Fixed Assets and Mineral Leaseholds (Forecast of Accretion Expense) (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Fixed Assets And Asset Retirement Obligations [Abstract]
Remainder of 2018	$ 2,459
2019	9,057
2020	8,710
2021	9,302
2022	$ 9,935

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