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Description of Business - Additional Information (Detail) | Jun. 30, 2020 Property State ft²
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Description Of Business [Line Items] |
Number of properties in portfolio | 946
Number of states in which our properties are located | State | 35
Space used for office | ft² | 8,900
Third Party Landlords [Member] |
Description Of Business [Line Items] |
Number of properties leased | 59
Owned Properties [Member] |
Description Of Business [Line Items] |
Number of properties | 887

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- Definition Description of business. + References No definition available. + Details
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Namespace Prefix: | gty_
Data Type: | xbrli:stringItemType
Balance Type: | na
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- Definition Lease space used for office. + References No definition available. + Details
Name: | gty_LeaseSpaceUsedForOffice
Namespace Prefix: | gty_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition The number of real estate properties in the portfolio, consisting of properties owned and properties leased from third party landlords. + References No definition available. + Details
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Namespace Prefix: | gty_
Data Type: | xbrli:integerItemType
Balance Type: | na
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- Definition The number of real estate properties leased from third-party landlords as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | gty_
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Balance Type: | na
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- Definition The number of states in which the company's properties, comprised of those that are owned and those that are leased from third party landlords, are located. + References No definition available. + Details
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Namespace Prefix: | gty_
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- Definition The number of real estate properties owned as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
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Period Type: | instant

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- Details
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Namespace Prefix: |
Data Type: | na
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- Details
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Namespace Prefix: |
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Period Type: |