Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

The change in goodwill by segment for 2017 and 2016 was as follows (in thousands):


	Power		Pipeline		Utilities		Civil		Total
Balance at January 1, 2016	$	20,731	$	42,252	$	18,312	$	42,866	$	124,161
Goodwill acquired during the year		3,781		—		2,000		—		5,781
Goodwill impairment		—		—		—		(2,716)		(2,716)
Balance at December 31, 2016	$	24,512	$	42,252	$	20,312	$	40,150	$	127,226
Goodwill acquired during the year		—		9,269		17,000		—		26,269
Purchase price allocation adjustments		(121)		—		—		—		(121)
Balance at December 31, 2017	$	24,391	$	51,521	$	37,312	$	40,150	$	153,374

Summary of intangible asset categories, amounts and the average amortization periods

The table below summarizes the intangible asset categories, amounts and the average amortization periods, which are generally on a straight-line basis, at December 31 (in thousands):


		December 31, 2017				December 31, 2016
	Weighted Average Life	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Tradename	9 years	$	32,175	$	(22,238)	$	30,485	$	(18,733)
Customer relationships	10 years		49,900		(16,338)		33,579		(13,439)
Non-compete agreements	5 years		1,900		(820)		2,250		(1,301)
Other	3 years		275		(54)		—		—
		$	84,250	$	(39,450)	$	66,314	$	(33,473)

Schedule of estimated future amortization expense for intangible assets

In the second quarter of 2017, we recorded a $0.5 million impairment charge related to our tradename intangible assets. Estimated future amortization expense for intangible assets as of December 31, 2017 is as follows (in thousands):


	Estimated
	Intangible
For the Years Ending	Amortization
December 31,	Expense
2018	$	9,541
2019		9,193
2020		6,442
2021		5,203
2022		4,048
Thereafter		10,373
	$	44,800