Loans Receivable and Related Allowance for Loan Losses - Allowance required for loans (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Allowance for loan losses
Balance at the beginning of the period	$ 5,383	$ 4,375	$ 4,882	$ 4,414
Charge-offs	(36)	(64)	(89)	(213)
Recoveries	1	2	5	3
Provision	1,620	181	2,170	290
Balance at the end of the period	6,968	4,494	6,968	4,494
Evaluated for Impairment:
Collectively					$ 6,968	$ 4,882
Balance at the end of the period	5,383	4,494	4,882	4,494	6,968	4,882
Real Estate Loans \| One-to-four-family Residential and Construction
Allowance for loan losses
Balance at the beginning of the period	1,369	860	721	1,051
Charge-offs	(23)		(23)
Recoveries	1		3
Provision	(401)	(9)	245	(200)
Balance at the end of the period	946	851	946	851
Evaluated for Impairment:
Collectively					946	721
Balance at the end of the period	946	851	721	1,051	946	721
Real Estate Loans \| Commercial Real Estate and Construction
Allowance for loan losses
Balance at the beginning of the period	3,109	2,754	3,313	2,761
Charge-offs				(121)
Recoveries			1
Provision	2,204	82	1,999	196
Balance at the end of the period	5,313	2,836	5,313	2,836
Evaluated for Impairment:
Collectively					5,313	3,313
Balance at the end of the period	5,313	2,836	3,313	2,836	5,313	3,313
Real Estate Loans \| Home Equity Loans and Lines of Credit
Allowance for loan losses
Balance at the beginning of the period	354	298	310	312
Charge-offs		(59)	(13)	(59)
Recoveries		2		3
Provision	(76)	54	(19)	39
Balance at the end of the period	278	295	278	295
Evaluated for Impairment:
Collectively					278	310
Balance at the end of the period	278	295	310	312	278	310
Commercial Business
Allowance for loan losses
Balance at the beginning of the period	547	461	534	286
Charge-offs	(13)		(51)
Recoveries			1
Provision	(107)	49	(57)	224
Balance at the end of the period	427	510	427	510
Evaluated for Impairment:
Collectively					427	534
Balance at the end of the period	427	510	534	510	427	534
Other Loans
Allowance for loan losses
Balance at the beginning of the period	4	2	4	4
Charge-offs		(5)	(2)	(33)
Provision		5	2	31
Balance at the end of the period	4	2	4	2
Evaluated for Impairment:
Collectively					4	4
Balance at the end of the period	$ 4	$ 2	$ 4	$ 4	$ 4	$ 4

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

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- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

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- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

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