XML 60 R37.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Real Estate and Intangible Assets - Summary of Properties Acquired (Detail) $ in Thousands |  |  |  |  |  |  |  |  | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 27, 2018 USD ($) ft² | Oct. 30, 2018 USD ($) ft² property shares | Sep. 20, 2018 USD ($) ft² | Mar. 09, 2018 USD ($) ft² | Dec. 01, 2017 USD ($) ft² | Jul. 31, 2017 USD ($) ft² property | Jul. 07, 2017 USD ($) ft² | Jun. 22, 2017 USD ($) ft² | Dec. 31, 2018 USD ($) ft² | Dec. 31, 2017 USD ($) ft² | Dec. 31, 2016 USD ($) | Jul. 25, 2014 ft²
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  |  |  |  |  |  |  |  |  | 81,371
Aggregate Purchase Price |  |  |  |  |  |  |  |  | $ 63,245 | $ 132,157 |  |
Change in unrealized (loss) gain related to interest rate hedging instruments, net |  |  |  |  |  |  |  |  | $ (183) | $ 35 | $ 0 |
New fixed rate mortgage notes payable |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate (as a percent) |  |  |  |  |  |  |  |  | 4.76% |  |  |
Series of Property Acquisitions |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  |  |  |  |  |  | 591,037 | 871,038 |  |
Lease Term |  |  |  |  |  |  |  |  | 11 years 1 month 6 days | 10 years 1 month 6 days |  |
Aggregate Purchase Price |  |  |  |  |  |  |  |  | $ 63,245 | $ 132,157 |  |
Acquisition Expenses |  |  |  |  |  |  |  |  | 905 | 1,348 |  |
Aggregate Annualized GAAP Rent |  |  |  |  |  |  |  |  | 5,984 | 15,507 |  |
Aggregate Mortgage Debt Issued or Assumed |  |  |  |  |  |  |  |  | 11,663 | 54,887 |  |
Vance, Alabama |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  | 127,444 |  |  |  |  |  |  |  |
Lease Term |  |  |  | 9 years 9 months 18 days |  |  |  |  |  |  |  |
Aggregate Purchase Price |  |  |  | $ 14,300 |  |  |  |  |  |  |  |
Aggregate Annualized GAAP Rent |  |  |  | $ 1,100 |  |  |  |  |  |  |  |
Columbus, Ohio |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  | 157,810 |  | 102,559 |  |  |  |  |  |  |
Lease Term |  |  | 15 years 11 days |  | 6 years 10 months 24 days |  |  |  |  |  |  |
Aggregate Purchase Price |  |  | $ 8,500 |  | $ 17,300 |  |  |  |  |  |  |
Aggregate Annualized GAAP Rent |  |  | 800 |  | $ 1,700 |  |  |  |  |  |  |
Aggregate Mortgage Debt Issued or Assumed |  |  | $ 4,700 |  |  |  |  |  |  |  |  |
Stated interest rate (as a percent) |  |  | 3.22% |  |  |  |  |  |  |  |  |
Detroit, Michigan |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  | 218,703 |  |  |  |  |  |  |  |  |  |
Lease Term |  | 10 years 5 months 19 days |  |  |  |  |  |  |  |  |  |
Aggregate Purchase Price |  | $ 21,700 |  |  |  |  |  |  |  |  |  |
Aggregate Annualized GAAP Rent |  | 1,700 |  |  |  |  |  |  |  |  |  |
Aggregate Mortgage Debt Issued or Assumed |  | $ 6,900 |  |  |  |  |  |  |  |  |  |
Number of units issued in acquisition (in shares) | shares |  | 742,937 |  |  |  |  |  |  |  |  |  |
Number of properties in portfolio | property |  | 2 |  |  |  |  |  |  |  |  |  |
Lake Mary, Florida |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² | 87,080 |  |  |  |  |  |  |  |  |  |  |
Lease Term | 11 years |  |  |  |  |  |  |  |  |  |  |
Aggregate Purchase Price | $ 18,700 |  |  |  |  |  |  |  |  |  |  |
Aggregate Annualized GAAP Rent | $ 2,400 |  |  |  |  |  |  |  |  |  |  |
Conshohocken, Pennsylvania |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  |  |  |  |  | 60,016 |  |  |  |
Lease Term |  |  |  |  |  |  |  | 8 years 6 months |  |  |  |
Aggregate Purchase Price |  |  |  |  |  |  |  | $ 15,700 |  |  |  |
Aggregate Annualized GAAP Rent |  |  |  |  |  |  |  | 1,700 |  |  |  |
Aggregate Mortgage Debt Issued or Assumed |  |  |  |  |  |  |  | $ 11,200 |  |  |  |
Stated interest rate (as a percent) |  |  |  |  |  |  |  | 1.80% |  |  |  |
Philadelphia, Pennsylvania |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  |  |  |  | 300,000 |  |  |  |  |
Lease Term |  |  |  |  |  |  | 15 years 4 months 24 days |  |  |  |  |
Aggregate Purchase Price |  |  |  |  |  |  | $ 27,100 |  |  |  |  |
Aggregate Annualized GAAP Rent |  |  |  |  |  |  | 2,300 |  |  |  |  |
Aggregate Mortgage Debt Issued or Assumed |  |  |  |  |  |  | $ 14,900 |  |  |  |  |
Stated interest rate (as a percent) |  |  |  |  |  |  | 3.75% |  |  |  |  |
Maitland, Florida |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  |  |  | 306,435 |  |  |  |  |  |
