Quarterly report pursuant to Section 13 or 15(d)

Borrowings - Summary of Mortgage Note Payable and Line of Credit (Parenthetical) (Detail)

v2.4.1.9
Borrowings - Summary of Mortgage Note Payable and Line of Credit (Parenthetical) (Detail) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Mortgage Note Payable [Member] | MetLife [Member]    
Debt Instrument [Line Items]    
Effective interest rate percentage 3.61%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_LineOfCreditFacilityAxis
= land_MetlifeMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_NotesPayableToBanksMember
 
Remaining availability $ 7,500,000land_LongTermDebtAdditionalAvailableAmount
/ us-gaap_LineOfCreditFacilityAxis
= land_MetlifeMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_NotesPayableToBanksMember
$ 13,800,000land_LongTermDebtAdditionalAvailableAmount
/ us-gaap_LineOfCreditFacilityAxis
= land_MetlifeMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_NotesPayableToBanksMember
Line of Credit [Member] | MetLife [Member]    
Debt Instrument [Line Items]    
Remaining availability 7,500,000land_LongTermDebtAdditionalAvailableAmount
/ us-gaap_LineOfCreditFacilityAxis
= land_MetlifeMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember
13,800,000land_LongTermDebtAdditionalAvailableAmount
/ us-gaap_LineOfCreditFacilityAxis
= land_MetlifeMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember
Mortgage Notes Payable [Member] | Farm Credit [Member]    
Debt Instrument [Line Items]    
Effective interest rate percentage 12.70%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_LineOfCreditFacilityAxis
= land_FarmCreditMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_NotesPayableOtherPayablesMember
12.70%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_LineOfCreditFacilityAxis
= land_FarmCreditMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_NotesPayableOtherPayablesMember
Bond Payable [Member] | Farmer Mac [Member]    
Debt Instrument [Line Items]    
Remaining availability $ 0land_LongTermDebtAdditionalAvailableAmount
/ us-gaap_LineOfCreditFacilityAxis
= land_FarmerMacMember
/ us-gaap_LongtermDebtTypeAxis
= land_BondsPayableMember
$ 0land_LongTermDebtAdditionalAvailableAmount
/ us-gaap_LineOfCreditFacilityAxis
= land_FarmerMacMember
/ us-gaap_LongtermDebtTypeAxis
= land_BondsPayableMember