XML 44 R32.htm IDEA: XBRL DOCUMENT
v3.21.2

Real Estate and Intangible Assets - Weighted Average Amortization Period for Intangible Assets and Liabilities (Details) | 9 Months Ended
--- | ---
Sep. 30, 2021 | Sep. 30, 2020
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period (in years) | 16 years 6 months | 16 years 3 months 18 days
In-place leases |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period (in years) | 15 years | 15 years 8 months 12 days
Leasing costs |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period (in years) | 15 years | 15 years 8 months 12 days
Customer relationships |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period (in years) | 21 years 2 months 12 days | 18 years 10 months 24 days
Above market leases |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period (in years) | 14 years | 16 years 7 months 6 days
Below market leases |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |
Weighted average amortization period (in years) | 17 years 4 months 24 days | 14 years 2 months 12 days

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_AcquiredFiniteLivedIntangibleAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
Name: | us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=good_InPlaceLeasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=good_LeasingCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_AboveMarketLeasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=good_BelowMarketLeaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |