Exit Activity Costs and Asset Impairments (Summary of Exit Activity Costs and Asset Impairments by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	$ 0	$ (727)
Exit activity costs (recoveries), net	219	256
Total exit activity costs & asset impairments	219	(471)
Residential Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	(43)
Exit activity costs (recoveries), net	151	(123)
Total exit activity costs & asset impairments	151	(166)
Industrial and Infrastructure Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	(703)
Exit activity costs (recoveries), net	(33)	218
Total exit activity costs & asset impairments	(33)	(485)
Renewable Energy & Conservation
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	19
Exit activity costs (recoveries), net	94	117
Total exit activity costs & asset impairments	94	136
Corporate
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0
Exit activity costs (recoveries), net	7	44
Total exit activity costs & asset impairments	$ 7	$ 44