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Supplemental Financial Information (Schedule of Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Dec. 31, 2014 | Mar. 31, 2014 | Dec. 31, 2013
--- | --- | --- | --- | --- | --- | ---
Schedule Of Supplemental Financial Information [Line Items] |  |  |  |  |  |
Cash and cash equivalents | $ 173,062 | $ 68,858 | $ 43,331 | $ 110,610 | $ 43,331 | $ 110,610
Accounts receivable, net | 155,434 | 164,969 |  |  |  |
Intercompany balances | 0 | 0 |  |  |  |
Inventories | 92,778 | 107,058 |  |  |  |
Other current assets | 9,897 | 10,537 |  |  |  |
Total current assets | 431,171 | 351,422 |  |  |  |
Property, plant, and equipment, net | 106,315 | 118,932 |  |  |  |
Goodwill | 294,858 | 292,390 |  |  |  |
Acquired intangibles | 118,388 | 123,013 |  |  |  |
Other assets | 4,100 | 4,015 |  |  |  |
Investment in subsidiaries | 0 | 0 |  |  |  |
Total assets | 954,832 | 889,772 |  |  |  |
Accounts payable | 87,495 | 89,204 |  |  |  |
Accrued expenses | 63,111 | 67,605 |  |  |  |
Billings in excess of cost | 26,026 | 28,186 |  |  |  |
Current maturities of long-term debt | 400 | 400 |  |  |  |
Total current liabilities | 177,032 | 185,395 |  |  |  |
Long-term debt | 209,041 | 208,882 |  |  |  |
Deferred income taxes | 43,366 | 42,654 |  |  |  |
Other non-current liabilities | 55,748 | 42,755 |  |  |  |
Total shareholders’ equity | 469,645 | 410,086 |  |  |  |
Total liabilities and shareholders' equity | 954,832 | 889,772 |  |  |  |
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 | 8,234 | 15,023 |  |  |  |
Inventories | 0 | 0 |  |  |  |
Other current assets | 12,808 | 4,535 |  |  |  |
Total current assets | 21,042 | 19,558 |  |  |  |
Property, plant, and equipment, net | 0 | 0 |  |  |  |
Goodwill | 0 | 0 |  |  |  |
Acquired intangibles | 0 | 0 |  |  |  |
Other assets | 0 | 0 |  |  |  |
Investment in subsidiaries | 660,635 | 603,208 |  |  |  |
Total assets | 681,677 | 622,766 |  |  |  |
Accounts payable | 0 | 0 |  |  |  |
Accrued expenses | 4,116 | 5,127 |  |  |  |
Billings in excess of cost | 0 | 0 |  |  |  |
Current maturities of long-term debt | 0 | 0 |  |  |  |
Total current liabilities | 4,116 | 5,127 |  |  |  |
Long-term debt | 207,916 | 207,553 |  |  |  |
Deferred income taxes | 0 | 0 |  |  |  |
Other non-current liabilities | 0 | 0 |  |  |  |
Total shareholders’ equity | 469,645 | 410,086 |  |  |  |
Total liabilities and shareholders' equity | 681,677 | 622,766 |  |  |  |
Reportable Legal Entities | Guarantor Subsidiaries |  |  |  |  |  |
Schedule Of Supplemental Financial Information [Line Items] |  |  |  |  |  |
Cash and cash equivalents | 149,784 | 39,597 | 18,886 | 91,466 |  |
Accounts receivable, net | 146,258 | 142,674 |  |  |  |
Intercompany balances | (2,212) | 12,033 |  |  |  |
Inventories | 87,296 | 99,132 |  |  |  |
Other current assets | (8,672) | 2,957 |  |  |  |
Total current assets | 372,454 | 296,393 |  |  |  |
Property, plant, and equipment, net | 100,968 | 106,413 |  |  |  |
Goodwill | 270,017 | 270,017 |  |  |  |
Acquired intangibles | 106,097 | 111,734 |  |  |  |
Other assets | 4,100 | 4,015 |  |  |  |
Investment in subsidiaries | 64,525 | 54,792 |  |  |  |
Total assets | 918,161 | 843,364 |  |  |  |
Accounts payable | 84,040 | 81,551 |  |  |  |
Accrued expenses | 55,455 | 55,363 |  |  |  |
Billings in excess of cost | 21,758 | 20,548 |  |  |  |
Current maturities of long-term debt | 400 | 400 |  |  |  |
Total current liabilities | 161,653 | 157,862 |  |  |  |
Long-term debt | 1,125 | 1,329 |  |  |  |
Deferred income taxes | 39,000 | 38,763 |  |  |  |
Other non-current liabilities | 55,748 | 42,202 |  |  |  |
Total shareholders’ equity | 660,635 | 603,208 |  |  |  |
Total liabilities and shareholders' equity | 918,161 | 843,364 |  |  |  |
Reportable Legal Entities | Non-Guarantor Subsidiaries |  |  |  |  |  |
Schedule Of Supplemental Financial Information [Line Items] |  |  |  |  |  |
Cash and cash equivalents | 23,278 | 29,261 | 24,445 | 19,144 |  |
Accounts receivable, net | 9,176 | 22,295 |  |  |  |
Intercompany balances | (6,022) | (27,056) |  |  |  |
Inventories | 5,482 | 7,926 |  |  |  |
Other current assets | 5,761 | 3,045 |  |  |  |
Total current assets | 37,675 | 35,471 |  |  |  |
Property, plant, and equipment, net | 5,347 | 12,519 |  |  |  |
Goodwill | 24,841 | 22,373 |  |  |  |
Acquired intangibles | 12,291 | 11,279 |  |  |  |
Other assets | 0 | 0 |  |  |  |
Investment in subsidiaries | 0 | 0 |  |  |  |
Total assets | 80,154 | 81,642 |  |  |  |
Accounts payable | 3,455 | 7,653 |  |  |  |
Accrued expenses | 3,540 | 7,115 |  |  |  |
Billings in excess of cost | 4,268 | 7,638 |  |  |  |
Current maturities of long-term debt | 0 | 0 |  |  |  |
Total current liabilities | 11,263 | 22,406 |  |  |  |
Long-term debt | 0 | 0 |  |  |  |
Deferred income taxes | 4,366 | 3,891 |  |  |  |
Other non-current liabilities | 0 | 553 |  |  |  |
Total shareholders’ equity | 64,525 | 54,792 |  |  |  |
Total liabilities and shareholders' equity | 80,154 | 81,642 |  |  |  |
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 | (725,160) | (658,000) |  |  |  |
Total assets | (725,160) | (658,000) |  |  |  |
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 | (725,160) | (658,000) |  |  |  |
Total liabilities and shareholders' equity | $ (725,160) | $ (658,000) |  |  |  |

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