First Interstate BancSystem (FIBK) 10-Q 4 Nov 24 2024 Q3 Quarterly report Financial data

Cover Page

Cover Page	9 Months Ended
	Sep. 30, 2024 shares
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-34653
Entity Registrant Name	FIRST INTERSTATE BANCSYSTEM, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-0331430
Entity Address, Address Line One	401 North 31st Street
Entity Address, City or Town	Billings,
Entity Address, State or Province	MT
Entity Address, Postal Zip Code	59101
City Area Code	406
Local Phone Number	255-5311
Title of 12(b) Security	Common Stock, $0.00001 par value
Trading Symbol	FIBK
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Amendment Flag	false
Entity Central Index Key	0000860413
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Common Stock, Shares Outstanding	104,529,863

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Assets
Cash and due from banks	$ 438.9	$ 378.2
Interest-bearing deposits in banks	259.6	199.7
Federal funds sold	0.1	0.1
Total cash and cash equivalents	698.6	578
Investment securities:
Available-for-sale, at fair value	5,534.3	5,841.5
Held-to-maturity (estimated fair values of $2,480.5 at September 30, 2024 and $2,874.0 at December 31, 2023)	2,741.3	3,207.9
Total investment securities	8,275.6	9,049.4
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	155.5	223.2
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	20.9	47.4
Loans held for investment, net of deferred fees and costs	18,027.1	18,279.6
Allowance for credit losses	(225.4)	(227.7)
Net loans held for investment	17,801.7	18,051.9
Goodwill	1,100.9	1,100.9
Bank Owned Life Insurance	511	502.4
Premises and equipment, net of accumulated depreciation	432.7	444.3
Other intangibles, net of accumulated amortization	70.4	81.4
Accrued interest receivable	127.3	129.1
Mortgage servicing rights, net of accumulated amortization	26.3	28.3
Real Estate Acquired Through Foreclosure	4.4	16.5
Deferred tax assets	110.9	150
Other assets	259.3	268.4
Total assets	29,595.5	30,671.2
Deposits:
Non-interest bearing	5,919	6,029.6
Interest bearing	16,945.1	17,293.5
Total deposits	22,864.1	23,323.1
Securities sold under repurchase agreements	557.2	782.7
Accounts payable and accrued expenses	334.7	380.4
Accrued interest payable	87.7	52.2
Long-term debt	137.3	120.8
Other Short-term Borrowings	2,080	2,603
Allowance for credit losses on off-balance sheet credit exposures	5.6	18.4
Subordinated debentures held by subsidiary trusts	163.1	163.1
Total liabilities	26,229.7	27,443.7
Stockholders’ equity:
Preferred stock, no par value; 100,000 shares authorized; none issued and outstanding	0	0
Common stock and additional paid-in-capital, $0.00001 par value; 150,000,000 shares authorized; 104,529,863 and 103,941,626 shares were issued and outstanding at September 30, 2024 and December 31, 2023	2,457.4	2,448.9
Retained earnings	1,163.3	1,135.1
Accumulated other comprehensive loss, net	(254.9)	(356.5)
Total stockholders’ equity	3,365.8	3,227.5
Total liabilities and stockholders’ equity	$ 29,595.5	$ 30,671.2
Common Stock, Shares Authorized	150,000,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Investment securities:
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 0.7	$ 0.8
Estimated fair value	$ 2,480.5	$ 2,874
Stockholders' equity:
Nonvoting, noncumulative preferred stock, shares authorized (in shares)	100,000	100,000
Nonvoting, noncumulative preferred stock, shares issued (in shares)	0	0
Nonvoting, noncumulative preferred stock, shares outstanding (in shares)	0	0
Preferred Stock, Shares Outstanding	0	0
Shares outstanding (in shares)		103,941,626
Common Stock, Shares, Issued		103,941,626
Common Stock, Shares Authorized	150,000,000
Common Stock, Par or Stated Value Per Share	$ 0.00001	$ 0.00001
Preferred Stock, No Par Value	$ 0	$ 0
Estimated Fair Value	$ 5,534.3	$ 5,841.5
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	$ 0
Class A Common Stock
Stockholders' equity:
Shares outstanding (in shares)		103,941,626
Common Stock, Shares, Issued		103,941,626

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Interest income:
Interest and fees on loans	$ 258.9	$ 249.9	$ 763.8	$ 727.1
Interest and dividends on investment securities:
Taxable	60.7	66	187.5	204.3
Exempt from federal taxes	0.7	0.8	2.1	2.5
Other Interest and Dividend Income	2.8	2.9	9.4	9.3
Interest on deposits in banks	4.9	3	13.9	12.6
Total interest income	328	322.6	976.7	955.8
Interest expense:
Interest on deposits	84.2	68.8	244.2	162.7
Interest on securities sold under repurchase agreements	1.4	1.7	5.6	4.3
Interest Expense, Other Short-term Borrowings	32	33.6	99.4	104.1
Interest on long-term debt	1.6	1.5	10.3	4.4
Interest on subordinated debentures held by subsidiary trusts	3.3	3.3	9.9	9.3
Total interest expense	122.5	108.9	369.4	284.8
Net interest income	205.5	213.7	607.3	671
Provision for credit losses	19.8	(0.1)	34.1	26.8
Net interest income after provision for credit losses	185.7	213.8	573.2	644.2
Non-interest income:
Payment Services Revenues	18.7	19.2	55.7	58
Mortgage banking revenues	1.7	2	5.1	6.9
Wealth management revenues	9.6	8.7	28.2	26.5
Service Charges on Deposit Accounts	6.6	6	19	17
Non-interest income	2.2	2.2	6.5	7
Debt Securities, Available-for-sale, Gain (Loss)	0	0	0	(23.5)
Other income	7.6	3.9	16.6	10.6
Total non-interest income	46.4	42	131.1	102.5
Non-interest expense:
Salaries and wages	70.9	65.4	202.4	199.1
Employee benefits	19.7	19.7	55.9	61.8
Outsourced technology services	14.6	14.5	42.2	44.5
Occupancy, net	11.8	11.7	35.8	35.9
Furniture and equipment	5.2	5.3	15.4	16.8
OREO expense, net of income	0	0.5	4	1.3
Professional fees	4.2	5.1	16.1	14.9
FDIC insurance premiums	5.2	5	19.2	15.4
Other intangibles amortization	3.6	3.9	11	11.8
Other expenses	24.2	30	74.5	89.3
Noninterest Expense	159.4	161.1	476.5	490.8
Income before income tax	72.7	94.7	227.8	255.9
Provision for income tax	17.2	22	53.9	59.9
Net income	$ 55.5	$ 72.7	$ 173.9	$ 196
Earnings per common share, basic (in dollars per share)	$ 0.54	$ 0.70	$ 1.69	$ 1.89
Earnings per common share, diluted (in dollars per share)	$ 0.54	$ 0.70	$ 1.69	$ 1.89
Weighted average common shares outstanding, basic (in shares)	102,970,851	103,822,311	102,917,610	103,793,851
Weighted average common shares outstanding, diluted (in shares)	103,233,618	103,826,427	103,125,059	103,824,276

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 55.5	$ 72.7	$ 173.9	$ 196
Other comprehensive income (loss), before tax:
Change in net unrealized gains (losses) during the period	158.5	(72.1)	134.6	(51.4)
Reclassification adjustment for net losses included in income	0	0	0	23.5
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0	0	0	(7.2)
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax	(0.2)	(0.3)	(0.5)	(1.1)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	12.4	(13.1)	(10.1)	(27.2)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	3.1	2.1	11.2	4.1
Deferred tax (expense) benefit related to other comprehensive (loss) income	(43.2)	20.7	(33.6)	14.7
Other comprehensive income (loss), net of tax	130.6	(62.7)	101.6	(44.6)
Other comprehensive income (loss), before tax	173.8	(83.4)	135.2	(59.3)
Comprehensive income, net of tax	$ 186.1	$ 10	$ 275.5	$ 151.4

Consolidated Statement of Chang

Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Cumulative change related to the adoption of ASU 2016-13	Cumulative effect, period of adoption, adjusted balance	Common Stock Including Additional Paid in Capital [Member]	Common Stock Including Additional Paid in Capital [Member] Cumulative change related to the adoption of ASU 2016-13	Common Stock Including Additional Paid in Capital [Member] Cumulative effect, period of adoption, adjusted balance	Retained earnings	Retained earnings Cumulative change related to the adoption of ASU 2016-13	Retained earnings Cumulative effect, period of adoption, adjusted balance	Accumulated other comprehensive loss	Accumulated other comprehensive loss Cumulative change related to the adoption of ASU 2016-13	Accumulated other comprehensive loss Cumulative effect, period of adoption, adjusted balance
Equity, beginning balance at Dec. 31, 2022	$ 3,073.8			$ 2,478.2			$ 1,072.7			$ (477.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	196			0			196			0
Other comprehensive income (loss), net of tax expense	$ (44.6)			0			0			(44.6)
Stock repurchased and retired (in shares)	55,922
Non-vested common shares issued (in shares)	683,574
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	58,304
Common stock transactions:
Common shares purchased and retired	$ (1.9)			(1.9)			0			0
Non-vested common shares issued	0			0			0			0
Non-vested common shares forfeited or canceled	0			0			0			0
Stock-based compensation expense	$ 8.6			8.6			0			0
Common dividends (in dollars per share)	$ 1.41
Common cash dividend declared	$ (146.4)			0			(146.4)			0
Equity, ending balance at Sep. 30, 2023	3,085.5			2,484.9			1,122.3			(521.7)
Equity, beginning balance at Jun. 30, 2023	3,121.1			2,481.3			1,098.8			(459)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	72.7			0			72.7			0
Other comprehensive income (loss), net of tax expense	$ (62.7)			0			0			(62.7)
Stock repurchased and retired (in shares)	494
Non-vested common shares issued (in shares)	12,663
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	21,481
Common stock transactions:
Common shares purchased and retired	$ 0			0			0			0
Non-vested common shares issued	0			0			0			0
Non-vested common shares forfeited or canceled	0			0			0			0
Stock-based compensation expense	$ 3.6			3.6			0			0
Common dividends (in dollars per share)	$ 0.47
Common cash dividend declared	$ (49.2)			0			(49.2)			0
Equity, ending balance at Sep. 30, 2023	3,085.5			2,484.9			1,122.3			(521.7)
Equity, beginning balance at Dec. 31, 2023	3,227.5	$ 1.2	$ 3,228.7	2,448.9	$ 0	$ 2,448.9	1,135.1	$ 1.2	$ 1,136.3	(356.5)	$ 0	$ (356.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	173.9			0			173.9			0
Other comprehensive income (loss), net of tax expense	$ 101.6			0			0			101.6
Stock repurchased and retired (in shares)	49,420
Non-vested common shares issued (in shares)	742,979
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	105,322
Common stock transactions:
Common shares purchased and retired	$ (1.2)			(1.2)			0			0
Non-vested common shares issued	0			0			0			0
Non-vested common shares forfeited or canceled	0			0			0			0
Stock-based compensation expense	$ 9.7			9.7			0			0
Common dividends (in dollars per share)	$ 1.41
Common cash dividend declared	$ (146.9)			0			(146.9)			0
Equity, ending balance at Sep. 30, 2024	3,365.8			2,457.4			1,163.3			(254.9)
Equity, beginning balance at Jun. 30, 2024	3,225.3			2,453.9			1,156.9			(385.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	55.5			0			55.5			0
Other comprehensive income (loss), net of tax expense	$ 130.6			0			0			130.6
Stock repurchased and retired (in shares)	3,972
Non-vested common shares issued (in shares)	4,881
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	31,664
Common stock transactions:
Common shares purchased and retired	$ (0.1)			(0.1)			0			0
Non-vested common shares issued	0			0			0			0
Non-vested common shares forfeited or canceled	0			0			0			0
Stock-based compensation expense	$ 3.6			3.6			0			0
Common dividends (in dollars per share)	$ 0.47
Common cash dividend declared	$ (49.1)			0			(49.1)			0
Equity, ending balance at Sep. 30, 2024	$ 3,365.8			$ 2,457.4			$ 1,163.3			$ (254.9)

Consolidated Statement of Cha_2

Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Stockholders' Equity [Abstract]
Stock repurchased and retired (in shares)	3,972	494	49,420	55,922
Non-vested common shares issued (in shares)	4,881	12,663	742,979	683,574
Non-vested common shares forfeited (in shares)	31,664	21,481	105,322	58,304
Common dividends (in dollars per share)	$ 0.47	$ 0.47	$ 1.41	$ 1.41

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	$ 173.9	$ 196
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Provision for credit losses	34.1	26.8
Gain (Loss) on Disposition of Property Plant Equipment	0	(1.7)
Depreciation, Depletion and Amortization	41.4	40.5
Accretion (Amortization) of Discounts and Premiums, Investments	0.9	1.7
Debt and Equity Securities, Gain (Loss)	0	23.5
Gain (Loss) on Sale of Loans and Leases	(1.4)	(2.3)
Impairment of Real Estate and Other Assets Pending Disposal	4.2	1.1
Deferred Income Tax Expense (Benefit)	6.6	9.9
Life Insurance, Corporate or Bank Owned, Change in Value	(10.7)	(8.1)
Share-Based Payment Arrangement, Noncash Expense	9.7	8.6
Payments for Origination of Mortgage Loans Held-for-sale	(131.4)	(250.8)
Proceeds from Sale of Mortgage Loans Held-for-sale	130.7	255.9
Increase (Decrease) in Operating Capital [Abstract]
Increase (Decrease) in Accrued Interest Receivable, Net	1.8	(10.9)
Increase (Decrease) in Other Operating Assets	10.9	38.5
Increase (Decrease) in Interest Payable, Net	35.5	49.2
Increase (Decrease) in Accounts Payable and Accrued Liabilities	(46)	(19.1)
Net Cash Provided by (Used in) Operating Activities, Total	259.8	358.7
Payments to Acquire Investments [Abstract]
Payments to Acquire Debt Securities, Available-for-Sale	(102.2)	0
Proceeds from Sale, Maturity and Collection of Investments [Abstract]
Proceeds from Sale and Maturity of Held-to-Maturity Securities	470	174
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	539.4	1,276.3
Purchases of Federal Home Loan Bank and Federal Reserve Bank stock	92.4	187.3
Proceeds from Federal Home Loan Bank and Federal Reserve Bank stock	160.1	196.4
Proceeds from Life Insurance Policy	2.1	5.2
Payments for (Proceeds from) Other Loans and Leases	226.5	(118.1)
Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans	12.9	2.6
Payments for (Proceeds from) Productive Assets	(16.4)	(19.4)
Net Cash Provided by (Used in) Investing Activities, Total	1,200	1,329.7
Net Cash Provided by (Used in) Financing Activities [Abstract]
Increase (Decrease) in Deposits	(459)	(1,394.1)
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	(225.5)	(163.4)
Proceeds from (Repayments of) Other Debt	(773)	(260)
Repayments of Other Long-Term Debt	(0.1)	(0.1)
Proceeds from Issuance of Unsecured Debt	266.5	0
Payments for Repurchase of Common Stock	(1.2)	(1.8)
Payments of Ordinary Dividends, Common Stock	(146.9)	(146.4)
Net Cash Provided by (Used in) Financing Activities, Total	(1,339.2)	(1,965.8)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	120.6	(277.4)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning Balance	578	870.5
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Ending Balance	698.6	593.1
Supplemental Cash Flow Information [Abstract]
Income Taxes Paid	12.1	39
Interest Paid, Excluding Capitalized Interest, Operating Activities	333.9	235.6
Supplemental Cash Flow Elements [Abstract]
Finance Lease, Right-of-Use Asset, Amortization	1.1	6.4
Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity	0	23
Transfer of loans to held-for-sale	0	3.1
Real Estate Owned, Transfer to Real Estate Owned	4.6	2.5
Capitalization Of Internally Originated Mortgage Servicing Rights, Noncash Supplemental Disclosures	0.5	0.9
Gains (Losses) on Sales of Other Real Estate	$ (0.4)	$ (0.1)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited consolidated financial statements of First Interstate BancSystem, Inc., and its consolidated subsidiaries, including its wholly-owned subsidiary, First Interstate Bank (“FIB”) (collectively, the “Company”) contain all adjustments (all of which are of a normal recurring nature) necessary to present fairly the financial position of the Company at September 30, 2024 and December 31, 2023, the results of operations, changes in stockholders’ equity, and cash flows for each of the three and the nine months ended September 30, 2024 and 2023, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2023 is derived from audited consolidated financial statements. The unaudited consolidated financial statements have been prepared in conformity with the required interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X; and therefore, do not include all of the information and footnotes required by GAAP for a complete set of financial statements. Certain reclassifications, none of which were material, have been made to conform the Company’s prior year financial statements to the financial statements as of September 30, 2024. These reclassifications did not change previously reported net income, financial condition, cash flows, or stockholders’ equity. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, which includes a description of significant accounting policies. Operating results for the three and the nine months ended September 30, 2024 are not necessarily indicative of the results that may be expected for the year ending December 31, 2024.

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Investment Securities	The amortized cost and the approximate fair values of investment securities are summarized as follows: September 30, 2024 Amortized Gross Gross Estimated Available-for-Sale: U.S. Treasury notes $ 250.2 $ — $ (19.2) $ 231.0 State, county, and municipal securities 252.8 — (31.9) 220.9 Obligations of U.S. government agencies 171.9 — (6.5) 165.4 U.S. agency commercial mortgage-backed securities 1,164.1 1.4 (60.2) 1,105.3 U.S. agency residential mortgage-backed securities 1,354.2 2.4 (94.2) 1,262.4 Collateralized mortgage obligations 1,202.1 2.2 (87.7) 1,116.6 Private mortgage-backed securities 223.3 — (23.7) 199.6 Collateralized loan obligation 987.4 0.6 — 988.0 Corporate securities 260.0 — (14.9) 245.1 Total $ 5,866.0 $ 6.6 $ (338.3) $ 5,534.3 September 30, 2024 Amortized Cost 1 Allowance for Credit Losses Net Amortized Cost Gross Gross Estimated Held-to-Maturity: U.S. Treasury notes $ 99.6 $ — $ 99.6 $ — $ (0.4) $ 99.2 State, county, and municipal securities 176.7 — 176.7 0.3 (20.6) 156.4 Obligations of U.S. government agencies 356.4 — 356.4 — (32.0) 324.4 U.S. agency commercial mortgage-backed securities 493.0 — 493.0 — (41.8) 451.2 U.S. agency residential mortgage-backed securities 1,119.5 — 1,119.5 0.5 (106.2) 1,013.8 Collateralized mortgage obligations 439.8 — 439.8 0.8 (57.8) 382.8 Corporate securities 57.0 (0.7) 56.3 — (3.6) 52.7 Total $ 2,742.0 $ (0.7) $ 2,741.3 $ 1.6 $ (262.4) $ 2,480.5 (1) Amortized cost presented above includes $8.6 million of unamortized gains in U.S. agency residential and commercial mortgage-backed securities and collateralized mortgage obligations related to the 2021 transfer of securities from available-for-sale to held-to-maturity, and $16.5 million of unamortized losses in state, county, and municipal, obligations of U.S. government agencies and collateralized loan obligations related to the 2022 transfer of securities from available-for-sale to held-to-maturity. December 31, 2023 Amortized Gross Gross Estimated Available-for-Sale: U.S. Treasury notes $ 250.2 $ — $ (25.5) $ 224.7 State, county, and municipal securities 256.7 — (36.9) 219.8 Obligations of U.S. government agencies 179.4 — (10.9) 168.5 U.S. agency commercial mortgage-backed securities 1,192.7 0.6 (87.7) 1,105.6 U.S. agency residential mortgage-backed securities 1,496.3 1.2 (130.6) 1,366.9 Collateralized mortgage obligations 1,308.5 1.3 (120.3) 1,189.5 Private mortgage-backed securities 241.3 — (30.9) 210.4 Collateralized loan obligation 1,121.9 0.1 (2.3) 1,119.7 Corporate securities 260.8 — (24.4) 236.4 Total $ 6,307.8 $ 3.2 $ (469.5) $ 5,841.5 December 31, 2023 Amortized Cost 1 Allowance for Credit Losses Net Amortized Cost Gross Gross Estimated Held-to-Maturity: U.S. Treasury notes $ 399.0 $ — $ 399.0 $ — $ (2.8) $ 396.2 State, county, and municipal securities 179.2 — 179.2 0.2 (24.2) 155.2 Obligations of U.S. government agencies 354.5 — 354.5 — (42.4) 312.1 U.S. agency commercial mortgage-backed securities 510.5 — 510.5 — (52.9) 457.6 U.S. agency residential mortgage-backed securities 1,232.6 — 1,232.6 — (137.0) 1,095.6 Collateralized mortgage obligations 475.9 — 475.9 0.2 (69.0) 407.1 Corporate securities 57.0 (0.8) 56.2 — (6.0) 50.2 Total $ 3,208.7 $ (0.8) $ 3,207.9 $ 0.4 $ (334.3) $ 2,874.0 (1) Amortized cost presented above includes $10.7 million of unamortized gains and $18.1 million of unamortized losses related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity. The following tables show the gross unrealized losses and fair values of available-for-sale investment securities and the length of time individual investment securities have been in an unrealized loss position as of September 30, 2024 and December 31, 2023. Less than 12 Months 12 Months or More Total September 30, 2024 Fair Gross Fair Gross Fair Gross Available-for-Sale: U.S. Treasury notes $ — $ — $ 231.0 $ (19.2) $ 231.0 $ (19.2) State, county, and municipal securities — — 218.8 (31.9) 218.8 (31.9) Obligations of U.S. government agencies — — 165.1 (6.5) 165.1 (6.5) U.S. agency commercial mortgage-backed securities 0.1 — 1,048.8 (60.2) 1,048.9 (60.2) U.S. agency residential mortgage-backed securities — — 1,167.0 (94.2) 1,167.0 (94.2) Collateralized mortgage obligations 3.2 — 1,048.5 (87.7) 1,051.7 (87.7) Private mortgage-backed securities — — 199.5 (23.7) 199.5 (23.7) Corporate securities — — 217.0 (14.9) 217.0 (14.9) Total $ 3.3 $ — $ 4,295.7 $ (338.3) $ 4,299.0 $ (338.3) Less than 12 Months 12 Months or More Total December 31, 2023 Fair Gross Fair Gross Fair Gross Available-for-Sale: U.S. Treasury notes $ — $ — $ 224.7 $ (25.5) $ 224.7 $ (25.5) State, county, and municipal securities — — 217.1 (36.9) 217.1 (36.9) Obligations of U.S. government agencies — — 168.0 (10.9) 168.0 (10.9) U.S. agency commercial mortgage-backed securities 0.2 — 1,083.1 (87.7) 1,083.3 (87.7) U.S. agency residential mortgage-backed securities 0.7 — 1,287.5 (130.6) 1,288.2 (130.6) Collateralized mortgage obligations — — 1,142.4 (120.3) 1,142.4 (120.3) Private mortgage-backed securities — — 210.5 (30.9) 210.5 (30.9) Collateralized loan obligation — — 935.7 (2.3) 935.7 (2.3) Corporate securities — — 236.5 (24.4) 236.5 (24.4) Total $ 0.9 $ — $ 5,505.5 $ (469.5) $ 5,506.4 $ (469.5) As of September 30, 2024 and December 31, 2023, there were no holdings of securities of any issuer in an amount greater than 10% of stockholders’ equity, other than holdings in the U.S. government and its agencies. The Company determines the allowance for credit losses on both available-for-sale and held-to-maturity investment securities by a discounted cash flow approach when needed, using each security’s effective interest rate at the time of purchase or upon acquisition. The allowance for credit losses is measured as the amount by which an investment security’s amortized cost exceeds the net present value of expected future cash flows. However, the amount of credit losses for available-for-sale investment securities is limited to the amount of a security’s unrealized loss. The allowance for credit loss on held-to-maturity investment securities is representative of current expected credit losses that management expects to be incurred over the life of the investment and established through a charge to provision for credit losses in current period earnings. For held-to-maturity investment securities, the Company has the intent and ability to hold these investment securities to maturity. The investment securities portfolio primarily contains securities that are guaranteed by a sovereign entity or are generally considered to have non-credit related risks, such as interest rate risk or liquidity factors. The Company considers whether the securities are issued by the federal government or its agencies and whether downgrades by bond rating agencies have occurred. As of September 30, 2024 and December 31, 2023, the Company had 648 and 704 individual available-for-sale investment securities, respectively, that were in an unrealized loss position, which was related primarily to fluctuations in current interest rates. The Company does not intend to sell any of the available-for-sale securities, and the Company does not anticipate it will be required to sell any securities before a recovery in cost. On a quarterly basis, the Company refreshes the credit quality indicator of each held-to-maturity security. The following table summarizes the credit quality indicators of held-to-maturity securities at amortized cost for the periods indicated: September 30, 2024 AAA AA A BBB BB Not Rated Total U.S. Treasury notes $ 99.6 $ — $ — $ — $ — $ — $ 99.6 State, county, and municipal securities 85.7 74.2 10.1 — — 6.7 176.7 Obligations of U.S. government agencies 356.4 — — — — — 356.4 U.S. agency commercial mortgage-backed securities FNMA/FHLMC 349.7 — — — — — 349.7 GNMA 143.3 — — — — — 143.3 U.S. agency residential mortgage-backed securities FNMA/FHLMC 1,080.7 — — — — — 1,080.7 GNMA 38.8 — — — — — 38.8 Collateralized mortgage obligations FNMA/FHLMC 308.5 — — — — — 308.5 GNMA 131.3 — — — — — 131.3 Corporate securities — — — 47.0 5.0 5.0 57.0 Total $ 2,594.0 $ 74.2 $ 10.1 $ 47.0 $ 5.0 $ 11.7 $ 2,742.0 December 31, 2023 AAA AA A BBB BB Not Rated Total U.S. Treasury notes $ 399.0 $ — $ — $ — $ — $ — $ 399.0 State, county, and municipal securities 69.0 92.3 10.6 — — 7.3 179.2 Obligations of U.S. government agencies 354.5 — — — — — 354.5 U.S. agency commercial mortgage-backed securities FNMA/FHLMC 359.7 — — — — — 359.7 GNMA 150.8 — — — — — 150.8 U.S. agency residential mortgage-backed securities FNMA/FHLMC 1,189.8 — — — — — 1,189.8 GNMA 42.8 — — — — — 42.8 Collateralized mortgage obligations FNMA/FHLMC 334.1 — — — — — 334.1 GNMA 141.8 — — — — — 141.8 Corporate securities — — — 47.0 5.0 5.0 57.0 Total $ 3,041.5 $ 92.3 $ 10.6 $ 47.0 $ 5.0 $ 12.3 $ 3,208.7 As of September 30, 2024 and December 31, 2023, the Company had $33.1 million and $38.5 million, respectively, of accrued interest receivable from investment securities on the consolidated balance sheets. Accrued interest receivable is presented as a separate line item on the consolidated balance sheets and the Company does not include accrued interest receivable in the carrying amount of financial assets held at the amortized cost basis or in the related allowance for credit losses calculation. As of September 30, 2024 and December 31, 2023, there were no available-for-sale or held-to-maturity securities on nonaccrual status. All securities in the portfolio were current with their contractual principal and interest payments. As of September 30, 2024 and December 31, 2023, there were no collateral-dependent available-for-sale or held-to-maturity securities. There were no material gross realized gains and no material gross realized losses during the three and the nine month periods ended September 30, 2024. During the three months ended September 30, 2023, there were no material gross realized gains and no material gross realized losses, and during the nine months ended September 30, 2023 there were no material gross realized gains and $23.5 million in gross realized losses on the disposition of available-for-sale investment securities, resulting from the sale of $853.0 million of investment securities. The following schedule represents the amortized cost of debt securities by contractual maturity except for maturities of mortgage-backed securities, which have been adjusted to reflect shorter maturities based upon estimated prepayments of principal. Available-for-Sale Held-to-Maturity September 30, 2024 Amortized Estimated Amortized Estimated Within one year $ 88.7 $ 87.5 $ 101.1 $ 100.6 After one year but within five years 1,326.9 1,265.9 416.0 396.8 After five years but within ten years 1,166.4 1,095.1 485.5 437.5 After ten years 3,284.0 3,085.8 1,739.4 1,545.6 Total $ 5,866.0 $ 5,534.3 $ 2,742.0 $ 2,480.5 As of September 30, 2024, the Company held investment securities callable within one year having amortized costs and estimated fair values of $1,514.6 million and $1,478.0 million, respectively. These investment securities are primarily included in the “after five year” categories in the table above. As of September 30, 2024, the Company had no callable structured notes. As of September 30, 2024 and December 31, 2023, the Company had amortized costs of $3,159.8 million and $3,858.6 million, respectively, for investment securities pledged to secure public deposits, derivatives, and securities sold under repurchase agreements that had estimated fair values of $2,888.0 million and $3,462.2 million, as of September 30, 2024 and December 31, 2023, respectively. All securities sold under repurchase agreements are with clients and mature on the next banking day. The Company retains possession of the underlying securities sold under repurchase agreements. As of September 30, 2024 and December 31, 2023, the Company held $155.5 million and $223.2 million, respectively, in equity securities primarily in a combination of Federal Reserve Bank and Federal Home Loan Bank stocks, which are restricted nonmarketable securities acquired to meet regulatory requirements. These securities are carried at cost.

Loans Held for Sale

Loans Held for Sale	9 Months Ended
	Sep. 30, 2024
Loans Held for Sale [Abstract]
Loans Held for Sale	The following table presents loans held for sale by class of receivable for the dates indicated: September 30, December 31, Loans held for sale: Agricultural, at lower of cost or market $ 18.8 $ 19.6 Commercial real estate, at lower of cost or market — 27.3 Residential mortgage, at fair value 2.1 0.5 Total loans held for sale $ 20.9 $ 47.4 The table below presents the non-residential mortgage loans held for sale activity for the 2024 period: Agricultural Commercial Beginning balance as of December 31, 2023 $ 19.6 $ 27.3 Repayments (0.8) — Loan disposals — (27.3) Ending balance as of September 30, 2024 $ 18.8 $ — As of September 30, 2024, loans held for sale included nonaccrual agricultural loans of $18.8 million. As of December 31, 2023, loans held for sale included a nonaccrual commercial real estate loan of $27.3 million.

Loans Held for Investment

Loans Held for Investment	9 Months Ended
	Sep. 30, 2024
Receivables [Abstract]
Loans	The following table presents loans by class of receivable and portfolio segment as of the dates indicated: September 30, December 31, Real estate: Commercial $ 9,219.3 $ 8,869.2 Construction 1,307.9 1,826.5 Residential 2,217.8 2,244.3 Agricultural 726.4 716.8 Total real estate 13,471.4 13,656.8 Consumer: Indirect 742.2 740.9 Direct and advance lines 136.9 141.6 Credit card 76.4 76.5 Total consumer 955.5 959.0 Commercial 2,919.7 2,906.8 Agricultural 689.8 769.4 Other, including overdrafts 2.5 0.1 Loans held for investment 18,038.9 18,292.1 Deferred loan fees and costs (11.8) (12.5) Loans held for investment, net of deferred fees and costs 18,027.1 18,279.6 Allowance for credit losses (225.4) (227.7) Net loans held for investment $ 17,801.7 $ 18,051.9 Allowance for Credit Losses The following tables represent, by loan portfolio segments, the activity in the allowance for credit losses for loans held for investment: Three Months Ended September 30, 2024 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 139.7 $ 18.3 $ (22.2) $ 0.2 $ 136.0 Consumer 18.5 1.5 (4.1) 1.3 17.2 Commercial 69.2 (0.1) (2.5) 0.2 66.8 Agricultural 5.4 0.3 (0.3) — 5.4 Total allowance for credit losses $ 232.8 $ 20.0 $ (29.1) $ 1.7 $ 225.4 Nine Months Ended September 30, 2024 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 160.1 $ 10.3 $ (35.5) $ 1.1 $ 136.0 Consumer 13.0 12.5 (11.9) 3.6 17.2 Commercial 50.2 23.2 (8.7) 2.1 66.8 Agricultural 4.4 1.0 (0.3) 0.3 5.4 Total allowance for credit losses $ 227.7 $ 47.0 $ (56.4) $ 7.1 $ 225.4 Three Months Ended September 30, 2023 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 158.7 $ 1.8 $ (1.8) $ 3.5 $ 162.2 Consumer 13.7 1.8 (3.7) 1.1 12.9 Commercial 49.5 (0.9) (0.7) 0.5 48.4 Agricultural 2.7 0.5 — — 3.2 Total allowance for credit losses $ 224.6 $ 3.2 $ (6.2) $ 5.1 $ 226.7 Nine Months Ended September 30, 2023 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 138.7 $ 35.6 $ (16.6) $ 4.5 $ 162.2 Consumer 23.3 (3.7) (10.4) 3.7 12.9 Commercial 54.9 (6.2) (2.2) 1.9 48.4 Agricultural 3.2 (0.4) — 0.4 3.2 Total allowance for credit losses $ 220.1 $ 25.3 $ (29.2) $ 10.5 $ 226.7 (1) Amounts presented exclude the allowance for credit losses related to unfunded commitments and investment securities. The allowance for credit losses related to unfunded commitments and investment securities are included in the “Financial Instruments with Off-Balance Sheet Risk” Note and “Investment Securities” Note, respectively. (2) Loans, or portions thereof, are charged-off against the allowance for credit losses when management believes the collectability of the principal is unlikely, or, with respect to consumer installment loans, according to an established delinquency schedule. Collateral-Dependent Loans A collateral-dependent loan relies substantially on the operation or sale of the collateral securing the loan for repayment. A loan may become collateral-dependent when foreclosure is probable or the borrower is experiencing financial difficulty and its sources of repayment become inadequate over time. At such time, the Company develops an expectation that repayment will be provided substantially through the operation or sale of the collateral. The following tables present the principal balance of collateral-dependent loans by class of receivable as of the dates indicated: Collateral Type As of September 30, 2024 Business Assets Real Property Other Total Real estate: Commercial $ — $ 34.1 $ — $ 34.1 Construction — — — — Residential — 1.9 — 1.9 Agricultural — 1.0 — 1.0 Total real estate — 37.0 — 37.0 Commercial 71.2 0.1 0.7 72.0 Agricultural — 0.5 0.1 0.6 Total collateral-dependent loans $ 71.2 $ 37.6 $ 0.8 $ 109.6 Collateral Type As of December 31, 2023 Business Assets Real Property Other Total Real estate: Commercial $ — $ 26.6 $ — $ 26.6 Construction — 17.0 — 17.0 Residential — 0.5 — 0.5 Agricultural — 1.2 — 1.2 Total real estate — 45.3 — 45.3 Commercial 4.5 1.4 0.7 6.6 Agricultural 0.7 — — 0.7 Total collateral-dependent loans $ 5.2 $ 46.7 $ 0.7 $ 52.6 Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Loans classified in the following table as 90 days or more past due continue to accrue interest. The following tables present the contractual aging of the Company’s recorded principal balance of loans by class of receivable as of the dates indicated: Total Loans 30 - 59 60 - 89 90 or more 30 or More Days Days Days Days Current Non-accrual Total As of September 30, 2024 Past Due Past Due Past Due Past Due Loans Loans (1) Loans Real estate: Commercial $ 5.1 $ 6.8 $ — $ 11.9 $ 9,162.2 $ 45.2 $ 9,219.3 Construction 3.6 0.1 — 3.7 1,304.1 0.1 1,307.9 Residential 2.6 2.1 0.2 4.9 2,198.6 14.3 2,217.8 Agricultural 2.4 — — 2.4 719.3 4.7 726.4 Total real estate 13.7 9.0 0.2 22.9 13,384.2 64.3 13,471.4 Consumer: Indirect 6.4 1.6 0.1 8.1 730.7 3.4 742.2 Direct and advance lines 1.0 0.4 — 1.4 135.1 0.4 136.9 Credit card 0.7 0.5 0.7 1.9 74.5 — 76.4 Total consumer 8.1 2.5 0.8 11.4 940.3 3.8 955.5 Commercial 4.3 1.5 0.6 6.4 2,831.7 81.6 2,919.7 Agricultural 1.6 — 0.2 1.8 665.0 23.0 689.8 Other, including overdrafts — — — — 2.5 — 2.5 Loans held for investment $ 27.7 $ 13.0 $ 1.8 $ 42.5 $ 17,823.7 $ 172.7 $ 18,038.9 Total Loans 30 - 59 60 - 89 90 or more 30 or More Days Days Days Days Current Non-accrual Total As of December 31, 2023 Past Due Past Due Past Due Past Due Loans Loans (1) Loans Real estate: Commercial $ 12.7 $ 6.1 $ — $ 18.8 $ 8,822.2 $ 28.2 $ 8,869.2 Construction 3.1 0.4 — 3.5 1,805.8 17.2 1,826.5 Residential 11.9 3.1 0.6 15.6 2,218.0 10.7 2,244.3 Agricultural 1.8 — — 1.8 709.6 5.4 716.8 Total real estate 29.5 9.6 0.6 39.7 13,555.6 61.5 13,656.8 Consumer: Indirect 8.0 2.2 0.4 10.6 727.6 2.7 740.9 Direct and advance lines 0.9 0.2 — 1.1 140.2 0.3 141.6 Credit card 0.7 0.5 0.6 1.8 74.7 — 76.5 Total consumer 9.6 2.9 1.0 13.5 942.5 3.0 959.0 Commercial 14.5 1.1 0.3 15.9 2,879.4 11.5 2,906.8 Agricultural 0.1 — 3.0 3.1 735.9 30.4 769.4 Other, including overdrafts — — — — 0.1 — 0.1 Loans held for investment $ 53.7 $ 13.6 $ 4.9 $ 72.2 $ 18,113.5 $ 106.4 $ 18,292.1 (1) As of September 30, 2024 and December 31, 2023, none of our non-accrual loans were earning interest income. Additionally, no material interest income was recognized on non-accrual loans during the three and the nine months ended September 30, 2024 and 2023, respectively. There were $0.4 million and $2.4 million in reversals of accrued interest during the three and the nine months ended September 30, 2024, and $1.0 million and $1.9 million in reversals of accrued interest during the three and the nine months ended September 30, 2023. Modifications to Borrowers Experiencing Financial Difficulty Modifications of loans are made in the ordinary course of business and are completed on a case-by-case basis through negotiation with the borrower in connection with the ongoing loan collection processes. Loan modifications are made to provide payment relief to borrowers experiencing financial difficulty. From time to time, we may modify certain loans to borrowers who are experiencing financial difficulty. In some cases, these modifications may result in new loans. Loan modifications to borrowers experiencing financial difficulty may be in the form of principal forgiveness, an interest rate reduction, an other-than-insignificant payment delay, a term extension, or a combination thereof, among other things. The following table presents the amortized cost basis of loans, by class and by type of modification, at September 30, 2024 and 2023 that were both experiencing financial difficulty and modified during the periods indicated. The percentage of the principal balance of loans that were modified to borrowers in financial distress as compared to the principal balance of each class of receivable is also presented below: Three Months Ended September 30, 2024 Principal Forgiveness Term Extension Term Extension and Interest Rate Reduction Total % of Total Class of Loans Held for Investment (1) Real estate: Commercial $ — $ 0.5 $ — $ 0.5 0.01 % Construction — 1.9 — 1.9 0.15 Agricultural — 6.5 — 6.5 0.89 Total real estate — 8.9 — 8.9 0.07 Commercial — 0.9 0.5 1.4 0.05 Agricultural — 21.4 — 21.4 3.10 Loans held for investment (2) $ — $ 31.2 $ 0.5 $ 31.7 0.18 Nine Months Ended September 30, 2024 Real estate: Commercial $ — $ 14.7 $ — $ 14.7 0.16 % Construction — 1.9 — 1.9 0.15 Residential — 0.1 0.3 0.4 0.02 Agricultural — 12.1 — 12.1 1.67 Total real estate — 28.8 0.3 29.1 0.22 Commercial — 14.4 0.5 14.9 0.51 Agricultural — 23.2 22.2 45.4 6.58 Loans held for investment (2) $ — $ 66.4 $ 23.0 $ 89.4 0.50 Three Months Ended September 30, 2023 Principal Forgiveness Term Extension Term Extension and Interest Rate Reduction Total % of Total Class of Loans Held for Investment (1) Real estate: Commercial $ — $ 10.9 $ 0.6 $ 11.5 0.13 % Construction — 13.1 — 13.1 0.68 Residential — 0.4 — 0.4 0.02 Agricultural — 6.1 — 6.1 0.83 Total real estate — 30.5 0.6 31.1 0.23 Commercial — 1.6 — 1.6 0.05 Agricultural — 0.5 — 0.5 0.07 Loans held for investment (2) $ — $ 32.6 $ 0.6 $ 33.2 0.18 Nine Months Ended September 30, 2023 Real estate: Commercial $ 1.6 $ 23.0 $ 0.6 $ 25.2 0.29 % Construction — 13.2 — 13.2 0.68 Residential 0.1 0.5 — 0.6 0.03 Agricultural — 6.4 — 6.4 0.87 Total real estate 1.7 43.1 0.6 45.4 0.33 Commercial — 9.4 — 9.4 0.32 Agricultural — 36.4 — 36.4 5.27 Loans held for investment (2) $ 1.7 $ 88.9 $ 0.6 $ 91.2 0.50 (1) Based on the principal balance as of period end, divided by the period end principal balance of the corresponding class of receivables. (2) As of September 30, 2024 and 2023, the Company excluded $1.1 million and $1.7 million, respectively, in accrued interest from the amortized cost of the identified loans. The following tables present the financial effect of the loan modifications presented above to borrowers experiencing financial difficulty during the periods indicated: Term Extension and Interest Rate Reduction Three Months Ended September 30, 2024 Principal Forgiveness Weighted-Average Months of Term Extension Weighted-Average Months of Term Extension Weighted-Average Interest Rate Reduction Real estate: Commercial $ — 5.9 0.0 — % Construction — 4.0 0.0 — Agricultural — 7.7 0.0 — Total real estate — Commercial — 5.3 59.0 0.8 Agricultural — 3.9 0.0 — Loans held for investment (1) $ — Nine Months Ended September 30, 2024 Real estate: Commercial $ — 6.8 0.0 — % Construction — 4.0 0.0 — Residential — 11.0 31.2 3.4 Agricultural — 7.4 0.0 — Total real estate — Commercial — 7.7 9.2 1.0 Agricultural — 4.1 55.2 1.1 Loans held for investment (1) $ — Term Extension and Interest Rate Reduction Three Months Ended September 30, 2023 Principal Forgiveness Weighted-Average Months of Term Extension Weighted-Average Months of Term Extension Weighted-Average Interest Rate Reduction Real estate: Commercial $ — 4.6 6.0 0.25 % Construction — 9.0 0.0 — Residential — 144.4 0.0 — Agricultural — 4.0 0.0 — Total real estate — Commercial — 7.8 0.0 — Agricultural — 3.5 0.0 — Loans held for investment (1) $ — Nine Months Ended September 30, 2023 Real estate: Commercial $ 1.3 5.7 6.0 0.25 % Construction — 9.0 0.0 — Residential 0.3 139.2 0.0 — Agricultural — 4.6 0.0 — Total real estate 1.6 Commercial — 8.8 0.0 — Agricultural — 9.2 0.0 — Loans held for investment (1) $ 1.6 (1) Balances based on loan original contractual terms. The Company monitors the performance of loan modifications to borrowers experiencing financial difficulty to understand the effectiveness of its modification efforts. Of the loans that were modified during the twelve-months ended September 30, 2024, there were $0.5 million of loans classified as past due 30 days or more, with the remaining loans performing in accordance with the modified terms and classified as current at September 30, 2024. There were no commitments to lend additional funds to borrowers experiencing financial difficulty whose terms were modified during the three months ended September 30, 2024 through either principal forgiveness, interest rate reduction, term extension, or other than insignificant payment delay. There were $1.3 million of payment defaults on these loans subsequent to their modifications during the twelve-months ended September 30, 2024. The Company considers a payment default to occur when the loan is 90 days or more past due or the loan is placed on non-accrual status after the modification. The Company monitors the performance of modified loans on an ongoing basis. In the event of subsequent default, the allowance for credit losses continues to be reassessed based on an individual evaluation of each loan. The modifications made during the periods presented did not significantly impact the Company’s determination of the allowance for credit losses. Credit Quality Indicators As part of the on-going and continuous monitoring of the credit quality of the Company’s loan portfolio, management tracks internally assigned risk classifications of loans based on relevant information about the ability of borrowers to service their debt. The factors considered by the Company include, among other factors, the borrower’s current financial information, historical payment experience, credit documentation, public information, and current economic trends. The Company analyzes loans individually to classify the credit risk of the loans. This analysis generally includes loans with an outstanding balance greater than $1.0 million, which are generally considered non-homogeneous loans, such as commercial loans and commercial real estate loans. This analysis is performed no less than on an annual basis, depending upon the size of exposure and the contractual obligations governing the borrower’s financial reporting frequency. Homogeneous loans, including small business loans, are typically monitored by payment performance. The Company internally risk rates its loans in accordance with a Uniform Classification System developed jointly by the various bank regulatory agencies. The Uniform Classification System defines three broad categories of criticized assets, which the Company uses as credit quality indicators in addition to the 6 Pass ratings in its 10-point rating scale: Special Mention — includes loans that exhibit a potential weakness in financial condition, loan structure, or documentation that warrants management’s close attention. If not promptly corrected, the potential weaknesses may result in deterioration of the repayment prospects for the loan or of the institution’s credit position at some future date. Substandard — includes loans that are inadequately protected by the current net worth and paying capacity of the borrower which have well-defined weaknesses that jeopardize the liquidation of the debt. Although the primary source of repayment for a substandard loan may not currently be sufficient, collateral or other sources of repayment are sufficient to satisfy the debt. Continuance of a substandard loan is not warranted unless positive steps are taken to improve the worthiness of the credit. Doubtful — includes loans that exhibit pronounced weaknesses based on currently existing facts, conditions, and values to a point where collection or liquidation for full repayment is highly questionable and improbable. Doubtful loans are required to be placed on non-accrual status and are assigned specific loss exposure. Loans not meeting the criteria above that are analyzed individually as part of the above-described process are considered pass-rated loans. The Company evaluates the credit quality and loan performance for the allowance for credit losses of the following class of receivables by origination year using the origination date or the loan’s subsequent renewal or modification date based on the aforementioned risk scale as of and for the periods ended: As of and for the nine months ended September 30, 2024 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2024 2023 2022 2021 2020 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Commercial real estate: Pass $ 1,026.8 $ 1,366.2 $ 1,981.5 $ 1,441.7 $ 1,137.3 $ 1,922.5 $ 48.2 $ 56.7 $ 8,980.9 Special mention 12.6 9.4 21.1 18.3 2.2 36.9 — — 100.5 Substandard 27.6 10.7 4.6 39.3 7.9 47.8 — — 137.9 Total $ 1,067.0 $ 1,386.3 $ 2,007.2 $ 1,499.3 $ 1,147.4 $ 2,007.2 $ 48.2 $ 56.7 $ 9,219.3 Current-period gross charge-offs — 5.7 — 15.8 — 0.1 — — 21.6 Construction real estate: Pass $ 256.1 $ 263.4 $ 484.4 $ 114.0 $ 19.7 $ 24.2 $ 129.3 $ 4.9 $ 1,296.0 Special mention 3.2 — 6.4 — — — — — 9.6 Substandard 1.9 — — — — 0.4 — — 2.3 Total $ 261.2 $ 263.4 $ 490.8 $ 114.0 $ 19.7 $ 24.6 $ 129.3 $ 4.9 $ 1,307.9 Current-period gross charge-offs — — 13.1 — 0.1 — — — 13.2 Agricultural real estate: Pass $ 92.2 $ 65.0 $ 113.6 $ 121.4 $ 79.9 $ 159.4 $ 25.8 $ — $ 657.3 Special mention 1.1 6.6 5.9 5.1 7.6 1.0 — — 27.3 Substandard 12.2 4.4 19.2 3.7 1.4 0.9 — — 41.8 Total $ 105.5 $ 76.0 $ 138.7 $ 130.2 $ 88.9 $ 161.3 $ 25.8 $ — $ 726.4 Current-period gross charge-offs — — — — — — — — — Commercial: Pass $ 386.0 $ 395.5 $ 406.9 $ 335.8 $ 176.1 $ 278.3 $ 783.5 $ 6.7 $ 2,768.8 Special mention 3.0 6.9 8.8 1.5 1.0 1.0 17.5 — 39.7 Substandard 28.9 4.2 5.6 5.2 8.1 3.6 7.1 — 62.7 Doubtful 1.2 1.7 2.5 — — — 43.1 — 48.5 Total $ 419.1 $ 408.3 $ 423.8 $ 342.5 $ 185.2 $ 282.9 $ 851.2 $ 6.7 $ 2,919.7 Current-period gross charge-offs 0.4 1.9 1.0 0.3 0.1 0.1 1.9 3.0 8.7 Agricultural: Pass $ 81.3 $ 52.5 $ 43.2 $ 20.5 $ 16.7 $ 7.4 $ 355.7 $ — $ 577.3 Special mention 0.5 3.6 0.7 0.1 1.0 0.2 5.2 0.1 11.4 Substandard 51.9 24.6 — 0.1 0.6 — 23.9 — 101.1 Total $ 133.7 $ 80.7 $ 43.9 $ 20.7 $ 18.3 $ 7.6 $ 384.8 $ 0.1 $ 689.8 Current-period gross charge-offs — — — 0.3 — — — — 0.3 December 31, 2023 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2023 2022 2021 2020 2019 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Commercial real estate: Pass $ 1,268.0 $ 2,065.0 $ 1,612.2 $ 1,200.1 $ 716.5 $ 1,660.5 $ 46.5 $ 28.1 $ 8,596.9 Special mention 4.2 9.1 42.6 12.9 27.5 17.1 0.3 — 113.7 Substandard 65.4 11.8 18.9 2.4 30.1 28.5 0.2 — 157.3 Doubtful — — 1.3 — — — — — 1.3 Total $ 1,337.6 $ 2,085.9 $ 1,675.0 $ 1,215.4 $ 774.1 $ 1,706.1 $ 47.0 $ 28.1 $ 8,869.2 Current-period gross charge-offs 1.7 0.3 1.7 2.6 — 1.3 — — 7.6 Construction: Pass $ 493.7 $ 735.3 $ 331.2 $ 36.7 $ 16.8 $ 36.2 $ 104.4 $ 13.7 $ 1,768.0 Special mention 0.5 6.6 1.3 — — 0.2 — 0.9 9.5 Substandard 7.0 4.0 24.4 0.2 — 0.4 — — 36.0 Doubtful — 13.0 — — — — — — 13.0 Total $ 501.2 $ 758.9 $ 356.9 $ 36.9 $ 16.8 $ 36.8 $ 104.4 $ 14.6 $ 1,826.5 Current-period gross charge-offs — — 0.1 — 0.6 — — 9.6 10.3 Agricultural real estate: Pass $ 86.2 $ 123.7 $ 126.2 $ 93.5 $ 56.7 $ 124.3 $ 31.8 $ 7.0 $ 649.4 Special mention 2.6 9.5 3.5 1.9 1.5 11.3 0.5 — 30.8 Substandard 8.1 20.8 3.6 2.6 0.4 1.1 — — 36.6 Total $ 96.9 $ 154.0 $ 133.3 $ 98.0 $ 58.6 $ 136.7 $ 32.3 $ 7.0 $ 716.8 Current-period gross charge-offs — — — — — — — — — Commercial: Pass $ 481.6 $ 507.7 $ 389.8 $ 215.1 $ 108.7 $ 272.9 $ 762.3 $ 7.6 $ 2,745.7 Special mention 7.3 4.7 6.6 3.1 0.9 1.9 14.8 0.2 39.5 Substandard 15.8 19.6 9.0 7.0 1.6 3.0 58.8 0.4 115.2 Doubtful 3.3 1.3 1.6 — — 0.1 0.1 — 6.4 Total $ 508.0 $ 533.3 $ 407.0 $ 225.2 $ 111.2 $ 277.9 $ 836.0 $ 8.2 $ 2,906.8 Current-period gross charge-offs 0.2 0.4 0.5 0.5 0.2 0.1 1.4 0.1 3.4 Agricultural: Pass $ 105.7 $ 57.7 $ 31.6 $ 22.4 $ 6.1 $ 7.2 $ 421.9 $ 3.4 $ 656.0 Special mention 2.6 0.8 0.5 0.2 0.1 0.1 9.0 3.1 16.4 Substandard 43.8 0.3 2.7 0.7 28.8 2.2 18.5 — 97.0 Total $ 152.1 $ 58.8 $ 34.8 $ 23.3 $ 35.0 $ 9.5 $ 449.4 $ 6.5 $ 769.4 Current-period gross charge-offs — — — — — — — — — The Company evaluates the credit quality, loan performance, and the allowance for credit losses of its residential and consumer loan portfolios based primarily on the aging status of the loan and borrower payment activity. Accordingly, loans on nonaccrual status, loans past due 90 days or more and still accruing interest are considered nonperforming for purposes of credit quality evaluation. The following tables present the recorded investment of these loan portfolios based on the credit risk profile of loans that are performing and loans that are nonperforming as of the periods indicated: As of and for the nine months ended September 30, 2024 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2024 2023 2022 2021 2020 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Residential: Performing $ 14.6 $ 70.5 $ 419.9 $ 489.5 $ 454.7 $ 264.6 $ 480.2 $ 9.3 $ 2,203.3 Nonperforming 1.0 0.8 3.6 1.8 1.6 5.4 — 0.3 14.5 Total $ 15.6 $ 71.3 $ 423.5 $ 491.3 $ 456.3 $ 270.0 $ 480.2 $ 9.6 $ 2,217.8 Current-period gross charge-offs — 0.2 0.1 0.1 0.2 0.1 — — 0.7 Consumer indirect: Performing $ 203.0 $ 146.9 $ 194.8 $ 83.0 $ 55.4 $ 55.6 $ — $ — $ 738.7 Nonperforming 0.3 0.8 1.0 0.5 0.4 0.5 — — 3.5 Total $ 203.3 $ 147.7 $ 195.8 $ 83.5 $ 55.8 $ 56.1 $ — $ — $ 742.2 Current-period gross charge-offs 0.2 1.7 2.9 0.9 0.3 0.9 — — 6.9 Consumer direct and advance lines: Performing $ 37.1 $ 29.8 $ 22.2 $ 12.0 $ 5.5 $ 5.9 $ 24.0 $ — $ 136.5 Nonperforming 0.1 0.1 0.1 — — 0.1 — — 0.4 Total $ 37.2 $ 29.9 $ 22.3 $ 12.0 $ 5.5 $ 6.0 $ 24.0 $ — $ 136.9 Current-period gross charge-offs 0.1 0.5 0.7 0.2 0.1 1.3 — — 2.9 Consumer credit card: Performing $ — $ — $ — $ — $ — $ — $ 75.7 $ — $ 75.7 Nonperforming — — — — — — 0.7 — 0.7 Total $ — $ — $ — $ — $ — $ — $ 76.4 $ — $ 76.4 Current-period gross charge-offs — — — — — — 2.1 — 2.1 December 31, 2023 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2023 2022 2021 2020 2019 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Residential: Performing $ 44.7 $ 356.9 $ 521.3 $ 500.6 $ 88.5 $ 217.1 $ 471.8 $ 32.1 $ 2,233.0 Nonperforming 1.1 2.1 1.2 1.1 0.7 5.1 — — 11.3 Total $ 45.8 $ 359.0 $ 522.5 $ 501.7 $ 89.2 $ 222.2 $ 471.8 $ 32.1 $ 2,244.3 Current-period gross charge-offs 0.3 — 0.1 0.1 — 0.1 — — 0.6 Consumer indirect: Performing $ 194.9 $ 264.7 $ 115.4 $ 81.1 $ 32.9 $ 48.8 $ — $ — $ 737.8 Nonperforming 0.4 0.9 0.6 0.4 0.2 0.6 — — 3.1 Total $ 195.3 $ 265.6 $ 116.0 $ 81.5 $ 33.1 $ 49.4 $ — $ — $ 740.9 Current-period gross charge-offs 0.5 3.2 1.8 0.8 0.3 0.7 — — 7.3 Consumer direct and advance lines: Performing $ 44.5 $ 32.9 $ 18.5 $ 9.4 $ 3.6 $ 6.0 $ 26.2 $ 0.2 $ 141.3 Nonperforming 0.1 0.1 0.1 — — — — — 0.3 Total $ 44.6 $ 33.0 $ 18.6 $ 9.4 $ 3.6 $ 6.0 $ 26.2 $ 0.2 $ 141.6 Current-period gross charge-offs 0.2 0.5 0.2 0.4 0.1 2.6 0.1 — 4.1 Consumer credit card: Performing $ — $ — $ — $ — $ — $ — $ 75.9 $ — $ 75.9 Nonperforming — — — — — — 0.6 — 0.6 Total $ — $ — $ — $ — $ — $ — $ 76.5 $ — $ 76.5 Current-period gross charge-offs — — — — — — 2.6 — 2.6

