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Acquisitions (Narrative) (Details) $ in Thousands |  |  |  |  | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 11, 2020 USD ($) | Oct. 15, 2020 USD ($) | Feb. 13, 2020 USD ($) | Jan. 15, 2020 USD ($) | Mar. 31, 2021 business | Jun. 30, 2021 USD ($) | Sep. 30, 2021 USD ($) | Dec. 31, 2020 USD ($)
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of businesses acquired | business |  |  |  |  | 5 |  |  |
Goodwill |  |  |  |  |  |  | $ 508,660 | $ 514,279
Renewables |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of businesses acquired | business |  |  |  |  | 2 |  |  |
Goodwill |  |  |  |  |  |  | 187,214 | 192,527
Agtech |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of businesses acquired | business |  |  |  |  | 2 |  |  |
Goodwill |  |  |  |  |  |  | 84,316 | 84,622
Residential |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of businesses acquired | business |  |  |  |  | 1 |  |  |
Goodwill |  |  |  |  |  |  | $ 205,452 | 205,452
TerraSmart LLC |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Acquisition purchase price |  |  |  |  |  | $ 223,900 |  |
Goodwill |  |  |  |  |  |  |  | $ 139,106
Sunfig Corporation |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Acquisition purchase price | $ 3,800 |  |  |  |  |  |  |
Goodwill | $ 3,500 |  |  |  |  |  |  |
Architectural Mailboxes, LLC |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Acquisition purchase price |  | $ 26,900 |  |  |  |  |  |
Goodwill |  | $ 7,400 |  |  |  |  |  |
Delta Separations, LLC |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Acquisition purchase price |  |  | $ 47,100 |  |  |  |  |
Goodwill |  |  | $ 32,200 |  |  |  |  |
Thermo Energy Systems |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Acquisition purchase price |  |  |  | $ 7,300 |  |  |  |
Goodwill |  |  |  | $ 18,700 |  |  |  |

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