Supplemental Financial Information (Schedule Of Consolidating Statements Of Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule Of Supplemental Financial Information [Line Items]
Net income (loss)	$ 9,540	$ (13,727)	$ 13,885	$ (9,642)
Other comprehensive income (loss):
Foreign currency translation adjustment	(2,734)	2,539	(2,096)	(1,362)
Change in unrealized loss on cash flow hedges, net of tax	714	0	(242)	0
Adjustment to retirement benefit liability, net of tax	2	3	6	7
Adjustment to post-retirement health care liability, net of tax	19	18	56	56
Other comprehensive (loss) income	(1,999)	2,560	(2,276)	(1,299)
Total comprehensive income (loss)	7,541	(11,167)	11,609	(10,941)
Gibraltar Industries, Inc.
Schedule Of Supplemental Financial Information [Line Items]
Net income (loss)	9,794	(13,471)	14,673	(8,652)
Other comprehensive income (loss):
Foreign currency translation adjustment	0	0	0	0
Change in unrealized loss on cash flow hedges, net of tax	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 (loss) income	0	0	0	0
Total comprehensive income (loss)	9,794	(13,471)	14,673	(8,652)
Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net income (loss)	12,059	(11,229)	21,399	2,635
Other comprehensive income (loss):
Foreign currency translation adjustment	0	0	0	0
Change in unrealized loss on cash flow hedges, net of tax	714		(242)
Adjustment to retirement benefit liability, net of tax	2	3	6	7
Adjustment to post-retirement health care liability, net of tax	19	18	56	56
Other comprehensive (loss) income	735	21	(180)	63
Total comprehensive income (loss)	12,794	(11,208)	21,219	2,698
Non-Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Net income (loss)	854	(21,882)	2,216	(20,831)
Other comprehensive income (loss):
Foreign currency translation adjustment	(2,734)	2,539	(2,096)	(1,362)
Change in unrealized loss on cash flow hedges, net of tax	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 (loss) income	(2,734)	2,539	(2,096)	(1,362)
Total comprehensive income (loss)	(1,880)	(19,343)	120	(22,193)
Eliminations
Schedule Of Supplemental Financial Information [Line Items]
Net income (loss)	(13,167)	32,855	(24,403)	17,206
Other comprehensive income (loss):
Foreign currency translation adjustment	0	0	0	0
Change in unrealized loss on cash flow hedges, net of tax	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 (loss) income	0	0	0	0
Total comprehensive income (loss)	$ (13,167)	$ 32,855	$ (24,403)	$ 17,206