Supplemental Financial Information (Schedule of Consolidating Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	$ 215,337	$ 206,605
Cost of sales	167,019	157,350
Gross profit	48,318	49,255
Selling, general, and administrative expense	34,475	39,576
Income from operations	13,843	9,679
Interest expense	3,269	3,576
Other (income) expense	(585)	54
Income before taxes	11,159	6,049
Provision for income taxes	2,807	2,053
Income from continuing operations	8,352	3,996
Equity in earnings from subsidiaries	0	0
Net income	8,352	3,996
Reportable Legal Entities | Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	204,467	197,748
Cost of sales	158,584	150,507
Gross profit	45,883	47,241
Selling, general, and administrative expense	32,724	36,506
Income from operations	13,159	10,735
Interest expense	(84)	192
Other (income) expense	28	130
Income before taxes	13,215	10,413
Provision for income taxes	3,335	3,378
Equity in earnings from subsidiaries	1,090	(692)
Net income	10,970	6,343
Reportable Legal Entities | Non-Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	12,330	11,242
Cost of sales	9,758	8,982
Gross profit	2,572	2,260
Selling, general, and administrative expense	1,707	3,027
Income from operations	865	(767)
Interest expense	(49)	(18)
Other (income) expense	(613)	(76)
Income before taxes	1,527	(673)
Provision for income taxes	437	19
Equity in earnings from subsidiaries	0	0
Net income	1,090	(692)
Reportable Legal Entities | Gibraltar Industries, Inc.
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general, and administrative expense	44	43
Income from operations	(44)	(43)
Interest expense	3,402	3,402
Other (income) expense	0	0
Income before taxes	(3,446)	(3,445)
Provision for income taxes	(965)	(1,344)
Equity in earnings from subsidiaries	10,970	6,343
Net income	8,489	4,242
Eliminations
Schedule Of Supplemental Financial Information [Line Items]
Net Sales	(1,460)	(2,385)
Cost of sales	(1,323)	(2,139)
Gross profit	(137)	(246)
Selling, general, and administrative expense	0	0
Income from operations	(137)	(246)
Interest expense	0	0
Other (income) expense	0	0
Income before taxes	(137)	(246)
Provision for income taxes	0	0
Equity in earnings from subsidiaries	(12,060)	(5,651)
Net income	$ (12,197)	$ (5,897)