Loans Receivable, Part V (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) Payment Loan	Dec. 31, 2018 USD ($) Loan
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 4,018,000	$ 6,732,000
Total number of troubled debt restructurings | Loan	11	12
Valuation allowance with respect to troubled debt restructurings	$ 7,000	$ 67,000
Troubled Debt Restructurings by Concession Type [Abstract]
Loans Receivable, Modifications, Loans Performing in Accordance with Modified Terms	$ 3,570,000	$ 6,186,000
Number of loans performing in accordance with modified terms | Loan	9	10
Loans Receivable, Modifications, Loans in Default	$ 448,000	$ 546,000
Number of Loans in Default | Loan	2	2
Loans Receivable, Modifications, Total	$ 4,018,000	$ 6,732,000
Number of Loans, Total | Loan	11	12
Data on Troubled Debt Restructuring [Abstract]
Loans modified as a troubled debt restructure	$ 0	$ 2,476,000
Number of loans modified as a troubled debt restructuring | Loan	0	1
Non-accrual Loans [Abstract]
Total non-accrual loans	$ 7,025,000	$ 6,555,000
Ratio of total non-accrual loans to total loans, net of allowance	0.51%	0.48%
Ratio of total non-accrual loans to total assets	0.35%	0.34%
Residential Real Estate [Member] | One-to-Four Family [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 3,425,000	$ 3,584,000
Total number of troubled debt restructurings | Loan	7	7
Non-accrual Loans [Abstract]
Total non-accrual loans	$ 5,985,000	$ 4,902,000
Residential Real Estate [Member] | Multi Family [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 308,000	$ 372,000
Total number of troubled debt restructurings | Loan	2	2
Non-accrual Loans [Abstract]
Total non-accrual loans	$ 667,000	$ 1,309,000
Residential Real Estate [Member] | Home Equity [Member]
Non-accrual Loans [Abstract]
Total non-accrual loans	70,000	201,000
Construction and Land [Member]
Non-accrual Loans [Abstract]
Total non-accrual loans	0	0
Commercial Real Estate [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 285,000	$ 2,776,000
Total number of troubled debt restructurings | Loan	2	3
Data on Troubled Debt Restructuring [Abstract]
Loans modified as a troubled debt restructure	$ 0	$ 2,476,000
Number of loans modified as a troubled debt restructuring | Loan	0	1
Non-accrual Loans [Abstract]
Total non-accrual loans	$ 303,000	$ 125,000
Commercial [Member]
Non-accrual Loans [Abstract]
Total non-accrual loans	0	18,000
Consumer [Member]
Non-accrual Loans [Abstract]
Total non-accrual loans	$ 0	0
Minimum [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Period of principal forbearance, reduction in interest rate or both included in typical restructured terms	6 months
Minimum number of consecutive contractual payments received prior to consideration for a return to accrual status | Payment	6
Maximum [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Period of principal forbearance, reduction in interest rate or both included in typical restructured terms	12 months
Accruing [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 3,018,000	$ 5,499,000
Total number of troubled debt restructurings | Loan	3	4
Accruing [Member] | Residential Real Estate [Member] | One-to-Four Family [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 2,740,000	$ 2,740,000
Total number of troubled debt restructurings | Loan	2	2
Accruing [Member] | Residential Real Estate [Member] | Multi Family [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 0	$ 0
Total number of troubled debt restructurings | Loan	0	0
Accruing [Member] | Commercial Real Estate [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 278,000	$ 2,759,000
Total number of troubled debt restructurings | Loan	1	2
Non-Accruing [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 1,000,000	$ 1,233,000
Total number of troubled debt restructurings | Loan	8	8
Non-Accruing [Member] | Residential Real Estate [Member] | One-to-Four Family [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 685,000	$ 844,000
Total number of troubled debt restructurings | Loan	5	5
Non-Accruing [Member] | Residential Real Estate [Member] | Multi Family [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 308,000	$ 372,000
Total number of troubled debt restructurings | Loan	2	2
Non-Accruing [Member] | Commercial Real Estate [Member]
Troubled Debt Restructuring Note, Debtor [Abstract]
Amount of troubled debt restructuring	$ 7,000	$ 17,000
Total number of troubled debt restructurings | Loan	1	1
Interest Reduction and Principal Forbearance [Member]
Troubled Debt Restructurings by Concession Type [Abstract]
Loans Receivable, Modifications, Loans Performing in Accordance with Modified Terms	$ 3,246,000	$ 5,848,000
Number of loans performing in accordance with modified terms | Loan	6	7
Loans Receivable, Modifications, Loans in Default	$ 448,000	$ 546,000
Number of Loans in Default | Loan	2	2
Loans Receivable, Modifications, Total	$ 3,694,000	$ 6,394,000
Number of Loans, Total | Loan	8	9
Interest Reduction [Member]
Troubled Debt Restructurings by Concession Type [Abstract]
Loans Receivable, Modifications, Loans Performing in Accordance with Modified Terms	$ 324,000	$ 338,000
Number of loans performing in accordance with modified terms | Loan	3	3
Loans Receivable, Modifications, Loans in Default	$ 0	$ 0
Number of Loans in Default | Loan	0	0
Loans Receivable, Modifications, Total	$ 324,000	$ 338,000
Number of Loans, Total | Loan	3	3