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Stock Options (Narrative) (Details) (USD $) | 0 Months Ended | 12 Months Ended | 0 Months Ended |
--- | --- | --- | --- | ---
Feb. 01, 2008 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Jan. 05, 2015 | Oct. 25, 2000
Stock Options [Line Items] |  |  |  |  |  |
Number of shares that may be granted |  |  |  |  |  | 7,000,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Number of additional shares that may be granted | 3,500,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized |  |  |  |  |
Purchase price floor of fair market value |  | 85.00%tgc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePriceFloorOfFairMarketValue |  |  |  |
Weighted average fair value of options granted |  | $ 0.22 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue | $ 0.25 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue |  |  |
Compensation expense |  | $ 32,000 us-gaap_ShareBasedCompensation | $ 50,000 us-gaap_ShareBasedCompensation | $ 52,000 us-gaap_ShareBasedCompensation |  |
Expected volatility |  | 53.30%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 47.60%us-gaap_FairValueAssumptionsExpectedVolatilityRate | 65.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate |  |
Risk free interest rate |  | 3.27%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 2.97%us-gaap_FairValueAssumptionsRiskFreeInterestRate | 2.71%us-gaap_FairValueAssumptionsRiskFreeInterestRate |  |
Stock Options [Member] |  |  |  |  |  |
Stock Options [Line Items] |  |  |  |  |  |
Compensation expense |  | 32,000 us-gaap_ShareBasedCompensation / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | (28,000)us-gaap_ShareBasedCompensation / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 52,000 us-gaap_ShareBasedCompensation / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |
Current year compensation expense |  |  | 32,000 tgc_ShareBasedCompensationGross / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Reversal of compensation expense |  |  | $ 59,500 tgc_ReversalOfShareBasedCompensation / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Minimum [Member] |  |  |  |  |  |
Stock Options [Line Items] |  |  |  |  |  |
Voting power |  | 10.00%tgc_PercentOfVotingPower / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |
option life remaining |  | 1 month 6 days | 1 month 6 days | 1 month 6 days |  |
Maximum [Member] |  |  |  |  |  |
Stock Options [Line Items] |  |  |  |  |  |
option life remaining |  | 4 years 9 months 18 days | 4 years 9 months 18 days | 4 years 9 months 18 days |  |
Voluntary Resignation [Member] |  |  |  |  |  |
Stock Options [Line Items] |  |  |  |  |  |
Stock Incentive Plan exercisable period |  | 3 months |  |  |  |
10% Of Total Voting Power [Member] |  |  |  |  |  |
Stock Options [Line Items] |  |  |  |  |  |
Stock Incentive Plan exercisable period |  | 5 years |  |  |  |
Purchase price floor of fair market value |  | 110.00%tgc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePriceFloorOfFairMarketValue / tgc_ShareBasedCompensationVestingPeriodDescriptionAxis = tgc_TenPercentOfTotalVotingPowerMember |  |  |  |
Subsequent Event [Member] |  |  |  |  |  |
Stock Options [Line Items] |  |  |  |  |  |
Options issued to purchase |  |  |  |  | 25,000 us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |
Price per share |  |  |  |  | $ 0.25 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |

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- Definition Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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- Definition The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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