Supplemental Financial Information (Consolidating Statements of Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Statement of Income Captions [Line Items]
Net (loss) income	$ (95,709)	$ 9,540	$ 6,431	$ (2,086)	$ 4,009	$ (13,727)	$ 7,732	$ (3,647)	$ (81,824)	$ (5,633)	$ 12,645
Other comprehensive (loss) income:
Foreign currency translation adjustment									(4,364)	(2,108)	2,353
Adjustment to retirement benefit liability, net of tax									(24)	53	(79)
Adjustment to post-retirement healthcare benefit liability, net of tax									(1,435)	45	(499)
Unrealized loss on cash flow hedges, net of tax									(143)	0	0
Other comprehensive (loss) income									(5,966)	(2,010)	1,775
Total comprehensive (loss) income									(87,790)	(7,643)	14,420
Gibraltar Industries, Inc.
Condensed Statement of Income Captions [Line Items]
Net (loss) income									(80,650)	(4,864)	13,614
Other comprehensive (loss) income:
Foreign currency translation adjustment									0	0	0
Adjustment to retirement benefit liability, net of tax									0	0	0
Adjustment to post-retirement healthcare benefit liability, net of tax									0	0	0
Unrealized loss on cash flow hedges, net of tax									0
Other comprehensive (loss) income									0	0	0
Total comprehensive (loss) income									(80,650)	(4,864)	13,614
Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net (loss) income									(71,191)	9,041	24,535
Other comprehensive (loss) income:
Foreign currency translation adjustment									0	0	0
Adjustment to retirement benefit liability, net of tax									3	53	(79)
Adjustment to post-retirement healthcare benefit liability, net of tax									(1,435)	45	(499)
Unrealized loss on cash flow hedges, net of tax									(143)
Other comprehensive (loss) income									(1,575)	98	(578)
Total comprehensive (loss) income									(72,766)	9,139	23,957
Non-Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net (loss) income									2,929	(19,351)	3,960
Other comprehensive (loss) income:
Foreign currency translation adjustment									(4,364)	(2,108)	2,353
Adjustment to retirement benefit liability, net of tax									(27)	0	0
Adjustment to post-retirement healthcare benefit liability, net of tax									0	0	0
Unrealized loss on cash flow hedges, net of tax									0
Other comprehensive (loss) income									(4,391)	(2,108)	2,353
Total comprehensive (loss) income									(1,462)	(21,459)	6,313
Eliminations
Condensed Statement of Income Captions [Line Items]
Net (loss) income									67,088	9,541	(29,464)
Other comprehensive (loss) income:
Foreign currency translation adjustment									0	0	0
Adjustment to retirement benefit liability, net of tax									0	0	0
Adjustment to post-retirement healthcare benefit liability, net of tax									0	0	0
Unrealized loss on cash flow hedges, net of tax									0
Other comprehensive (loss) income									0	0	0
Total comprehensive (loss) income									$ 67,088	$ 9,541	$ (29,464)