Effective Income Tax Rate Reconciliation, Estimated Annual Tax Rate

No definition available.

Name:	tgc_EffectiveIncomeTaxRateReconciliationEstimatedAnnualTaxRate
Namespace Prefix:	tgc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Income Taxes [Line Items]

+ References

No definition available.

+ Details

Name:	tgc_IncomeTaxesLineItems
Namespace Prefix:	tgc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

+ Details

Name:	us-gaap_DeferredTaxAssetsLiabilitiesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 6.I.Fact.4)
-URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

+ Details

Name:	us-gaap_OperatingLossCarryforwards
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Expiration date of each operating loss carryforward included in operating loss carryforward, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_OperatingLossCarryforwardsExpirationDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 10B
-URI http://asc.fasb.org/extlink&oid=120406818&loc=SL37586934-109318

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

+ Details

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_TaxPeriodAxis=tgc_TaxPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=tgc_IndefiniteTaxPeriodMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Income Taxes (Narrative) (Q2) (Details) - USD ($)	6 Months Ended	12 Months Ended
Income Taxes (Narrative) (Q2) (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Unrecognized tax benefits	$ 0	$ 0
Federal net operating loss carryforwards		33,800,000
Deferred tax asset	$ 0	$ 65,000	$ 130,000
Federal tax rate	21.00%	21.00%	21.00%
Estimated annual effective tax rate	0.00%
Tax Period Between 2020 And 2037 [Member]
Income Taxes [Line Items]
Federal net operating loss carryforwards		$ 31,500,000
Indefinite Tax Period [Member]
Income Taxes [Line Items]
Federal net operating loss carryforwards		$ 2,300,000
Minimum [Member] \| Tax Period Between 2020 And 2037 [Member]
Income Taxes [Line Items]
Federal net operating loss carryforwards expiration between, years	Jan. 01, 2020	Dec. 31, 2020
Maximum [Member] \| Tax Period Between 2020 And 2037 [Member]
Income Taxes [Line Items]
Federal net operating loss carryforwards expiration between, years	Dec. 31, 2037	Dec. 31, 2037