GOODWILL AND INTANGIBLE ASSETS

The changes in goodwill included in the core banking segment during the three month periods ended March 31, 2020 and 2019 were as follows (in thousands):



	2020		2019
Beginning of year	$	21,824	$	21,824
Acquired goodwill	—		—
Ending balance March 31,	$	21,824	$	21,824

Acquired intangible assets were as follows at March 31, 2020 and December 31, 2019 (in thousands):



	At March 31, 2020				At December 31, 2019
	Balance Acquired		Accumulated Amortization		Balance Acquired		Accumulated Amortization
Core deposit intangibles	$	5,975	$	5,875	$	5,975	$	5,832
Other customer relationship intangibles	5,633		5,123		5,633		5,034
Total	$	11,608	$	10,998	$	11,608	$	10,866

Aggregate amortization expense was $0.1 million and $0.2 million for the three month periods ended March 31, 2020 and 2019, respectively.

The remaining estimated aggregate amortization expense at March 31, 2020 is listed below (in thousands):



Year	Estimated Expense
2020	$	352
2021	258
2022
2023	—
2024	—
Total	$	610

The amount of goodwill reflected in the Corporation's Unaudited Consolidated Financial Statements is required to be tested by management for impairment on at least an annual basis. The test for impairment of goodwill on the identified reporting unit is considered a critical accounting estimate because it requires judgment on the part of management and the use of estimates related to the growth assumptions and market multiples used in the valuation model. The goodwill impairment testing is performed annually as of December 31 and no impairment charges were incurred.

Changes in the macroeconomic environment resulting from the COVID-19 pandemic created a triggering event in the three month period ended March 31, 2020 and the Corporation performed an interim impairment test. The impairment test performed for the quarter ended March 31, 2020 determined no additional impairment was required.