Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items]
Number of reportable segments | segment			3
Net Sales	$ 285,814	$ 262,655	$ 535,253	$ 490,072
Total consolidated income from operations	34,591	26,606	49,781	37,172
Renewable Energy and Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	98,259	76,004	194,756	144,841
Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	139,472	130,433	242,891	234,142
Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	48,083	56,218	97,606	111,089
Operating Segments | Renewable Energy and Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	98,259	76,004	194,756	144,841
Total consolidated income from operations	9,188	9,649	14,887	11,281
Operating Segments | Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	139,472	130,433	242,891	234,142
Total consolidated income from operations	27,964	20,778	41,689	32,868
Operating Segments | Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	48,263	56,547	98,064	111,735
Total consolidated income from operations	6,644	4,069	10,633	8,198
Intersegment Elimination
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net Sales	(180)	(329)	(458)	(646)
Corporate
Segment Reporting, Other Significant Reconciling Item [Line Items]
Unallocated Corporate Expenses	$ (9,205)	$ (7,890)	$ (17,428)	$ (15,175)