Revenue - Revenue from External Customers by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total	$ 117,630	$ 114,450	$ 329,279	$ 312,603
North America
Disaggregation of Revenue [Line Items]
Total	105,766	104,840	299,550	281,339
Pacific Rim
Disaggregation of Revenue [Line Items]
Total	7,914	5,466	18,862	18,215
Europe
Disaggregation of Revenue [Line Items]
Total	1,729	2,395	5,297	7,630
Other
Disaggregation of Revenue [Line Items]
Total	2,221	1,749	5,570	5,419
Energy
Disaggregation of Revenue [Line Items]
Total	31,801	33,813	81,611	113,546
Industrial
Disaggregation of Revenue [Line Items]
Total	40,576	29,843	111,796	97,437
Transportation
Disaggregation of Revenue [Line Items]
Total	$ 45,253	$ 50,794	$ 135,872	$ 101,620