Description Of Business And Significant Accounting Policies (Reconciliations Of The Numerators And Denominators Of Our Basic And Diluted Earnings Per Share) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified

3 Months Ended

12 Months Ended

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Earnings Per Share [Abstract]

Net income (loss) from continuing operations

$ (2,014)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 425us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 377us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 424us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 638us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 535us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 805us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 978us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ (788)us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 2,956us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

$ 4,244us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest

Net loss from discontinued operations

(9)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax

(54)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax

(33)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax

(41)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax

(137)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax

(4,311)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax

Weighted average shares - basic

60,842,413us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

60,778,356us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

Dilution effect of share-based compensation, treasury method

$ 7,518tgc_DilutionEffectOfShareBasedCompensationTreasuryMethod

$ 77,465tgc_DilutionEffectOfShareBasedCompensationTreasuryMethod

$ 376,275tgc_DilutionEffectOfShareBasedCompensationTreasuryMethod

Weighted average shares - dilutive

60,849,931us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

60,919,878us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

61,154,631us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

Continuing Operations

$ (0.01)us-gaap_IncomeLossFromContinuingOperationsPerBasicAndDilutedShare

$ 0.05us-gaap_IncomeLossFromContinuingOperationsPerBasicAndDilutedShare

$ 0.07us-gaap_IncomeLossFromContinuingOperationsPerBasicAndDilutedShare

Discontinued Operations

$ 0.00us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShare

$ (0.07)us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicAndDilutedShare

- Definition

Dilution Effect Of Share-Based Compensation, Treasury Method

+ References

No definition available.

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- Details

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- Definition

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items, and noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 19

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

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- Definition

The amount of net income (loss) from continuing operations per each basic and diluted share of common stock or unit when the per share amount is the same for both basic and diluted shares.

+ References

No definition available.

+ Details

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- Definition

Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 3

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-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.12)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 13

-Article 7

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-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

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-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.14)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 15

-Article 5

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- Definition

Per basic and diluted share amount, after tax, of income (loss) from the day-to-day business activities of the discontinued operation and gain (loss) from the disposal of the discontinued operation, when the per share amount is the same.

+ References

No definition available.

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References

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- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Weighted-Average Number of Common Shares Outstanding

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