Loans Receivable, Part IV (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable [Abstract]
At December 31, 2020	$ 1,205,785,000	$ 1,375,137,000
Loans requiring an officers' loans committee review and approval, minimum	500,000
Minimum amount of potential loan exposure to be reviewed by credit management personnel	$ 1,000,000.0
Maximum period of time loan reviewed under renewal condition	1 year
Period of time sales of real estate owned fair value is based	2 years
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	$ 0	208,000
Total Impaired, with no Reserve, Recorded Investment	7,893,000	16,389,000
Total Impaired, Recorded Investment	7,893,000	16,597,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	208,000
Total Impaired with no Reserve, Unpaid Principal Balance	7,923,000	17,255,000
Total Impaired, Unpaid Principal Balance, Total	7,923,000	17,463,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	23,000
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	23,000
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	30,000	866,000
Total Impaired, Cumulative Charge-offs	30,000	866,000
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	213,000
Total Impaired with no Reserve, Average Recorded Investment	7,942,000	16,633,000
Total Impaired, Average Recorded Investment, Total	7,942,000	16,846,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	15,000
Total Impaired with no Reserve, Interest Paid YTD	298,000	706,000
Total Impaired, Interest Paid YTD	298,000	721,000
Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	13,498,000	15,172,000
Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	21,250,000	23,054,000
Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	1,171,037,000	1,336,911,000
Residential Real Estate [Member] | One-to-Four Family [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	300,523,000	426,792,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	208,000
Total Impaired, with no Reserve, Recorded Investment	5,420,000	7,597,000
Total Impaired, Recorded Investment	5,420,000	7,805,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	208,000
Total Impaired with no Reserve, Unpaid Principal Balance	5,450,000	8,444,000
Total Impaired, Unpaid Principal Balance, Total	5,450,000	8,652,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	23,000
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	23,000
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	30,000	847,000
Total Impaired, Cumulative Charge-offs	30,000	847,000
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	213,000
Total Impaired with no Reserve, Average Recorded Investment	5,465,000	7,770,000
Total Impaired, Average Recorded Investment, Total	5,465,000	7,983,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	15,000
Total Impaired with no Reserve, Interest Paid YTD	186,000	349,000
Total Impaired, Interest Paid YTD	186,000	364,000
Residential Real Estate [Member] | One-to-Four Family [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	5,420,000	7,804,000
Residential Real Estate [Member] | One-to-Four Family [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	7,937,000	7,667,000
Residential Real Estate [Member] | One-to-Four Family [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	287,166,000	411,321,000
Residential Real Estate [Member] | Multi Family [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	537,956,000	571,948,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	0
Total Impaired, with no Reserve, Recorded Investment	128,000	341,000
Total Impaired, Recorded Investment	128,000	341,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	0
Total Impaired with no Reserve, Unpaid Principal Balance	128,000	352,000
Total Impaired, Unpaid Principal Balance, Total	128,000	352,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	0
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	0
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	0	11,000
Total Impaired, Cumulative Charge-offs	0	11,000
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	0
Total Impaired with no Reserve, Average Recorded Investment	129,000	353,000
Total Impaired, Average Recorded Investment, Total	129,000	353,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	0
Total Impaired with no Reserve, Interest Paid YTD	4,000	17,000
Total Impaired, Interest Paid YTD	4,000	17,000
Residential Real Estate [Member] | Multi Family [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	128,000	341,000
Residential Real Estate [Member] | Multi Family [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	0	275,000
Residential Real Estate [Member] | Multi Family [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	537,828,000	571,332,000
Residential Real Estate [Member] | Home Equity [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	11,012,000	14,820,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	0
Total Impaired, with no Reserve, Recorded Investment	26,000	63,000
Total Impaired, Recorded Investment	26,000	63,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	0
Total Impaired with no Reserve, Unpaid Principal Balance	26,000	63,000
Total Impaired, Unpaid Principal Balance, Total	26,000	63,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	0
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	0
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	0	0
Total Impaired, Cumulative Charge-offs	0	0
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	0
Total Impaired with no Reserve, Average Recorded Investment	29,000	67,000
Total Impaired, Average Recorded Investment, Total	29,000	67,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	0
Total Impaired with no Reserve, Interest Paid YTD	2,000	4,000
Total Impaired, Interest Paid YTD	2,000	4,000
Residential Real Estate [Member] | Home Equity [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	26,000	248,000
