XML 42 R31.htm IDEA: XBRL DOCUMENT
v3.22.1

Real Estate and Intangible Assets - Carrying Value of Intangible Assets and Accumulated Amortization (Detail) - USD ($) $ in Thousands | Mar. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Finite-Lived Intangible Assets [Line Items] |  |
Below market leases and deferred revenue, gross | $ (51,581) | $ (48,241)
Below market leases and deferred revenue, accumulated amortization | 22,284 | 21,471
Lease Intangibles |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 262,201 | 259,300
Accumulated Amortization | (149,546) | (144,806)
In-place leases |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 106,738 | 105,891
Accumulated Amortization | (64,497) | (62,604)
Leasing costs |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 82,974 | 81,487
Accumulated Amortization | (45,477) | (43,982)
Customer relationships |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 72,489 | 71,922
Accumulated Amortization | (39,572) | (38,220)
Above market leases |  |
Finite-Lived Intangible Assets [Line Items] |  |
Lease Intangibles | 15,817 | 15,538
Accumulated Amortization | $ (11,718) | $ (11,520)

X
- Definition Amount of accumulated amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. + References No definition available. + Details
Name: | us-gaap_BelowMarketLeaseAccumulatedAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life. + References No definition available. + Details
Name: | us-gaap_BelowMarketLeaseGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 928 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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: |