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, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment recoveries, net	$ (727)	$ (917)
Exit activity costs, net	256	3,919
Total exit activity costs & asset impairments	(471)	3,002
Residential Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment recoveries, net	(43)	(21)
Exit activity costs, net	(123)	185
Total exit activity costs & asset impairments	(166)	164
Industrial and Infrastructure Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment recoveries, net	(703)	(896)
Exit activity costs, net	218	2,656
Total exit activity costs & asset impairments	(485)	1,760
Renewable Energy & Conservation
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment recoveries, net	19	0
Exit activity costs, net	117	1,050
Total exit activity costs & asset impairments	136	1,050
Corporate
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment recoveries, net	0	0
Exit activity costs, net	44	28
Total exit activity costs & asset impairments	$ 44	$ 28