Note 5 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Valuation allowance	$ 1,017		$ 1,612
Loans recorded balance	16,136		20,552
Loans unpaid principal	17,369		21,870
Loans average investment in impaired loans	18,075	$ 14,023
Loans interest income recognized	5	71
Residential Portfolio Segment [Member] \| Real Estate Residential, One To Four Family Units [Member]
Loans without a specific valuation allowance, recorded balance	943		2
Loans without a specific valuation allowance, unpaid principal	943		2
Loans with a specific valuation allowance, recorded balance	1,224		4,518
Loans with a specific valuation allowance, unpaid principal	1,224		4,518
Valuation allowance	202		573
Loans recorded balance	2,167		4,520
Loans unpaid principal	2,167		4,520
Loans without a specific valuation allowance, average investment in impaired loans	1,046	1,649
Loans without a specific valuation allowance, interest income recognized	1
Loans with a specific valuation allowance, average investment in impaired loans	1,970	2,671
Loans with a specific valuation allowance, interest income recognized
Loans average investment in impaired loans	3,016	4,320
Loans interest income recognized	1
Residential Portfolio Segment [Member] \| Real Estate Residential, Multi Family Units [Member]
Loans without a specific valuation allowance, recorded balance	5,930		5,952
Loans without a specific valuation allowance, unpaid principal	5,930		5,952
Loans with a specific valuation allowance, recorded balance
Loans with a specific valuation allowance, unpaid principal
Valuation allowance
Loans recorded balance	5,930		5,952
Loans unpaid principal	5,930		5,952
Loans without a specific valuation allowance, average investment in impaired loans	5,933	1,006
Loans without a specific valuation allowance, interest income recognized		25
Loans with a specific valuation allowance, average investment in impaired loans		666
Loans with a specific valuation allowance, interest income recognized
Loans average investment in impaired loans	5,933	1,672
Loans interest income recognized		25
Residential Portfolio Segment [Member] \| Construction Loans [Member]
Loans without a specific valuation allowance, average investment in impaired loans		1,525
Loans without a specific valuation allowance, interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	3,866	2,774
Loans with a specific valuation allowance, interest income recognized
Loans average investment in impaired loans	3,866	4,299
Loans interest income recognized
Real Estate, Construction [Member]
Loans without a specific valuation allowance, recorded balance
Loans without a specific valuation allowance, unpaid principal
Loans with a specific valuation allowance, recorded balance	3,815		4,088
Loans with a specific valuation allowance, unpaid principal	5,048		5,321
Valuation allowance	554		552
Loans recorded balance	3,815		4,088
Loans unpaid principal	5,048		5,321
Commercial Real Estate Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	2,921		3,138
Loans without a specific valuation allowance, unpaid principal	2,921		3,138
Loans with a specific valuation allowance, recorded balance	162		1,232
Loans with a specific valuation allowance, unpaid principal	162		1,317
Valuation allowance	24		106
Loans recorded balance	3,083		4,370
Loans unpaid principal	3,083		4,455
Loans without a specific valuation allowance, average investment in impaired loans	3,353	2,383
Loans without a specific valuation allowance, interest income recognized	4	46
Loans with a specific valuation allowance, average investment in impaired loans	657	81
Loans with a specific valuation allowance, interest income recognized
Loans average investment in impaired loans	4,010	2,464
Loans interest income recognized	4	46
Commercial Portfolio Segment [Member]
Loans without a specific valuation allowance, recorded balance	25		216
Loans without a specific valuation allowance, unpaid principal	25		216
Loans with a specific valuation allowance, recorded balance	641		1,062
Loans with a specific valuation allowance, unpaid principal	641		1,062
Valuation allowance	214		363
Loans recorded balance	666		1,278
Loans unpaid principal	666		1,278
Loans without a specific valuation allowance, average investment in impaired loans	161	658
Loans without a specific valuation allowance, interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	702	457
Loans with a specific valuation allowance, interest income recognized
Loans average investment in impaired loans	863	1,115
Loans interest income recognized
Consumer and Other Loans [Member]
Loans without a specific valuation allowance, recorded balance	363		225
Loans without a specific valuation allowance, unpaid principal	363		225
Loans with a specific valuation allowance, recorded balance	112		119
Loans with a specific valuation allowance, unpaid principal	112		119
Valuation allowance	23		18
Loans recorded balance	475		344
Loans unpaid principal	475		$ 344
Consumer Portfolio Segment [Member]
Loans without a specific valuation allowance, average investment in impaired loans	268	37
Loans without a specific valuation allowance, interest income recognized
Loans with a specific valuation allowance, average investment in impaired loans	119	116
Loans with a specific valuation allowance, interest income recognized
Loans average investment in impaired loans	387	153
Loans interest income recognized

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

+ Details

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

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

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

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524

+ Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

+ Details

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

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables that are recognized as impaired, for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

+ References

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=gfed_RealEstateConstructionMember
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:

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=gfed_ConsumerAndOtherLoansMember
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: