XML 260 R44.htm IDEA: XBRL DOCUMENT
v3.20.4

Mortgage Notes Payable and Credit Facility - Company's Mortgage Notes Payable and Line of Credit Additional Information (Detail) |  | 12 Months Ended
--- | --- | ---
Oct. 27, 2017 | Dec. 31, 2020 property mortgage
Debt Instrument [Line Items] |  |
Weighted average interest rate on debt outstanding (as percent) |  | 3.45%
Encumbered properties |  | 118
LIBOR |  |
Debt Instrument [Line Items] |  |
Spread on LIBOR (as percent) | 2.75% |
Mortgage notes payable |  |
Debt Instrument [Line Items] |  |
Number of mortgage notes payable | mortgage |  | 53
Maturity date of mortgage notes payable, start date |  | Nov. 01, 2021
Maturity date of mortgage notes payable, end date |  | Aug. 01, 2037
Weighted average interest rate on debt outstanding (as percent) |  | 4.24%
Encumbered properties |  | 68
Fixed rate mortgage loans |  |
Debt Instrument [Line Items] |  |
Stated interest rate (as a percent) |  | 5.19%
Encumbered properties |  | 61
Fixed rate mortgage loans | Minimum |  |
Debt Instrument [Line Items] |  |
Stated interest rate (as a percent) |  | 2.80%
Fixed rate mortgage loans | Maximum |  |
Debt Instrument [Line Items] |  |
Stated interest rate (as a percent) |  | 6.63%
Variable rate mortgage loans |  |
Debt Instrument [Line Items] |  |
Encumbered properties |  | 7
Variable rate mortgage loans | LIBOR |  |
Debt Instrument [Line Items] |  |
Variable rate at period end (as percent) |  | 0.14%
Variable rate mortgage loans | Minimum | LIBOR |  |
Debt Instrument [Line Items] |  |
Spread on LIBOR (as percent) |  | 2.35%
Variable rate mortgage loans | Maximum | LIBOR |  |
Debt Instrument [Line Items] |  |
Spread on LIBOR (as percent) |  | 2.75%
Variable rate revolving credit facility |  |
Debt Instrument [Line Items] |  |
Encumbered properties |  | 50
Variable rate revolving credit facility | Revolving credit facility |  |
Debt Instrument [Line Items] |  |
Encumbered properties |  | 50
Variable rate revolving credit facility | LIBOR | Revolving credit facility |  |
Debt Instrument [Line Items] |  |
Spread on LIBOR (as percent) |  | 1.65%

X
- Definition Debt Instrument, Interest Rate, Variable Rate at Period End + References No definition available. + Details
Name: | good_DebtInstrumentInterestRateVariableRateatPeriodEnd
Namespace Prefix: | good_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Number of mortgage notes payable. + References No definition available. + Details
Name: | good_NumberOfMortgageNotesPayable
Namespace Prefix: | good_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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 Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format. + 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)(2)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentMaturityDateRangeEnd1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format. + 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)(2)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentMaturityDateRangeStart1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
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
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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_DebtInstrumentAxis=good_FixedRateMortgageLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |