Segment Information (Summary Of Financial Data) (Details) - USD ($)					3 Months Ended									9 Months Ended	12 Months Ended
		Dec. 28, 2020	Sep. 01, 2019	Nov. 15, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	[1]	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues					$ 478,764,000	$ 424,062,000	$ 388,024,000		$ 632,869,000	$ 715,677,000	$ 632,350,000	$ 630,570,000	$ 438,641,000		$ 1,923,719,000	$ 2,417,238,000	$ 2,983,932,000
Cost of goods sold															1,812,163,000	2,384,947,000	2,806,968,000
Operating income (loss)					(34,795,000)	(14,205,000)	$ (19,368,000)		$ (54,328,000)	$ (14,922,000)	$ (42,365,000)	$ (46,645,000)	$ (38,638,000)		(122,696,000)	(142,570,000)	89,954,000
Depreciation and amortization															78,244,000	72,127,000	98,258,000
Capital expenditures															111,799,000	76,472,000	38,343,000
Gain (loss) on disposal of assets						2,000,000.0								$ 2,000,000.0	(20,860,000)		150,351,000
Goodwill impairment						0									24,091,000
Hereford Ethanol Plant [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets		$ 22,400,000			(22,400,000)
Green Plains Cattle Company LLC [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets			$ 0		$ (500,000)	$ 2,000,000.0
Bluffton, Lakota and Riga Ethanol Plants [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets				$ 92,200,000
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues															2,029,797,000	2,520,053,000	3,111,486,000
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															(106,078,000)	(102,815,000)	(127,554,000)
Cost of goods sold															(104,579,000)	(103,904,000)	(124,270,000)
Operating income (loss)															(1,400,000)	1,188,000	(3,110,000)
Ethanol Production [Member]
Segment Reporting Information [Line Items]
Revenues															1,502,581,000	1,700,715,000	2,120,661,000
Goodwill impairment															24,091,000
Ethanol Production [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues															1,502,481,000	1,700,615,000	2,120,475,000
Cost of goods sold															1,507,335,000	1,791,099,000	2,118,787,000
Operating income (loss)	[2]														(129,618,000)	(178,575,000)	(111,823,000)
Depreciation and amortization															67,956,000	63,073,000	80,227,000
Capital expenditures															109,970,000	72,374,000	27,322,000
Gain (loss) on disposal of assets															(3,900,000)
Goodwill impairment															24,100,000
Ethanol Production [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															(100,000)	(100,000)	(186,000)
Agribusiness & Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues															443,871,000	735,500,000	768,956,000
Agribusiness & Energy Services [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues															416,403,000	708,316,000	735,855,000
Cost of goods sold															409,407,000	696,226,000	717,772,000
Operating income (loss)															15,773,000	22,777,000	29,076,000
Depreciation and amortization															2,512,000	2,222,000	2,470,000
Capital expenditures															1,195,000	2,251,000	277,000
Agribusiness & Energy Services [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															(27,468,000)	(27,184,000)	(33,101,000)
Food & Ingredients [Member]
Segment Reporting Information [Line Items]
Revenues																1,451,000	121,121,000
Food & Ingredients [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues																1,451,000	121,121,000
Cost of goods sold																1,526,000	94,679,000
Operating income (loss)																(76,000)	14,354,000
Depreciation and amortization																	7,553,000
Capital expenditures																	9,025,000
Green Plains Partners [Member]
Segment Reporting Information [Line Items]
Revenues															83,345,000	82,387,000	100,748,000
Goodwill impairment
Green Plains Partners [Member] | Bluffton, Lakota and Riga Ethanol Plants [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets				2,700,000
Green Plains Partners [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues															4,835,000	6,856,000	6,481,000
Operating income (loss)															50,437,000	50,635,000	64,770,000
Depreciation and amortization															3,806,000	3,441,000	4,442,000
Capital expenditures															162,000	305,000	1,268,000
Green Plains Partners [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues															(78,510,000)	(75,531,000)	(94,267,000)
Corporate Activities [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	[3]														(57,888,000)	(38,519,000)	96,687,000
Depreciation and amortization															3,970,000	3,391,000	3,566,000
Capital expenditures															472,000	$ 1,542,000	451,000
Goodwill impairment															24,100,000
Corporate Activities [Member] | Hereford Ethanol Plant [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets		$ 18,500,000													(18,500,000)
Corporate Activities [Member] | Green Plains Cattle Company LLC [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets															$ 1,500,000
Corporate Activities [Member] | Bluffton, Lakota and Riga Ethanol Plants [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposal of assets				$ 89,500,000													$ 150,400,000

[1] During the third quarter of 2020, the company identified an immaterial issue which resulted in the overstatement of both revenues and cost of goods sold within the agribusiness and energy services segment as previously reported for the three and six months ended June 30, 2020. The second quarter revenues and cost of goods sold reflected in the quarterly financial data have been revised to correct these amounts.

[2] Operating loss for the ethanol production segment for fiscal year 2020 includes a goodwill impairment charge of $24.1 million and $3.9 million pretax loss on sale of assets from the sale of the Hereford, Texas ethanol plant.

[3] Corporate activities for fiscal year 2020 include a goodwill impairment charge of $24.1 million, $18.5 million pretax loss on sale of assets from the sale of the Hereford, Texas ethanol plant and a $1.5 million net gain from sale of GPCC. Fiscal year 2018 includes a $150.4 million gain on the sale of the Bluffton, Indiana, Lakota, Iowa, and Riga, Michigan ethanol plants, as well as Fleischmann’s Vinegar during the fourth quarter.