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Note 2 - Revenue (Details Textual) - USD ($) $ in Millions | Sep. 30, 2018 | Jan. 01, 2018
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Deferred Revenue [Member] |  |
Deposit Liability, Current | $ 11.7 | $ 3.8

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- Definition The current portion, due within one year or one operating cycle, if longer, of deposits held other than customer deposits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DepositLiabilityCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
Name: | us-gaap_BalanceSheetLocationAxis=gtn_DeferredRevenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |