Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Intangible Assets And Goodwill [Line Items]
Goodwill gross carrying amount	$ 47,124	$ 46,599
Goodwill accumulated amortization	0	0
Goodwill net carrying amount	47,124	46,599
Accumulated Amortization	3,798	3,227
Intangible Assets, Gross (Excluding Goodwill)	15,160	13,092
Intangible Assets, Net (Excluding Goodwill)	11,362	9,865
Gross carrying amount of goodwill and intangible assets	62,284	59,691
Net carrying amount of goodwill and intangible assets	58,486	56,464
T&D [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Goodwill gross carrying amount	40,567	40,042
Goodwill accumulated amortization	0	0
Goodwill net carrying amount	40,567	40,042
C&I [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Goodwill gross carrying amount	6,557	6,557
Goodwill accumulated amortization	0	0
Goodwill net carrying amount	6,557	6,557
Backlog [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	765	521
Accumulated Amortization	695	521
Amortizable intangible assets net carrying amount	70	0
Customer Relationships [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	5,144	4,015
Accumulated Amortization	3,103	2,706
Amortizable intangible assets net carrying amount	2,041	1,309
Trade Names [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	695	0
Accumulated Amortization	0	0
Amortizable intangible assets net carrying amount	695	0
Indefinite-lived Intangible Assets	$ 8,556	$ 8,556