Fair Value of Financial Instruments - Corporation's assets measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for investment, at fair value	$ 1,972	$ 2,258
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	4,158	4,717
Loans held for investment, at fair value	1,972	2,258
Interest-only strips	12	14
Total assets	6,142	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	2,551	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	1,434	1,577
Recurring | Private issue CMO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - available for sale	173	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	3,985	4,520
Loans held for investment, at fair value	0	0
Interest-only strips	0	0
Total assets	3,985	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	2,551	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	1,434	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	173	197
Loans held for investment, at fair value	1,972	2,258
Interest-only strips	12	14
Total assets	2,157	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	$ 173	$ 197