Revenue Recognition - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Revenues	$ 105,041
United States
Disaggregation of Revenue [Line Items]
Revenues	91,153
Asia
Disaggregation of Revenue [Line Items]
Revenues	1,700
Canada
Disaggregation of Revenue [Line Items]
Revenues	3,260
Europe
Disaggregation of Revenue [Line Items]
Revenues	5,047
Mexico
Disaggregation of Revenue [Line Items]
Revenues	623
Middle East
Disaggregation of Revenue [Line Items]
Revenues	2,152
Other
Disaggregation of Revenue [Line Items]
Revenues	1,106
Revenue recognized over time
Disaggregation of Revenue [Line Items]
Revenues	2,687
Revenue recognized at a point in time
Disaggregation of Revenue [Line Items]
Revenues	$ 102,354