Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Goodwill and other intangible assets
Goodwill	$ 126,161	$ 124,161
West
Goodwill and other intangible assets
Goodwill	45,239	45,239
East
Goodwill and other intangible assets
Goodwill	42,866	42,866
Energy
Goodwill and other intangible assets
Goodwill	38,056	36,056
Rockford | West
Goodwill and other intangible assets
Goodwill	32,079	32,079
Q3 Contracting | West
Goodwill and other intangible assets
Goodwill	13,160	13,160
James Construction Group LLC | East
Goodwill and other intangible assets
Goodwill	42,866	42,866
PES | Energy
Goodwill and other intangible assets
Goodwill	28,463	28,463
Aevenia | Energy
Goodwill and other intangible assets
Goodwill	7,152	5,152
OnQuest Canada, ULC | Energy
Goodwill and other intangible assets
Goodwill	$ 2,441	$ 2,441