Business Acquisitions - Additional Information (Details) - USD ($)	1 Months Ended						3 Months Ended		9 Months Ended
	Aug. 31, 2021	Jul. 31, 2021	Jun. 30, 2021	Apr. 30, 2021	Jan. 31, 2021	Apr. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Transaction costs related to business combinations							$ 913,000	$ 6,000	$ 1,656,000	$ 3,767,000
Number of common stock shares issued in connection with business acquisition							62,738		143,800	791,139
Revenues from discontinued service lines							$ 0	$ 0	$ 0	$ 3,800,000
MSE Group
Business Acquisition [Line Items]
Percentage of interests acquired					100.00%
Number of common stock shares issued in connection with business acquisition									71,740
MSE Group | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets					7 years
MSE Group | Related Backlog
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets					2 years
MSE Group | Trade Names
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets					2 years
MSE Group | Covenants Not to Compete
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets					5 years
Vista
Business Acquisition [Line Items]
Percentage of interests acquired			100.00%
Number of common stock shares issued in connection with business acquisition									9,322
Vista | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets			10 years
Vista | Trade Names
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets			3 years
Vista | Covenants Not to Compete
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets			5 years
EI
Business Acquisition [Line Items]
Percentage of interests acquired		100.00%
Number of common stock shares issued in connection with business acquisition									43,100
EI | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets		10 years
EI | Trade Names
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets		5 years
EI | Covenants Not to Compete
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets		5 years
Sensible
Business Acquisition [Line Items]
Percentage of interests acquired	100.00%
Number of common stock shares issued in connection with business acquisition									19,638
Sensible | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets	10 years
Sensible | Acquired Technology
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets	5 years
MSE Group ,Vista and Sensible
Business Acquisition [Line Items]
Revenue							11,900,000		$ 19,700,000
Pre-tax loss							(200,000)		0
MSE Group ,Vista and Sensible | 2022 Earn Out
Business Acquisition [Line Items]
Business combination, earn-out payment, maximum							12,700,000		12,700,000
MSE Group ,Vista and Sensible | 2023 Earn Out
Business Acquisition [Line Items]
Business combination, earn-out payment, maximum							$ 12,700,000		$ 12,700,000
CTEH
Business Acquisition [Line Items]
Percentage of interests acquired						100.00%
Number of common stock shares issued in connection with business acquisition						791,139
CTEH | External Proprietary Software
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets						5 years
CTEH | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets						15 years
CTEH | Trade Names
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets						5 years
CTEH | Covenants Not to Compete
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets						5 years
CTEH | Proprietary Software
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets						3 years
CTEH | 2020 Earn Out
Business Acquisition [Line Items]
Business combination, earn-out payment, maximum						$ 50,000,000.0
Business combination, contingent consideration arrangements, basis for amount									The CTEH first year earn-out was calculated at twelve times CTEH’s 2020 EBITDA (as defined in the purchase agreement) in excess of $18.3 million, with a maximum first year earn-out payment of $50.0 million, which was fully achieved.
Business combination, contingent consideration arrangements, description									The 2020 earn-out was initially payable 100.0% in common stock, but as a result of the completion of the Company’s IPO (Note 1), 50.0% was payable in cash. In April 2021, the 2020 earn-out payment was made with 50.0% paid in cash and the remaining 50.0% paid in common stock of the Company (Notes 14 and 18).
Business combination, minimum EBITDA for contingent consideration arrangements						$ 18,300,000
Percentage of earn out payable in common stock						100.00%
Percentage of earn out paid in cash, as result of completing of IPO				50.00%
Percentage of earn out paid in common stock, as a result of completion of IPO				50.00%
CTEH | 2020 Earn Out | Minimum
Business Acquisition [Line Items]
Business combination, actual EBITDA						$ 18,300,000
CTEH | 2020 Earn Out | Maximum
Business Acquisition [Line Items]
Business combination, actual EBITDA						22,500,000
CTEH | 2021 Earn Out
Business Acquisition [Line Items]
Business combination, earn-out payment, maximum						$ 30,000,000.0
Business combination, contingent consideration arrangements, basis for amount									The second year earn-out is to be calculated at ten times CTEH’s 2021 EBITDA in excess of actual 2020 EBITDA (with actual 2020 EBITDA subject to a minimum of $18.3 million and a maximum of $22.5 million), with a maximum second year earn-out payment of $30.0 million.
Business combination, contingent consideration arrangements, description									The 2021 earn-out, if any, is payable 100.0% in cash.
Percentage of earn out payable in cash						100.00%
Other Acquisition | Covenants Not to Compete
Business Acquisition [Line Items]
Weighted average useful lives for acquired intangible assets						4 years