Loans and Allowance for Credit Losses - Loan portfolio aging analysis (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2022	Jun. 30, 2022
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	$ 2,976,989,000	$ 2,719,843,000
Greater than 90 Days Past Due and Accruing	301,000
Current Loans, not past due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2,970,717,000	2,715,257,000
Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	6,272,000	4,586,000
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,879,000	2,432,000
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	977,000	732,000
Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,416,000	1,422,000
PCD loans that were greater than 90 days past due	0	0
Residential Real Estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,006,925,000	904,160,000
Greater than 90 Days Past Due and Accruing	301,000
Residential Real Estate | Current Loans, not past due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,004,170,000	901,694,000
Residential Real Estate | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2,755,000	2,466,000
Residential Real Estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,448,000	1,402,000
Residential Real Estate | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	88,000
Residential Real Estate | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,219,000	1,064,000
Construction Real Estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	154,829,000	134,416,000
Construction Real Estate | Current Loans, not past due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	154,689,000	134,416,000
Construction Real Estate | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	140,000
Construction Real Estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	140,000
Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,232,331,000	1,146,673,000
Commercial Real Estate | Current Loans, not past due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,230,593,000	1,145,354,000
Commercial Real Estate | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,738,000	1,319,000
Commercial Real Estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,071,000	416,000
Commercial Real Estate | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	583,000	615,000
Commercial Real Estate | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	84,000	288,000
Consumer loans
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	100,170,000	92,996,000
Consumer loans | Current Loans, not past due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	99,454,000	92,554,000
Consumer loans | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	716,000	442,000
Consumer loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	439,000	340,000
Consumer loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	204,000	45,000
Consumer loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	73,000	57,000
Commercial loans
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	482,734,000	441,598,000
Commercial loans | Current Loans, not past due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	481,811,000	441,239,000
Commercial loans | Total Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	923,000	359,000
Commercial loans | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	781,000	274,000
Commercial loans | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	102,000	72,000
Commercial loans | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	$ 40,000	$ 13,000