Derivative Instruments and Hedging Activities - Gain (Loss) for Derivative Instruments Not Designated or Qualifying as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized gains (losses)			$ 30,158	$ (22,173)
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)	$ (2,870)	$ (8,516)	3,748	(28,987)
Foreign currency exchange (loss) gain (notes 8 and 11)	(2,843)	(11,624)	4,117	(6,885)
Unrealized gains (losses)			8,199	(3,660)
Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)	(3,555)	10,607
Realized gains (losses)	(1,293)	(35,274)		(37,091)
Unrealized gains (losses)	(2,262)	45,881
Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)			(26,410)	(6,814)
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)			3,748	(28,987)
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net			30,158	(22,173)
Interest rate swap agreements \| Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(3,925)	(3,662)	(8,398)	(6,573)
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)	(2,870)	(8,516)	21,760	(28,948)
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net	1,055	(4,854)	30,158	(22,375)
Foreign Exchange Forward [Member] \| Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)			0	(241)
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)			0	(39)
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net			0	202
Cross currency swap agreements \| Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)	(1,293)	(1,430)
Unrealized gains (losses)	(2,262)	45,881
Cross-currency swap agreements termination \| Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Foreign currency exchange (loss) gain (notes 8 and 11)	0	(33,844)	0	(33,844)
Realized gains (losses)	0	(33,844)	0	(33,844)
Unrealized gains (losses)	0	0	0	0
Cross-currency swap agreements \| Foreign Currency Gain (Loss) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)			229	(40,750)
Foreign currency exchange (loss) gain (notes 8 and 11)	$ (3,555)	$ 44,451	229	(6,906)
Realized gains (losses)			(2,638)	(3,247)
Unrealized gains (losses)			2,867	(3,659)
Interest rate swaps terminated \| Gain (Loss) on Derivative Instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized gains (losses)			(18,012)	0
Realized and unrealized (loss) gain on non-designated derivative instruments (note 11)			(18,012)	0
Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net			$ 0	$ 0

Derivative instruments not designated as hedging instruments realized gain (loss) net.

No definition available.

Name:	tgp_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRealizedGainLossNet
Namespace Prefix:	tgp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Derivative Instruments Not Designated As Hedging Instruments Unrealized Gain (Loss) Net

+ References

No definition available.

+ Details

Name:	tgp_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsUnrealizedGainLossNet
Namespace Prefix:	tgp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=125521441&loc=d3e30690-110894

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 35
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123602790&loc=d3e30226-110892

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 10
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=120253306&loc=d3e28228-110885

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124440516&loc=d3e30840-110895

+ Details

Name:	us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

+ References

+ Details

Name:	us-gaap_ForeignCurrencyTransactionGainLossRealized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount before tax of foreign currency transaction unrealized gain (loss) recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124440516&loc=d3e30840-110895

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=125521441&loc=d3e30690-110894

+ Details

Name:	us-gaap_ForeignCurrencyTransactionGainLossUnrealized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

+ Details

Name:	us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_ForeignCurrencyGainLossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_GainLossOnDerivativeInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeForwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CurrencySwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=tgp_CrossCurrencyInterestRateContractTerminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CrossCurrencyInterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=tgp_InterestRateSwapsTerminatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: