XML 59 R48.htm IDEA: XBRL DOCUMENT v3.8.0.1

Summary of Insurance Enhanced Municipal Bonds Backed by Financial Guarantors (Detail) $ in Thousands	Mar. 31, 2018 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Investments in insurance enhanced municipal bonds	$ 1,136
Municipal Bond Insurance Association
Schedule of Available-for-sale Securities [Line Items]
Investments in insurance enhanced municipal bonds	1,136
Financial Guarantors
Schedule of Available-for-sale Securities [Line Items]
Investments in insurance enhanced municipal bonds	1,136
Exposure Net Of Pre-refunded & Government Guaranteed Securities
Schedule of Available-for-sale Securities [Line Items]
Investments in insurance enhanced municipal bonds	1,136
Exposure Net Of Pre-refunded & Government Guaranteed Securities | Municipal Bond Insurance Association
Schedule of Available-for-sale Securities [Line Items]
Investments in insurance enhanced municipal bonds	1,136
Exposure Net Of Pre-refunded & Government Guaranteed Securities | Financial Guarantors
Schedule of Available-for-sale Securities [Line Items]
Investments in insurance enhanced municipal bonds	$ 1,136

X

- Definition

Investment In Insurance Enhanced Municipal Bonds

+ References

No definition available.

+ Details

Name:	gbli_InvestmentInInsuranceEnhancedMunicipalBonds
Namespace Prefix:	gbli_
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_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_InvestmentTypeAxis=gbli_MunicipalBondInsuranceAssociationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=gbli_FinancialGuarantorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	gbli_InsuranceEnhancedMuniBondsByFinancialGuarantorsAxis=gbli_ExposureNetOfPreRefundedAndGovernmentGuaranteedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: