Fair Value Measurements - Schedule of financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Letter of Credit
Carrying amount of financial instruments	$ 0	$ 0
Line of Credit
Carrying amount of financial instruments	0	0
Financial liabilities | Subordinated Debt
Carrying amount of financial instruments	15,193	15,142
Financial liabilities | Federal Home Loan Bank Advances
Carrying amount of financial instruments	63,286	70,024
Financial assets | Loans Receivable
Carrying amount of financial instruments	2,121,399	2,141,929
Financial assets | Cash and Cash Equivalents
Carrying amount of financial instruments	149,520	54,245
Financial assets | Interest-bearing time deposits
Carrying amount of financial instruments	976	974
Financial assets | Investment in Federal Home Loan Bank Stock
Carrying amount of financial instruments	5,987	6,390
Financial assets | Investment in Stock of Federal Reserve Bank of St. Louis
Carrying amount of financial instruments	5,017	4,363
Financial assets | Accrued interest receivable
Carrying amount of financial instruments	12,377	12,116
Deposits | Financial liabilities
Carrying amount of financial instruments	2,265,087	2,184,847
Accrued interest payable | Financial liabilities
Carrying amount of financial instruments	1,106	1,646
Commitments to Extend Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Letter of Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Line of Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Financial liabilities | Subordinated Debt
Carrying amount of financial instruments		0
Fair Value, Inputs, Level 1 | Financial liabilities | Federal Home Loan Bank Advances
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Financial assets | Loans Receivable
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Financial assets | Cash and Cash Equivalents
Carrying amount of financial instruments	149,520	54,245
Fair Value, Inputs, Level 1 | Financial assets | Interest-bearing time deposits
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Financial assets | Investment in Federal Home Loan Bank Stock
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Financial assets | Investment in Stock of Federal Reserve Bank of St. Louis
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Financial assets | Accrued interest receivable
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Deposits | Financial liabilities
Carrying amount of financial instruments	1,642,913	1,508,740
Fair Value, Inputs, Level 1 | Accrued interest payable | Financial liabilities
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 1 | Commitments to Extend Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 2 | Letter of Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 2 | Line of Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 2 | Financial liabilities | Subordinated Debt
Carrying amount of financial instruments		0
Fair Value, Inputs, Level 2 | Financial liabilities | Federal Home Loan Bank Advances
Carrying amount of financial instruments	64,992	72,136
Fair Value, Inputs, Level 2 | Financial assets | Loans Receivable
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 2 | Financial assets | Cash and Cash Equivalents
Carrying amount of financial instruments		0
Fair Value, Inputs, Level 2 | Financial assets | Interest-bearing time deposits
Carrying amount of financial instruments	976	974
Fair Value, Inputs, Level 2 | Financial assets | Investment in Federal Home Loan Bank Stock
Carrying amount of financial instruments	5,987	6,390
Fair Value, Inputs, Level 2 | Financial assets | Investment in Stock of Federal Reserve Bank of St. Louis
Carrying amount of financial instruments	5,017	4,363
Fair Value, Inputs, Level 2 | Financial assets | Accrued interest receivable
Carrying amount of financial instruments	12,377	12,116
Fair Value, Inputs, Level 2 | Deposits | Financial liabilities
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 2 | Accrued interest payable | Financial liabilities
Carrying amount of financial instruments	1,106	1,646
Fair Value, Inputs, Level 2 | Commitments to Extend Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Letter of Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Line of Credit
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Financial liabilities | Subordinated Debt
Carrying amount of financial instruments	13,849	11,511
Fair Value, Inputs, Level 3 | Financial liabilities | Federal Home Loan Bank Advances
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Financial assets | Loans Receivable
Carrying amount of financial instruments	2,142,067	2,143,823
Fair Value, Inputs, Level 3 | Financial assets | Cash and Cash Equivalents
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Financial assets | Interest-bearing time deposits
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Financial assets | Investment in Federal Home Loan Bank Stock
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Financial assets | Investment in Stock of Federal Reserve Bank of St. Louis
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Financial assets | Accrued interest receivable
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Deposits | Financial liabilities
Carrying amount of financial instruments	625,697	676,816
Fair Value, Inputs, Level 3 | Accrued interest payable | Financial liabilities
Carrying amount of financial instruments	0	0
Fair Value, Inputs, Level 3 | Commitments to Extend Credit
Carrying amount of financial instruments	$ 0	$ 0