Exit Activity Costs and Asset Impairments (Summary of Exit Activity Costs and Asset Impairments by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	$ 1,750	$ 806	$ 1,088	$ (1,931)
Exit activity costs (recoveries), net	1,910	761	2,264	6,706
Total exit activity costs & asset impairments	3,660	1,567	3,352	4,775
Residential Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	1,392	442	1,349	295
Exit activity costs (recoveries), net	485	566	333	958
Total exit activity costs & asset impairments	1,877	1,008	1,682	1,253
Industrial and Infrastructure Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	358	98	(345)	(2,492)
Exit activity costs (recoveries), net	1,417	(12)	1,607	2,959
Total exit activity costs & asset impairments	1,775	86	1,262	467
Renewable Energy & Conservation
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	266	84	266
Exit activity costs (recoveries), net	(156)	191	(107)	2,610
Total exit activity costs & asset impairments	(156)	457	(23)	2,876
Corporate
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	0
Exit activity costs (recoveries), net	164	16	431	179
Total exit activity costs & asset impairments	$ 164	$ 16	$ 431	$ 179