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The total amount of revenue recognized for the period from operating leases, direct financing leases, above and below market leases and sublease revenue.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Leases.

No definition available.

Name:	gty_LeasesLineItems
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The number of real estate properties in the portfolio, consisting of properties owned and properties leased from third party landlords.

No definition available.

Name:	gty_NumberOfPropertiesInPortfolio
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Data Type:	xbrli:integerItemType
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Period Type:	instant

The number of real estate properties leased from third-party landlords as of the balance sheet date.

No definition available.

Name:	gty_NumberOfPropertiesLeasedFromLandlords
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Data Type:	xbrli:integerItemType
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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.

No definition available.

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Real estate non-cash adjustments.

No definition available.

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The dollar amount of real estate taxes and other municipal charges paid by the company and then reimbursed by tenants included in revenues from rental properties and rental property expenses.

No definition available.

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Data Type:	xbrli:monetaryItemType
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The number of real estate properties owned as of the balance sheet date.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-2

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Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479773/842-30-50-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-6A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479016/842-30-45-3

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Present value of lessee's discounted obligation for lease payments from operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of lessee's right to use underlying asset under operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of lease income from variable lease payments, interest income from net investment on sales-type lease, and profit (loss) recognized at commencement.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479773/842-30-50-6

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

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