Revenues - Disaggreation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 339,679	$ 341,872	$ 999,570	$ 1,021,520
Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	212,602	241,010	641,004	700,638
Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	101,917	78,075	294,979	252,908
Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	22,756	22,656	61,150	67,530
License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,404	131	2,437	444
United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	262,298	250,815	779,206	787,046
Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	35,920	41,939	95,185	98,053
Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16,281	17,367	48,135	51,656
Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	25,180	31,751	77,044	84,765
Infrastructure Solutions
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	155,681	174,161	450,840	451,340
Infrastructure Solutions | Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	141,598	163,043	416,392	419,991
Infrastructure Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Infrastructure Solutions | Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11,679	10,987	32,011	30,905
Infrastructure Solutions | License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,404	131	2,437	444
Infrastructure Solutions | United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	111,902	128,356	323,327	328,627
Infrastructure Solutions | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16,153	17,936	44,028	42,170
Infrastructure Solutions | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13,460	13,900	39,600	41,196
Infrastructure Solutions | Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	14,166	13,969	43,885	39,347
Corrosion Protection
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	105,624	102,276	300,118	353,381
Corrosion Protection | Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	68,935	76,419	210,819	276,431
Corrosion Protection | Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	25,612	14,188	60,160	40,325
Corrosion Protection | Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11,077	11,669	29,139	36,625
Corrosion Protection | License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Corrosion Protection | United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	72,022	57,024	207,267	241,620
Corrosion Protection | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	19,767	24,003	51,157	55,883
Corrosion Protection | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,821	3,467	8,535	10,460
Corrosion Protection | Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11,014	17,782	33,159	45,418
Energy Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	78,374	65,435	248,612	216,799
Energy Services | Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,069	1,548	13,793	4,216
Energy Services | Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	76,305	63,887	234,819	212,583
Energy Services | Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Energy Services | License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Energy Services | United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	78,374	65,435	248,612	216,799
Energy Services | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Energy Services | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0	0
Energy Services | Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 0	$ 0	$ 0	$ 0