Debt (Narrative) (Details) - USD ($)	3 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Senior unsecured notes	$ 1,814,712,000	$ 1,813,169,000
6.000% senior unsecured notes due May 2023
Debt Instrument [Line Items]
Senior unsecured notes	$ 393,509,000	$ 393,242,000
Senior unsecured notes, stated rate	6.00%	6.00%
Debt Instrument, Face Amount	$ 400,000,000	$ 400,000,000
Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, amount outstanding	1,210,000,000.0
Total amount available for borrowings under credit facility	481,300,000
Senior Secured Credit Facility [Member] \| Letters Of Credit [Member]
Debt Instrument [Line Items]
Letters of credit, outstanding amount	8,700,000
5.750% senior unsecured notes due February 2021
Debt Instrument [Line Items]
Senior unsecured notes	$ 346,092,000	$ 345,837,000
Senior unsecured notes, stated rate	5.75%	5.75%
Debt Instrument, Face Amount	$ 350,000,000	$ 350,000,000
5.625% senior unsecured notes due June 2024
Debt Instrument [Line Items]
Senior unsecured notes	$ 343,611,000	$ 343,386,000
Senior unsecured notes, stated rate	5.625%	5.625%
Debt Instrument, Face Amount	$ 350,000,000	$ 350,000,000
6.75% Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Senior unsecured notes	$ 731,500,000	$ 730,704,000
Senior unsecured notes, stated rate	6.75%	6.75%
Debt Instrument, Face Amount	$ 750,000,000	$ 750,000,000
Amended Facility [Member] \| Accordion Feature [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Aggregate Maximum Borrowing Capacity	2,000,000,000
Amended Facility [Member] \| Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	1,700,000,000
Amended Facility [Member] \| Senior Secured Credit Facility [Member] \| Accordion Feature [Member]
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 300,000,000
Minimum [Member]
Debt Instrument [Line Items]
Letter of Credit, Fee Percentage	1.50%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Minimum [Member] \| Eurodollar Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Minimum [Member] \| Alternate Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Maximum [Member]
Debt Instrument [Line Items]
Letter of Credit, Fee Percentage	2.50%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
Maximum [Member] \| Eurodollar Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.75%
Maximum [Member] \| Senior Secured Credit Facility [Member] \| Letters Of Credit [Member]
Debt Instrument [Line Items]
Letters of credit, outstanding amount	$ 100,000,000
Maximum [Member] \| Alternate Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Petroleum Products [Member] \| Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, amount outstanding	$ 70,000,000

The annual rate paid for the use of letters of credit.

No definition available.

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- Definition

Line of credit facility, aggregate maximum borrowing capacity after accordion feature adjustment.

+ References

No definition available.

+ Details

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Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
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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

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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- 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.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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- 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

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- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

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