Other Real Estate Owned

Other Real Estate Owned	9 Months Ended
	Sep. 30, 2024
Repossessed Assets [Abstract]
Other Real Estate Owned	Other real estate owned (“OREO”) is a category of real estate owned by the Company resulting from a default by the borrower. Information with respect to the Company’s OREO is reflected in the following table: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Beginning balance $ 6.7 $ 14.4 $ 16.5 $ 12.7 Additions 0.9 — 4.6 2.5 Valuation adjustments — (0.3) (4.2) (1.1) Dispositions (3.2) (2.5) (12.5) (2.5) Ending balance $ 4.4 $ 11.6 $ 4.4 $ 11.6 The carrying value of foreclosed residential real estate properties included in OREO was not material as of September 30, 2024 and December 31, 2023, respectively. The Company had $1.7 million and $0.5 million recorded investments in consumer mortgage loans secured by residential real estate for which formal foreclosure proceedings were in process of foreclosure as of September 30, 2024 and December 31, 2023, respectively.

Derivatives and Hedging Activit

Derivatives and Hedging Activities	9 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative and Hedging Activities	The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through the management of its business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its assets and liabilities and derivative financial instruments. The Company enters into derivative financial instruments, such as interest rate swap contracts to manage or hedge exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates and interest rate exposures. The Company does not enter into interest rate swap agreements for trading or speculative purposes. The Company sells residential mortgage loans on either a best efforts or mandatory delivery basis. The Company mitigates the effect of the interest rate risk inherent in providing interest rate lock commitments by entering into forward loan sales contracts. The forward loan sales contracts are recorded at fair value with changes in fair value recorded through earnings and are not designated as accounting hedges. Exclusive of the fair value component associated with the projected cash flows from the loan delivery to the investor, the changes in fair value related to movements in market rates of the interest rate lock commitments and the forward loan sales contracts generally move in opposite directions, and the net impact of changes in these valuations on net income during the loan commitment period is generally inconsequential. When the loan is funded to the borrower, the interest rate lock commitment derivative expires, and the Company records a loan held for sale. The forward loan sales contract acts as a hedge against the variability in cash to be received from the loan sale. The changes in measurement of the estimated fair values of the interest rate lock commitments and forward loan sales contracts are included in mortgage banking revenues in the accompanying consolidated statements of income. The Company also enters into certain interest rate swap contracts that are not designated as hedging instruments. These derivative contracts relate to transactions in which the Company enters into an interest rate swap with a client while at the same time entering into an offsetting interest rate swap with a third-party financial institution. Because the Company acts as an intermediary for the client, changes in the fair value of the underlying derivative contracts primarily offset each other and do not significantly impact the Company’s results of operations. Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest income (expense) and to manage its exposure to interest rate movements. To accomplish these objectives, the Company primarily uses interest rate swaps and collars as part of its interest rate risk management strategy. As part of the Company’s overall asset and liability management strategy, in 2022 the Company entered into two interest rate collars related to variable-rate loans that were designated as cash flow hedges with a total notional amount of $300.0 million and entered into four swaps, two of which were related to variable-rate loans and two that were related to variable-rate securities that were designated as cash flow hedges with a total notional amount of $850.0 million. The collars designated as cash flow hedges synthetically fix the interest income received by the Company when the interest index falls below a floor rate on a rate reset and when the interest index exceeds the cap rate on a rate reset. Each of the swaps designated as cash flow hedges synthetically fixes the interest income received by the Company. During the quarter, the Company voluntarily terminated three swaps, two of which were related to variable-rate loans and one related to variable-rate securities that were designated as cash flow hedges with a total notional amount of $550.0 million. The termination of the cash flow hedges resulted in a net loss of $0.2 million being captured in accumulated other comprehensive income, net of tax, and reclassified to interest income over the period the forecasted transactions affects earnings. The two interest rate collars and one remaining swap designated as cash flow hedges were effective with a total notional amount of $600.0 million. For derivatives that are designated and that qualify as cash flow hedges of interest rate risk, the gain or loss on the derivative is recorded in accumulated other comprehensive income and subsequently reclassified into interest income in the same period(s) during which the hedged transaction affects earnings. Amounts reported in accumulated other comprehensive income related to derivatives will be reclassified as interest income when interest payments on the Company’s hedged items are earned. During the next twelve months, based on implied forward curves, the Company estimates that $1.7 million will be reclassified to interest income. Fair Value Hedges of Interest Rate Risk The Company is exposed to changes in the fair value of fixed-rate assets due to changes in benchmark interest rates. The Company uses interest rate swaps to manage its exposure to changes in fair value on these instruments attributable to changes in the designated benchmark interest rate. Interest rate swaps designated as fair value hedges involve the payment of fixed-rate amounts to a counterparty in exchange for the Company receiving variable-rate payments over the life of the agreements without the exchange of the underlying notional amount. During the third quarter of 2022, the Company terminated the $200.0 million, three-year forward starting, four-year pay fixed interest rate swap, resulting in a $8.5 million gain that will be accreted into income through July 2028 or until the securities are sold. The Company accreted $0.4 million of the gain into interest income during the three months ended September 30, 2024. For derivatives designated and that qualify as fair value hedges, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in interest income. The following amounts were recorded on the consolidated balance sheets related to cumulative basis adjustment for fair value hedges for the periods indicated: September 30, 2024 December 31, 2023 Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Available-for-sale securities $ 194.3 $ 5.7 $ 193.3 $ 6.7 Non-designated Hedge Derivatives Derivative instruments not designated as accounting hedges are not speculative and result from a service the Company provides to certain customers. The Company executes interest rate swaps with commercial banking customers to facilitate their respective risk management strategies. Those interest rate swaps are simultaneously economically hedged by offsetting derivatives that the Company executes with a third party, such that the Company minimizes its net risk exposure resulting from such transactions. As the interest rate derivatives associated with this program do not meet the strict hedge accounting requirements, changes in the fair value of both the customer derivatives and the offsetting derivatives are recognized directly in earnings. Risk Participation Agreements The Company acquired, from Great Western Bank, risk participation agreements under which it assumes credit risk associated with a borrower’s performance related to derivative contracts. The Company only entered into these credit risk participation agreements in instances in which the Company was also a party to the related loan participation agreements for such borrowers. The Company manages its credit risk under risk participation agreements by monitoring the creditworthiness of the borrower, based on its normal credit review process. The following table summarizes the fair values of our derivative instruments on a gross and net basis for the periods indicated. The derivative asset and liability balances are presented on a gross basis, prior to the application of bilateral collateral and master netting agreements, but after the variation margin payments with central clearing organizations have been applied as settlement, as applicable. Total derivative assets and liabilities are adjusted to account for the impact of legally enforceable master netting agreements that allow us to settle all derivative contracts with a single counterparty on a net basis and to offset the net derivative position with the related cash collateral. Securities collateral related to legally enforceable master netting agreements is not offset on the consolidated balance sheets. September 30, 2024 December 31, 2023 Notional Amount Consolidated Balance Sheet Location Estimated Notional Amount Consolidated Balance Sheet Location Estimated Derivatives designated as accounting hedges: Interest rate swap contracts $ 300.0 $ 0.3 $ 550.0 $ 3.0 Derivatives not designated as accounting hedges: Interest rate swap contracts 1,468.5 28.3 1,589.0 34.3 Interest rate lock commitments 5.3 — 5.7 0.1 Derivative assets $ 1,773.8 Other assets $ 28.6 $ 2,144.7 Other assets $ 37.4 Derivatives designated as accounting hedges: Interest rate collars $ 300.0 $ 1.2 $ 300.0 $ 3.6 Interest rate swap contracts — — 300.0 2.4 Derivatives not designated as accounting hedges: Interest rate swap contracts 1,468.5 93.0 1,589.0 121.1 Risk participation agreements 95.5 — 101.1 0.1 Forward loan sales contracts 4.9 — 5.6 0.1 Derivative liabilities $ 1,868.9 Accounts payable and accrued expenses $ 94.2 $ 2,295.7 Accounts payable and accrued expenses $ 127.3 There was an unrealized fair value gain on cash flow hedging derivative instruments in accumulated other comprehensive income of $12.4 million and an unrealized fair value loss of $10.1 million during the three and the nine months ended September 30, 2024, respectively. There was an unrealized fair value loss on cash flow hedging derivative instruments in accumulated other comprehensive income of $13.1 million and $27.2 million during the three and the nine months ended September 30, 2023. There was a loss of $3.1 million and $11.2 million reclassified from accumulated other comprehensive loss into the consolidated statements of income during the three and the nine months ended September 30, 2024 from the Company’s cash flow hedged derivative financial instruments, and a loss of $2.1 million and $4.1 million reclassified during the comparable 2023 periods. The table below presents the effect of the Company’s derivative financial instruments that are not designated as hedging instruments on the consolidated statements of income for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Location of Gain (Loss) Recognized in Income on Derivative Amount of Gain (Loss) Recognized in Income on Derivative Location of Gain (Loss) Recognized in Income on Derivative Amount of Gain (Loss) Recognized in Income on Derivative Interest rate lock commitments Mortgage banking revenues $ — $ 0.1 Mortgage banking revenues $ — $ (0.1) The Company includes swap fee revenues in other service charges, commissions, and fees on the consolidated statements of income. The Company had no material swap fee revenues during the three and the nine months ended September 30, 2024 and 2023. The tables below present the gross presentation, the effects of offsetting, and a net presentation of the Company’s derivatives as of the dates indicated: September 30, 2024 Gross Assets Recognized Gross Assets Offset in the Balance Sheet Net Assets in the Balance Sheet Financial Instruments Cash Collateral Received (1) Net Amount Interest rate swap and collar contracts $ 28.6 $ — $ 28.6 $ — $ 25.8 $ 2.8 Total derivatives 28.6 — 28.6 — 25.8 2.8 Total assets $ 28.6 $ — $ 28.6 $ — $ 25.8 $ 2.8 (1) Netting adjustments represent the amounts recorded to convert derivatives assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The application of the collateral cannot reduce the net derivative position below zero. Therefore, excess collateral, if any, is not reflected above. Gross Liabilities Recognized Gross Liabilities Offset in the Balance Sheet Net Liabilities in the Balance Sheet Financial Instruments Cash Collateral Posted Net Amount Interest rate swap and collar contracts $ 94.2 $ — $ 94.2 $ — $ — $ 94.2 Total derivatives 94.2 — 94.2 — — 94.2 Repurchase agreements (2) 557.2 — 557.2 — — 557.2 Total liabilities $ 651.4 $ — $ 651.4 $ — $ — $ 651.4 (2) Repurchase agreements are fully collateralized by investment securities. December 31, 2023 Gross Assets Recognized Gross Assets Offset in the Balance Sheet Net Assets in the Balance Sheet Financial Instruments Cash Collateral Received (1) Net Amount Interest rate swap and collar contracts $ 37.3 $ — $ 37.3 $ — $ 32.7 $ 4.6 Interest rate lock commitments 0.1 — 0.1 — — 0.1 Total derivatives 37.4 — 37.4 — 32.7 4.7 Total assets $ 37.4 $ — $ 37.4 $ — $ 32.7 $ 4.7 (1) Netting adjustments represent the amounts recorded to convert derivatives assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The application of the collateral cannot reduce the net derivative position below zero. Therefore, excess collateral, if any, is not reflected above. Gross Liabilities Recognized Gross Liabilities Offset in the Balance Sheet Net Liabilities in the Balance Sheet Financial Instruments Cash Collateral Posted Net Amount Interest rate swap and collar contracts $ 127.1 $ — $ 127.1 $ — $ — $ 127.1 Risk participation agreements 0.1 — 0.1 — — 0.1 Forward loan sales contracts 0.1 — 0.1 — — 0.1 Total derivatives 127.3 — 127.3 — — 127.3 Repurchase agreements (2) 782.7 — 782.7 — — 782.7 Total liabilities $ 910.0 $ — $ 910.0 $ — $ — $ 910.0 (2) Repurchase agreements are fully collateralized by investment securities. Credit-risk-related Contingent Feature The Company has agreements with each of its derivative counterparties that contain a provision where if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations. The Company has agreements with certain of its derivative counterparties that contain a provision where if the Company fails to maintain its status as a well / adequately capitalized institution, then the counterparty could terminate the derivative positions and the Bank would be required to settle its obligations. Similarly, the Bank could be required to settle its obligations under certain of its agreements if specific regulatory events occur, such as a publicly issued prompt corrective action directive, cease and desist order, or a capital maintenance agreement that required the Bank to maintain a specific capital level. If the Bank had breached any of these provisions at September 30, 2024 or December 31, 2023, it could have been required to settle its obligations under the agreements at the termination value. As of September 30, 2024, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, was zero related to these agreements. As of September 30, 2024, the Company has minimum collateral posting thresholds with certain of its derivative counterparties and has not posted excess collateral. If the Company had breached any of these provisions at September 30, 2024, it could have been required to settle its obligations under the agreements at their termination value.

