XML 262 R46.htm IDEA: XBRL DOCUMENT
v3.20.4

Mortgage Notes Payable and Credit Facility - Mortgage Notes Payable (Detail) $ in Thousands |  |  |  |  |  | 12 Months Ended
--- | --- | --- | --- | --- | --- | ---
Dec. 21, 2020 USD ($) | Dec. 18, 2020 USD ($) | Mar. 09, 2020 USD ($) | Jan. 27, 2020 USD ($) property | Oct. 27, 2017 | Dec. 31, 2020 USD ($) property mortgage | Dec. 31, 2019 USD ($) property | Dec. 31, 2018 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt repaid |  |  |  |  |  | $ 50,662 | $ 57,438 | $ 27,850
Weighted Average Interest Rate on Fixed Rate Debt Extended |  |  |  |  |  | 3.45% |  |
Number of properties acquired | property |  |  |  |  |  | 9 | 18 |
Fixed rate mortgage loans |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt repaid |  |  |  |  |  | $ 18,109 |  |
Stated interest rate (as a percent) |  |  |  |  |  | 5.19% |  |
Variable rate mortgage loans |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt repaid |  |  |  |  |  | $ 19,284 |  |
New fixed rate mortgage notes payable |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Aggregate Fixed Rate Debt Issued |  |  |  |  |  | $ 52,578 |  |
Weighted Average Interest Rate on Fixed Rate Debt Extended |  |  |  |  |  | 3.18% |  |
Mortgage notes payable |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Number of mortgages repaid | mortgage |  |  |  |  |  | 7 |  |
Number of properties collateralized | property |  |  |  |  |  | 8 |  |
Number of long-term mortgages issued | mortgage |  |  |  |  |  | 6 |  |
Number of properties to issue collateralized mortgage notes payable | property |  |  |  |  |  | 6 |  |
Weighted Average Interest Rate on Fixed Rate Debt Extended |  |  |  |  |  | 4.24% |  |
LIBOR |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Weighted Average Interest Rate on Variable Rate Debt Repaid |  |  |  |  | 2.75% |  |  |
LIBOR | Variable rate mortgage loans | Weighted Average |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Weighted Average Interest Rate on Variable Rate Debt Repaid |  |  |  |  |  | 2.20% |  |
Property Maturing February 1, 2030 | New fixed rate mortgage notes payable |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Aggregate Fixed Rate Debt Issued |  |  |  | $ 18,300 |  |  |  |
Weighted Average Interest Rate on Fixed Rate Debt Extended |  |  |  | 3.625% |  |  |  |
Number of properties acquired | property |  |  |  | 3 |  |  |  |
Property Maturing March 9, 2030 | New fixed rate mortgage notes payable |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Aggregate Fixed Rate Debt Issued |  |  | $ 17,500 |  |  |  |  |
Weighted Average Interest Rate on Fixed Rate Debt Extended |  |  | 2.80% |  |  |  |  |
Property Maturing January 1, 2028 | New fixed rate mortgage notes payable |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Aggregate Fixed Rate Debt Issued |  | $ 10,300 |  |  |  |  |  |
Weighted Average Interest Rate on Fixed Rate Debt Extended |  | 3.00% |  |  |  |  |  |
Property Maturing December 23, 2030 | New fixed rate mortgage notes payable |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Aggregate Fixed Rate Debt Issued | $ 6,400 |  |  |  |  |  |  |
Weighted Average Interest Rate on Fixed Rate Debt Extended | 3.25% |  |  |  |  |  |  |

X
- Definition Number of long term mortgages issued. + References No definition available. + Details
Name: | good_NumberOfLongTermMortgagesIssued
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Long Term Mortgages Repaid + References No definition available. + Details
Name: | good_NumberOfLongTermMortgagesRepaid
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of properties acquired. + References No definition available. + Details
Name: | good_NumberOfPropertiesAcquired
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Properties Issued To Collateralized Mortgage Notes Payable + References No definition available. + Details
Name: | good_NumberOfPropertiesIssuedToCollateralizedMortgageNotesPayable
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Properties Repaid To Collateralized Mortgage Notes Payable + References No definition available. + Details
Name: | good_NumberofPropertiesRepaidToCollateralizedMortgageNotesPayable
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
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=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
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_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average interest rate of debt outstanding. + References No definition available. + Details
Name: | us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + 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=121583591&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 4 -URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4313-108586 Reference 3: 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=121583591&loc=d3e4332-108586 + Details
Name: | us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585 + Details
Name: | us-gaap_RepaymentsOfSecuredDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

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

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=good_MortgageNotesPayableMember
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: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_PropertyMaturingFebruary12030Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_PropertyMaturingMarch92030Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_PropertyMaturingJanuary12028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=good_PropertyMaturingDecember232030Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |