Loans Receivable, Part III (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 [Roll Forward]
Balance at beginning of period	$ 13,226	$ 12,561	$ 12,387	$ 13,249
Provision (credit) for loan losses	4,500	30	5,285	(650)
Charge-offs	(27)	(7)	(34)	(39)
Recoveries	35	33	96	57
Balance at end of period	17,734	12,617	17,734	12,617
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					$ 27	$ 39
Allowance related to loans collectively evaluated for impairment					17,707	12,348
Provision for loan losses	13,226	12,561	17,734	12,617	17,734	12,387
Loans individually evaluated for impairment					8,537	10,057
Loans collectively evaluated for impairment					1,425,266	1,377,974
Total gross loans					1,433,803	1,388,031
Total loans					1,433,803	1,388,031
Residential Real Estate [Member] | One-to-Four Family [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	4,714	5,181	4,907	5,742
Provision (credit) for loan losses	988	101	754	(449)
Charge-offs	(1)	(1)	(7)	(25)
Recoveries	14	22	61	35
Balance at end of period	5,715	5,303	5,715	5,303
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					27	32
Allowance related to loans collectively evaluated for impairment					5,688	4,875
Provision for loan losses	4,714	5,181	5,715	5,303	5,715	4,907
Loans individually evaluated for impairment					7,478	8,725
Loans collectively evaluated for impairment					459,868	471,555
Total gross loans					467,346	480,280
Total loans					467,346	480,280
Residential Real Estate [Member] | Multi Family [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	4,301	4,331	4,138	4,153
Provision (credit) for loan losses	1,568	(20)	1,728	154
Charge-offs	(5)	(1)	(5)	(1)
Recoveries	6	5	9	9
Balance at end of period	5,870	4,315	5,870	4,315
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					0	0
Allowance related to loans collectively evaluated for impairment					5,870	4,138
Provision for loan losses	4,301	4,331	5,870	4,315	5,870	4,138
Loans individually evaluated for impairment					639	667
Loans collectively evaluated for impairment					598,285	584,192
Total gross loans					598,924	584,859
Total loans					598,924	584,859
Residential Real Estate [Member] | Home Equity [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	239	276	201	325
Provision (credit) for loan losses	(20)	(7)	12	(54)
Charge-offs	(13)	0	(13)	(8)
Recoveries	12	6	18	12
Balance at end of period	218	275	218	275
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					0	0
Allowance related to loans collectively evaluated for impairment					218	201
Provision for loan losses	239	276	218	275	218	201
Loans individually evaluated for impairment					77	84
Loans collectively evaluated for impairment					16,332	17,987
Total gross loans					16,409	18,071
Total loans					16,409	18,071
Construction and Land [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	687	353	610	400
Provision (credit) for loan losses	466	59	542	12
Charge-offs	0	0	0	0
Recoveries	0	0	1	0
Balance at end of period	1,153	412	1,153	412
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					0	0
Allowance related to loans collectively evaluated for impairment					1,153	610
Provision for loan losses	687	353	1,153	412	1,153	610
Loans individually evaluated for impairment					0	0
Loans collectively evaluated for impairment					48,850	37,033
Total gross loans					48,850	37,033
Total loans					48,850	37,033
Commercial Real Estate [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	2,803	2,005	2,145	2,126
Provision (credit) for loan losses	1,318	(92)	1,972	(214)
Charge-offs	0	0	0	0
Recoveries	3	0	7	1
Balance at end of period	4,124	1,913	4,124	1,913
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					0	7
Allowance related to loans collectively evaluated for impairment					4,124	2,138
Provision for loan losses	2,803	2,005	4,124	1,913	4,124	2,145
Loans individually evaluated for impairment					343	581
Loans collectively evaluated for impairment					244,432	236,122
Total gross loans					244,775	236,703
Total loans					244,775	236,703
Consumer [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	23	7	14	20
Provision (credit) for loan losses	15	10	25	(3)
Charge-offs	0	(5)	(1)	(5)
Recoveries	0	0	0	0
Balance at end of period	38	12	38	12
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					0	0
Allowance related to loans collectively evaluated for impairment					38	14
Provision for loan losses	23	7	38	12	38	14
Loans individually evaluated for impairment					0	0
Loans collectively evaluated for impairment					860	832
Total gross loans					860	832
Total loans					860	832
Commercial Loans [Member]
Allowance for loan losses [Roll Forward]
Balance at beginning of period	459	408	372	483
Provision (credit) for loan losses	165	(21)	252	(96)
Charge-offs	(8)	0	(8)	0
Recoveries	0	0	0	0
Balance at end of period	616	387	616	387
Summary of the allowance for loan loss for loans evaluated individually and collectively for impairment by collateral class [Abstract]
Allowance related to loans individually evaluated for impairment					0	0
Allowance related to loans collectively evaluated for impairment					616	372
Provision for loan losses	$ 459	$ 408	$ 616	$ 387	616	372
Loans individually evaluated for impairment					0	0
Loans collectively evaluated for impairment					56,639	30,253
Total gross loans					56,639	30,253
Total loans					$ 56,639	$ 30,253