Goodwill and Related Intangible Assets (Schedule of Impairment Charges) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Impairment of indefinite-lived intangibles	$ 0	$ 1,237	$ 247
Impairment of definite-lived intangibles	0	315	0
Renewable Energy & Conservation
Finite-Lived Intangible Assets [Line Items]
Impairment of indefinite-lived intangibles	0	1,037	247
Impairment of definite-lived intangibles	0	315	0
Residential Products
Finite-Lived Intangible Assets [Line Items]
Impairment of indefinite-lived intangibles	0	200	0
Impairment of definite-lived intangibles	0	0	0
Industrial and Infrastructure Products
Finite-Lived Intangible Assets [Line Items]
Impairment of indefinite-lived intangibles	0	0	0
Impairment of definite-lived intangibles	$ 0	$ 0	$ 0