Loans and Allowance for Credit Losses - Schedule of loan portfolio aging analysis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Residential real estate loans
Financing Receivable Recorded Investment	$ 904
Financing Receivables Past Due
Financing Receivable Recorded Investment	7,655	$ 6,393
Financing Receivables Past Due | Consumer Loan
Financing Receivable Recorded Investment	865	426
Financing Receivables Past Due | Commercial Loan
Financing Receivable Recorded Investment	1,746	2,122
Financing Receivables Past Due | Construction Real Estate
Financing Receivable Recorded Investment		0
Financing Receivables Past Due | Residential real estate loans
Financing Receivable Recorded Investment	2,625	1,804
Financing Receivables Past Due | Commercial Real Estate
Financing Receivable Recorded Investment	2,419	2,041
Loans Receivable
Financing Receivable Recorded Investment		2,171,463
Loans Receivable | Consumer Loan
Financing Receivable Recorded Investment	79,590	80,767
Loans Receivable | Commercial Loan
Financing Receivable Recorded Investment	427,345	468,448
Loans Receivable | Construction Real Estate
Financing Receivable Recorded Investment	112,994	107,472
Loans Receivable | Residential real estate loans
Financing Receivable Recorded Investment	636,690	627,357
Loans Receivable | Commercial Real Estate
Financing Receivable Recorded Investment	902,564	887,419
Total Loans
Financing Receivable Recorded Investment	2,159,183
Financial Asset, 30 to 59 Days Past Due | Consumer Loan
Financing Receivable Recorded Investment	486	180
Financial Asset, 30 to 59 Days Past Due | Commercial Loan
Financing Receivable Recorded Investment	1,269	93
Financial Asset, 30 to 59 Days Past Due | Construction Real Estate
Financing Receivable Recorded Investment		0
Financial Asset, 30 to 59 Days Past Due | Residential real estate loans
Financing Receivable Recorded Investment	383	772
Financial Asset, 30 to 59 Days Past Due | Commercial Real Estate
Financing Receivable Recorded Investment	923	641
Financial Asset, 30 to 59 Days Past Due | Total Loans
Financing Receivable Recorded Investment	3,061	1,686
Financial Asset, 60 to 89 Days Past Due | Consumer Loan
Financing Receivable Recorded Investment	152	53
Financial Asset, 60 to 89 Days Past Due | Commercial Loan
Financing Receivable Recorded Investment	83	1,219
Financial Asset, 60 to 89 Days Past Due | Construction Real Estate
Financing Receivable Recorded Investment		0
Financial Asset, 60 to 89 Days Past Due | Residential real estate loans
Financing Receivable Recorded Investment	944	378
Financial Asset, 60 to 89 Days Past Due | Commercial Real Estate
Financing Receivable Recorded Investment	880	327
Financial Asset, 60 to 89 Days Past Due | Total Loans
Financing Receivable Recorded Investment	2,059	1,977
Financial Asset, Greater than 90 Days Past Due | Consumer Loan
Financing Receivable Recorded Investment	227	193
Financial Asset, Greater than 90 Days Past Due | Commercial Loan
Financing Receivable Recorded Investment	394	810
Financial Asset, Greater than 90 Days Past Due | Construction Real Estate
Financing Receivable Recorded Investment		0
Financial Asset, Greater than 90 Days Past Due | Residential real estate loans
Financing Receivable Recorded Investment	1,298	654
Financial Asset, Greater than 90 Days Past Due | Commercial Real Estate
Financing Receivable Recorded Investment	616	1,073
Financial Asset, Greater than 90 Days Past Due | Total Loans
Financing Receivable Recorded Investment	2,535	2,730
Financing Receivables, Current | Consumer Loan
Financing Receivable Recorded Investment	78,725	80,341
Financing Receivables, Current | Commercial Loan
Financing Receivable Recorded Investment	425,599	466,326
Financing Receivables, Current | Construction Real Estate
Financing Receivable Recorded Investment	112,994	107,472
Financing Receivables, Current | Residential real estate loans
Financing Receivable Recorded Investment	634,065	625,553
Financing Receivables, Current | Commercial Real Estate
Financing Receivable Recorded Investment	900,145	885,378
Financing Receivables, Current | Total Loans
Financing Receivable Recorded Investment	$ 2,151,528	2,165,070
Financing Receivables, Greater than 90 Days Past Due and Accruing | Consumer Loan
Financing Receivable Recorded Investment		0
Financing Receivables, Greater than 90 Days Past Due and Accruing | Commercial Loan
Financing Receivable Recorded Investment		0
Financing Receivables, Greater than 90 Days Past Due and Accruing | Construction Real Estate
Financing Receivable Recorded Investment		0
Financing Receivables, Greater than 90 Days Past Due and Accruing | Residential real estate loans
Financing Receivable Recorded Investment		0
Financing Receivables, Greater than 90 Days Past Due and Accruing | Commercial Real Estate
Financing Receivable Recorded Investment		0
Financing Receivables, Greater than 90 Days Past Due and Accruing | Total Loans
Financing Receivable Recorded Investment		$ 0