Revenues - Disaggreation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 324,861	$ 325,175
Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	208,921	219,025
Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	99,679	82,886
Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16,241	23,108
License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	20	156
United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	250,032	257,724
Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	28,839	26,827
Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16,009	16,145
Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	29,981	24,479
Infrastructure Solutions
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	134,427	128,868
Infrastructure Solutions | Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	125,263	118,998
Infrastructure Solutions | Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Infrastructure Solutions | Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9,144	9,714
Infrastructure Solutions | License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	20	156
Infrastructure Solutions | United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	93,845	93,904
Infrastructure Solutions | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	12,269	10,817
Infrastructure Solutions | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13,143	12,960
Infrastructure Solutions | Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	15,170	11,187
Corrosion Protection
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	98,105	123,390
Corrosion Protection | Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	77,901	98,520
Corrosion Protection | Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13,107	11,476
Corrosion Protection | Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7,097	13,394
Corrosion Protection | License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Corrosion Protection | United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	63,858	90,903
Corrosion Protection | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16,570	16,010
Corrosion Protection | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,866	3,185
Corrosion Protection | Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	14,811	13,292
Energy Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	92,329	72,917
Energy Services | Fixed fee
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5,757	1,507
Energy Services | Time and materials
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	86,572	71,410
Energy Services | Product sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Energy Services | License fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Energy Services | United States
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	92,329	72,917
Energy Services | Canada
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Energy Services | Europe
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0
Energy Services | Other foreign
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 0	$ 0