Derivative Financial Instruments (Details) - Jun. 30, 2016 CAD in Millions, $ in Millions	CAD item	USD ($) item
Exchange-Traded Derivatives \| Long [Member]
Volume of activity related to derivative financial instruments
Nonmonetary units	58,999	58,999
Exchange-Traded Derivatives \| Short [Member]
Volume of activity related to derivative financial instruments
Nonmonetary units	61,531	61,531
OTC Derivatives (Petroleum/Ethanol) \| Long [Member]
Volume of activity related to derivative financial instruments
Nonmonetary units	7,721	7,721
OTC Derivatives (Petroleum/Ethanol) \| Short [Member]
Volume of activity related to derivative financial instruments
Nonmonetary units	5,209	5,209
OTC Derivatives (Natural Gas) \| Long [Member]
Volume of activity related to derivative financial instruments
Nonmonetary units	13,617	13,617
OTC Derivatives (Natural Gas) \| Short [Member]
Volume of activity related to derivative financial instruments
Nonmonetary units	12,819	12,819
Interest Rate Swaps
Volume of activity related to derivative financial instruments
Monetary units \| $		$ 100.0
Foreign Currency Derivatives
Volume of activity related to derivative financial instruments
Monetary units \| CAD	CAD 1.4
Open Forward Exchange Contracts
Volume of activity related to derivative financial instruments
Monetary units \| $		$ 1.1
Forward rate of CAD to USD	1.2967	1.2967

- Definition

Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual rate at which a foreign currency can be purchased or sold.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
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

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- Details

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- Details

Name:	us-gaap_PositionAxis=us-gaap_LongMember
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- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=glp_DerivativesPetroleumEthanolMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=glp_CommodityContractNaturalGasMember
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Data Type:	na
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
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- Details

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