Real Estate and Intangible Assets - Schedule of Revenue and Earnings Recognized on Properties Acquired (Parenthetical) (Detail)

v2.4.1.9

Real Estate and Intangible Assets - Schedule of Revenue and Earnings Recognized on Properties Acquired (Parenthetical) (Detail) (Monroe, MI [Member])	0 Months Ended
	Dec. 23, 2014 Lease Property	Dec. 23, 2014 Property
Monroe, MI [Member]
Business Acquisition [Line Items]
Number of properties acquired	2good_NumberOfPropertiesAcquired / us-gaap_BusinessAcquisitionAxis = good_MonroeMember	2good_NumberOfPropertiesAcquired / us-gaap_BusinessAcquisitionAxis = good_MonroeMember
Number of leases acquired	2good_NumberOfLeaseAgreementsAcquired / us-gaap_BusinessAcquisitionAxis = good_MonroeMember