Securities (Details)	3 Months Ended		6 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2024 USD ($) Category	Dec. 31, 2023 USD ($)	Jun. 30, 2024 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Accrued interest receivable	$ 4,500,000		$ 4,500,000		$ 4,000,000
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued interest receivable		Accrued interest receivable		Accrued interest receivable
Allowance for credit loss	$ 0		$ 0		$ 0
Accrued interest receivable	$ 5,200,000		$ 5,200,000		$ 4,100,000
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued interest receivable		Accrued interest receivable		Accrued interest receivable
Number of categories utilized under risk management approach of diversified investing (in Category) | Category			3
Available for sale securities transferred at fair value to held to maturity	$ 0	$ 0	$ 0	$ 0
Proceeds from sale of available-for-sale securities	0	0	0	0
Gross realized gains (losses) on sale of available-for-sale securities	0	0	0	0
Investment in Federal Home Loan Bank Stock [Member]
Debt Securities, Available-for-Sale [Line Items]
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Writeoff	0	$ 0	0	$ 0
Deposits in Excess of FDIC Insurance Limits [Member] | Asset Pledged as Collateral [Member]
Debt Securities, Available-for-Sale [Line Items]
Securities, fair value	1,000,000,000		1,000,000,000		$ 894,500,000
Potential Borrowings at Federal Reserve Bank Discount Window and Bank Term Funding Program [Member] | Asset Pledged as Collateral [Member]
Debt Securities, Available-for-Sale [Line Items]
Securities, fair value	$ 19,400,000		$ 19,400,000		$ 40,000,000