Loans Receivable and Allowance for Loan Losses - Loans Individually Evaluated for Impairment (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Recorded Investment
With no allowance recorded	$ 17,280	$ 19,061
With a specific allowance recorded	7,007	26,086
Recorded investment	24,287	45,147
Unpaid Principal Balance
With no allowance recorded	18,653	19,788
With a specific allowance recorded	7,028	26,708
Unpaid principal balance	25,681	46,496
Specific Allowance
Specific allowance	378	1,088
Real estate loans | One-to-four family
Recorded Investment
With no allowance recorded	1,882	3,344
With a specific allowance recorded	3,302	3,913
Recorded investment	5,184	7,257
Unpaid Principal Balance
With no allowance recorded	2,421	3,898
With a specific allowance recorded	3,321	3,919
Unpaid principal balance	5,742	7,817
Specific Allowance
Specific allowance	258	391
Real estate loans | Multifamily and commercial
Recorded Investment
With no allowance recorded	14,623	13,058
With a specific allowance recorded	1,969	19,734
Recorded investment	16,592	32,792
Unpaid Principal Balance
With no allowance recorded	15,351	13,094
With a specific allowance recorded	1,971	20,350
Unpaid principal balance	17,322	33,444
Specific Allowance
Specific allowance	97	601
Commercial business loans
Recorded Investment
With no allowance recorded	573	1,945
With a specific allowance recorded	1,233	1,502
Recorded investment	1,806	3,447
Unpaid Principal Balance
With no allowance recorded	573	1,945
With a specific allowance recorded	1,233	1,502
Unpaid principal balance	1,806	3,447
Specific Allowance
Specific allowance	16	84
Consumer loans | Home equity loans and advances
Recorded Investment
With no allowance recorded	202	714
With a specific allowance recorded	503	937
Recorded investment	705	1,651
Unpaid Principal Balance
With no allowance recorded	308	851
With a specific allowance recorded	503	937
Unpaid principal balance	811	1,788
Specific Allowance
Specific allowance	$ 7	$ 12