Long-Term Debt and Other Borrow

Long-Term Debt and Other Borrowed Funds	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Long-Term Debt and Other Borrowed Funds	A summary of long-term debt follows: September 30, 2024 December 31, 2023 Parent Company: Fixed to floating subordinated notes, 5.25% fixed rate effective May 2020 through May 2025 $ 99.1 $ 99.0 Subsidiaries: 0.00% FHLB borrowings maturing in August 2029 3.9 — 8.00% finance lease obligation with term ending October 31, 2029 0.8 0.9 1.00% note payable maturing December 31, 2041, interest only payable quarterly until September 30, 2024 and then principal and interest until maturity 5.1 5.1 Note payable maturing March 31, 2038, interest only payable at 1.30% monthly until March 31, 2025 and then principal and interest at 3.25% until maturity 2.0 2.0 1.30% note payable maturing June 1, 2034, interest only payable monthly until March 31, 2025 and then principal and interest until maturity 0.6 0.6 1.12% note payable maturing December 31, 2045, interest only payable annually until December 31, 2028 and then principal and interest until maturity 6.8 6.8 1.35% note payable maturing December 31, 2046 interest only payable annually until December 31, 2025 and then principal and interest until maturity 6.4 6.4 1.26% note payable maturing December 31, 2051 interest only payable annually until December 31, 2031 and then principal and interest until maturity 12.6 — Total long-term debt $ 137.3 $ 120.8 In addition to the long-term debt instruments noted above, at September 30, 2024, the Company had other borrowed funds totaling $2,080.0 million of outstanding Bank Term Funding Program (“BTFP”) and FHLB fixed rate borrowings with remaining tenors of up to twelve-months at an average rate of 4.86%, as compared to $2,603.0 million of outstanding FHLB fixed rate borrowings with tenors of up to three-months at an average rate of 5.52% at December 31, 2023. As of September 30, 2024 and December 31, 2023, the Company had no other material outstanding borrowings classified as other borrowed funds. At September 30, 2024, the Company has remaining available lines of credit with the FHLB of approximately $4,885.2 million, subject to collateral availability. The available line of credit and outstanding borrowings with the FHLB are collateralized by certain loans and securities with an advance equivalent collateral value of $5,969.0 million. The following table presents outstanding FHLB and BTFP borrowings by original maturity classification for the dates indicated: As of September 30, 2024 Average Rate Outstanding Balance Fixed rate borrowings with tenors of up to twelve-months 4.87 % $ 1,830.0 Fixed rate borrowings with tenors over twelve-months 4.72 250.0 $ 2,080.0 As of December 31, 2023 Average Rate Outstanding Balance Fixed rate borrowings with tenors of up to three-months 5.52 % $ 2,603.0 $ 2,603.0

Capital Stock

Capital Stock	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Capital Stock	Capital Stock On May 24, 2023, the Company’s shareholders approved the proposed change of the Company’s state of incorporation from Montana to Delaware. As a result, each outstanding share of the then Company’s Class A common stock became an outstanding share of common stock of the Company and each outstanding option, warrant or other right to acquire shares of the Company’s previously designated Class A common stock became an outstanding option, warrant or other right to acquire shares of common stock of the Company. On May 21, 2024, the Company’s 2023 Equity and Incentive Plan was amended to increase the number of shares of common stock authorized for issuance thereunder by an additional two million shares, all of which were registered pursuant to a Registration Statement on Form S-8 filed with the SEC on May 23, 2024. As of September 30, 2024, the Company is authorized to issue an aggregate of 150,100,000 shares of capital stock, of which 150,000,000 shares are designated as common stock, and 100,000 are designated as preferred stock. Our common stock is uncertificated and has one vote per share. The Company had 104,529,863 shares and 103,941,626 shares of common stock outstanding as of September 30, 2024 and December 31, 2023, respectively, and no shares of preferred stock outstanding as of September 30, 2024 and December 31, 2023. During the nine months ended September 30, 2024, the Company issued 43,514 shares of its common stock to directors for their annual service on the Company's board of directors. The aggregate value of the shares issued to directors of $1.2 million is amortized into stock-based compensation expense in the accompanying consolidated statements of changes in stockholders’ equity over a one-year service-based period.

Earnings per Common Share

Earnings per Common Share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common Share Basic earnings per common share is calculated by dividing net income by the weighted average number of common shares outstanding during the period presented, excluding unvested restricted stock. Diluted earnings per share is calculated by dividing net income by the weighted average number of common shares determined for the basic earnings per share computation plus the dilutive effects of stock-based compensation using the treasury stock method. The following table sets forth the computation of basic and diluted earnings per share for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Net income $ 55.5 $ 72.7 $ 173.9 $ 196.0 Weighted average common shares outstanding for basic earnings per share computation 102,970,851 103,822,311 102,917,610 103,793,851 Dilutive effects of stock-based compensation 262,767 4,116 207,449 30,425 Weighted average common shares outstanding for diluted earnings per common share computation 103,233,618 103,826,427 103,125,059 103,824,276 Basic earnings per common share $ 0.54 $ 0.70 $ 1.69 $ 1.89 Diluted earnings per common share 0.54 0.70 1.69 1.89 Anti-dilutive unvested time restricted stock 5,841 162,231 47,854 162,231 The Company had 773,563 and 967,996 shares of unvested restricted stock as of September 30, 2024 and 2023, respectively, that were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met.

Regulatory Capital

Regulatory Capital	9 Months Ended
	Sep. 30, 2024
Banking and Thrift, Other Disclosure [Abstract]
Regulatory Capital	As of September 30, 2024 and December 31, 2023, the Company exceeded all capital adequacy requirements to which it is subject. Actual capital amounts and ratios for the Company and its subsidiary Bank, as of September 30, 2024 and December 31, 2023 are presented in the following tables: Actual Minimum Required for Capital Adequacy Purposes For Capital Adequacy Purposes Plus Capital Conservation Buffer (1) Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements (2) September 30, 2024 Amount Ratio Amount Ratio Amount Ratio Amount Ratio Total risk-based capital: Consolidated $ 2,976.2 14.11 % $ 1,687.2 8.00 % $ 2,214.4 10.50 % $ 2,109.0 10.00 % FIB 2,701.2 12.84 1,683.6 8.00 2,209.7 10.50 2,104.5 10.00 Tier 1 risk-based capital: Consolidated 2,495.8 11.83 1,265.4 6.00 1,792.6 8.50 1,687.2 8.00 FIB 2,478.4 11.78 1,262.7 6.00 1,788.8 8.50 1,683.6 8.00 Common equity tier 1 risk-based capital: Consolidated 2,495.8 11.83 949.0 4.50 1,476.3 7.00 1,370.8 6.50 FIB 2,478.4 11.78 947.0 4.50 1,473.1 7.00 1,367.9 6.50 Leverage capital ratio: Consolidated 2,495.8 8.57 1,164.9 4.00 1,164.9 4.00 1,456.2 5.00 FIB 2,478.4 8.52 1,163.1 4.00 1,163.1 4.00 1,453.9 5.00 Actual Minimum Required for Capital Adequacy Purposes For Capital Adequacy Purposes Plus Capital Conservation Buffer (1) Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements (2) December 31, 2023 Amount Ratio Amount Ratio Amount Ratio Amount Ratio Total risk-based capital: Consolidated $ 2,941.1 13.28 % $ 1,771.6 8.00 % $ 2,325.2 10.50 % $ 2,214.5 10.00 % FIB 2,662.0 12.04 1,768.3 8.00 2,320.8 10.50 2,210.3 10.00 Tier 1 risk-based capital: Consolidated 2,454.4 11.08 1,328.7 6.00 1,882.3 8.50 1,771.6 8.00 FIB 2,433.0 11.01 1,326.2 6.00 1,878.8 8.50 1,768.3 8.00 Common equity tier 1 risk-based capital: Consolidated 2,454.4 11.08 996.5 4.50 1,550.1 7.00 1,439.4 6.50 FIB 2,433.0 11.01 994.6 4.50 1,547.2 7.00 1,436.7 6.50 Leverage capital ratio: Consolidated 2,454.4 8.22 1,193.9 4.00 1,193.9 4.00 1,492.3 5.00 FIB 2,433.0 8.16 1,192.2 4.00 1,192.2 4.00 1,490.2 5.00 (1) The capital conservation buffer is an additional 2.5% of the amount necessary to meet the minimum risk-based capital requirements for total, tier 1, and common equity tier 1 risk-based capital. (2) The ratios to meet the requirements to be deemed “well-capitalized” are only applicable to FIB. However, the Company manages its capital position as if the requirements apply to the consolidated company and has presented the ratios as if they also applied on a consolidated basis. In connection with the adoption of CECL on January 1, 2020, the Company recognized an after-tax cumulative effect on retained earnings with a reduction totaling $24.1 million. In March 2020, the Office of the Comptroller of Currency, the Board of Governors of the Federal Reserve System, and the FDIC issued an interim final rule that allows banking organizations to mitigate the effects of ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies In the normal course of business, the Company is involved in various claims and litigation. The Company establishes accruals for legal matters when potential losses associated with the actions become probable and the amount of loss can be reasonably estimated. There is no assurance that the ultimate resolution of these matters will not significantly exceed the amounts that the Company has accrued. Accruals for legal matters are based on management’s best judgment after consultation with counsel and others. In the opinion of management, following consultation with legal counsel, the ultimate liability or disposition of all such claims and litigation is not expected to have a material adverse effect on the consolidated financial condition, results of operations, or liquidity of the Company. As of September 30, 2024, the Company had commitments under construction contracts of $5.5 million.

