Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

7. Goodwill and Intangible Assets

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

	2018						2017
(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		16,364		—		16,364		6,770		—		6,770
Total goodwill	$	56,588	$	—	$	56,588	$	46,994	$	—	$	46,994
Amortizable Intangible Assets
Backlog	$	2,789	$	1,889	$	900	$	989	$	989	$	—
Customer relationships		17,280		4,970		12,310		5,277		4,069		1,208
Trade names		695		172		523		695		125		570
Indefinite-lived Intangible Assets
Trade names		19,533		—		19,533		9,074		—		9,074
Total Intangible assets	$	40,297	$	7,031	$	33,266	$	16,035	$	5,183	$	10,852

The increase in goodwill as of December 31, 2018 compared to December 31, 2017 was due to the allocation of $9.6 million of goodwill related to the

acquisition of the

Huen

Companies identified during the ongoing analysis of the purchase accounting.

The increase in intangible

assets also related to the

acquisition of the

Huen

Companies and are being amortized on a straight-line basis over periods ranging up to 12 years. Additional financial information related to this acquisition is provided in Note 2 — Acquisitions to the Financial Statements. Immaterial foreign currency translation adjustments related to goodwill and intangible assets are netted with the amounts indicated above.

Customer relationships and backlog are being amortized on a straight-line method over an estimated useful life

ranging up to

12 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 $1.8 million, $0.5 million and $0.9 million for the years ended December 31, 2018, 2017 and 2016, respectively.

As of December 31, 2018, estimated future intangible asset amortization expense for the each of the next five years and thereafter was as follows:

(In thousands)	Future Amortization Expense
2019	$	2,037
2020		1,137
2021		1,137
2022		1,137
2023		1,137
Thereafter		7,148
Total	$	13,733