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, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	$ 65	$ (1,820)	$ (662)	$ (2,737)
Exit activity (recoveries) costs, net	98	2,026	354	5,945
Total exit activity costs & asset impairments	163	206	(308)	3,208
Residential Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	(126)	(43)	(147)
Exit activity (recoveries) costs, net	(29)	207	(152)	392
Total exit activity costs & asset impairments	(29)	81	(195)	245
Industrial and Infrastructure Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	(1,694)	(703)	(2,590)
Exit activity (recoveries) costs, net	(28)	315	190	2,971
Total exit activity costs & asset impairments	(28)	(1,379)	(513)	381
Renewable Energy & Conservation
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	65	0	84	0
Exit activity (recoveries) costs, net	(68)	1,369	49	2,419
Total exit activity costs & asset impairments	(3)	1,369	133	2,419
Corporate
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	0
Exit activity (recoveries) costs, net	223	135	267	163
Total exit activity costs & asset impairments	$ 223	$ 135	$ 267	$ 163