Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 103,542	$ 113,648	$ 208,423	$ 218,689
Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenues	4,003	3,061	7,756	5,748
Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenues	99,539	110,587	200,667	212,941
United States
Disaggregation of Revenue [Line Items]
Revenues	90,258	97,910	181,757	189,063
Asia
Disaggregation of Revenue [Line Items]
Revenues	2,287	3,161	3,739	4,861
Canada
Disaggregation of Revenue [Line Items]
Revenues	3,821	3,529	7,318	6,789
Europe
Disaggregation of Revenue [Line Items]
Revenues	4,449	5,101	9,801	10,148
Mexico
Disaggregation of Revenue [Line Items]
Revenues	1,003	483	1,837	1,106
Middle East
Disaggregation of Revenue [Line Items]
Revenues	1,481	3,204	3,065	5,356
Other
Disaggregation of Revenue [Line Items]
Revenues	$ 243	$ 260	$ 906	$ 1,366