XML 37 R26.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Note 1 - Basis of Presentation (Details Textual) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2018 | Dec. 31, 2019
Period for Creating Allowance for Doubtful Accounts | 120 days |
Scenario, Forecast [Member] | Accounting Standards Update 2016-02 [Member] |  |
New Accounting Pronouncement Effect, Lease Obligation Asset and Liability, Percent |  | 1.00%

X
- Definition The percentage of effect of change in accounting principle on lease obligation asset and liability. + References No definition available. + Details
Name: | gtn_NewAccountingPronouncementEffectLeaseObligationAssetAndLiabilityPercent
Namespace Prefix: | gtn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period for creating allowance for doubtful accounts. + References No definition available. + Details
Name: | gtn_PeriodForCreatingAllowanceForDoubtfulAccounts
Namespace Prefix: | gtn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |