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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	$ 0	$ 65	$ 0	$ (662)
Exit activity costs (recoveries), net	2,136	98	2,355	354
Total exit activity costs & asset impairments	2,136	163	2,355	(308)
Residential Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	(43)
Exit activity costs (recoveries), net	219	(29)	370	(152)
Total exit activity costs & asset impairments	219	(29)	370	(195)
Industrial and Infrastructure Products
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	(703)
Exit activity costs (recoveries), net	1,346	(28)	1,313	190
Total exit activity costs & asset impairments	1,346	(28)	1,313	(513)
Renewable Energy and Conservation
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	65	0	84
Exit activity costs (recoveries), net	(95)	(68)	(1)	49
Total exit activity costs & asset impairments	(95)	(3)	(1)	133
Corporate
Restructuring Cost and Reserve [Line Items]
Inventory write-downs &/or asset impairment charges	0	0	0	0
Exit activity costs (recoveries), net	666	223	673	267
Total exit activity costs & asset impairments	$ 666	$ 223	$ 673	$ 267