Exit Activity Costs and Asset Impairments (Summary of Exit Activity Costs and Asset Impairments by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	$ 346	$ 0	$ 346	$ 0
Exit activity costs	664	2,136	955	2,355
Total	1,010	2,136	1,301	2,355
Renewable Energy and Conservation
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	72	0	72	0
Exit activity costs	316	(95)	334	(1)
Total	388	(95)	406	(1)
Residential Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	0
Exit activity costs	263	219	484	370
Total	263	219	484	370
Industrial and Infrastructure Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	274	0	274	0
Exit activity costs	40	1,346	38	1,313
Total	314	1,346	312	1,313
Corporate
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	0
Exit activity costs	45	666	99	673
Total	$ 45	$ 666	$ 99	$ 673