Segment Information (Details) $ in Thousands	3 Months Ended
Mar. 31, 2017 USD ($) segment	Mar. 31, 2016 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items]
Number of reportable segments \| segment	3
Net sales:	$ 206,605	$ 237,671
Income from operations:	49,255	54,150
Unallocated Corporate Expenses	(9,265)	(6,103)
Total income from operations	9,679	17,761
Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	104,551	100,147
Income from operations:	15,641	12,231
Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	50,718	80,017
Income from operations:	(37)	3,326
Renewable Energy & Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	51,792	57,874
Income from operations:	3,340	8,307
Intersegment Elimination
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	(456)	(367)
Intersegment Elimination \| Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	$ 50,262	$ 79,650

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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