Commitments, Off-Balance Sheet Arrangements, Legal Proceedings and Regulatory Matters (Details Textuals) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025	Jan. 01, 2022
Other Commitments [Line Items]
Investment Program, Proportional Amortization Method, Elected, Impairment Loss	$ 0		$ 0
Loans Repurchased Under Make Whole Requests	$ 2,200,000		3,500,000
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				$ 4,100,000,000
Loans Sold To Outside Investors Remaining Outstanding Amount	$ 1,800,000,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	39,276,000		41,276,000
Financing Receivable, before Allowance for Credit Loss	31,798,164,000		31,163,614,000
Loss on Sale of Investments			0
Residential Mortgage [Member]
Other Commitments [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	200,000		300,000
Residential Mortgage [Member] | Recourse
Other Commitments [Line Items]
Financing Receivable, before Allowance for Credit Loss	13,900,000		11,400,000
Residential Mortgage [Member] | Recourse | Credit Risk
Other Commitments [Line Items]
Financing Receivable, before Allowance for Credit Loss	290,700,000		273,400,000
Loss on Sale of Investments	0
Affordable Housing Projects and Other [Member]
Other Commitments [Line Items]
Other Investments	165,900,000		174,300,000
Investment Program, Proportional Amortization Method, Applied, Amortization Expense	8,500,000	$ 8,700,000
Investment, Proportional Amortization Method, Elected, Amount	166,600,000		172,200,000
Accrued Liabilities	22,000,000.0		22,800,000
Loan Pool CRA Investments [Member]
Other Commitments [Line Items]
Other Investments	$ 65,100,000		$ 62,300,000