Fair Value - Valuation Methodology and Unobservable Inputs (Details) - Non-Recurring Basis - Significant Unobservable Inputs (Level 3) - item	Jun. 30, 2019	Dec. 31, 2018
Impaired loans carried at fair value of collateral
Fair Value Pending Completion
Valuation Technique(s)	gaap:MeasurementInputAppraisedValueMember	gaap:MeasurementInputAppraisedValueMember
Unobservable Input(s)	gaap:MarketApproachValuationTechniqueMember	gaap:MarketApproachValuationTechniqueMember
Impaired loans carried at fair value of collateral \| Minimum
Fair Value Pending Completion
Adjustment for differences between the comparable sales (as a percent)	(0.03)	(0.03)
Impaired loans carried at fair value of collateral \| Maximum
Fair Value Pending Completion
Adjustment for differences between the comparable sales (as a percent)	(0.01)	(0.01)
Impaired loans carried at fair value of collateral \| Weighted Average
Fair Value Pending Completion
Adjustment for differences between the comparable sales (as a percent)	0.0253	(0.0283)
Real estate owned
Fair Value Pending Completion
Adjustment for differences between the comparable sales (as a percent)	0.00	(0.11)
Valuation Technique(s)	gaap:MeasurementInputAppraisedValueMember	gaap:MeasurementInputAppraisedValueMember
Unobservable Input(s)	gaap:MarketApproachValuationTechniqueMember	gaap:MarketApproachValuationTechniqueMember
Real estate owned \| Weighted Average
Fair Value Pending Completion
Adjustment for differences between the comparable sales (as a percent)	0.00	(0.1085)

Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Indicates measurement input for investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleMeasurementInputExtensibleList
Namespace Prefix:	us-gaap_
Data Type:	srt-types:extensibleListItemType
Balance Type:	na
Period Type:	instant

- Definition

Indicates valuation technique for measuring investment in debt security at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleValuationTechniqueExtensibleList
Namespace Prefix:	us-gaap_
Data Type:	srt-types:extensibleListItemType
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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=byfc_ImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_RealEstateAcquiredInSatisfactionOfDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: