Revenues - Disaggreation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 276,904	$ 324,861
Fixed fee
Disaggregation of Revenue [Line Items]
Revenues	162,406	208,921
Time and materials
Disaggregation of Revenue [Line Items]
Revenues	94,921	99,679
Product sales
Disaggregation of Revenue [Line Items]
Revenues	19,427	16,241
License fees
Disaggregation of Revenue [Line Items]
Revenues	150	20
United States
Disaggregation of Revenue [Line Items]
Revenues	208,775	236,530
Canada
Disaggregation of Revenue [Line Items]
Revenues	24,068	28,839
Europe
Disaggregation of Revenue [Line Items]
Revenues	16,003	16,009
Other foreign
Disaggregation of Revenue [Line Items]
Revenues	28,058	43,483
Infrastructure Solutions
Disaggregation of Revenue [Line Items]
Revenues	131,543	134,427
Infrastructure Solutions | Fixed fee
Disaggregation of Revenue [Line Items]
Revenues	118,915	125,263
Infrastructure Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Revenues	0	0
Infrastructure Solutions | Product sales
Disaggregation of Revenue [Line Items]
Revenues	12,478	9,144
Infrastructure Solutions | License fees
Disaggregation of Revenue [Line Items]
Revenues	150	20
Infrastructure Solutions | United States
Disaggregation of Revenue [Line Items]
Revenues	97,891	93,845
Infrastructure Solutions | Canada
Disaggregation of Revenue [Line Items]
Revenues	10,611	12,269
Infrastructure Solutions | Europe
Disaggregation of Revenue [Line Items]
Revenues	12,525	13,143
Infrastructure Solutions | Other foreign
Disaggregation of Revenue [Line Items]
Revenues	10,516	15,170
Corrosion Protection
Disaggregation of Revenue [Line Items]
Revenues	64,498	98,105
Corrosion Protection | Fixed fee
Disaggregation of Revenue [Line Items]
Revenues	42,572	77,901
Corrosion Protection | Time and materials
Disaggregation of Revenue [Line Items]
Revenues	14,977	13,107
Corrosion Protection | Product sales
Disaggregation of Revenue [Line Items]
Revenues	6,949	7,097
Corrosion Protection | License fees
Disaggregation of Revenue [Line Items]
Revenues		0
Corrosion Protection | United States
Disaggregation of Revenue [Line Items]
Revenues	30,021	50,356
Corrosion Protection | Canada
Disaggregation of Revenue [Line Items]
Revenues	13,457	16,570
Corrosion Protection | Europe
Disaggregation of Revenue [Line Items]
Revenues	3,478	2,866
Corrosion Protection | Other foreign
Disaggregation of Revenue [Line Items]
Revenues	17,542	28,313
Energy Services
Disaggregation of Revenue [Line Items]
Revenues	80,863	92,329
Energy Services | Fixed fee
Disaggregation of Revenue [Line Items]
Revenues	919	5,757
Energy Services | Time and materials
Disaggregation of Revenue [Line Items]
Revenues	79,944	86,572
Energy Services | Product sales
Disaggregation of Revenue [Line Items]
Revenues	0	0
Energy Services | License fees
Disaggregation of Revenue [Line Items]
Revenues	0	0
Energy Services | United States
Disaggregation of Revenue [Line Items]
Revenues	80,863	92,329
Energy Services | Canada
Disaggregation of Revenue [Line Items]
Revenues	0	0
Energy Services | Europe
Disaggregation of Revenue [Line Items]
Revenues	0	0
Energy Services | Other foreign
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0