Quarterly report pursuant to Section 13 or 15(d)

Mortgage Notes Payable and Line of Credit - Schedule of Principal Payments of Mortgage Notes Payable (Parenthetical) (Detail)

v2.4.1.9
Mortgage Notes Payable and Line of Credit - Schedule of Principal Payments of Mortgage Notes Payable (Parenthetical) (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Debt Instrument [Line Items]  
Refinance of principal payment maturity period, description We plan to refinance the 3 balloon principal payments that mature in the second half of 2015 with a combination of new mortgage debt and equity.
Liabilities related to assets held for sale $ 2,587us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
Mortgage Notes Payable [Member]  
Debt Instrument [Line Items]  
Liabilities related to assets held for sale 2,500us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
/ us-gaap_DebtInstrumentAxis
= good_MortgageNotesPayableMember
Premiums and discounts, net $ 630us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet
/ us-gaap_DebtInstrumentAxis
= good_MortgageNotesPayableMember