Supplemental Financial Information (Consolidating Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Statement of Income Captions [Line Items]
Net income (loss)	$ 220	$ 13,632	$ 4,087	$ 5,509	$ (95,709)	$ 9,540	$ 6,431	$ (2,086)	$ 23,448	$ (81,824)	$ (5,633)
Other comprehensive (loss) income:
Foreign currency translation adjustment									(6,228)	(4,364)	(2,108)
Unrealized loss on cash flow hedges, net of tax									143	(143)	0
Adjustment to retirement benefit liability, net of tax									49	(24)	53
Adjustment to post-retirement healthcare benefit liability, net of tax									171	(1,435)	45
Other comprehensive loss									(5,865)	(5,966)	(2,010)
Total comprehensive income (loss)									17,583	(87,790)	(7,643)
Gibraltar Industries, Inc.
Condensed Statement of Income Captions [Line Items]
Net income (loss)									27,036	(80,650)	(4,864)
Other comprehensive (loss) income:
Foreign currency translation adjustment									0	0	0
Unrealized loss on cash flow hedges, net of tax									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
Other comprehensive loss									0	0	0
Total comprehensive income (loss)									27,036	(80,650)	(4,864)
Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income (loss)									36,401	(71,191)	9,041
Other comprehensive (loss) income:
Foreign currency translation adjustment									0	0	0
Unrealized loss on cash flow hedges, net of tax									143	(143)
Adjustment to retirement benefit liability, net of tax									34	3	53
Adjustment to post-retirement healthcare benefit liability, net of tax									171	(1,435)	45
Other comprehensive loss									348	(1,575)	98
Total comprehensive income (loss)									36,749	(72,766)	9,139
Non-Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income (loss)									(1,213)	2,929	(19,351)
Other comprehensive (loss) income:
Foreign currency translation adjustment									(6,228)	(4,364)	(2,108)
Unrealized loss on cash flow hedges, net of tax									0	0
Adjustment to retirement benefit liability, net of tax									15	(27)	0
Adjustment to post-retirement healthcare benefit liability, net of tax									0	0	0
Other comprehensive loss									(6,213)	(4,391)	(2,108)
Total comprehensive income (loss)									(7,426)	(1,462)	(21,459)
Eliminations
Condensed Statement of Income Captions [Line Items]
Net income (loss)									(38,776)	67,088	9,541
Other comprehensive (loss) income:
Foreign currency translation adjustment									0	0	0
Unrealized loss on cash flow hedges, net of tax									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
Other comprehensive loss									0	0	0
Total comprehensive income (loss)									$ (38,776)	$ 67,088	$ 9,541