Amount available for dividend distribution without prior approval from regulatory agency which would be distributed to wholly owned parent company.

No definition available.

+ Details

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

- Definition

Amount of paid and unpaid cash, stock, and paid-in-kind (PIK) dividends declared, for example, but not limited to, common and preferred stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-SubTopic 405
-Topic 942
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481071/942-405-45-2

+ Details

Name:	us-gaap_Dividends
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

+ Details

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

- Definition

Amount of dividends that can be declared or paid without approval of regulatory agency.

+ References

No definition available.

+ Details

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

- Details

Name:	dei_LegalEntityAxis=gbli_PennPatriotInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=gbli_UnitedNationalInsuranceCompaniesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=gbli_PennAmericaInsuranceCompaniesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=gbli_InsuranceSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Statutory Financial Information - Additional Information (Detail) - USD ($)													12 Months Ended
	Dec. 29, 2023	Oct. 16, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 30, 2022	Oct. 11, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statutory Accounting Practices [Line Items]
Dividends	$ 3,385,000	$ 3,385,000	$ 3,375,000	$ 3,410,000	$ 3,389,000	$ 3,616,000	$ 3,602,000	$ 3,597,000	$ 3,587,000	$ 3,583,000	$ 3,579,000	$ 3,570,000	$ 13,469,000	$ 14,543,000	$ 14,578,000
Penn Patriot Insurance Company
Statutory Accounting Practices [Line Items]
Maximum amount of dividends that could be paid in 2024 under applicable laws and regulations without regulatory approval													40,200,000
United National Insurance Companies
Statutory Accounting Practices [Line Items]
Maximum amount of dividends that could be paid in 2024 under applicable laws and regulations without regulatory approval													29,800,000
Penn- America Insurance Companies
Statutory Accounting Practices [Line Items]
Maximum amount of dividends that could be paid in 2024 under applicable laws and regulations without regulatory approval													12,600,000
Maximum amount of dividends payable under applicable laws and regulations without regulatory approval which would be distributed to wholly owned parent company													4,100,000
Insurance Subsidiaries
Statutory Accounting Practices [Line Items]
Dividends													$ 0