Fair Value of Financial Instruments - Corporation's assets measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for investment, at fair value	$ 2,240	$ 2,258
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	4,416	4,717
Loans held for investment, at fair value	2,240	2,258
Interest-only strips	13	14
Total assets	6,669	6,989
Liabilities	0
Total liabilities	0
Recurring | U.S. government agency MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	2,726	2,943
Recurring | U.S. government sponsored enterprise MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	1,506	1,577
Recurring | Private issue CMO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	184	197
Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Loans held for investment, at fair value	0	0
Interest-only strips	0	0
Total assets	0	0
Liabilities	0	0
Total liabilities	0	0
Recurring | Fair Value, Inputs, Level 1 | U.S. government agency MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Recurring | Fair Value, Inputs, Level 1 | U.S. government sponsored enterprise MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Recurring | Fair Value, Inputs, Level 1 | Private issue CMO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	4,232	4,520
Loans held for investment, at fair value	0	0
Interest-only strips	0	0
Total assets	4,232	4,520
Liabilities	0	0
Total liabilities	0	0
Recurring | Fair Value, Inputs, Level 2 | U.S. government agency MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	2,726	2,943
Recurring | Fair Value, Inputs, Level 2 | U.S. government sponsored enterprise MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	1,506	1,577
Recurring | Fair Value, Inputs, Level 2 | Private issue CMO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	184	197
Loans held for investment, at fair value	2,240	2,258
Interest-only strips	13	14
Total assets	2,437	2,469
Liabilities	0	0
Total liabilities	0	0
Recurring | Fair Value, Inputs, Level 3 | U.S. government agency MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Recurring | Fair Value, Inputs, Level 3 | U.S. government sponsored enterprise MBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	0	0
Recurring | Fair Value, Inputs, Level 3 | Private issue CMO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	$ 184	$ 197