|
Real Estate and Intangible Assets - Fair Value of Acquired Assets and Liabilities Assumed (Detail) (USD $)
In Thousands, unless otherwise specified
|
3 Months Ended |
|
Mar. 31, 2015
|
Mar. 31, 2014
|
| Business Acquisition [Line Items] |
|
|
| Total Purchase Price |
$ 28,348good_PurchasePriceOfAcquiredProperty
|
$ 10,048good_PurchasePriceOfAcquiredProperty
|
| Customer Relationships [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
2,275us-gaap_FairValueOfAssetsAcquired
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
|
399us-gaap_FairValueOfAssetsAcquired
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
|
| Above Market Leases [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
975us-gaap_FairValueOfAssetsAcquired
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_AboveMarketLeasesMember
|
|
| Below Market Leases [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
6us-gaap_FairValueOfAssetsAcquired
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= good_BelowMarketLeaseMember
|
| Discount on Assumed Debt [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
131us-gaap_FairValueOfAssetsAcquired
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= good_DiscountPremiumOnAssumedDebtMember
|
| Richardson, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Total Purchase Price |
24,700good_PurchasePriceOfAcquiredProperty
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
|
|
| Richardson, TX [Member] | Customer Relationships [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
1,915us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
|
|
| Richardson, TX [Member] | Above Market Leases [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
975us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_AboveMarketLeasesMember
|
|
| Birmingham, AL [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Total Purchase Price |
3,648good_PurchasePriceOfAcquiredProperty
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
|
|
| Birmingham, AL [Member] | Customer Relationships [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
360us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
|
|
| Allen, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Total Purchase Price |
|
5,525good_PurchasePriceOfAcquiredProperty
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
|
| Allen, TX [Member] | Customer Relationships [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
218us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
|
| Allen, TX [Member] | Discount on Assumed Debt [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
72us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= good_DiscountPremiumOnAssumedDebtMember
|
| Colleyville, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Total Purchase Price |
|
4,523good_PurchasePriceOfAcquiredProperty
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
|
| Colleyville, TX [Member] | Customer Relationships [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
181us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= us-gaap_CustomerRelationshipsMember
|
| Colleyville, TX [Member] | Below Market Leases [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
6us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= good_BelowMarketLeaseMember
|
| Colleyville, TX [Member] | Discount on Assumed Debt [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
59us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
= good_DiscountPremiumOnAssumedDebtMember
|
| Land [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
3,359us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandMember
|
2,151us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandMember
|
| Land [Member] | Richardson, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
2,709us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandMember
|
|
| Land [Member] | Birmingham, AL [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
650us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandMember
|
|
| Land [Member] | Allen, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
874us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandMember
|
| Land [Member] | Colleyville, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
1,277us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandMember
|
| Building [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
14,186us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
|
5,816us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
|
| Building [Member] | Richardson, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
12,503us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
|
|
| Building [Member] | Birmingham, AL [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
1,683us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
|
|
| Building [Member] | Allen, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
3,509us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
|
| Building [Member] | Colleyville, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
2,307us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_BuildingMember
|
| Tenant Improvements [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
3,112us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_TenantImprovementMember
|
242us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_TenantImprovementMember
|
| Tenant Improvements [Member] | Richardson, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
2,761us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_TenantImprovementMember
|
|
| Tenant Improvements [Member] | Birmingham, AL [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
351us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_TenantImprovementMember
|
|
| Tenant Improvements [Member] | Allen, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
125us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_TenantImprovementMember
|
| Tenant Improvements [Member] | Colleyville, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
117us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_TenantImprovementMember
|
| In-Place Leases [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
2,504us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_InPlaceLeasesMember
|
1,084us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_InPlaceLeasesMember
|
| In-Place Leases [Member] | Richardson, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
2,046us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_InPlaceLeasesMember
|
|
| In-Place Leases [Member] | Birmingham, AL [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
458us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_InPlaceLeasesMember
|
|
| In-Place Leases [Member] | Allen, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
598us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_InPlaceLeasesMember
|
| In-Place Leases [Member] | Colleyville, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
486us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_InPlaceLeasesMember
|
| Leasing Costs [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
1,937us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_LeasingCostsMember
|
493us-gaap_FairValueOfAssetsAcquired
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_LeasingCostsMember
|
| Leasing Costs [Member] | Richardson, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
1,791us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_RichardsonTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_LeasingCostsMember
|
|
| Leasing Costs [Member] | Birmingham, AL [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
146us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_BirminghamAlMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_LeasingCostsMember
|
|
| Leasing Costs [Member] | Allen, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
273us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_AllenTXMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_LeasingCostsMember
|
| Leasing Costs [Member] | Colleyville, TX [Member] |
|
|
| Business Acquisition [Line Items] |
|
|
| Fair value of acquired assets related to the properties acquired |
|
$ 220us-gaap_FairValueOfAssetsAcquired
/ us-gaap_BusinessAcquisitionAxis
= good_ColleyvilleTxMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= good_LeasingCostsMember
|