Segment Information (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) segment	Jun. 30, 2016 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items]
Number of reportable segments \| segment			3
Net sales:	$ 247,627	$ 265,738	$ 454,232	$ 503,409
Income from operations:	61,825	68,843	111,080	122,993
Unallocated Corporate Expenses	(4,538)	(8,635)	(13,803)	(14,738)
Total income from operations	24,930	28,576	34,609	46,337
Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	127,252	119,965	231,803	220,112
Income from operations:	22,579	20,725	38,220	32,956
Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	57,926	81,380	108,644	161,397
Income from operations:	3,397	6,190	3,360	9,516
Renewable Energy & Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	62,763	64,766	114,555	122,640
Income from operations:	3,492	10,296	6,832	18,603
Intersegment Elimination
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	(314)	(373)	(770)	(740)
Intersegment Elimination \| Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	$ 57,612	$ 81,007	$ 107,874	$ 160,657

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1,2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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