Loans Receivable - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 9,628	$ 9,533
(Recapture of) provision for loan losses	1,266	335
Charge-offs	(134)	(190)
Recoveries	70	81
Ending balance	10,830	9,759
Total ALLL	10,830	9,759	$ 10,830	$ 9,628
General reserve			10,721	9,426
Specific reserve			109	202
Total loans			905,675	883,757
Loans collectively evaluated			899,372	877,368
Loans individually evaluated			6,303	6,389
Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans			700,368	695,021
Real Estate \| Real estate loans \| One-to-four family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3,024	3,297
(Recapture of) provision for loan losses	319	142
Charge-offs	0	0
Recoveries	53	2
Ending balance	3,396	3,441
Total ALLL	3,396	3,441	3,396	3,024
General reserve			3,363	2,993
Specific reserve			33	31
Total loans			302,688	306,014
Loans collectively evaluated			299,947	303,026
Loans individually evaluated			2,741	2,988
Real Estate \| Real estate loans \| Multi-family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	888	762
(Recapture of) provision for loan losses	35	7
Charge-offs	0	0
Recoveries	0	0
Ending balance	923	769
Total ALLL	923	769	923	888
General reserve			922	887
Specific reserve			1	1
Total loans			88,794	96,098
Loans collectively evaluated			88,391	95,991
Loans individually evaluated			403	107
Real Estate \| Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,243	2,289
(Recapture of) provision for loan losses	479	48
Charge-offs	0	0
Recoveries	0	0
Ending balance	2,722	2,337
Total ALLL	2,722	2,337	2,722	2,243
General reserve			2,713	2,235
Specific reserve			9	8
Total loans			260,321	255,722
Loans collectively evaluated			258,451	253,839
Loans individually evaluated			1,870	1,883
Real Estate \| Construction and land
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	399	585
(Recapture of) provision for loan losses	191	115
Charge-offs	0	0
Recoveries	2	0
Ending balance	592	700
Total ALLL	592	700	592	399
General reserve			591	399
Specific reserve			1	0
Total loans			48,565	37,187
Loans collectively evaluated			48,537	37,158
Loans individually evaluated			28	29
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total loans			149,454	147,165
Consumer \| Home equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	454	480
(Recapture of) provision for loan losses	(6)	(14)
Charge-offs	0	0
Recoveries	1	1
Ending balance	449	467
Total ALLL	449	467	449	454
General reserve			443	439
Specific reserve			6	15
Total loans			35,260	35,046
Loans collectively evaluated			34,971	34,775
Loans individually evaluated			289	271
Consumer \| Auto and other consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,261	1,611
(Recapture of) provision for loan losses	176	177
Charge-offs	(134)	(186)
Recoveries	14	76
Ending balance	2,317	1,678
Total ALLL	2,317	1,678	2,317	2,261
General reserve			2,263	2,119
Specific reserve			54	142
Total loans			114,194	112,119
Loans collectively evaluated			113,485	111,271
Loans individually evaluated			709	848
Commercial business
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	208	334
(Recapture of) provision for loan losses	42	(141)
Charge-offs	0	(4)
Recoveries	0	2
Ending balance	250	191
Total ALLL	250	191	250	208
General reserve			245	203
Specific reserve			5	5
Total loans			55,853	41,571
Loans collectively evaluated			55,590	41,308
Loans individually evaluated			263	263
Unallocated
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	151	175
(Recapture of) provision for loan losses	30	1
Charge-offs	0	0
Recoveries	0	0
Ending balance	181	176
Total ALLL	$ 181	$ 176	181	151
General reserve			181	151
Specific reserve			0	0
Total loans			0	0
Loans collectively evaluated			0	0
Loans individually evaluated			$ 0	$ 0

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

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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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