| Document And Entity Information | Oct. 01, 2020 |
| Document And Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 1, 2020 |
| Entity Registrant Name | GREEN PLAINS INC. |
| Entity Incorporation, State or Country Code | IA |
| Entity File Number | 001-32924 |
| Entity Tax Identification Number | 84-1652107 |
| Entity Address, Address Line One | 1811 Aksarben Drive |
| Entity Address, City or Town | Omaha |
| Entity Address, State or Province | NE |
| Entity Address, Postal Zip Code | 68106 |
| City Area Code | 402 |
| Local Phone Number | 884-8700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.001 per share |
| Trading Symbol | GPRE |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001309402 |
| Amendment Flag | false |
| Current Fiscal Year End Date | --12-31 |
