Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail)

v2.4.1.9
Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail) (Subsequent Event [Member], USD $)
0 Months Ended
Jan. 13, 2015
Jan. 13, 2015
Subsequent Event [Line Items]    
Distribution per Common Share $ 0.105us-gaap_DividendsPayableAmountPerShare $ 0.105us-gaap_DividendsPayableAmountPerShare
Dividend Period One [Member]
   
Subsequent Event [Line Items]    
Record Date Jan. 23, 2015  
Payment Date Feb. 03, 2015  
Distribution per Common Share $ 0.035us-gaap_DividendsPayableAmountPerShare
/ us-gaap_DividendsAxis
= land_DividendPeriodOneMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
$ 0.035us-gaap_DividendsPayableAmountPerShare
/ us-gaap_DividendsAxis
= land_DividendPeriodOneMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Dividend Period Two [Member]
   
Subsequent Event [Line Items]    
Record Date Feb. 18, 2015  
Payment Date Feb. 27, 2015  
Distribution per Common Share $ 0.035us-gaap_DividendsPayableAmountPerShare
/ us-gaap_DividendsAxis
= land_DividendPeriodTwoMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
$ 0.035us-gaap_DividendsPayableAmountPerShare
/ us-gaap_DividendsAxis
= land_DividendPeriodTwoMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Dividend Period Three [Member]
   
Subsequent Event [Line Items]    
Record Date Mar. 20, 2015  
Payment Date Mar. 31, 2015  
Distribution per Common Share $ 0.035us-gaap_DividendsPayableAmountPerShare
/ us-gaap_DividendsAxis
= land_DividendPeriodThreeMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
$ 0.035us-gaap_DividendsPayableAmountPerShare
/ us-gaap_DividendsAxis
= land_DividendPeriodThreeMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember