Goodwill and Intangible Assets - Schedule of Amounts Related to Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Goodwill [Line Items]
Beginning balance	$ 127,058
Goodwill acquired during the year	147,609
Ending balance	274,667
Assessment, Permitting and Response
Goodwill [Line Items]
Beginning balance	15,173
Goodwill acquired during the year	146,983
Ending balance	162,156
Measurement and Analysis
Goodwill [Line Items]
Beginning balance	68,628
Goodwill acquired during the year	426
Ending balance	69,054
Remediation and Reuse Segment
Goodwill [Line Items]
Beginning balance	43,257
Goodwill acquired during the year	200
Ending balance	$ 43,457