Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 111,230	$ 101,687	$ 115,573	$ 81,169	$ 212,916	$ 196,742
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Provision for Loan, Lease, and Other Losses	17,996		23,008		30,999	47,009
Depreciation					26,006	24,519
Mortgage Servicing Rights (MSR) Impairment (Recovery)					1,632	(2,567)
Amortization of Intangible Assets	2,203		2,203		4,405	4,405
Accretion (Amortization) of Discounts and Premiums, Investments					18,278	20,405
Other Depreciation and Amortization					17,058	17,788
Marketable Securities, Gain (Loss)					0	(3,857)
Gain (Loss) on Disposition of Assets	1,735		627		2,613	933
(Gain) loss on mortgage banking activities, net					(683)	882
Gain (Loss) on Sale of Mortgage Loans	0		0		6,976	0
Payment for Origination and Purchase, Loan, Held-for-Sale					(273,947)	(274,358)
Proceeds from Sale, Loan, Mortgage, Held-for-Sale					238,557	228,732
Increase (Decrease) in Other Operating Assets and Liabilities, Net [Abstract]
Increase (Decrease) in Accrued Interest Receivable, Net					(854)	(3,537)
Increase (Decrease) in Interest Payable, Net					(3,681)	13,646
Increase (Decrease) in Other Accounts Payable and Accrued Liabilities					(11,116)	(15,042)
Increase (Decrease) in Derivative Assets and Liabilities					(50,962)	10,523
Increase (Decrease) in Other Operating Assets and Liabilities, Net					21,440	1,772
Net Cash Provided by (Used in) Operating Activities, Total					239,637	267,996
Net Cash Provided by (Used in) Investing Activities [Abstract]
Payments for (Proceeds from) Loans and Leases					(865,086)	(378,926)
Payments for Investing Activities [Abstract]
Payments to Acquire Debt Securities, Available-for-Sale					(910,262)	(695,457)
Payments to Acquire Held-to-Maturity Securities					(994)	0
Payments to Acquire Federal Home Loan Bank Stock					(177,712)	(99,192)
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					76,535	139,110
Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale					504,380	328,990
Proceeds from Maturities, Prepayments and Calls of Held-to-Maturity Securities					69,279	62,894
Proceeds from Sale and Maturity of Other Investments					7,813	1,700
Payments for (Proceeds from) Productive Assets					(18,046)	(20,016)
Net Change in Tax Credit Investments					(14,903)	(3,667)
Net Cash Provided by (Used in) Investing Activities, Total					(764,621)	(655,093)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Increase (Decrease) in Deposits					(500,869)	(755,009)
Proceeds from (Repayments of) Short-Term Debt					(394,784)	532,759
Increase (Decrease) in Loans from Federal Home Loan Banks					2,220,000	735,000
Payments of FHLBank Borrowings, Financing Activities					(400,065)	(696)
Proceeds from FHLBank Borrowings, Financing Activities					200,000	2,656
Finance Lease, Principal Payments					(45)	(44)
Repayments of Senior Debt					(250,000)	0
Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Including Option Exercised					2,286	4,436
Payments of Ordinary Dividends, Common Stock					(77,036)	(67,034)
Payments of Ordinary Dividends, Preferred Stock and Preference Stock					(5,750)	(5,750)
Proceeds from (Payments for) Other Financing Activities					(52)	0
Net Cash Provided by (Used in) Financing Activities, Total					765,485	422,369
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total					240,501	35,272
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning Balance		1,019,604		923,823	1,019,604	923,823	$ 923,823
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Ending Balance	1,260,105		959,094		1,260,105	959,094	1,019,604
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities					488,277	525,006
Income Taxes Paid, Net					(13,942)	3,413
Real Estate Owned, Transfer to Real Estate Owned					22,038	1,340
Servicing Asset at Fair Value, Additions					3,256	2,490	$ 6,707
Loan and Lease, Transfer from Held-in-Portfolio to Held-for-Sale					(43,020)	(84,559)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	3,352		(2,522)		13,755	(18,848)
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					(11,096)	9,779
Other Assets [Member]
Supplemental Cash Flow Information [Abstract]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge					(4,579)	2,113
Performance/Service Based RSAs, RSA,
Net Cash Provided by (Used in) Financing Activities [Abstract]
Payments for Repurchase of Common Stock					(5,910)	(5,660)
Retained Earnings [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 111,230	$ 101,687	$ 115,573	$ 81,169	$ 212,916	$ 196,742