Segment Information (Measurements Used by Management to Assess Performance of Segments) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales	$ 282,093	$ 304,994	$ 253,171	$ 200,615	$ 201,994	$ 234,101	$ 234,960	$ 191,032	$ 1,040,873	$ 862,087	$ 827,567
Income (loss) from operations:	4,520	$ 23,394	$ 11,201	$ 8,970	(103,872)	$ 18,392	$ 14,730	$ 333	48,085	(70,417)	21,480
Depreciation and amortization									30,548	25,432	27,050
Total assets	889,772				810,471				889,772	810,471	889,571
Capital expenditures									12,373	23,291	14,940
Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Income (loss) from operations:									12,659	0	0
Intersegment sales
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:									(1,536)	(1,260)	(1,672)
Unallocated Corporate Expenses
Segment Reporting, Other Significant Reconciling Item [Line Items]
Income (loss) from operations:									(26,959)	(12,199)	(20,654)
Depreciation and amortization									662	823	941
Total assets	37,235				108,229				37,235	108,229	88,972
Capital expenditures									328	135	248
Residential Products | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales									475,653	431,915	394,071
Income (loss) from operations:									46,804	16,416	34,965
Depreciation and amortization									9,967	10,699	11,421
Total assets	363,339				394,092				363,339	394,092	389,506
Capital expenditures									3,328	12,731	5,937
Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales									376,688	430,172	433,496
Industrial and Infrastructure Products | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:									378,224	431,432	435,168
Income (loss) from operations:									15,581	(74,634)	7,169
Depreciation and amortization									12,108	13,910	14,688
Total assets	273,987				308,150				273,987	308,150	411,093
Capital expenditures									4,846	10,425	8,755
Renewable Energy and Conservation | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales									188,532	0	0
Depreciation and amortization									7,811	0	0
Total assets	$ 215,211				$ 0				215,211	0	0
Capital expenditures									$ 3,871	$ 0	$ 0