Goodwill and Related Intangible Assets (Schedule of Changes in Carrying Amount of Goodwill) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Goodwill [Roll Forward]
Balance at December 31, 2019	$ 329,705
Acquired goodwill	52,659
Adjustments to prior year acquisitions	75
Foreign currency translation	(394)
Balance at March 31, 2020	382,045
Renewable Energy and Conservation
Goodwill [Roll Forward]
Balance at December 31, 2019	77,602
Acquired goodwill	52,659
Adjustments to prior year acquisitions	75
Foreign currency translation	75
Balance at March 31, 2020	130,411
Residential Products
Goodwill [Roll Forward]
Balance at December 31, 2019	198,075
Acquired goodwill	0
Adjustments to prior year acquisitions	0
Foreign currency translation	0
Balance at March 31, 2020	198,075
Industrial and Infrastructure Products
Goodwill [Roll Forward]
Balance at December 31, 2019	54,028
Acquired goodwill	0
Adjustments to prior year acquisitions	0
Foreign currency translation	(469)
Balance at March 31, 2020	$ 53,559