Loans - Non-performing Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loans ninety days or more past due and still accruing	$ 1,925	$ 2,748
Multi-family Residential Portfolio Segment [Member]
Loans ninety days or more past due and still accruing		201
Commercial Real Estate
Loans ninety days or more past due and still accruing		2,547
Commercial Business and Other Portfolio Segment [Member]
Loans ninety days or more past due and still accruing	1,052
Performing Financial Instruments [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Non-accrual loans	$ 300	300
Performing Financial Instruments [Member] | Taxi Medallion Portfolio Segment [Member]
Non-accrual loans		400
Performing Financial Instruments [Member] | Commercial Business and Other Portfolio Segment [Member]
Non-accrual loans		$ 2,200