Annual report pursuant to Section 13 and 15(d)

Real Estate and Lease Intangibles - Summary of Total Revenue and Earnings Recognized on Properties Acquired (Detail)

v2.4.1.9
Real Estate and Lease Intangibles - Summary of Total Revenue and Earnings Recognized on Properties Acquired (Detail) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Real Estate Properties [Line Items]      
Rental revenue $ 7,170,318us-gaap_OperatingLeasesIncomeStatementLeaseRevenue $ 4,027,687us-gaap_OperatingLeasesIncomeStatementLeaseRevenue $ 3,390,594us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
Natividad Road [Member]      
Real Estate Properties [Line Items]      
Rental revenue   413,476us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_NatividadRoadMember 		 
2014 New Real Estate Activity [Member]      
Real Estate Properties [Line Items]      
Rental revenue 1,026,625us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 444,208land_RealEstatePropertiesEarningsRecognized
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Collins Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date May 30, 2014    
Rental revenue 106,658us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_CollinsRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 33,303land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_CollinsRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Spring Valley [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Jun. 13, 2014    
Rental revenue 148,996us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_SpringValleyMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 81,073land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_SpringValleyMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | McIntosh Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Jun. 20, 2014    
Rental revenue 58,021us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_McintoshRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings (22,902)land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_McintoshRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Naumann Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Jul. 23, 2014    
Rental revenue 145,337us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_NaumannRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 104,726land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_NaumannRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Sycamore Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Jul. 25, 2014    
Rental revenue 80,328us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_SycamoreRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 39,574land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_SycamoreRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Wauchula Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Sep. 29, 2014    
Rental revenue 226,978us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_WauchulaRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 101,794land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_WauchulaRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Santa Clara Avenue [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Oct. 29, 2014    
Rental revenue 212,078us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_SantaClaraAvenueMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 73,833land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_SantaClaraAvenueMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2014 New Real Estate Activity [Member] | Dufau Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date Nov. 04, 2014    
Rental revenue 48,229us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_DufauRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
Earnings 32,807land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_DufauRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandFourteenNewRealEstateActivityMember 		   
2013 New Real Estate Activity [Member]      
Real Estate Properties [Line Items]      
Rental revenue   305,438us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   206,460land_RealEstatePropertiesEarningsRecognized
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | 38th Avenue [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   Apr. 05, 2013  
Rental revenue   64,494us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_ThirtyEightAvenueMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   35,996land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_ThirtyEightAvenueMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | Sequoia Street [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   May 31, 2013  
Rental revenue   112,944us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_SequoiaStreetMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   83,262land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_SequoiaStreetMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | Natividad Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   Oct. 21, 2013  
Rental revenue   86,510us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_NatividadRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   63,133land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_NatividadRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | 20th Avenue [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   May 11, 2013  
Rental revenue   20,184us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_TwentiethAvenueMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   6,919land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_TwentiethAvenueMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | Broadway Road [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   Dec. 16, 2013  
Rental revenue   7,396us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_BroadwayRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   3,713land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_BroadwayRoadMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | Oregon Trail [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   Dec. 27, 2013  
Rental revenue   10,195us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_OregonTrailMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   10,154land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_OregonTrailMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
2013 New Real Estate Activity [Member] | East Shelton [Member]      
Real Estate Properties [Line Items]      
Acquisition Date   Dec. 27, 2013  
Rental revenue   3,715us-gaap_OperatingLeasesIncomeStatementLeaseRevenue
/ us-gaap_RealEstatePropertiesAxis
= land_EastSheltonMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember 		 
Earnings   $ 3,283land_RealEstatePropertiesEarningsRecognized
/ us-gaap_RealEstatePropertiesAxis
= land_EastSheltonMember
/ us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis
= land_TwoThousandThirteenNewRealEstateActivityMember