Loans Receivable and Allowance for Loan Losses (Schedule of allowance for credit losses on financing receivables) (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Allowance for Credit Losses:
Beginning Balance	$ 768	$ 756	$ 756
Charge-offs	(18)		(9)
Recoveries	6		16
Provision		5	5
Ending Balance	756		768
Ending Balance: Individually Evaluated for Impairment	85		10
Ending Balance: Collectively Evaluated for Impairment	671		758
Loans Receivable:
Ending Balance	106,365		100,282
Ending Balance: Individually Evaluated for Impairment	836		100
Ending Balance: Collectively Evaluated for Impairment	105,529		100,182
Real Estate | Commercial
Allowance for Credit Losses:
Beginning Balance	113	94	94
Charge-offs	0		(1)
Recoveries	5		3
Provision	(23)		17
Ending Balance	95		113
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	95		113
Loans Receivable:
Ending Balance	22,627		21,868
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	22,627		21,868
Real Estate | Land
Allowance for Credit Losses:
Beginning Balance	23	56	56
Charge-offs	0		0
Recoveries	0		0
Provision	(4)		(33)
Ending Balance	19		23
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	19		23
Loans Receivable:
Ending Balance	2,288		2,211
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	2,288		2,211
Real Estate | One-to-Four Family
Allowance for Credit Losses:
Beginning Balance	519	545	545
Charge-offs	0		0
Recoveries	0		13
Provision	(14)		(39)
Ending Balance	505		519
Ending Balance: Individually Evaluated for Impairment	85		10
Ending Balance: Collectively Evaluated for Impairment	420		509
Loans Receivable:
Ending Balance	72,303		69,414
Ending Balance: Individually Evaluated for Impairment	836		100
Ending Balance: Collectively Evaluated for Impairment	71,467		69,314
Real Estate | Construction
Allowance for Credit Losses:
Beginning Balance	16	8	8
Charge-offs	0		0
Recoveries	0		0
Provision	3		8
Ending Balance	19		16
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	19		16
Loans Receivable:
Ending Balance	4,241		2,947
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	4,241		2,947
Real Estate | Multi-family
Allowance for Credit Losses:
Beginning Balance	5	4	4
Charge-offs	0		0
Recoveries	0		0
Provision	1		1
Ending Balance	6		5
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	6		5
Loans Receivable:
Ending Balance	2,115		1,524
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	2,115		1,524
Consumer
Allowance for Credit Losses:
Beginning Balance	9	1	1
Charge-offs	(18)		(8)
Recoveries	1		0
Provision	31		16
Ending Balance	23		9
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	23		9
Loans Receivable:
Ending Balance	257		354
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	257		354
Commercial
Allowance for Credit Losses:
Beginning Balance	83	$ 48	48
Charge-offs	0		0
Recoveries	0		0
Provision	6		35
Ending Balance	89		83
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	89		83
Loans Receivable:
Ending Balance	2,534		1,964
Ending Balance: Individually Evaluated for Impairment	0		0
Ending Balance: Collectively Evaluated for Impairment	$ 2,534		$ 1,964