Summary of Significant Accounting Policies - Loans Receivable Held for Investment (Details)	12 Months Ended
Dec. 31, 2017
Summary of Significant Accounting Policies
Delinquency period for interest income to be discontinued on loans	90 days

Represents the delinquency period for interest income on loans to be discontinued.

No definition available.

Name:	byfc_FinancingReceivableDelinquencyPeriodForInterestIncomeOnLoansToBeDiscontinued
Namespace Prefix:	byfc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration