Loans Receivable - Nonaccrual Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Reserve For Uncollected Loan Interest	$ 94	$ 81
Unpaid Principal Balance	780	925
Recorded Investment	764	800
Loans Past Due Over 90 Days, still accruing	0	47
One-to-four family residential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	500	598
Recorded Investment	476	512
Loans Past Due Over 90 Days, still accruing	0	0
Wholesale Commercial Lending [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance		280
Loans Past Due Over 90 Days, still accruing		0
Nonresidential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	280
Recorded Investment	288	$ 288
Loans Past Due Over 90 Days, still accruing	$ 0