Revenue (Tables)

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table summarizes the Company's net sales by major product category:

	Three Months Ended March 31,
	2018		2017
Rail Products	$	36,034	$	34,365
Rail Technologies	26,136		22,115
Rail Products and Services	62,170		56,480
Piling and Fabricated Bridge	18,861		29,223
Precast Concrete Products	10,039		8,099
Construction Products	28,900		37,322
Test, Inspection, and Threading	14,213		10,882
Protective Coatings and Measurement Solutions	17,171		14,018
Tubular and Energy Services	31,384		24,900
Total net sales	$	122,454	$	118,702

Net sales by the timing of the transfer of goods and services is as follows:

Three Months Ended March 31, 2018	Rail Products and Services		Construction Products		Tubular and Energy Services		Total
Point in time	$	45,871	$	18,926	$	26,435	$	91,232
Over time	16,299		9,974		4,949		31,222
Total net sales	$	62,170	$	28,900	$	31,384	$	122,454
Three Months Ended March 31, 2017	Rail Products and Services		Construction Products		Tubular and Energy Services		Total
Point in time	$	45,566	$	24,624	$	20,939	$	91,129
Over time	10,914		12,698		3,961		27,573
Total net sales	$	56,480	$	37,322	$	24,900	$	118,702