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Supplemental Financial Information (Schedule of Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016 | Jun. 30, 2016 | Dec. 31, 2015
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Schedule Of Supplemental Financial Information [Line Items] |  |  |  |
Cash and cash equivalents | $ 182,379 | $ 170,177 | $ 124,114 | $ 68,858
Accounts receivable, net | 138,871 | 124,072 |  |
Intercompany balances | 0 | 0 |  |
Inventories | 86,065 | 89,612 |  |
Other current assets | 8,351 | 7,336 |  |
Total current assets | 415,666 | 391,197 |  |
Property, plant, and equipment, net | 95,869 | 108,304 |  |
Goodwill | 320,848 | 304,032 |  |
Acquired intangibles | 110,325 | 110,790 |  |
Other assets | 4,750 | 3,922 |  |
Investment in subsidiaries | 0 | 0 |  |
Total assets | 947,458 | 918,245 |  |
Accounts payable | 88,007 | 69,944 |  |
Accrued expenses | 69,389 | 70,392 |  |
Billings in excess of cost | 13,963 | 11,352 |  |
Current maturities of long-term debt | 400 | 400 |  |
Total current liabilities | 171,759 | 152,088 |  |
Long-term debt | 209,229 | 209,237 |  |
Deferred income taxes | 38,203 | 38,002 |  |
Other non-current liabilities | 46,364 | 58,038 |  |
Total shareholders’ equity | 481,903 | 460,880 |  |
Total liabilities and shareholders' equity | 947,458 | 918,245 |  |
Reportable Legal Entities | Guarantor Subsidiaries |  |  |  |
Schedule Of Supplemental Financial Information [Line Items] |  |  |  |
Cash and cash equivalents | 158,843 | 143,826 | 100,762 | 39,597
Accounts receivable, net | 131,513 | 117,526 |  |
Intercompany balances | 15,604 | 6,152 |  |
Inventories | 81,927 | 85,483 |  |
Other current assets | 1,498 | (10,070) |  |
Total current assets | 389,385 | 342,917 |  |
Property, plant, and equipment, net | 92,450 | 104,642 |  |
Goodwill | 298,399 | 282,300 |  |
Acquired intangibles | 101,232 | 101,520 |  |
Other assets | 4,750 | 3,922 |  |
Investment in subsidiaries | 58,978 | 58,477 |  |
Total assets | 945,194 | 893,778 |  |
Accounts payable | 84,230 | 66,363 |  |
Accrued expenses | 60,533 | 60,004 |  |
Billings in excess of cost | 11,524 | 9,301 |  |
Current maturities of long-term debt | 400 | 400 |  |
Total current liabilities | 156,687 | 136,068 |  |
Long-term debt | 950 | 1,200 |  |
Deferred income taxes | 35,583 | 35,354 |  |
Other non-current liabilities | 46,364 | 58,038 |  |
Total shareholders’ equity | 705,610 | 663,118 |  |
Total liabilities and shareholders' equity | 945,194 | 893,778 |  |
Reportable Legal Entities | Non-Guarantor Subsidiaries |  |  |  |
Schedule Of Supplemental Financial Information [Line Items] |  |  |  |
Cash and cash equivalents | 23,536 | 26,351 | 23,352 | 29,261
Accounts receivable, net | 7,358 | 6,546 |  |
Intercompany balances | (4,815) | (5,537) |  |
Inventories | 4,138 | 4,129 |  |
Other current assets | 4,123 | 3,623 |  |
Total current assets | 34,340 | 35,112 |  |
Property, plant, and equipment, net | 3,419 | 3,662 |  |
Goodwill | 22,449 | 21,732 |  |
Acquired intangibles | 9,093 | 9,270 |  |
Other assets | 0 | 0 |  |
Investment in subsidiaries | 0 | 0 |  |
Total assets | 69,301 | 69,776 |  |
Accounts payable | 3,777 | 3,581 |  |
Accrued expenses | 1,487 | 3,019 |  |
Billings in excess of cost | 2,439 | 2,051 |  |
Current maturities of long-term debt | 0 | 0 |  |
Total current liabilities | 7,703 | 8,651 |  |
Long-term debt | 0 | 0 |  |
Deferred income taxes | 2,620 | 2,648 |  |
Other non-current liabilities | 0 | 0 |  |
Total shareholders’ equity | 58,978 | 58,477 |  |
Total liabilities and shareholders' equity | 69,301 | 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 | (10,789) | (615) |  |
Inventories | 0 | 0 |  |
Other current assets | 2,730 | 13,783 |  |
Total current assets | (8,059) | 13,168 |  |
Property, plant, and equipment, net | 0 | 0 |  |
Goodwill | 0 | 0 |  |
Acquired intangibles | 0 | 0 |  |
Other assets | 0 | 0 |  |
Investment in subsidiaries | 705,610 | 663,118 |  |
Total assets | 697,551 | 676,286 |  |
Accounts payable | 0 | 0 |  |
Accrued expenses | 7,369 | 7,369 |  |
Billings in excess of cost | 0 | 0 |  |
Current maturities of long-term debt | 0 | 0 |  |
Total current liabilities | 7,369 | 7,369 |  |
Long-term debt | 208,279 | 208,037 |  |
Deferred income taxes | 0 | 0 |  |
Other non-current liabilities | 0 | 0 |  |
Total shareholders’ equity | 481,903 | 460,880 |  |
Total liabilities and shareholders' equity | 697,551 | 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 | (764,588) | (721,595) |  |
Total assets | (764,588) | (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 | (764,588) | (721,595) |  |
Total liabilities and shareholders' equity | $ (764,588) | $ (721,595) |  |

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