Business Segment and Related Information - Summarized Financial Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			2
Segment Reporting Information [Line Items]
Revenue	$ 118,715	$ 121,113	$ 416,491	$ 405,307
Segment gross profit	12,043	13,859	33,574	27,173
Segment depreciation and amortization expense	(78)	5,399	13,196	17,034
Expenditures for segment assets	1,952	2,181	3,556	13,672
Property and equipment, net	64,769		64,769		$ 85,294
Segment goodwill	74,213		74,213		74,213
Maintenance and Technical Services
Segment Reporting Information [Line Items]
Revenue	72,915	75,100	296,164	263,961
Operating Segments
Segment Reporting Information [Line Items]
Property and equipment, net	64,769		64,769		85,294
Segment goodwill	74,213		74,213		74,213
Operating Segments | Environmental Solutions
Segment Reporting Information [Line Items]
Revenue	45,800	46,013	120,327	141,346
Segment gross profit	6,483	6,789	14,568	5,868
Segment depreciation and amortization expense	(4,761)	1,394	(423)	5,084
Expenditures for segment assets	605	1,933	1,664	8,890
Property and equipment, net	34,948		34,948		47,856
Segment goodwill	57,591		57,591		57,591
Operating Segments | Maintenance and Technical Services
Segment Reporting Information [Line Items]
Revenue	72,915	75,100	296,164	263,961
Segment gross profit	5,560	7,070	19,006	21,305
Segment depreciation and amortization expense	2,656	2,014	7,649	5,980
Expenditures for segment assets	1,042	248	1,554	4,750
Property and equipment, net	29,612		29,612		37,251
Segment goodwill	16,622		16,622		16,622
All Other
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Segment gross profit	0	0	0	0
Segment depreciation and amortization expense	2,027	1,991	5,970	5,970
Expenditures for segment assets	305	$ 0	338	$ 32
Property and equipment, net	209		209		187
Segment goodwill	$ 0		$ 0		$ 0