Loans Receivable - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 9,533	$ 8,760
Provision for (recapture of) loan losses	669	1,174
Charge-offs	(887)	(656)
Recoveries	313	255
Ending balance	9,628	9,533
Total ALLL	9,628	9,533	$ 9,628	$ 9,533
General reserve			9,426	9,257
Specific reserve			202	276
Total loans			883,757	869,730
General reserves			877,368	863,172
Specific reserves			6,389	6,558
Residential segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans			695,021	725,846
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans			147,165	124,986
Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	334	265
Provision for (recapture of) loan losses	(125)	68
Charge-offs	(3)	0
Recoveries	2	1
Ending balance	208	334
Total ALLL	208	334	208	334
General reserve			203	168
Specific reserve			5	166
Total loans			41,571	18,898
General reserves			41,308	18,453
Specific reserves			263	445
Unallocated
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	175	792
Provision for (recapture of) loan losses	(24)	(617)
Charge-offs	0	0
Recoveries	0	0
Ending balance	151	175
Total ALLL	151	175	151	175
General reserve			151	175
Specific reserve			0	0
Total loans			0	0
General reserves			0	0
Specific reserves			0	0
Real estate loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans			730,200	767,600
Real estate loans \| One- to four-family \| Residential segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3,297	3,061
Provision for (recapture of) loan losses	(278)	249
Charge-offs	0	(18)
Recoveries	5	5
Ending balance	3,024	3,297
Total ALLL	3,024	3,297	3,024	3,297
General reserve			2,993	3,262
Specific reserve			31	35
Total loans			306,014	336,178
General reserves			303,026	333,062
Specific reserves			2,988	3,116
Real estate loans \| Multi-family \| Residential segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	762	648
Provision for (recapture of) loan losses	126	114
Charge-offs	0	0
Recoveries	0	0
Ending balance	888	762
Total ALLL	888	762	888	762
General reserve			887	761
Specific reserve			1	1
Total loans			96,098	82,331
General reserves			95,991	82,221
Specific reserves			107	110
Commercial real estate \| Residential segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,289	1,847
Provision for (recapture of) loan losses	(46)	442
Charge-offs	0	0
Recoveries	0	0
Ending balance	2,243	2,289
Total ALLL	2,243	2,289	2,243	2,289
General reserve			2,235	2,281
Specific reserve			8	8
Total loans			255,722	253,235
General reserves			253,839	251,263
Specific reserves			1,883	1,972
Construction and land \| Residential segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	585	648
Provision for (recapture of) loan losses	(188)	(65)
Charge-offs	0	0
Recoveries	2	2
Ending balance	399	585
Total ALLL	399	585	399	585
General reserve			399	584
Specific reserve			0	1
Total loans			37,187	54,102
General reserves			37,158	54,058
Specific reserves			29	44
Home equity \| Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	480	787
Provision for (recapture of) loan losses	(71)	(332)
Charge-offs	0	0
Recoveries	45	25
Ending balance	454	480
Total ALLL	454	480	454	480
General reserve			439	474
Specific reserve			15	6
Total loans			35,046	37,629
General reserves			34,775	37,002
Specific reserves			271	627
Auto and other consumer \| Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,611	712
Provision for (recapture of) loan losses	1,275	1,315
Charge-offs	(884)	(638)
Recoveries	259	222
Ending balance	2,261	1,611
Total ALLL	$ 2,261	$ 1,611	2,261	1,611
General reserve			2,119	1,552
Specific reserve			142	59
Total loans			112,119	87,357
General reserves			111,271	87,113
Specific reserves			$ 848	$ 244

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

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

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

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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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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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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

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