XML 52 R37.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Real Estate and Intangible Assets - Summary of Properties Acquired (Detail) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 USD ($) ft² | Dec. 31, 2015 USD ($) ft² lease tenant | Jul. 25, 2014 ft²
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² |  |  | 81,371
Aggregate Purchase Price | $ 66,570 | $ 77,798 |
Series of Property Acquisitions [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² | 329,620 | 520,053 |
Aggregate Purchase Price | $ 66,570 | $ 77,798 |
Acquisition Expenses | 179 | 586 |
Aggregate Annualized GAAP Rent | 5,589 | 7,984 |
Aggregate Debt Issued | $ 38,800 | $ 43,379 |
Salt Lake City, UT [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² | 107,062 | 86,409 |
Lease Term | 6 years | 6 years 6 months |
Aggregate Purchase Price | $ 17,000 | $ 22,200 |
Aggregate Annualized GAAP Rent | 1,400 | 2,400 |
Aggregate Debt Issued | $ 9,900 | $ 13,000 |
Fort Lauderdale, FL [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² | 119,224 |  |
Lease Term | 9 years |  |
Aggregate Purchase Price | $ 23,900 |  |
Aggregate Debt Issued | $ 14,100 |  |
King of Prussia, PA [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² | 103,334 |  |
Lease Term | 15 years |  |
Aggregate Purchase Price | $ 25,700 |  |
Acquisition Expenses | 200 |  |
Aggregate Annualized GAAP Rent | 2,200 |  |
Aggregate Debt Issued | $ 14,800 |  |
Richardson, TX [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² |  | 155,984 |
Lease Term |  | 9 years 6 months |
Aggregate Purchase Price |  | $ 24,700 |
Aggregate Annualized GAAP Rent |  | 2,700 |
Aggregate Debt Issued |  | $ 14,600 |
Birmingham, AL [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² |  | 30,850 |
Lease Term |  | 8 years 6 months |
Aggregate Purchase Price |  | $ 3,600 |
Aggregate Annualized GAAP Rent |  | $ 300 |
Columbus, OH [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² |  | 78,033 |
Lease Term |  | 15 years |
Aggregate Purchase Price |  | $ 7,700 |
Aggregate Annualized GAAP Rent |  | 600 |
Aggregate Debt Issued |  | $ 4,500 |
Atlanta, GA [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² |  | 78,151 |
Lease Term |  | 7 years |
Aggregate Purchase Price |  | $ 13,000 |
Aggregate Annualized GAAP Rent |  | 1,300 |
Aggregate Debt Issued |  | $ 7,500 |
Number of tenants | tenant |  | 1 |
Number of leases | lease |  | 2 |
Atlanta, GA [Member] | Fifteen Year Lease [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Lease Term |  | 15 years |
Percentage of building occupied by tenant (as percent) |  | 30.00% |
Villa Rica, GA [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Aggregate Square Footage | ft² |  | 90,626 |
Lease Term |  | 18 years |
Aggregate Purchase Price |  | $ 6,600 |
Aggregate Annualized GAAP Rent |  | 600 |
Aggregate Debt Issued |  | $ 3,800 |
Weighted Average [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Lease Term | 3 years 10 months 24 days | 7 years 3 months 18 days |
Weighted Average [Member] | Series of Property Acquisitions [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Lease Term | 10 years 6 months | 9 years 10 months 24 days |

X
- Definition Annualized straight line rent. + References No definition available. + Details
Name: | good_AnnualizedStraightLineRent
Namespace Prefix: | good_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Business acquisition expenses. + References No definition available. + Details
Name: | good_BusinessAcquisitionExpenses
Namespace Prefix: | good_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Lease term available for lease. + References No definition available. + Details
Name: | good_LeaseTermAvailableForLease
Namespace Prefix: | good_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Leases + References No definition available. + Details
Name: | good_NumberofLeases
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Tenants + References No definition available. + Details
Name: | good_NumberofTenants
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage Of Building Occupied By Tenant + References No definition available. + Details
Name: | good_PercentageOfBuildingOccupiedByTenant
Namespace Prefix: | good_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Purchase price of acquired property. + References No definition available. + Details
Name: | good_PurchasePriceOfAcquiredProperty
Namespace Prefix: | good_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total amount of new mortgage loans on real estate during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29.6) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674 + Details
Name: | us-gaap_MortgageLoansOnRealEstateNewMortgageLoans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_SeriesofPropertyAcquisitionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_SaltLakeCityUTMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_FortLauderdaleFLMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_KingofPrussiaPAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_RichardsonTxMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_BirminghamAlMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_ColumbusOHMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_AtlantaGeorgiaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LeaseArrangementTypeAxis=good_FifteenYearLeaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=good_VillaRicaGeorgiaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |