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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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