Goodwill and Intangible Assets
 12 Months Ended
Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]  
Goodwill and Intangible Assets
GOODWILL AND INTANGIBLE ASSETS
The Company tests goodwill for impairment on the first day of the Company's fourth fiscal quarter each year, or more frequently should circumstances change or events occur that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The annual tests performed in the three years ended December 31, 2020 resulted in no impairment of goodwill.
The change in the net carrying amount of goodwill for 2019 and 2020 is as follows (in thousands):
Balance at December 31, 2018$233,619 
Acquisition of Advantor28,364
Balance at December 31, 2019$261,983 
Adjustment to Advantor Purchase Price Allocation147
Acquisition of HHB10,647 
Acquisition of Zenetex66,925 
Balance at December 31, 2020$339,702 
Other identifiable intangible assets consist of the following:    
December 31, 2020December 31, 2019
(In thousands)Gross Carrying AmountAccumulated AmortizationNet Carrying AmountGross Carrying AmountAccumulated AmortizationNet Carrying Amount
Contract backlogs and recompetes$48,800 $(6,645)$42,155 $11,600 $(4,300)$7,300 
Customer contracts7,200 (2,133)5,067 7,200 (692)6,508 
Trade names and other1,243 (360)883 1,236 (118)1,118 
Total intangible assets$57,243 $(9,138)$48,105 $20,036 $(5,110)$14,926 
The increase during 2020 was due to $33.2 million from the acquisition of Zenetex and $4.0 million from the acquisition of HHB on December 31, 2020. This increase was partially offset by intangible amortization expense of approximately $4.0 million and $3.1 million for years ended 2020 and 2019, respectively. As of December 31, 2020, the weighted-average intangible asset amortization period was 7.0 years.
The estimated amortization expense for intangible assets for the next five years is as follows (in thousands):
PeriodAmortization
2021$8,679 
2022$7,151 
2023$7,054 
2024$5,947 
2025$5,150 
After 2025$14,124