Quarterly report pursuant to Section 13 or 15(d)

Real Estate Held for Sale - Components of Income from Real Estate and Related Assets Held for Sale (Detail)

v2.4.1.9
Real Estate Held for Sale - Components of Income from Real Estate and Related Assets Held for Sale (Detail) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Real Estate Properties [Line Items]    
Other expense $ 7,546good_BusinessAcquisitionProFormaOtherExpenses $ 7,914good_BusinessAcquisitionProFormaOtherExpenses
Total operating revenues 19,880us-gaap_RealEstateRevenueNet 17,136us-gaap_RealEstateRevenueNet
Real Estate Held for Sale [Member]    
Real Estate Properties [Line Items]    
Operating revenue 83good_RealEstateOperatingIncomeNet
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember 		77good_RealEstateOperatingIncomeNet
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember
Operating expense 14good_RealEstateOperatingExpensesNet
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember 		23good_RealEstateOperatingExpensesNet
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember
Other expense 39good_BusinessAcquisitionProFormaOtherExpenses
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember 		40good_BusinessAcquisitionProFormaOtherExpenses
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember
Total operating revenues $ 30us-gaap_RealEstateRevenueNet
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember 		$ 14us-gaap_RealEstateRevenueNet
/ us-gaap_RealEstatePropertiesAxis
= good_RealEstateHeldForSaleMember