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v3.20.2

Business and Organization - Additional Information (Detail) | Sep. 30, 2020 | Dec. 31, 2019
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OP Unit Holder |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |
Company's ownership percent (as percent) | 100.00% | 98.60%

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- Definition Organization consolidation and presentation of financial statements disclosure. + References No definition available. + Details
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Namespace Prefix: | land_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | srt_OwnershipAxis=land_OPUnitHolderMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |