Lessee operating lease contraction fee on exercising contraction clause.

No definition available.

Name:	gbli_LesseeOperatingLeaseContractionFeeOnExercisingContractionClause
Namespace Prefix:	gbli_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Lessee operating lease existence of option to retract.

+ References

No definition available.

+ Details

Name:	gbli_LesseeOperatingLeaseExistenceOfOptionToRetract
Namespace Prefix:	gbli_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessee, operating lease, number of leases, contraction clause exercised.

+ References

No definition available.

+ Details

Name:	gbli_LesseeOperatingLeaseNumberOfLeasesContractionClauseExercised
Namespace Prefix:	gbli_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Payments of sublease expected amount beginning month and year.

+ References

No definition available.

+ Details

Name:	gbli_PaymentsOfSubleaseExpectedAmountBeginningMonthAndYear
Namespace Prefix:	gbli_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Payments of sublease expected amount ending year and month.

+ References

No definition available.

+ Details

Name:	gbli_PaymentsOfSubleaseExpectedAmountEndingYearAndMonth
Namespace Prefix:	gbli_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Portion of office subleased.

+ References

No definition available.

+ Details

Name:	gbli_PortionOfOfficeSubleased
Namespace Prefix:	gbli_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates (true false) whether lessee has option to terminate operating lease.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseExistenceOfOptionToTerminate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Remaining lease term of operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRemainingLeaseTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of loss from impairment of right-of-use asset from operating lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 25
-Paragraph 6
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=123399704&loc=SL77918431-209957

+ Details

Name:	us-gaap_OperatingLeaseImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI https://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

+ Details

Name:	us-gaap_SubleaseIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=gbli_OmahaNebraskaBuildingAndParkingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=gbli_ScottsdaleArizonaBuildingAndParkingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=gbli_CavanIrelandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=gbli_FarmRanchAndStableLinesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=gbli_RenewalRightsRelatedToManufacturedAndDwellingHomeProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RestructuringCostAndReserveAxis=gbli_EarlyTerminationClauseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
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- Details

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Leases - Additional Information (Detail) $ in Thousands	12 Months Ended			98 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) Lease	Dec. 31, 2020 USD ($)	Nov. 30, 2029 USD ($)	Dec. 30, 2022	Dec. 30, 2021
Lessee Lease Description [Line Item]
Operating lease, existence of option to terminate [true false]	true
Operating lease, existence of option to extend [true false]	true
Operating lease, existence of option to retract [true false]	true
Operating lease, number of leases, contraction clause exercised \| Lease		1
Operating lease, contraction fee on exercising contraction clause	$ 300
Impairment of lease cost	1,337	$ 1,515	$ 0
Payments of sublease expected amount	331	55	0
Omaha Nebraska Building and Parking
Lessee Lease Description [Line Item]
Impairment of lease cost	488	0	0
Scottsdale Arizona Building and Parking
Lessee Lease Description [Line Item]
Impairment of lease cost	681	1,515	0
Cavan Ireland
Lessee Lease Description [Line Item]
Impairment of lease cost	168	0	$ 0
Farm, Ranch & Stable Business Lines
Lessee Lease Description [Line Item]
Impairment of lease cost	$ 500
Farm, Ranch & Stable Business Lines \| Omaha Nebraska Building and Parking
Lessee Lease Description [Line Item]
Lessee, operating lease, term	65 months				125 months
Renewal Rights Related to Manufactured and Dwelling Homes Products
Lessee Lease Description [Line Item]
Impairment of lease cost	$ 700	$ 1,500
Payments of sublease expected amount beginning month and year	2021-10
Payments of sublease expected amount ending year and month	2029-11
Portion of office subleased	one third
Renewal Rights Related to Manufactured and Dwelling Homes Products \| Early Termination Clause
Lessee Lease Description [Line Item]
Payments of sublease expected amount	$ 1,600
Renewal Rights Related to Manufactured and Dwelling Homes Products \| Scenario Forecast
Lessee Lease Description [Line Item]
Payments of sublease expected amount				$ 2,400
Renewal Rights Related to Manufactured and Dwelling Homes Products \| Scottsdale Arizona Building and Parking
Lessee Lease Description [Line Item]
Lessee, operating lease, term		95 months				131 months
Minimum [Member]
Lessee Lease Description [Line Item]
Operating lease, remaining lease term	8 months
Maximum
Lessee Lease Description [Line Item]
Operating lease, remaining lease term	7 years