Loans and Allowance for Credit Losses - Loan portfolio aging analysis (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) loan	Jun. 30, 2024 USD ($) loan
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	$ 3,966,736,000	$ 3,850,035,000
Number of PCD loans greater than 90 days past due | loan	3	1
Purchased credit-impaired loans	$ 558,000	$ 560,000
Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	13,350,000	9,201,000
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,425,000	3,128,000
60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,611,000	2,621,000
Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	6,314,000	3,452,000
Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,953,386,000	3,840,834,000
Construction and land development
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	351,481,000
Agriculture real estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	239,787,000
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	457,018,000	450,147,000
Commercial and industrial | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	2,509,000	2,059,000
Commercial and industrial | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,042,000	641,000
Commercial and industrial | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	210,000	83,000
Commercial and industrial | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,257,000	1,335,000
Commercial and industrial | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	454,509,000	448,088,000
Agriculture production
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	200,215,000	175,968,000
Agriculture production | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	92,000	394,000
Agriculture production | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable		50,000
Agriculture production | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	66,000
Agriculture production | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	26,000	344,000
Agriculture production | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	200,123,000	175,574,000
Consumer
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	58,735,000	59,671,000
Consumer | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	489,000	399,000
Consumer | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	251,000	311,000
Consumer | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	139,000	74,000
Consumer | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	99,000	14,000
Consumer | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	58,246,000	59,272,000
All other loans
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,699,000	3,981,000
All other loans | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,699,000	3,981,000
Secured by real estate | 1-4 residential real estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	942,916,000	925,397,000
Secured by real estate | 1-4 residential real estate | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	6,597,000	3,641,000
Secured by real estate | 1-4 residential real estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,688,000	890,000
Secured by real estate | 1-4 residential real estate | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	3,196,000	2,087,000
Secured by real estate | 1-4 residential real estate | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,713,000	664,000
Secured by real estate | 1-4 residential real estate | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	936,319,000	921,756,000
Secured by real estate | Commercial Real Estate | Non-owner occupied
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	903,678,000	899,770,000
Secured by real estate | Commercial Real Estate | Non-owner occupied | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	106,000	107,000
Secured by real estate | Commercial Real Estate | Non-owner occupied | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	106,000	107,000
Secured by real estate | Commercial Real Estate | Non-owner occupied | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	903,572,000	899,663,000
Secured by real estate | Commercial Real Estate | Owner occupied
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	438,030,000	427,476,000
Secured by real estate | Commercial Real Estate | Owner occupied | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,308,000	1,365,000
Secured by real estate | Commercial Real Estate | Owner occupied | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	135,000	305,000
Secured by real estate | Commercial Real Estate | Owner occupied | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,173,000	1,060,000
Secured by real estate | Commercial Real Estate | Owner occupied | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	436,722,000	426,111,000
Secured by real estate | Multi-family real estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	371,177,000	384,564,000
Secured by real estate | Multi-family real estate | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	371,177,000	384,564,000
Secured by real estate | Construction and land development
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	351,481,000	290,541,000
Secured by real estate | Construction and land development | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	363,000	628,000
Secured by real estate | Construction and land development | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	176,000	251,000
Secured by real estate | Construction and land development | 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable		377,000
Secured by real estate | Construction and land development | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	187,000
Secured by real estate | Construction and land development | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	351,118,000	289,913,000
Secured by real estate | Agriculture real estate
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	239,787,000	232,520,000
Secured by real estate | Agriculture real estate | Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,886,000	608,000
Secured by real estate | Agriculture real estate | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	27,000	573,000
Secured by real estate | Agriculture real estate | Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	1,859,000	35,000
Secured by real estate | Agriculture real estate | Current
Financing Receivable, Past Due [Line Items]
Total Loans Receivable	$ 237,901,000	$ 231,912,000