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Revenue - Disaggregated Revenues by Segment (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 171,163	$ 174,556	$ 177,677	$ 153,735	$ 160,777	$ 147,894	$ 124,435	$ 159,465	$ 178,991	$ 192,192	$ 200,616	$ 176,787	$ 677,131	$ 592,571	$ 748,586
United States
Disaggregation of Revenue [Line Items]
Revenue													475,222	411,489	495,132
Other Americas
Disaggregation of Revenue [Line Items]
Revenue													83,643	72,835	111,740
Europe
Disaggregation of Revenue [Line Items]
Revenue													109,614	100,541	127,885
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue													8,652	7,706	13,829
Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue													366,920	319,483	409,441
Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue													68,392	70,271	93,851
Industrials
Disaggregation of Revenue [Line Items]
Revenue													67,715	66,428	89,214
Power Generation and Transmission
Disaggregation of Revenue [Line Items]
Revenue													52,746	39,887	43,315
Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue													51,399	34,871	39,109
Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue													32,290	33,787	33,105
Petrochemical
Disaggregation of Revenue [Line Items]
Revenue													19,605	19,280	26,577
Other
Disaggregation of Revenue [Line Items]
Revenue													18,064	8,564	13,974
Operating segments | Services
Disaggregation of Revenue [Line Items]
Revenue													555,387	476,164	595,130
Operating segments | Services | United States
Disaggregation of Revenue [Line Items]
Revenue													472,125	406,437	487,408
Operating segments | Services | Other Americas
Disaggregation of Revenue [Line Items]
Revenue													80,013	68,150	104,081
Operating segments | Services | Europe
Disaggregation of Revenue [Line Items]
Revenue													1,841	904	2,342
Operating segments | Services | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue													1,408	673	1,299
Operating segments | Services | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue													330,880	279,723	364,830
Operating segments | Services | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue													51,593	50,813	51,390
Operating segments | Services | Industrials
Disaggregation of Revenue [Line Items]
Revenue													41,873	44,919	64,622
Operating segments | Services | Power Generation and Transmission
Disaggregation of Revenue [Line Items]
Revenue													39,966	30,005	30,300
Operating segments | Services | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue													38,742	24,671	28,495
Operating segments | Services | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue													16,809	17,070	14,269
Operating segments | Services | Petrochemical
Disaggregation of Revenue [Line Items]
Revenue													19,378	18,882	25,985
Operating segments | Services | Other
Disaggregation of Revenue [Line Items]
Revenue													16,146	10,081	15,239
Operating segments | International
Disaggregation of Revenue [Line Items]
Revenue													117,245	107,556	144,271
Operating segments | International | United States
Disaggregation of Revenue [Line Items]
Revenue													912	911	631
Operating segments | International | Other Americas
Disaggregation of Revenue [Line Items]
Revenue													5,003	4,581	7,659
Operating segments | International | Europe
Disaggregation of Revenue [Line Items]
Revenue													108,411	99,953	127,581
Operating segments | International | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue													2,919	2,111	8,400
Operating segments | International | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue													35,232	39,383	43,855
Operating segments | International | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue													16,513	18,166	41,224
Operating segments | International | Industrials
Disaggregation of Revenue [Line Items]
Revenue													24,000	19,657	21,405
Operating segments | International | Power Generation and Transmission
Disaggregation of Revenue [Line Items]
Revenue													9,927	7,559	10,289
Operating segments | International | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue													12,593	10,029	10,196
Operating segments | International | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue													11,496	10,353	9,520
Operating segments | International | Petrochemical
Disaggregation of Revenue [Line Items]
Revenue													227	345	592
Operating segments | International | Other
Disaggregation of Revenue [Line Items]
Revenue													7,257	2,064	7,190
Operating segments | Products & Systems
Disaggregation of Revenue [Line Items]
Revenue													13,831	16,449	18,583
Operating segments | Products & Systems | United States
Disaggregation of Revenue [Line Items]
Revenue													6,469	7,551	12,011
Operating segments | Products & Systems | Other Americas
Disaggregation of Revenue [Line Items]
Revenue													395	550	407
Operating segments | Products & Systems | Europe
Disaggregation of Revenue [Line Items]
Revenue													2,174	3,154	1,940
Operating segments | Products & Systems | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue													4,793	5,194	4,225
Operating segments | Products & Systems | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue													808	377	756
Operating segments | Products & Systems | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue													286	1,292	1,237
Operating segments | Products & Systems | Industrials
Disaggregation of Revenue [Line Items]
Revenue													1,842	1,852	3,187
Operating segments | Products & Systems | Power Generation and Transmission
Disaggregation of Revenue [Line Items]
Revenue													2,853	2,323	2,726
Operating segments | Products & Systems | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue													64	171	418
Operating segments | Products & Systems | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue													3,985	6,364	9,316
Operating segments | Products & Systems | Petrochemical
Disaggregation of Revenue [Line Items]
Revenue													0	53	0
Operating segments | Products & Systems | Other
Disaggregation of Revenue [Line Items]
Revenue													3,993	4,017	943
Corp/Elim
Disaggregation of Revenue [Line Items]
Revenue													(9,332)	(7,598)	(9,398)
Corp/Elim | United States
Disaggregation of Revenue [Line Items]
Revenue													(4,284)	(3,410)	(4,918)
Corp/Elim | Other Americas
Disaggregation of Revenue [Line Items]
Revenue													(1,768)	(446)	(407)
Corp/Elim | Europe
Disaggregation of Revenue [Line Items]
Revenue													(2,812)	(3,470)	(3,978)
Corp/Elim | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue													(468)	(272)	(95)
Corp/Elim | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Industrials
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Power Generation and Transmission
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Petrochemical
Disaggregation of Revenue [Line Items]
Revenue													0	0	0
Corp/Elim | Other
Disaggregation of Revenue [Line Items]
Revenue													$ (9,332)	$ (7,598)	$ (9,398)

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