Loans Held For Investment - Schedule of Past Due Status of Loans Held for Investment, Gross (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans deemed uncollectible, period of delinquency	90 days	90 days
Current	$ 937,242	$ 874,032
30-89 Days Past Due	986	665
Non-Accrual	3,512	6,641
Total Loans Held for Investment, Gross	941,740	881,338	$ 877,073
Mortgage loans, Single-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	342,893	318,671
30-89 Days Past Due	982	660
Non-Accrual	3,469	5,621
Total Loans Held for Investment, Gross	347,344	324,952	312,499
Mortgage loans, Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	107,613	111,928
30-89 Days Past Due	0	0
Non-Accrual	0	0
Total Loans Held for Investment, Gross	107,613	111,928	112,830
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	6,914	3,667
30-89 Days Past Due	0	0
Non-Accrual	0	971
Total Loans Held for Investment, Gross	6,914	4,638	3,986
Commercial business loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	535	429
30-89 Days Past Due	0	0
Non-Accrual	43	49
Total Loans Held for Investment, Gross	578	478	455
Consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	136	129
30-89 Days Past Due	4	5
Non-Accrual	0	0
Total Loans Held for Investment, Gross	140	134	103
Mortgage Loans, Multi Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	479,151	439,041
30-89 Days Past Due	0	0
Non-Accrual	0	0
Total Loans Held for Investment, Gross	$ 479,151	439,041	447,033
Bankruptcy [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans deemed uncollectible, period of delinquency	60 days
Mortgage Loans Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current		167
30-89 Days Past Due		0
Non-Accrual		0
Total Loans Held for Investment, Gross		$ 167	$ 167
Troubled Debt Restructurings [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans deemed uncollectible, period of delinquency	90 days
Commercial Real Estate Or Second Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans deemed uncollectible, period of delinquency	120 days