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Acquisitions (Narrative) (Details) $ in Thousands							12 Months Ended
	Dec. 11, 2020 USD ($)	Oct. 15, 2020 USD ($)	Feb. 13, 2020 USD ($)	Jan. 15, 2020 USD ($)	Aug. 30, 2019 USD ($)	Aug. 21, 2018 USD ($)	Dec. 31, 2020 USD ($) business	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Number of businesses acquired | business							5
Goodwill							$ 514,279	$ 307,355	$ 301,580
Renewable Energy & Conservation
Business Acquisition [Line Items]
Number of businesses acquired | business							4
Residential Products
Business Acquisition [Line Items]
Number of businesses acquired | business							1
Apeks
Business Acquisition [Line Items]
Acquisition purchase price					$ 12,600
Goodwill					$ 6,436
SolarBOS
Business Acquisition [Line Items]
Acquisition purchase price						$ 6,400
Goodwill						$ 2,879
Thermo Energy Systems Inc., Delta Separations, LLC, Architectural Mailboxes LLC , Sunfig Corporation, and TerraSmart LLC
Business Acquisition [Line Items]
Acquisition purchase price							$ 313,300
TerraSmart LLC
Business Acquisition [Line Items]
Acquisition purchase price							228,200
Goodwill							$ 143,245
Sunfig Corporation
Business Acquisition [Line Items]
Acquisition purchase price	$ 3,800
Goodwill	$ 3,200
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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