| Document And Entity Information | Mar. 17, 2021 |
| Document Information [Line Items] | |
| Entity, Registrant Name | GRANITE CONSTRUCTION INCORPORATED |
| Document, Type | 8-K |
| Document, Period End Date | Mar. 17, 2021 |
| Entity, Incorporation, State or Country Code | DE |
| Entity, File Number | 1-12911 |
| Entity, Tax Identification Number | 77-0239383 |
| Entity, Address, Address Line One | 585 West Beach Street |
| Entity, Address, City or Town | Watsonville |
| Entity, Address, State or Province | CA |
| Entity, Address, Postal Zip Code | 95076 |
| City Area Code | 831 |
| Local Phone Number | 724-1011 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | GVA |
| Security Exchange Name | NYSE |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000861459 |
