XML 67 R38.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Real Estate and Intangible Assets - Carrying Value of Intangible Assets and Accumulated Amortization (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items] |  |  |
Below market leases, gross | $ (34,322) | $ (29,807) |
Below market leases, accumulated amortization | 15,000 | 12,502 |
Amortization of intangible assets | 19,200 | 17,700 | $ 15,900
Amortization related to below-market lease | 2,500 | 2,000 | 1,500
Lease Intangibles [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-lived intangible assets, gross | 226,525 | 204,020 |
Finite-lived intangible assets, accumulated amortization | (111,060) | (92,572) |
In-place Leases |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-lived intangible assets, gross | 92,906 | 83,894 |
Finite-lived intangible assets, accumulated amortization | (48,468) | (40,445) |
Leasing Costs |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-lived intangible assets, gross | 68,256 | 59,671 |
Finite-lived intangible assets, accumulated amortization | (33,705) | (28,092) |
Customer Relationships |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-lived intangible assets, gross | 65,363 | 60,455 |
Finite-lived intangible assets, accumulated amortization | (28,887) | (24,035) |
Above and Below Market Leases |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-lived intangible liabilities, gross | (17,820) | (15,256) |
Finite-lived intangible liabilities, accumulated amortization | 4,995 | 3,521 |
Above Market Leases |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Finite-lived intangible assets, gross | 16,502 | 14,551 |
Finite-lived intangible assets, accumulated amortization | (10,005) | (8,981) |
Amortization related to above-market lease | $ 1,100 |  |
Amortization related to above-market lease |  | $ 1,100 | $ 700

X
- Definition Finite lived intangible assets (liabilities) accumulated amortization. + References No definition available. + Details
Name: | good_FiniteLivedIntangibleAssetsLiabilitiesAccumulatedAmortization
Namespace Prefix: | good_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Finite lived intangible assets (liabilities) gross. + References No definition available. + Details
Name: | good_FiniteLivedIntangibleAssetsLiabilitiesGross
Namespace Prefix: | good_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Operating Lease, Right-of-Use Asset, Amortization + References No definition available. + Details
Name: | good_OperatingLeaseRightofUseAssetAmortization
Namespace Prefix: | good_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of amortization of acquired 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_AmortizationOfBelowMarketLease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 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)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 + Details
Name: | us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The expense charged against earnings for the periodic recognition of capitalized leases. This element may apply to energy companies that lease mineral producing properties and to other enterprises that capitalize property, plant, or equipment obtained through capital leases. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84164758&loc=d3e45031-112735 + Details
Name: | us-gaap_AmortizationOfLeasedAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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=good_AboveAndBelowMarketLeasesMember
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: |