Goodwill and Intangible Assets - Schedule of Amounts Related to Goodwill (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Goodwill [Line Items]
Balance	$ 274,667
Goodwill acquired during the period	12,626
Balance	287,293
Assessment, Permitting and Response
Goodwill [Line Items]
Balance	162,156
Balance	162,156
Measurement and Analysis
Goodwill [Line Items]
Balance	69,054
Goodwill acquired during the period	5,013
Balance	74,067
Remediation and Reuse Segment
Goodwill [Line Items]
Balance	43,457
Goodwill acquired during the period	7,613
Balance	$ 51,070