Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 09, 2022	Jun. 30, 2021
Document And Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Entity File Number	001-32924
Entity Registrant Name	Green Plains Inc.
Entity Central Index Key	0001309402
Entity Incorporation, State or Country Code	IA
Entity Tax Identification Number	84-1652107
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		53,616,152
Entity Public Float			$ 1,560.7
Entity Small Business	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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
ICFR Auditor Attestation Flag	true
Amendment Flag	false
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
Entity Shell Company	false
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive Proxy Statement for the 2022 Annual Meeting of Shareholders are incorporated by reference in Part III herein. The company intends to file such Proxy Statement with the Securities and Exchange Commission no later than 120 days after the end of the period covered by this report on Form 10-K.
Auditor Firm ID	185
Auditor Location	Omaha, NE
Auditor Name	KPMG LLP