| COVER PAGE COVER PAGE | Feb. 25, 2021 |
| Cover page. [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 25, 2021 |
| Entity Registrant Name | GIBRALTAR INDUSTRIES, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 0-22462 |
| Entity Tax Identification Number | 16-1445150 |
| Entity Address, Address Line One | 3556 Lake Shore Road |
| Entity Address, Address Line Two | P.O. Box 2028 |
| Entity Address, City or Town | Buffalo |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 14219-0228 |
| City Area Code | 716 |
| Local Phone Number | 826-6500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 par value per share |
| Trading Symbol | ROCK |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000912562 |
| Amendment Flag | false |
