Business Acquisitions - Summary of Purchase Price Attributable to Acquisitions (Details) - USD ($) $ in Thousands	Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Cash	$ 1,119	[1]	$ 3,753	$ 1,527
Accounts receivable and contract assets	7,846	[1]	11,788	17,059
Other current assets	572	[1]	404	1,265
Current assets	9,537	[1]	15,945	19,851
Property and equipment	183	[1]	1,713	7,117
Operating lease right-of-use asset—net	3,110	[1]	3,079
Goodwill	12,543	[1]	36,705	147,609
Total assets	39,560	[1]	95,542	253,586
Current liabilities	3,034	[1]	6,077	9,721
Operating lease liability—net of current portion	2,438	[1]	2,389
Total liabilities	5,472	[1]	8,466	9,721
Purchase price	34,088	[1]	87,076	243,865
Customer Relationships
Business Acquisition [Line Items]
Intangible assets	11,619	[1]	31,623	56,000
Trade Names
Business Acquisition [Line Items]
Intangible assets	1,649	[1]	3,475	4,200
Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets	919	[1]	2,681	4,109
Acquired Technology
Business Acquisition [Line Items]
Intangible assets			321
Proprietary Software
Business Acquisition [Line Items]
Intangible assets				14,700
Environmental Standards
Business Acquisition [Line Items]
Cash	295
Accounts receivable and contract assets	5,200
Other current assets	456
Current assets	5,951
Property and equipment	168
Operating lease right-of-use asset—net	2,895
Goodwill	4,131
Total assets	20,231
Current liabilities	1,720
Operating lease liability—net of current portion	2,328
Total liabilities	4,048
Purchase price	16,183
Environmental Standards | Customer Relationships
Business Acquisition [Line Items]
Intangible assets	5,807
Environmental Standards | Trade Names
Business Acquisition [Line Items]
Intangible assets	1,010
Environmental Standards | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets	269
All Other 2022 Acquisitions
Business Acquisition [Line Items]
Cash	824
Accounts receivable and contract assets	2,646
Other current assets	116
Current assets	3,586
Property and equipment	15
Operating lease right-of-use asset—net	215
Goodwill	8,412
Total assets	19,329
Current liabilities	1,314
Operating lease liability—net of current portion	110
Total liabilities	1,424
Purchase price	17,905
All Other 2022 Acquisitions | Customer Relationships
Business Acquisition [Line Items]
Intangible assets	5,812
All Other 2022 Acquisitions | Trade Names
Business Acquisition [Line Items]
Intangible assets	639
All Other 2022 Acquisitions | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets	$ 650
MSE Group
Business Acquisition [Line Items]
Cash			2,810
Accounts receivable and contract assets			2,980
Other current assets			31
Current assets			5,821
Property and equipment			513
Operating lease right-of-use asset—net			740
Goodwill			8,176
Total assets			25,413
Current liabilities			1,007
Operating lease liability—net of current portion			548
Total liabilities			1,555
Purchase price			23,858
MSE Group | Customer Relationships
Business Acquisition [Line Items]
Intangible assets			8,720
MSE Group | Trade Names
Business Acquisition [Line Items]
Intangible assets			521
MSE Group | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets			922
EI
Business Acquisition [Line Items]
Cash			250
Accounts receivable and contract assets			4,675
Other current assets			84
Current assets			5,009
Property and equipment			32
Operating lease right-of-use asset—net			106
Goodwill			8,960
Total assets			25,687
Current liabilities			2,719
Operating lease liability—net of current portion			36
Total liabilities			2,755
Purchase price			22,932
EI | Customer Relationships
Business Acquisition [Line Items]
Intangible assets			10,073
EI | Trade Names
Business Acquisition [Line Items]
Intangible assets			996
EI | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets			511
All Other 2021 Acquisitions
Business Acquisition [Line Items]
Cash			693
Accounts receivable and contract assets			4,133
Other current assets			289
Current assets			5,115
Property and equipment			1,168
Operating lease right-of-use asset—net			2,233
Goodwill			19,569
Total assets			44,442
Current liabilities			2,351
Operating lease liability—net of current portion			1,805
Total liabilities			4,156
Purchase price			40,286
All Other 2021 Acquisitions | Customer Relationships
Business Acquisition [Line Items]
Intangible assets			12,830
All Other 2021 Acquisitions | Trade Names
Business Acquisition [Line Items]
Intangible assets			1,958
All Other 2021 Acquisitions | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets			1,248
All Other 2021 Acquisitions | Acquired Technology
Business Acquisition [Line Items]
Intangible assets			$ 321
CTEH
Business Acquisition [Line Items]
Cash				1,527
Accounts receivable and contract assets				17,059
Other current assets				1,265
Current assets				19,851
Property and equipment				7,042
Goodwill				146,983
Total assets				252,776
Current liabilities				9,721
Total liabilities				9,721
Purchase price				243,055
CTEH | Customer Relationships
Business Acquisition [Line Items]
Intangible assets				56,000
CTEH | Trade Names
Business Acquisition [Line Items]
Intangible assets				4,200
CTEH | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets				4,000
CTEH | Proprietary Software
Business Acquisition [Line Items]
Intangible assets				14,700
All Other 2020 Acquisitions
Business Acquisition [Line Items]
Property and equipment				75
Goodwill				626
Total assets				810
Purchase price				810
All Other 2020 Acquisitions | Covenants Not to Compete
Business Acquisition [Line Items]
Intangible assets				$ 109

[1] The Company is continuing to obtain information to complete the valuation of certain of these acquisitions' assets and liabilities.