LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES - Major Categories of Loans (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 291,237	$ 299,120
Less: Allowance for loan losses	(2,459)	(2,541)
Loans, net	$ 288,778	$ 296,579
Loans and lease receivable allowances, percentage	100.00%	100.00%
Increase (decrease) in loans and leases receivable	$ 7,800
Percentage of increase (decrease) in loans and leases receivable	2.63%
Consumer
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 12,259	$ 13,071
Loans and lease receivable allowances, percentage	4.00%	4.00%
Increase (decrease) in loans and leases receivable	$ 800
Percentage of increase (decrease) in loans and leases receivable	6.21%
Residential Real estate
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 81,213	$ 82,637
Loans and lease receivable allowances, percentage	28.00%	28.00%
Increase (decrease) in loans and leases receivable	$ 1,400	$ 82,600
Percentage of increase (decrease) in loans and leases receivable	1.72%
Indirect
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 110,716	$ 116,698
Loans and lease receivable allowances, percentage	38.00%	39.00%
Increase (decrease) in loans and leases receivable	$ 6,000	$ 116,700
Percentage of increase (decrease) in loans and leases receivable	5.13%
Commercial
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 12,065	$ 14,284
Loans and lease receivable allowances, percentage	4.00%	5.00%
Increase (decrease) in loans and leases receivable	$ 2,200
Percentage of increase (decrease) in loans and leases receivable	15.53%
Construction
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 2,886	$ 2,317
Loans and lease receivable allowances, percentage	1.00%	1.00%
Increase (decrease) in loans and leases receivable	$ 600
Percentage of increase (decrease) in loans and leases receivable	24.54%
Commercial Real Estate
Schedule of Available-for-sale Securities [Line Items]
Loans, net of deferred fees and costs	$ 72,098	$ 70,113
Loans and lease receivable allowances, percentage	25.00%	23.00%
Increase (decrease) in loans and leases receivable	$ 2,000
Percentage of increase (decrease) in loans and leases receivable	2.83%

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:	credit
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:	num: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:	num: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://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(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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=84173941&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=82894903&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=84173941&loc=SL6953423-111524

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-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=27010918&loc=d3e74567-122707

+ 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=82891408&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=6876686&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_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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