| Document And Entity Information | Nov. 24, 2020 |
| Document Information [Line Items] | |
| Entity, Registrant Name | AEGION CORPORATION |
| Document, Type | 8-K |
| Document, Period End Date | Nov. 24, 2020 |
| Entity, Incorporation, State or Country Code | DE |
| Entity, File Number | 001-35328 |
| Entity, Tax Identification Number | 45-3117900 |
| Entity, Address, Address Line One | 17988 Edison Avenue |
| Entity, Address, City or Town | Chesterfield |
| Entity, Address, State or Province | MO |
| Entity, Address, Postal Zip Code | 63005 |
| City Area Code | 636 |
| Local Phone Number | 530-8000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Shares |
| Trading Symbol | AEGN |
| Security Exchange Name | NASDAQ |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000353020 |
