Goodwill and Related Intangible Assets (Schedule of Changes in Carrying Amount of Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at	$ 304,032
Acquired goodwill	16,863
Adjustments to prior year acquisitions	(832)
Foreign currency translation	1,030
Balance at	321,093
Accumulated impairment losses	235,419	$ 234,490
Residential Products
Goodwill [Roll Forward]
Balance at	181,285
Acquired goodwill	16,863
Adjustments to prior year acquisitions	0
Foreign currency translation	0
Balance at	198,148
Industrial and Infrastructure Products
Goodwill [Roll Forward]
Balance at	53,884
Acquired goodwill	0
Adjustments to prior year acquisitions	0
Foreign currency translation	432
Balance at	54,316
Renewable Energy & Conservation
Goodwill [Roll Forward]
Balance at	68,863
Acquired goodwill	0
Adjustments to prior year acquisitions	(832)
Foreign currency translation	598
Balance at	$ 68,629