Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items]
Number of reportable segments | segment			3
Net Sales	$ 329,665	$ 299,236	$ 864,918	$ 789,308
Total consolidated income from operations	43,859	31,420	93,640	68,592
Renewable Energy and Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	128,258	116,771	323,014	261,612
Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	151,718	126,275	394,609	360,417
Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	49,689	56,190	147,295	167,279
Operating Segments | Renewable Energy and Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	128,258	116,771	323,014	261,612
Total consolidated income from operations	14,195	19,633	29,082	30,914
Operating Segments | Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	151,718	126,275	394,609	360,417
Total consolidated income from operations	32,454	17,012	74,143	49,880
Operating Segments | Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	49,767	56,361	147,831	168,096
Total consolidated income from operations	5,199	5,462	15,832	13,660
Intersegment Elimination
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	(78)	(171)	(536)	(817)
Corporate
Segment Reporting, Other Significant Reconciling Item [Line Items]
Unallocated Corporate Expenses	$ (7,989)	$ (10,687)	$ (25,417)	$ (25,862)