(2) Goodwill and Other Intangible Assets

A summary of the goodwill by segment and the changes in the carrying amount of goodwill is shown in the following table (in thousands).

 

 

As of December 31, 2016, the Company had no accumulated goodwill impairment losses.

A summary of Forrester’s intangible assets is as follows (in thousands):

 

 

 

Amortization expense related to intangible assets was approximately $0.8 million, $0.9 million and $2.2 million during the years ended December 31, 2016, 2015 and 2014, respectively. Estimated amortization expense related to intangible assets that will continue to be amortized is as follows (in thousands):