Additional Letter Of Credit Outstanding, Amount

No definition available.

Name:	gnl_AdditionalLetterOfCreditOutstandingAmount
Namespace Prefix:	gnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Amount Outstanding, Cash Sweep Event

+ References

No definition available.

+ Details

Name:	gnl_DebtInstrumentAmountOutstandingCashSweepEvent
Namespace Prefix:	gnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Cash Sweep Event Balance

+ References

No definition available.

+ Details

Name:	gnl_DebtInstrumentCashSweepEventBalance
Namespace Prefix:	gnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Cash Sweep Event, Rollover Reserve Maximum Amount

+ References

No definition available.

+ Details

Name:	gnl_DebtInstrumentCashSweepEventRolloverReserveMaximumAmount
Namespace Prefix:	gnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Collateral, Percent Of Excess Cash Flow Retained

+ References

No definition available.

+ Details

Name:	gnl_DebtInstrumentCollateralPercentOfExcessCashFlowRetained
Namespace Prefix:	gnl_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Minimum Weighted Average Unexpired Lease Term

+ References

No definition available.

+ Details

Name:	gnl_DebtInstrumentMinimumWeightedAverageUnexpiredLeaseTerm
Namespace Prefix:	gnl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Weighted Average Unexpired Lease Term

+ References

No definition available.

+ Details

Name:	gnl_DebtInstrumentWeightedAverageUnexpiredLeaseTerm
Namespace Prefix:	gnl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Real Estate Properties, Encumbered

+ References

No definition available.

+ Details

Name:	gnl_NumberOfRealEstatePropertiesEncumbered
Namespace Prefix:	gnl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Real Estate and Accumulated Depreciation, Unencumbered Assets

+ References

No definition available.

+ Details

Name:	gnl_RealEstateandAccumulatedDepreciationUnencumberedAssets
Namespace Prefix:	gnl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 3: 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))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: 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 https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_USD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_GBP
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gnl_U.S.MultiTenantMortgageLoanIIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gnl_MultiTenantMortgageLoanIVMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gnl_McLarenLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Mortgage Notes Payable, Net - Narrative (Details) $ in Thousands, € in Millions, £ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($) property	Jun. 30, 2022 EUR (€) property	Dec. 31, 2021 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Apr. 30, 2021 USD ($)	Apr. 30, 2021 GBP (£)
Debt Instrument [Line Items]
Carrying value of encumbered assets	$ 2,000,000
Mortgage notes payable
Debt Instrument [Line Items]
Encumbered properties (property) \| property	119	119
Balance outstanding with cash sweep event trigger	$ 73,200	€ 70.0
Weighted average unexpired lease term	3 years
Percent of excess cash flow retained	30.00%
Cash sweep balance	$ 4,900	€ 4.7
Minimum weighted average unexpired lease term	4 years
Term Loan	$ 1,361,366		$ 1,449,867
Mortgage discount	$ 1,676		2,374
Mortgage notes payable \| USD
Debt Instrument [Line Items]
Encumbered properties (property) \| property	54	54
Term Loan	$ 665,330		665,330
Mortgage notes payable \| GBP
Debt Instrument [Line Items]
Encumbered properties (property) \| property	45	45
Term Loan	$ 366,329		426,657
Multi-Tenant Mortgage Loan III \| Mortgage notes payable
Debt Instrument [Line Items]
Balance outstanding with cash sweep event trigger	$ 98,500
Letters of credit outstanding					$ 3,200
Multi-Tenant Mortgage Loan III \| Mortgage notes payable \| USD
Debt Instrument [Line Items]
Encumbered properties (property) \| property	7	7
Term Loan	$ 98,500		98,500
Multi-Tenant Mortgage Loan IV \| Mortgage notes payable
Debt Instrument [Line Items]
Balance outstanding with cash sweep event trigger	97,500
Rollover reserve aggregate cap	$ 800
Multi-Tenant Mortgage Loan IV \| Mortgage notes payable \| USD
Debt Instrument [Line Items]
Encumbered properties (property) \| property	16	16
Term Loan	$ 97,500		97,500
McLaren \| Mortgage notes payable
Debt Instrument [Line Items]
Mortgage discount						$ 3,100
McLaren \| Mortgage notes payable \| GBP
Debt Instrument [Line Items]
Encumbered properties (property) \| property	3	3
Term Loan	$ 122,684		$ 136,471				£ 101.0
Stated interest rate						6.00%	6.00%
Line of Credit
Debt Instrument [Line Items]
Carrying value of encumbered assets	$ 1,200,000
Line of Credit \| Multi-Tenant Mortgage Loan III \| Mortgage notes payable
Debt Instrument [Line Items]
Letters of credit outstanding				$ 7,400	$ 7,400
Additional letters of credit outstanding				$ 4,200