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Acquisitions - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended			18 Months Ended	30 Months Ended
	Jul. 15, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2020
CSI Electrical Contractors, Inc
Business Acquisition [Line Items]
Preliminary estimated net asset adjustments	$ 633				$ 987
Total consideration, net of net asset adjustments	$ 80,353				$ 80,707
CSI Electrical Contractors, Inc | Margin Guarantee
Business Acquisition [Line Items]
Change in contingent consideration		$ 600	$ 2,000
CSI Electrical Contractors, Inc | Certain Performance Targets and Continued Employment of Key Executives
Business Acquisition [Line Items]
Change in contingent consideration		4,000	400
Huen Electric Inc
Business Acquisition [Line Items]
Preliminary estimated net asset adjustments						$ 10,800
Total consideration, net of net asset adjustments						$ 57,900
Huen Electric Inc | Margin Guarantee
Business Acquisition [Line Items]
Change in contingent consideration			1,500	$ 3,900
Huen Electric Inc | Certain Performance Targets and Continued Employment of Key Executives
Business Acquisition [Line Items]
Change in contingent consideration		$ (2,500)	$ 1,900	$ 600

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