31, 2019 was $8.4 million. The net carrying value of the identifiable intangible assets as of December 31, 2019 and December 31, 2018 is as follows:

The following table displays a roll forward of the carrying amount of goodwill from January 1, 2018 to December 31, 2019:

Amortization expense was approximately $4.0 million and $3.6 million for the years ended December 31, 2019 and 2018, respectively. Estimated amortization expense for the next five years is as follows: