LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES - Major Categories of Loans (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 224,674	$ 253,772
Less: Allowance for credit losses (1)	(2,790)	(1,476)
Loans, net	$ 221,884	$ 252,296
Loans and lease receivable allowances, percentage	100.00%	100.00%
Increase (decrease) in loans and leases receivable	$ (30,400)
Percentage of increase (decrease) in loans and leases receivable	(12.05%)
Real Estate Loan
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 144,062	$ 148,555
Less: Allowance for credit losses (1)		(781)
Commercial and Industrial
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	19,579	27,912
Less: Allowance for credit losses (1)		(115)
Consumer Loans
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	61,033	77,305
Less: Allowance for credit losses (1)		(580)
Construction And Land Development [Member] \| Real Estate Loan
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 3,662	2,553
Less: Allowance for credit losses (1)		$ (10)
Loans and lease receivable allowances, percentage	2.00%	1.00%
Increase (decrease) in loans and leases receivable	$ 1,100
Percentage of increase (decrease) in loans and leases receivable	43.44%
Farmland \| Real Estate Loan
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 345	$ 350
Less: Allowance for credit losses (1)		(2)
Increase (decrease) in loans and leases receivable	$ (100)
Percentage of increase (decrease) in loans and leases receivable	(1.58%)
Single-family \| Real Estate Loan
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 79,049	82,520
Less: Allowance for credit losses (1)		$ (512)
Loans and lease receivable allowances, percentage	36.00%	33.00%
Increase (decrease) in loans and leases receivable	$ (3,500)
Percentage of increase (decrease) in loans and leases receivable	(4.21%)
Multi-family \| Real Estate Loan
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 5,846	$ 6,105
Less: Allowance for credit losses (1)		$ (39)
Loans and lease receivable allowances, percentage	3.00%	2.00%
Increase (decrease) in loans and leases receivable	$ (300)
Percentage of increase (decrease) in loans and leases receivable	(4.24%)
Commercial \| Real Estate Loan
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 55,160	$ 57,027
Less: Allowance for credit losses (1)		$ (218)
Loans and lease receivable allowances, percentage	25.00%	23.00%
Increase (decrease) in loans and leases receivable	$ (1,900)
Percentage of increase (decrease) in loans and leases receivable	(3.27%)
Commercial \| Consumer Loans
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 61,033
Commercial and industrial \| Commercial and Industrial
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 10,078	$ 10,800
Less: Allowance for credit losses (1)		$ (67)
Loans and lease receivable allowances, percentage	4.00%	4.00%
Increase (decrease) in loans and leases receivable	$ (700)
Percentage of increase (decrease) in loans and leases receivable	(6.68%)
SBA Guaranty \| Commercial and Industrial
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 6,930	$ 7,200
Less: Allowance for credit losses (1)		$ (48)
Loans and lease receivable allowances, percentage	3.00%	3.00%
Increase (decrease) in loans and leases receivable	$ (300)
Percentage of increase (decrease) in loans and leases receivable	(3.76%)
Comm SBA PPP \| Commercial and Industrial
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 2,571	$ 9,912
Loans and lease receivable allowances, percentage	1.00%	4.00%
Increase (decrease) in loans and leases receivable	$ (7,300)
Percentage of increase (decrease) in loans and leases receivable	(74.06%)
Consumer and Indirect \| Consumer Loans
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 2,398	$ 3,063
Less: Allowance for credit losses (1)		$ (11)
Loans and lease receivable allowances, percentage	1.00%	1.00%
Increase (decrease) in loans and leases receivable	$ (700)
Percentage of increase (decrease) in loans and leases receivable	(21.72%)
Automobile \| Consumer Loans
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 58,635	$ 74,242
Less: Allowance for credit losses (1)		$ (569)
Loans and lease receivable allowances, percentage	25.00%	29.00%
Increase (decrease) in loans and leases receivable	$ (15,600)
Percentage of increase (decrease) in loans and leases receivable	(21.02%)

The increase (decrease) during the reporting period in amount of loans and leases receivables.

No definition available.

Name:	glbz_IncreaseDecreaseInLoansAndLeasesReceivable
Namespace Prefix:	glbz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of increase (decrease) in loans and leases receivable.

+ References

No definition available.

+ Details

Name:	glbz_PercentageOfIncreaseDecreaseInLoansAndLeasesReceivable
Namespace Prefix:	glbz_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The Percentage of Loans and Leases Receivable Allowance.

+ References

No definition available.

+ Details

Name:	glbz_PercentageOfLoansAndLeasesReceivableAllowance
Namespace Prefix:	glbz_
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_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=122038336&loc=d3e74567-122707

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

+ Details

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

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialAndIndustrialSectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=glbz_ConstructionAndLandDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=glbz_FarmlandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=srt_SingleFamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=srt_MultifamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=glbz_CommercialAndIndustrialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=glbz_SbaGuarantyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=glbz_CommSbaPppMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_AutomobileLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: