Goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill [Abstract]

Schedule of goodwill by reporting segment

The changes in the carrying amount of goodwill by reporting segment during the years ended December 31, 2017 and 2016 are as follows:

	Infrastructure Group			Aggregate and Mining Group			Energy Group		Total
Balance, December 31, 2015	$	8,481		$	22,354		$	--	$	30,835
Acquisition		--			--			12,632		12,632
Foreign currency translation		(33	)		(2,630	)		--		(2,663	)
Balance, December 31, 2016		8,448			19,724			12,632		40,804
Acquisition		--			--			3,488		3,488
Foreign currency translation		125			1,315			--		1,440
Balance, December 31, 2017	$	8,573		$	21,039		$	16,120	$	45,732