Fixed Assets, Mineral Leaseholds, and Asset Retirement Obligations (Forecast of Accretion Expense) (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Fixed Assets And Asset Retirement Obligations [Abstract]
Remainder of 2020	$ 7,029
2021	9,402
2022	9,412
2023	10,075
2024	$ 10,786

Asset Retirement Obligation, Future Payments Due In Four Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueInFourYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due In Three Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueInThreeYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due In Two Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueInTwoYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due, Remainder of Fiscal Year

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueRemainderofFiscalYear
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due in Five Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueinFiveYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fixed Assets And Asset Retirement Obligations [Abstract]

No definition available.

Name:	gel_FixedAssetsAndAssetRetirementObligationsAbstract
Namespace Prefix:	gel_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration