Revenue - Revenue from External Customers by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total	$ 105,097	$ 115,787
North America
Disaggregation of Revenue [Line Items]
Total	94,520	97,679
Pacific Rim
Disaggregation of Revenue [Line Items]
Total	6,454	12,625
Europe
Disaggregation of Revenue [Line Items]
Total	2,657	3,377
Other
Disaggregation of Revenue [Line Items]
Total	1,466	2,106
Energy
Disaggregation of Revenue [Line Items]
Total	50,084	45,648
Industrial
Disaggregation of Revenue [Line Items]
Total	37,131	50,587
Transportation
Disaggregation of Revenue [Line Items]
Total	$ 17,882	$ 19,552