Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and intangible assets consisted of the following at December 31:


	2020						2019
(in thousands)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Goodwill
T&D	$	40,224	$	—	$	40,224	$	40,224	$	—	$	40,224
C&I	25,841		—		25,841		25,836		—		25,836
Total goodwill	$	66,065	$	—	$	66,065	$	66,060	$	—	$	66,060
Amortizable Intangible Assets
Backlog	$	5,289	$	5,289	$	—	$	5,289	$	4,039	$	1,250
Customer relationships	31,381		8,914		22,467		31,381		6,623		24,758
Trade names	696		264		432		695		218		477
Indefinite-lived Intangible Assets
Trade names	28,466		—		28,466		28,455		—		28,455
Total intangible assets	$	65,832	$	14,467	$	51,365	$	65,820	$	10,880	$	54,940

Customer relationships and backlog are being amortized on a straight-line method over an estimated useful life ranging up to 12.5 years and the remaining life of the contract, respectively, and have been determined to have no residual value. Amortizable trade names are being amortized on a straight-line basis over an estimated useful life of approximately 15 years. Certain trade names have indefinite lives and, therefore, are not being amortized. Intangible asset amortization expense was $3.6 million, $3.8 million and $1.8 million for the years ended December 31, 2020, 2019 and 2018, respectively. Immaterial foreign currency translation adjustments related to goodwill and intangible assets are netted with the amounts indicated above.

As of December 31, 2020, estimated future intangible asset amortization expense for the each of the next five years and thereafter was as follows:


(in thousands)	Future Amortization Expense
2021	$	2,312
2022	2,312
2023	2,312
2024	2,312
2025	2,312
Thereafter	11,339
Total	$	22,899