Lease Term |  |  |  |  |  | 8 years 7 months 6 days |  |  |  |  |  |
Aggregate Purchase Price |  |  |  |  |  | $ 51,600 |  |  |  |  |  |
Aggregate Annualized GAAP Rent |  |  |  |  |  | 6,800 |  |  |  |  |  |
Aggregate Mortgage Debt Issued or Assumed |  |  |  |  |  | $ 28,800 |  |  |  |  |  |
Stated interest rate (as a percent) |  |  |  |  |  | 3.89% |  |  |  |  |  |
Number of properties in portfolio | property |  |  |  |  |  | 3 |  |  |  |  |  |
Salt Lake City, Utah |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate Square Footage | ft² |  |  |  |  | 102,028 |  |  |  |  |  |  |
Lease Term |  |  |  |  | 10 years 1 month 6 days |  |  |  |  |  |  |
Aggregate Purchase Price |  |  |  |  | $ 20,500 |  |  |  |  |  |  |
Aggregate Annualized GAAP Rent |  |  |  |  | $ 3,000 |  |  |  |  |  |  |
Interest rate swaps |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Liabilities assumed |  |  |  |  |  |  |  |  | 0 | 42 |  |
Change in unrealized (loss) gain related to interest rate hedging instruments, net |  |  |  |  |  |  |  |  | $ (260) | $ 274 | $ 0 |
Interest rate swaps | Detroit, Michigan | New fixed rate mortgage notes payable |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate (as a percent) |  |  |  |  |  |  |  |  | 4.625% |  |  |
Interest rate swaps | Asset Acquisitions |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Change in unrealized (loss) gain related to interest rate hedging instruments, net |  |  |  |  |  |  |  |  | $ 500 |  |  |
Interest rate swap two | New fixed rate mortgage notes payable |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rate (as a percent) |  |  |  |  |  |  |  |  | 5.32% |  |  |
LIBOR | Interest rate swaps | Columbus, Ohio |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Derivative, basis spread on variable rate |  |  | 5.32% |  |  |  |  |  |  |  |  |
LIBOR | Interest rate swaps | Conshohocken, Pennsylvania |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Derivative, basis spread on variable rate |  |  |  |  |  |  |  | 3.55% |  |  |  |

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 Asset Acquisition, Equity Interest Issued or Issuable, Number of Shares + References No definition available. + Details
Name: | good_AssetAcquisitionEquityInterestIssuedorIssuableNumberofShares
Namespace Prefix: | good_
Data Type: | xbrli:sharesItemType
Balance Type: | na
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 Properties In Portfolio + References No definition available. + Details
Name: | good_NumberOfPropertiesInPortfolio
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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 Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage points added to the reference rate to compute the variable rate on the interest rate derivative. + References No definition available. + Details
Name: | us-gaap_DerivativeBasisSpreadOnVariableRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The fair value of liabilities assumed in noncash investing or financing activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586 + Details
Name: | us-gaap_LiabilitiesAssumed1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from new investment. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29(Footnote 6)) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 + Details
Name: | us-gaap_MortgageLoansOnRealEstateNewMortgageLoans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109978405&loc=d3e80720-113993 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=good_NewFixedRateMortgageNotesPayableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_VanceAlabamaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_ColumbusOhioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_DetroitMichiganMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_LakeMaryFloridaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_ConshohockenPennsylvaniaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_PhiladelphiaPennsylvaniaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_MaitlandFloridaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_AssetAcquisitionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=good_InterestRateSwapTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |