Supplemental Financial Information (Schedule of Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Supplemental Financial Information [Line Items]
Cash and cash equivalents	$ 208,032	$ 170,177	$ 173,062	$ 68,858
Accounts receivable, net	166,718	124,072
Intercompany balances	0	0
Inventories	85,156	89,612
Other current assets	8,195	7,336
Total current assets	468,101	391,197
Property, plant, and equipment, net	94,488	108,304
Goodwill	321,093	304,032
Acquired intangibles	107,943	110,790
Other assets	4,672	3,922
Investment in subsidiaries	0	0
Total assets	996,297	918,245
Accounts payable	96,181	69,944
Accrued expenses	83,264	70,392
Billings in excess of cost	18,234	11,352
Current maturities of long-term debt	400	400
Total current liabilities	198,079	152,088
Long-term debt	209,425	209,237
Deferred income taxes	38,162	38,002
Other non-current liabilities	45,200	58,038
Total shareholders’ equity	505,431	460,880
Total liabilities and shareholders' equity	996,297	918,245
Reportable Legal Entities | Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Cash and cash equivalents	182,827	143,826	149,784	39,597
Accounts receivable, net	158,877	117,526
Intercompany balances	21,351	6,152
Inventories	80,771	85,483
Other current assets	(32)	(10,070)
Total current assets	443,794	342,917
Property, plant, and equipment, net	90,933	104,642
Goodwill	298,331	282,300
Acquired intangibles	99,060	101,520
Other assets	4,672	3,922
Investment in subsidiaries	60,844	58,477
Total assets	997,634	893,778
Accounts payable	91,499	66,363
Accrued expenses	79,332	60,004
Billings in excess of cost	14,578	9,301
Current maturities of long-term debt	400	400
Total current liabilities	185,809	136,068
Long-term debt	1,025	1,200
Deferred income taxes	35,520	35,354
Other non-current liabilities	45,200	58,038
Total shareholders’ equity	730,080	663,118
Total liabilities and shareholders' equity	997,634	893,778
Reportable Legal Entities | Non-Guarantor Subsidiaries
Schedule Of Supplemental Financial Information [Line Items]
Cash and cash equivalents	25,205	26,351	23,278	29,261
Accounts receivable, net	7,841	6,546
Intercompany balances	(3,254)	(5,537)
Inventories	4,385	4,129
Other current assets	4,191	3,623
Total current assets	38,368	35,112
Property, plant, and equipment, net	3,555	3,662
Goodwill	22,762	21,732
Acquired intangibles	8,883	9,270
Other assets	0	0
Investment in subsidiaries	0	0
Total assets	73,568	69,776
Accounts payable	4,682	3,581
Accrued expenses	1,744	3,019
Billings in excess of cost	3,656	2,051
Current maturities of long-term debt	0	0
Total current liabilities	10,082	8,651
Long-term debt	0	0
Deferred income taxes	2,642	2,648
Other non-current liabilities	0	0
Total shareholders’ equity	60,844	58,477
Total liabilities and shareholders' equity	73,568	69,776
Reportable Legal Entities | Gibraltar Industries, Inc.
Schedule Of Supplemental Financial Information [Line Items]
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Intercompany balances	(18,097)	(615)
Inventories	0	0
Other current assets	4,036	13,783
Total current assets	(14,061)	13,168
Property, plant, and equipment, net	0	0
Goodwill	0	0
Acquired intangibles	0	0
Other assets	0	0
Investment in subsidiaries	730,080	663,118
Total assets	716,019	676,286
Accounts payable	0	0
Accrued expenses	2,188	7,369
Billings in excess of cost	0	0
Current maturities of long-term debt	0	0
Total current liabilities	2,188	7,369
Long-term debt	208,400	208,037
Deferred income taxes	0	0
Other non-current liabilities	0	0
Total shareholders’ equity	505,431	460,880
Total liabilities and shareholders' equity	716,019	676,286
Eliminations
Schedule Of Supplemental Financial Information [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts receivable, net	0	0
Intercompany balances	0	0
Inventories	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant, and equipment, net	0	0
Goodwill	0	0
Acquired intangibles	0	0
Other assets	0	0
Investment in subsidiaries	(790,924)	(721,595)
Total assets	(790,924)	(721,595)
Accounts payable	0	0
Accrued expenses	0	0
Billings in excess of cost		0
Current maturities of long-term debt	0	0
Total current liabilities	0	0
Long-term debt	0	0
Deferred income taxes	0	0
Other non-current liabilities	0	0
Total shareholders’ equity	(790,924)	(721,595)
Total liabilities and shareholders' equity	$ (790,924)	$ (721,595)