Derivative and Hedging Financial Instruments - Summary of Volumes and Average Contract Prices of Contracts (Detail) - Mar. 31, 2015	MMBTU $ / MMBTU
BP Hedge [Member]
Derivative [Line Items]
Volumes (MMBtu)	113,206
BP Hedge [Member] \| 2015 [Member]
Derivative [Line Items]
Volumes (MMBtu)	113,206
Commodity contracts, Weighted- Average Floor Price/mmbtu \| $ / MMBTU	4.00
Commodity contracts, Weighted- Average Ceiling Price/mmbtu \| $ / MMBTU	4.28
Morgan Stanley Fixed I [Member]
Derivative [Line Items]
Volumes (MMBtu)	10,567,599
Morgan Stanley Fixed I [Member] \| 2015 [Member]
Derivative [Line Items]
Volumes (MMBtu)	3,074,261
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	4.11
Morgan Stanley Fixed I [Member] \| 2016 [Member]
Derivative [Line Items]
Volumes (MMBtu)	3,002,489
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	4.06
Morgan Stanley Fixed I [Member] \| 2017 [Member]
Derivative [Line Items]
Volumes (MMBtu)	2,495,153
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	4.16
Morgan Stanley Fixed I [Member] \| 2018 [Member]
Derivative [Line Items]
Volumes (MMBtu)	1,995,696
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	4.29
Morgan Stanley Fixed II [Member]
Derivative [Line Items]
Volumes (MMBtu)	3,910,169
Morgan Stanley Fixed II [Member] \| 2015 [Member]
Derivative [Line Items]
Volumes (MMBtu)	1,542,873
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	3.92
Morgan Stanley Fixed II [Member] \| 2016 [Member]
Derivative [Line Items]
Volumes (MMBtu)	992,431
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	3.92
Morgan Stanley Fixed II [Member] \| 2017 [Member]
Derivative [Line Items]
Volumes (MMBtu)	771,407
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	3.92
Morgan Stanley Fixed II [Member] \| 2018 [Member]
Derivative [Line Items]
Volumes (MMBtu)	603,458
Commodity contracts, Weighted- Average Fixed Price/mmbtu \| $ / MMBTU	3.92
Morgan Stanley Fixed III [Member]
Derivative [Line Items]
Volumes (MMBtu)	6,562,333
Morgan Stanley Fixed III [Member] \| 2015 [Member]
Derivative [Line Items]
Volumes (MMBtu)	1,992,096
Commodity contracts, Basis Swap Fixed Price/mmbtu \| $ / MMBTU	(1.12)
Morgan Stanley Fixed III [Member] \| 2016 [Member]
Derivative [Line Items]
Volumes (MMBtu)	1,842,098
Commodity contracts, Basis Swap Fixed Price/mmbtu \| $ / MMBTU	(1.12)
Morgan Stanley Fixed III [Member] \| 2017 [Member]
Derivative [Line Items]
Volumes (MMBtu)	1,518,648
Commodity contracts, Basis Swap Fixed Price/mmbtu \| $ / MMBTU	(1.12)
Morgan Stanley Fixed III [Member] \| 2018 [Member]
Derivative [Line Items]
Volumes (MMBtu)	1,209,491
Commodity contracts, Basis Swap Fixed Price/mmbtu \| $ / MMBTU	(1.12)

The volume of energy of a commodity or material specified in an investment contract.

No definition available.

Name:	teng_InvestmentContractVolumeOfEnergy
Namespace Prefix:	teng_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

The average cap rate on a group of price risk derivatives such as caps or collars. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageCapPrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Definition

The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageFloorPrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
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

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

- Definition

Average fixed price related to the group of price risk swap derivatives.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeSwapTypeAverageFixedPrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Definition

Fixed price related to the price risk swap derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeSwapTypeFixedPrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_EnergyAxis=teng_NaturalGasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_EnergyAxis=teng_GasHedgesOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_EnergyAxis=teng_GasHedgesTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_EnergyAxis=teng_GasHedgesThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: