Supplemental Financial Information (Schedule of Consolidating Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule Of Supplemental Financial Information [Line Items]
Net income	$ 4,087	$ 6,431	$ 9,596	$ 4,345
Other comprehensive income:
Foreign currency translation adjustment	2,138	1,542	(1,662)	638
Reclassification of loss on cash flow hedges, net of tax	0	(956)	143	(956)
Adjustment to retirement benefit liability, net of tax	2	2	4	4
Adjustment to post-retirement health care liability, net of tax	37	18	74	37
Other comprehensive income (loss)	2,177	606	(1,441)	(277)
Total comprehensive income	6,264	7,037	8,155	4,068
Gibraltar Industries, Inc.
Schedule Of Supplemental Financial Information [Line Items]
Net income	4,438	6,784	10,050	4,879
Other comprehensive income:
Foreign currency translation adjustment	0	0	0	0
Reclassification of loss on cash flow hedges, net of tax	0	0	0	0
Adjustment to retirement benefit liability, net of tax	0	0	0	0
Adjustment to post-retirement health care liability, net of tax	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Total comprehensive income	4,438	6,784	10,050	4,879
Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net income	6,655	9,025	14,506	9,340
Other comprehensive income:
Foreign currency translation adjustment	0	0	0	0
Reclassification of loss on cash flow hedges, net of tax	0	(956)	143	(956)
Adjustment to retirement benefit liability, net of tax	2	2	4	4
Adjustment to post-retirement health care liability, net of tax	37	18	74	37
Other comprehensive income (loss)	39	(936)	221	(915)
Total comprehensive income	6,694	8,089	14,727	8,425
Non-Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net income	(272)	794	548	1,362
Other comprehensive income:
Foreign currency translation adjustment	2,138	1,542	(1,662)	638
Reclassification of loss on cash flow hedges, net of tax	0	0	0	0
Adjustment to retirement benefit liability, net of tax	0	0	0	0
Adjustment to post-retirement health care liability, net of tax	0	0	0	0
Other comprehensive income (loss)	2,138	1,542	(1,662)	638
Total comprehensive income	1,866	2,336	(1,114)	2,000
Eliminations
Schedule Of Supplemental Financial Information [Line Items]
Net income	(6,734)	(10,172)	(15,508)	(11,236)
Other comprehensive income:
Foreign currency translation adjustment	0	0	0	0
Reclassification of loss on cash flow hedges, net of tax	0	0	0	0
Adjustment to retirement benefit liability, net of tax	0	0	0	0
Adjustment to post-retirement health care liability, net of tax	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Total comprehensive income	$ (6,734)	$ (10,172)	$ (15,508)	$ (11,236)