Residential Real Estate [Member] | Home Equity [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	37,000	15,000
Residential Real Estate [Member] | Home Equity [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	10,949,000	14,557,000
Construction and Land [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	82,588,000	77,080,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	0
Total Impaired, with no Reserve, Recorded Investment	0	43,000
Total Impaired, Recorded Investment	0	43,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	0
Total Impaired with no Reserve, Unpaid Principal Balance	0	51,000
Total Impaired, Unpaid Principal Balance, Total	0	51,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	0
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	0
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	0	8,000
Total Impaired, Cumulative Charge-offs	0	8,000
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	0
Total Impaired with no Reserve, Average Recorded Investment	0	51,000
Total Impaired, Average Recorded Investment, Total	0	51,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	0
Total Impaired with no Reserve, Interest Paid YTD	0	1,000
Total Impaired, Interest Paid YTD	0	1,000
Construction and Land [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	0	43,000
Construction and Land [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	4,212,000	4,282,000
Construction and Land [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	78,376,000	72,755,000
Commercial Real Estate [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	250,676,000	238,375,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	0
Total Impaired, with no Reserve, Recorded Investment	1,222,000	7,248,000
Total Impaired, Recorded Investment	1,222,000	7,248,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	0
Total Impaired with no Reserve, Unpaid Principal Balance	1,222,000	7,248,000
Total Impaired, Unpaid Principal Balance, Total	1,222,000	7,248,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	0
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	0
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	0	0
Total Impaired, Cumulative Charge-offs	0	0
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	0
Total Impaired with no Reserve, Average Recorded Investment	1,222,000	7,295,000
Total Impaired, Average Recorded Investment, Total	1,222,000	7,295,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	0
Total Impaired with no Reserve, Interest Paid YTD	56,000	333,000
Total Impaired, Interest Paid YTD	56,000	333,000
Commercial Real Estate [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	6,827,000	6,026,000
Commercial Real Estate [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	5,870,000	6,714,000
Commercial Real Estate [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	237,979,000	225,635,000
Consumer [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	732,000	736,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	0
Total Impaired, with no Reserve, Recorded Investment	0	0
Total Impaired, Recorded Investment	0	0
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	0
Total Impaired with no Reserve, Unpaid Principal Balance	0	0
Total Impaired, Unpaid Principal Balance, Total	0	0
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	0
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	0
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	0	0
Total Impaired, Cumulative Charge-offs	0	0
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	0
Total Impaired with no Reserve, Average Recorded Investment	0	0
Total Impaired, Average Recorded Investment, Total	0	0
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	0
Total Impaired with no Reserve, Interest Paid YTD	0	0
Total Impaired, Interest Paid YTD	0	0
Consumer [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	0	0
Consumer [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	0	0
Consumer [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	732,000	736,000
Commercial [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	22,298,000	45,386,000
Minimum amount of potential loan exposure to be reviewed by credit management personnel	200,000
Impaired Loans Receivable, Recorded Investment [Abstract]
Total Impaired, with Reserve, Recorded Investment	0	0
Total Impaired, with no Reserve, Recorded Investment	1,097,000	1,097,000
Total Impaired, Recorded Investment	1,097,000	1,097,000
Impaired Loans Receivable, Unpaid Principal Balance [Abstract]
Total Impaired with Reserve, Unpaid Principal Balance	0	0
Total Impaired with no Reserve, Unpaid Principal Balance	1,097,000	1,097,000
Total Impaired, Unpaid Principal Balance, Total	1,097,000	1,097,000
Impaired Loans Receivable, Reserve [Abstract]
Total Impaired with Reserve, Reserve	0	0
Total Impaired with no Reserve, Reserve	0	0
Impaired Loans, Reserve	0	0
Impaired Loans Receivable, Cumulative Charge-Offs [Abstract]
Total Impaired with Reserve, Cumulative Charge-offs	0	0
Total Impaired with no Reserve, Cumulative Charge-offs	0	0
Total Impaired, Cumulative Charge-offs	0	0
Impaired Loans Receivable, Average Recorded Investment [Abstract]
Total Impaired with Reserve, Average Recorded Investment	0	0
Total Impaired with no Reserve, Average Recorded Investment	1,097,000	1,097,000
Total Impaired, Average Recorded Investment, Total	1,097,000	1,097,000
Impaired Loans Receivable, Interest Paid YTD [Abstract]
Total Impaired with Reserve, Interest Paid YTD	0	0
Total Impaired with no Reserve, Interest Paid YTD	50,000	2,000
Total Impaired, Interest Paid YTD	50,000	2,000
Commercial [Member] | Substandard [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	1,097,000	710,000
Commercial [Member] | Watch [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	3,194,000	4,101,000
Commercial [Member] | Pass [Member]
Loans and Leases Receivable [Abstract]
At December 31, 2020	$ 18,007,000	$ 40,575,000