Supplemental Financial Information (Schedule of Consolidating Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	$ 272,734	$ 265,738	$ 237,671	$ 304,994	$ 503,409	$ 776,143	$ 758,780
Cost of sales	204,847			243,598		585,263	623,350
Gross profit	67,887	68,843	54,150	61,396	122,993	190,880	135,430
Selling, general, and administrative expense	41,524			38,002		118,500	91,865
Income from operations	26,363	28,416	17,601	23,394	46,017	72,380	43,565
Interest expense	3,625			3,878		10,982	11,389
Other (income) expense	0			(1,780)		7,840	(4,238)
Income before taxes	22,738			21,296		53,558	36,414
Provision for income taxes	8,952	(1,897)	5,076	7,664	3,179	12,131	13,158
Income from continuing operations	13,786	16,715	14,105	13,632	30,820	41,427	23,256
Loss before taxes	0			0		0	(44)
Benefit of income taxes	0			0		0	(16)
Loss from discontinued operations	0			0		0	(28)
Equity in earnings from subsidiaries	0			0		0	0
Net income	13,786	$ 18,612	$ 9,029	13,632	$ 27,641	41,427	23,228
Reportable Legal Entities | Gibraltar Industries, Inc.
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	0			0		0	0
Cost of sales	0			0		0	0
Gross profit	0			0		0	0
Selling, general, and administrative expense	94			30		14,268	101
Income from operations	(94)			(30)		(14,268)	(101)
Interest expense	3,403			3,403		10,207	10,207
Other (income) expense	230			16		8,717	4
Income before taxes	(3,727)			(3,449)		(33,192)	(10,312)
Provision for income taxes	(1,416)			(1,210)		(10,898)	(3,617)
Income from continuing operations	(2,311)			(2,239)		(22,294)	(6,695)
Loss before taxes							0
Benefit of income taxes							0
Loss from discontinued operations							0
Equity in earnings from subsidiaries	15,746			17,742		64,006	32,248
Net income	13,435			15,503		41,712	25,553
Reportable Legal Entities | Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	265,657			280,828		728,782	700,646
Cost of sales	202,199			223,694		551,195	574,112
Gross profit	63,458			57,134		177,587	126,534
Selling, general, and administrative expense	38,664			33,392		100,101	83,076
Income from operations	24,794			23,742		77,486	43,458
Interest expense	241			494		836	1,254
Other (income) expense	(135)			(1,597)		(14)	(4,062)
Income before taxes	24,688			24,845		76,664	46,266
Provision for income taxes	10,804			8,514		22,189	15,949
Income from continuing operations	13,884			16,331		54,475	30,317
Loss before taxes							(44)
Benefit of income taxes							(16)
Loss from discontinued operations							(28)
Equity in earnings from subsidiaries	1,862			1,411		9,531	1,959
Net income	15,746			17,742		64,006	32,248
Reportable Legal Entities | Non-Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	15,799			34,565		63,014	76,732
Cost of sales	11,721			28,432		49,436	65,511
Gross profit	4,078			6,133		13,578	11,221
Selling, general, and administrative expense	2,766			4,580		4,131	8,688
Income from operations	1,312			1,553		9,447	2,533
Interest expense	(19)			(19)		(61)	(72)
Other (income) expense	(95)			(199)		(863)	(180)
Income before taxes	1,426			1,771		10,371	2,785
Provision for income taxes	(436)			360		840	826
Income from continuing operations	1,862			1,411		9,531	1,959
Loss before taxes							0
Benefit of income taxes							0
Loss from discontinued operations							0
Equity in earnings from subsidiaries	0			0		0	0
Net income	1,862			1,411		9,531	1,959
Eliminations
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	(8,722)			(10,399)		(15,653)	(18,598)
Cost of sales	(9,073)			(8,528)		(15,368)	(16,273)
Gross profit	351			(1,871)		(285)	(2,325)
Selling, general, and administrative expense	0			0		0	0
Income from operations	351			(1,871)		(285)	(2,325)
Interest expense	0			0		0	0
Other (income) expense	0			0		0	0
Income before taxes	351			(1,871)		(285)	(2,325)
Provision for income taxes	0			0		0	0
Income from continuing operations	351			(1,871)		(285)	(2,325)
Loss before taxes							0
Benefit of income taxes							0
Loss from discontinued operations							0
Equity in earnings from subsidiaries	(17,608)			(19,153)		(73,537)	(34,207)
Net income	$ (17,257)			$ (21,024)		$ (73,822)	$ (36,532)