Goodwill and Intangible Assets - Schedule of Amounts Related to Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Goodwill [Line Items]
Balance	$ 127,058
Goodwill acquired during the period	147,251
Balance	274,309
Assessment, Permitting and Response
Goodwill [Line Items]
Balance	15,173
Goodwill acquired during the period	146,625
Balance	161,798
Measurement and Analysis
Goodwill [Line Items]
Balance	68,628
Goodwill acquired during the period	426
Balance	69,054
Remediation and Reuse Segment
Goodwill [Line Items]
Balance	43,257
Goodwill acquired during the period	200
Balance	$ 43,457