Debt (Narrative - Partnership Segment, Covenant Compliance, And Restricted Net Assets) (Details)	3 Months Ended
Mar. 31, 2020 USD ($)
Debt Instrument [Line Items]
Restricted assets	$ 65,500,000
Partnership [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Additional amounts available under facility, accordion feature	20,000,000.0
Debt instrument, face amount	$ 200,000,000.0
Debt maturity dates	Jul. 01, 2020
Net leverage ratio	2.47
Interest coverage ratio	6.49
Consolidated Leverage Ratio Numerator	$ 5,000,000.0
Consolidated Leverage Ratio Denominator	$ 30,000,000.0
Partnership [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Unused capacity fee, percentage	0.35%
Interest coverage ratio	2.75
Partnership [Member] \| Revolving Credit Facility [Member] \| Minimum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Interest rate, basis spread on variable rate, percentage	2.25%
Partnership [Member] \| Revolving Credit Facility [Member] \| Minimum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Interest rate, basis spread on variable rate, percentage	1.25%
Partnership [Member] \| Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Unused capacity fee, percentage	0.50%
Net leverage ratio	3.50
Partnership [Member] \| Revolving Credit Facility [Member] \| Maximum [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Interest rate, basis spread on variable rate, percentage	3.00%
Partnership [Member] \| Revolving Credit Facility [Member] \| Maximum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Interest rate, basis spread on variable rate, percentage	2.00%

Consolidated Leverage Ratio Denominator

No definition available.

Name:	gpre_ConsolidatedLeverageRatioDenominator
Namespace Prefix:	gpre_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Consolidated Leverage Ratio Numerator

+ References

No definition available.

+ Details

Name:	gpre_ConsolidatedLeverageRatioNumerator
Namespace Prefix:	gpre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt Instrument Credit Facility Amounts Available Accordion Feature

+ References

No definition available.

+ Details

Name:	gpre_DebtInstrumentCreditFacilityAmountsAvailableAccordionFeature
Namespace Prefix:	gpre_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Interest coverage ratio.

+ References

No definition available.

+ Details

Name:	gpre_InterestCoverageRatio
Namespace Prefix:	gpre_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Net leverage ratio

+ References

No definition available.

+ Details

Name:	gpre_NetLeverageRatio
Namespace Prefix:	gpre_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e)(3)(ii))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_AmountOfRestrictedNetAssetsForConsolidatedAndUnconsolidatedSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=gpre_PartnershipSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: