Business Acquisitions - Summary of Elements of Purchase Price of Acquisitions (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Cash	$ 175,450	$ 87,285
Common Stock	25,000	4,047
Other Purchase Price Component Current	(2,247)
Other Purchase Price Component Long Term	100
Contingent Consideration Current	34,661
Contingent Consideration Long Term	10,543
Other Purchase Price Components		1,450
Contingent Consideration		5,401
Total Purchase Price	243,507	98,183
CTEH
Business Acquisition [Line Items]
Cash	175,000
Common Stock	25,000
Other Purchase Price Component Current	(2,297)
Contingent Consideration Current	34,451
Contingent Consideration Long Term	10,543
Total Purchase Price	242,697
All Other Acquisitions
Business Acquisition [Line Items]
Cash	450
Other Purchase Price Component Current	50
Other Purchase Price Component Long Term	100
Contingent Consideration Current	210
Total Purchase Price	$ 810
Golden
Business Acquisition [Line Items]
Cash		1,500
Contingent Consideration		477
Total Purchase Price		1,977
TES
Business Acquisition [Line Items]
Cash		2,359
Common Stock		322
Other Purchase Price Components		25
Contingent Consideration		4,911
Total Purchase Price		7,617
TESUS
Business Acquisition [Line Items]
Cash		18,683
Common Stock		3,041
Other Purchase Price Components		1,495
Total Purchase Price		23,219
AWS
Business Acquisition [Line Items]
Cash		6,020
Other Purchase Price Components		150
Total Purchase Price		6,170
AEC
Business Acquisition [Line Items]
Cash		808
Total Purchase Price		808
LEHDER
Business Acquisition [Line Items]
Cash		3,878
Common Stock		684
Contingent Consideration		13
Total Purchase Price		4,575
ECT2
Business Acquisition [Line Items]
Cash		54,037
Other Purchase Price Components		(220)
Total Purchase Price		$ 53,817