Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters (Details Textuals) - USD ($)	6 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2024	Dec. 31, 2024	Jan. 01, 2022
Other Commitments [Line Items]
Investment Program, Proportional Amortization Method, Elected, Impairment Loss	$ 0		$ 0
Loans Repurchased Under Make Whole Requests	$ 2,000,000.0			$ 3,200,000
Loans Sold To Outside Investors Loss Reimbursement Settlement Paid			0
Make Whole Requests, Loan Origination Date, Majority	Jan. 01, 2022
Loans Sold To Outside Investors Original Amount					$ 3,500,000,000
Loans Sold To Outside Investors Remaining Outstanding Amount	$ 1,500,000,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	35,276,000			38,776,000
Financing Receivable, before Allowance for Credit Loss	30,607,605,000			29,768,586,000
Loss on Sale of Investments			$ 0
Residential Mortgage [Member]
Other Commitments [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	600,000			600,000
Residential Mortgage [Member] | Recourse
Other Commitments [Line Items]
Financing Receivable, before Allowance for Credit Loss	13,300,000			13,700,000
Residential Mortgage [Member] | Recourse | Credit Risk
Other Commitments [Line Items]
Financing Receivable, before Allowance for Credit Loss	192,300,000			133,800,000
Loss on Sale of Investments	0
Affordable Housing Projects and Other [Member]
Other Commitments [Line Items]
Other Investments	186,800,000			204,800,000
Investment Program, Proportional Amortization Method, Applied, Amortization Expense	17,100,000	$ 17,800,000
Investment, Proportional Amortization Method, Elected, Amount	184,700,000			202,800,000
Accrued Liabilities	21,200,000			29,700,000
Loan Pool CRA Investments [Member]
Other Commitments [Line Items]
Other Investments	$ 60,300,000			$ 54,100,000