Summary of Significant Accounting Policies, Loans Receivable Held for Investment (FY) (Details)	12 Months Ended
Dec. 31, 2019
Loans Receivable Held for Investment [Abstract]
Delinquency period for interest income to be discontinued on loans	90 days

Period of interest income on loans to be discontinued, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

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