Goodwill and Related Intangible Assets (Schedule of Changes in Carrying Amount of Goodwill) (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Goodwill [Roll Forward]
Balance at	$ 321,074
Acquired goodwill	2,838
Adjustments to prior year acquisitions	(38)
Foreign currency translation	(553)
Balance at	323,321
Residential Products
Goodwill [Roll Forward]
Balance at	198,075
Acquired goodwill	0
Adjustments to prior year acquisitions	0
Foreign currency translation	0
Balance at	198,075
Industrial and Infrastructure Products
Goodwill [Roll Forward]
Balance at	54,280
Acquired goodwill	0
Adjustments to prior year acquisitions	(38)
Foreign currency translation	(165)
Balance at	54,077
Renewable Energy & Conservation
Goodwill [Roll Forward]
Balance at	68,719
Acquired goodwill	2,838
Adjustments to prior year acquisitions	0
Foreign currency translation	(388)
Balance at	$ 71,169

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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