Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters (Details Textuals) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Jun. 30, 2024	Dec. 31, 2024
Other Commitments [Line Items]
Investment Program, Proportional Amortization Method, Elected, Impairment Loss	$ 0		$ 0
Loans Repurchased Under Make Whole Requests	$ 866,000			$ 3,000,000
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	$ 3,400,000,000
Loans Sold To Outside Investors Remaining Outstanding Amount	1,400,000,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	35,276,000			38,776,000
Financing Receivable, before Allowance for Credit Loss	30,294,127,000			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	584,000			553,000
Residential Mortgage [Member] | Recourse
Other Commitments [Line Items]
Financing Receivable, before Allowance for Credit Loss	13,000,000			14,000,000
Residential Mortgage [Member] | Recourse | Credit Risk
Other Commitments [Line Items]
Financing Receivable, before Allowance for Credit Loss	159,000,000			134,000,000
Loss on Sale of Investments	0
Affordable Housing Projects and Other [Member]
Other Commitments [Line Items]
Other Investments	196,000,000			205,000,000
Investment Program, Proportional Amortization Method, Applied, Amortization Expense	9,000,000	$ 9,000,000
Investment, Proportional Amortization Method, Elected, Amount	194,000,000			203,000,000
Accrued Liabilities	26,000,000			30,000,000
Private SBA Loan Fund [Member]
Other Commitments [Line Items]
Equity Securities, FV-NI	3,000,000
Loan Pool CRA Investments [Member]
Other Commitments [Line Items]
Other Investments	$ 58,000,000			$ 54,000,000