Supplemental Financial Information (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Schedule Of Supplemental Financial Information [Line Items]
Net cash provided by (used in) operating activities	$ 48,831	$ 102,186
Cash Flows from Investing Activities
Cash paid for acquisitions, net of cash acquired	(18,494)	(2,314)
Net proceeds from sale of property and equipment	12,935	249
Purchases of property, plant, and equipment	(5,152)	(7,600)
Net proceeds from sale of business	0	8,250
Other, net	0	1,118
Net cash used in investing activities	(10,711)	(297)
Cash Flows from Financing Activities
Long-term debt payments	400	400
Purchase of treasury stock at market prices	(1,982)	(1,178)
Net proceeds from issuance of common stock	649	2,892
Payment of debt issuance costs	0	(54)
Intercompany financing	0	0
Net cash used in financing activities	(1,733)	1,260
Effect of exchange rate changes on cash	1,468	1,055
Net increase in cash and cash equivalents	37,855	104,204
Cash and cash equivalents at beginning of year	170,177	68,858
Cash and cash equivalents at end of period	208,032	173,062
Reportable Legal Entities | Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net cash provided by (used in) operating activities	64,702	119,790
Cash Flows from Investing Activities
Cash paid for acquisitions, net of cash acquired	(18,494)	(2,314)
Net proceeds from sale of property and equipment	12,935	220
Purchases of property, plant, and equipment	(4,929)	(7,177)
Net proceeds from sale of business		0
Other, net		1,118
Net cash used in investing activities	(10,488)	(8,153)
Cash Flows from Financing Activities
Long-term debt payments	400	400
Purchase of treasury stock at market prices	0	0
Net proceeds from issuance of common stock	0	0
Payment of debt issuance costs		(54)
Intercompany financing	(14,813)	(996)
Net cash used in financing activities	(15,213)	(1,450)
Effect of exchange rate changes on cash	0	0
Net increase in cash and cash equivalents	39,001	110,187
Cash and cash equivalents at beginning of year	143,826	39,597
Cash and cash equivalents at end of period	182,827	149,784
Reportable Legal Entities | Non-Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net cash provided by (used in) operating activities	(735)	16,582
Cash Flows from Investing Activities
Cash paid for acquisitions, net of cash acquired	0	0
Net proceeds from sale of property and equipment	0	29
Purchases of property, plant, and equipment	(223)	(423)
Net proceeds from sale of business		8,250
Other, net		0
Net cash used in investing activities	(223)	7,856
Cash Flows from Financing Activities
Long-term debt payments	0	0
Purchase of treasury stock at market prices	0	0
Net proceeds from issuance of common stock	0	0
Payment of debt issuance costs		0
Intercompany financing	(1,656)	(31,476)
Net cash used in financing activities	(1,656)	(31,476)
Effect of exchange rate changes on cash	1,468	1,055
Net increase in cash and cash equivalents	(1,146)	(5,983)
Cash and cash equivalents at beginning of year	26,351	29,261
Cash and cash equivalents at end of period	25,205	23,278
Reportable Legal Entities | Gibraltar Industries, Inc.
Schedule Of Supplemental Financial Information [Line Items]
Net cash provided by (used in) operating activities	(15,136)	(34,186)
Cash Flows from Investing Activities
Cash paid for acquisitions, net of cash acquired	0	0
Net proceeds from sale of property and equipment	0	0
Purchases of property, plant, and equipment	0	0
Net proceeds from sale of business		0
Other, net		0
Net cash used in investing activities	0	0
Cash Flows from Financing Activities
Long-term debt payments	0	0
Purchase of treasury stock at market prices	(1,982)	(1,178)
Net proceeds from issuance of common stock	649	2,892
Payment of debt issuance costs		0
Intercompany financing	16,469	32,472
Net cash used in financing activities	15,136	34,186
Effect of exchange rate changes on cash	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of year	0	0
Cash and cash equivalents at end of period	0	0
Eliminations
Schedule Of Supplemental Financial Information [Line Items]
Net cash provided by (used in) operating activities	0	0
Cash Flows from Investing Activities
Cash paid for acquisitions, net of cash acquired	0	0
Net proceeds from sale of property and equipment	0	0
Purchases of property, plant, and equipment	0	0
Net proceeds from sale of business		0
Other, net		0
Net cash used in investing activities	0	0
Cash Flows from Financing Activities
Long-term debt payments	0	0
Purchase of treasury stock at market prices	0	0
Net proceeds from issuance of common stock	0	0
Payment of debt issuance costs		0
Intercompany financing	0	0
Net cash used in financing activities	0	0
Effect of exchange rate changes on cash	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of year	0	0
Cash and cash equivalents at end of period	$ 0	$ 0