Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 101,687	$ 81,169
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Provision for Loan, Lease, and Other Losses	13,003	24,001
Depreciation	13,981	12,352
Mortgage Servicing Rights (MSR) Impairment (Recovery)	1,047	(1,646)
Amortization of Intangible Assets	2,203	2,203
Accretion (Amortization) of Discounts and Premiums, Investments	6,336	10,673
Other Depreciation and Amortization	8,689	8,990
Marketable Securities, Gain (Loss)	0	(3,857)
Gain (Loss) on Disposition of Assets	878	306
(Gain) loss on mortgage banking activities, net	329	(22)
Gain (Loss) on Sale of Mortgage Loans	6,976	0
Payment for Origination and Purchase, Loan, Held-for-Sale	(92,584)	(105,394)
Proceeds from Sale, Loan, Mortgage, Held-for-Sale	105,642	91,026
Increase (Decrease) in Other Operating Assets and Liabilities, Net [Abstract]
Increase (Decrease) in Accrued Interest Receivable, Net	8,044	2,477
Increase (Decrease) in Interest Payable, Net	(2,025)	15,590
Increase (Decrease) in Other Accounts Payable and Accrued Liabilities	(53,261)	(30,827)
Increase (Decrease) in Derivative Assets and Liabilities	(36,128)	35,008
Increase (Decrease) in Other Operating Assets and Liabilities, Net	13,349	12,453
Net Cash Provided by (Used in) Operating Activities, Total	98,166	154,500
Net Cash Provided by (Used in) Investing Activities [Abstract]
Payments for (Proceeds from) Loans and Leases	(513,237)	(222,656)
Payments for Investing Activities [Abstract]
Payments to Acquire Debt Securities, Available-for-Sale	(391,952)	(341,275)
Payments to Acquire Held-to-Maturity Securities	(994)	0
Payments to Acquire Federal Home Loan Bank Stock	(71,364)	(16,585)
Proceeds from Investing Activities [Abstract]
Proceeds from Sale of Debt Securities, Available-for-Sale	0	9,472
Proceeds from Sale of Federal Home Loan Bank Stock	56,786	98,005
Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale	206,882	176,266
Proceeds from Maturities, Prepayments and Calls of Held-to-Maturity Securities	34,673	28,026
Proceeds from Sale and Maturity of Other Investments	2,631	4,337
Payments for (Proceeds from) Productive Assets	(7,472)	(8,500)
Net Change in Tax Credit Investments	(7,448)	(2,409)
Net Cash Provided by (Used in) Investing Activities, Total	(127,119)	(275,320)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Increase (Decrease) in Deposits	548,279	267,109
Proceeds from (Repayments of) Short-Term Debt	(159,033)	438,891
Increase (Decrease) in Loans from Federal Home Loan Banks	170,000	(602,000)
Payments of FHLBank Borrowings, Financing Activities	(32)	(664)
Proceeds from FHLBank Borrowings, Financing Activities	0	619
Finance Lease, Principal Payments	(22)	(22)
Repayments of Senior Debt	(250,000)	0
Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Including Option Exercised	2,192	3,910
Payments of Ordinary Dividends, Common Stock	(38,538)	(33,527)
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	(2,875)	(2,875)
Proceeds from (Payments for) Other Financing Activities	(52)	0
Net Cash Provided by (Used in) Financing Activities, Total	241,810	48,580
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	212,856	(72,239)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning Balance	1,019,604	923,823	$ 923,823
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Ending Balance	1,232,460	851,583	1,019,604
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities	241,667	249,660
Income Taxes Paid, Net	(16,183)	1,995
Real Estate Owned, Transfer to Real Estate Owned	8,328	577
Servicing Asset at Fair Value, Additions	1,346	877	$ 6,707
Loan and Lease, Transfer from Held-in-Portfolio to Held-for-Sale	(45,077)	(86,096)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	10,403	(16,326)
Proceeds from Sale of Mortgage Portfolio	564,375	0
Board Authorized Purchase Program [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Payments for Repurchase of Common Stock	(22,292)	(18,289)
Other Liabilities [Member]
Supplemental Cash Flow Information [Abstract]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(6,997)	10,210
Other Assets [Member]
Supplemental Cash Flow Information [Abstract]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	(550)	2,708
Performance/Service Based RSAs, RSA,
Net Cash Provided by (Used in) Financing Activities [Abstract]
Payments for Repurchase of Common Stock	(5,816)	(4,572)
Retained Earnings [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 101,687	$ 81,169