Financial Instruments with Off-

Financial Instruments with Off-Balance Sheet Risk	9 Months Ended
	Sep. 30, 2024
Financial Instruments with Off-Balance Sheet Risk [Abstract]
Financial Instruments with Off-Balance Sheet Risk	In the normal course of business, the Company is a party to financial instruments with off-balance sheet risk to meet the financing needs of its clients. These financial instruments include commitments to extend credit and standby letters of credit. These instruments involve, to varying degrees, elements of credit and interest rate risk in excess of amounts recorded in the consolidated balance sheets. Commitments to extend credit are agreements to lend to a client so long as there is no violation of any condition established in the commitment contract. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Standby letters of credit are conditional commitments issued by the Company to guarantee the performance of a client to a third party. The credit risk involved in issuing letters of credit is essentially the same as the credit risk involved in extending loan facilities to clients. The Company’s policy for obtaining collateral, and determining the nature of such collateral, is essentially the same as in the Company’s policies for making commitments to extend credit. The estimated fair value of the obligation undertaken by the Company in issuing standby letters of credit is included in accounts payable and accrued expenses in the Company’s consolidated balance sheets. The following table presents our financial instruments with off-balance sheet risk, as well as the activity in the allowance for off-balance sheet credit losses related to those financial instruments: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Beginning balance $ 5.8 $ 20.8 $ 18.4 $ 16.2 Provision for credit loss expense (0.2) (2.0) (12.8) 2.6 Ending balance $ 5.6 $ 18.8 $ 5.6 $ 18.8 September 30, 2024 December 31, 2023 Unused credit card lines $ 861.4 $ 814.0 Commitments to extend credit 3,290.7 4,069.2 Standby letters of credit 88.7 97.1

Other Comprehensive Income_Loss

Other Comprehensive Income/Loss	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Other Comprehensive Income/Loss	Other Comprehensive Loss The gross amounts of each component of other comprehensive loss and the related tax effects are as follows: Pre-tax Tax (Expense) Benefit Net of Tax Three Months Ended September 30, 2024 2023 2024 2023 2024 2023 Investment securities available-for sale: Change in net unrealized gains (losses) during the period $ 158.5 $ (72.1) $ (39.4) $ 17.9 $ 119.1 $ (54.2) Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity (0.2) (0.3) — 0.1 (0.2) (0.2) Cash flow hedge: Change in unrealized gains (losses) on derivatives 12.4 (13.1) (3.0) 3.2 9.4 (9.9) Reclassification adjustment for derivatives net losses included in income 3.1 2.1 (0.8) (0.5) 2.3 1.6 Total other comprehensive income (loss) $ 173.8 $ (83.4) $ (43.2) $ 20.7 $ 130.6 $ (62.7) Pre-tax Tax (Expense) Benefit Net of Tax Nine Months Ended September 30, 2024 2023 2024 2023 2024 2023 Investment securities available-for sale: Change in net unrealized gains (losses) during the period $ 134.6 $ (51.4) $ (33.5) $ 12.7 $ 101.1 $ (38.7) Reclassification adjustment for net losses included in income — 23.5 — (5.8) — 17.7 Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale — (7.2) — 1.8 — (5.4) Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity (0.5) (1.1) — 0.3 (0.5) (0.8) Cash flow hedge: Change in unrealized gains on derivatives (10.1) (27.2) 2.8 6.7 (7.3) (20.5) Reclassification adjustment for derivatives net losses included in income 11.2 4.1 (2.9) (1.0) 8.3 3.1 Total other comprehensive income (loss) $ 135.2 $ (59.3) $ (33.6) $ 14.7 $ 101.6 $ (44.6) The components of accumulated other comprehensive loss, net of related tax effects, are as follows: September 30, 2024 December 31, 2023 Net unrealized loss on investment securities available-for-sale $ (249.0) $ (350.1) Net unrealized loss on investment securities transferred to held-to-maturity (5.9) (5.6) Net unrealized loss on derivatives — (0.8) Net accumulated other comprehensive loss $ (254.9) $ (356.5)

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or be paid to transfer a liability in an orderly transaction between market participants at the measurement date. There is a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The three levels of inputs to measure fair value are as follows: • Level 1 - Quoted prices in active markets for identical assets or liabilities • Level 2 - Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of assets or liabilities The methodologies used by the Company in determining the fair values of each class of financial instruments are based primarily on independent, market-based data to reflect a value that would be reasonably expected in an orderly transaction between market participants at the measurement date, and therefore, are classified within Level 2 of the valuation hierarchy. There have been no significant changes in the valuation techniques as of September 30, 2024. The Company’s policy is to recognize transfers between levels as of the end of the reporting period. Transfers in and out of Level 1, Level 2, and Level 3 are recognized on the actual transfer date. There were no significant transfers between fair value hierarchy levels as of September 30, 2024. Further details on the methods used to estimate the fair value of each class of financial instruments above are discussed below: Investment Debt Securities Available-for-Sale . The Company obtains fair value measurements for investment securities from an independent pricing service. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the investment’s terms and conditions, among others. Vendors chosen by the Company are widely recognized vendors whose evaluations support the pricing functions of financial institutions, investment and mutual funds, and portfolio managers. If needed, a broker may be utilized to determine the reported fair value of investment securities. Loans Held for Sale. Fair value measurements for residential mortgage loans held for sale are obtained from an independent pricing service. The fair value measurements consider observable data that may include binding contracts or quotes or bids from third party investors as well as loan level pricing adjustments. Commercial and agricultural loans held for sale are derived from quotes or bids from third party investors. Interest Rate Collars: The fair values of interest rate collars are obtained from an independent third party. The values are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates fell below (rise above) the strike rate of the floors (caps). The variable interest rates used in the calculation of projected receipts on the collars are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities. The Company also compares the reasonableness of the pricing quarterly through a validation process involving additional independent third parties. Interest Rate Swap Contracts. Fair values for derivative interest rate swap contracts are obtained from an independent third party. The values are based upon the estimated amounts to settle the contracts considering current interest rates and are calculated using discounted cash flows that are observable, or that can be corroborated by observable market data. The inputs used to determine fair value include the United States Dollar – Secured Overnight Financing Rate (“SOFR”) forward curve to estimate variable rate cash inflows and SOFR to estimate the discount rate. The estimated variable rate cash inflows are compared to the fixed rate outflows and such difference is discounted to a present value to estimate the fair value of the interest rate swaps. The Company also compares the reasonableness of the pricing quarterly through a validation process involving additional independent third parties. For purposes of potential valuation adjustments to our derivative positions, we evaluate both our credit risk and the credit risk of our counterparties. Accordingly, we have considered factors such as the likelihood of our default and the default of our counterparties, our net exposures and remaining contractual life, among other things, in determining if any fair value adjustments related to credit risk are required. The change in value of derivative assets and derivative liabilities attributable to credit risk was not significant during the reported periods. Interest Rate Lock Commitments. Fair value measurements for interest rate lock commitments are obtained from an independent pricing service. The fair value measurements consider observable data that may include prices available from secondary market investors taking into consideration various characteristics of the loan, including the loan amount, interest rate, value of the servicing, and loan to value ratio, among other things. Observable data is then adjusted to reflect changes in interest rates, the Company’s estimated pull-through rate, and estimated direct costs necessary to complete the commitment into a closed loan net of origination, and processing fees collected from the borrower. Forward Loan Sales Contracts. The fair value measurements for forward loan sales contracts are obtained from an independent pricing service. The fair value measurements consider observable data that includes sales of similar loans. Deferred Compensation Plan Assets and Liabilities. The fair values of deferred compensation plan assets and liabilities are based primarily on the use of independent, market-based data to reflect a value that would be reasonably expected in an orderly transaction between market participants at the measurement date. These investments are in the same funds and purchased in the same amounts as the participants’ selected investments, which represent the underlying liabilities to plan participants. Deferred compensation plan liabilities are recorded at amounts due to participants, based on the fair value of participants’ selected investments. Financial assets and financial liabilities measured at fair value on a recurring basis are as follows: Fair Value Measurements at Reporting Date Using As of September 30, 2024 Fair Value Quoted Prices in Significant Other Significant Investment debt securities available-for-sale: U.S. Treasury notes $ 231.0 $ — $ 231.0 $ — State, county, and municipal securities 220.9 — 220.9 — Obligations of U.S. government agencies 165.4 — 165.4 — U.S. agency commercial mortgage-backed securities 1,105.3 — 1,105.3 — U.S. agency residential mortgage-backed securities 1,262.4 — 1,262.4 — Collateralized mortgage obligations 1,116.6 — 1,116.6 — Private mortgage-backed securities 199.6 — 199.6 — Collateralized loan obligations 988.0 — 988.0 — Corporate securities 245.1 — 245.1 — Loans held for sale 2.1 — 2.1 — Derivative assets: Interest rate swap contracts 28.6 — 28.6 — Derivative liabilities: Interest rate collars 1.2 — 1.2 — Interest rate swap contracts 93.0 — 93.0 — Deferred compensation plan assets 21.8 21.8 — — Deferred compensation plan liabilities 21.8 21.8 — — Fair Value Measurements at Reporting Date Using As of December 31, 2023 Fair Value Quoted Prices in Significant Other Significant Investment debt securities available-for-sale: U.S. Treasury notes $ 224.7 $ — $ 224.7 $ — State, county and municipal securities 219.8 — 219.8 — Obligations of U.S. government agencies 168.5 — 168.5 — U.S. agency commercial mortgage-backed securities 1,105.6 — 1,105.6 — U.S. agency residential mortgage-backed securities 1,366.9 — 1,366.9 — Collateralized mortgage obligations 1,189.5 — 1,189.5 — Private mortgage-backed securities 210.4 — 210.4 — Collateralized loan obligations 1,119.7 — 1,119.7 — Corporate securities 236.4 — 236.4 — Loans held for sale 0.5 — 0.5 — Derivative assets: Interest rate swap contracts 37.3 — 37.3 — Forward loan sales contracts 0.1 — 0.1 — Derivative liabilities Interest rate collars 3.6 — 3.6 — Interest rate swap contracts 123.5 — 123.5 — Risk participation agreements 0.1 — 0.1 — Forward loan sales contracts 0.1 — 0.1 — Deferred compensation plan assets 19.2 19.2 — — Deferred compensation plan liabilities 19.2 19.2 — — Additionally, from time to time, certain assets are measured at fair value on a non-recurring basis. Adjustments to fair value generally result from the application of lower-of-cost-or-market accounting or write-downs of individual assets due to credit deterioration. The following table presents information about the Company’s assets and liabilities measured at fair value on a non-recurring basis: Fair Value Measurements at Reporting Date Using As of September 30, 2024 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Significant Collateral-dependent loans $ 109.6 $ — $ — $ 109.6 Loans held for sale 18.8 — — 18.8 Other real estate owned 4.4 — — 4.4 Long-lived assets to be disposed of by sale 1.0 — — 1.0 Fair Value Measurements at Reporting Date Using As of December 31, 2023 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Significant Collateral-dependent loans $ 52.6 $ — $ — $ 52.6 Loans held for sale 46.9 — — 46.9 Other real estate owned 16.5 — — 16.5 Long-lived assets to be disposed of by sale 1.0 — — 1.0 Collateral-dependent Loans. Collateral-dependent loans are reported at the fair value of the underlying collateral if repayment is expected solely from collateral. The collateral-dependent loans are reported at fair value through specific valuation allowance allocations. In addition, when it is determined that the fair value of a collateral-dependent loan is less than the recorded investment in the loan, the carrying value of the loan is adjusted to fair value through a charge to the allowance for credit losses. Collateral values are estimated using independent appraisals and management estimates of current market conditions. As of September 30, 2024 and December 31, 2023, the Company had collateral-dependent loans with a carrying and fair value of $109.6 million and $52.6 million, respectively. Loans Held for Sale. Fair value measurements for non-residential mortgage loans held for sale are derived from valuations, appraisals, and quotes or bids from third party investors. The fair value measurements consider observable data that may include binding contracts or quotes or bids from third party investors as well as loan level pricing adjustments. OREO. The fair values of OREO are estimated using independent appraisals and management estimates of current market conditions. Upon initial recognition, write-downs based on the foreclosed asset’s fair value at foreclosure are reported through charges to the allowance for credit losses. Periodically, the fair value of foreclosed assets is remeasured with any subsequent write-downs charged to OREO expense in the period in which they are identified. Long-lived Assets to be Disposed of by Sale. Long-lived assets to be disposed of by sale are carried at the lower of carrying value or fair value less estimated costs to sell. The fair values of long-lived assets to be disposed of by sale are based upon observable market data and management estimates of current market conditions. As of September 30, 2024 and December 31, 2023, the Company had long-lived assets to be disposed of by sale with carrying and fair values aggregating $1.0 million. The following table presents additional quantitative information about assets measured at fair value on a non-recurring basis and for which the Company has utilized Level 3 inputs to determine fair values: Fair Value As of September 30, 2024 December 31, 2023 Valuation Unobservable Range Collateral-dependent loans $ 109.6 $ 52.6 Appraisal Appraisal adjustment 0% - 71% (41%) Loans held for sale 18.8 46.9 Fair value of collateral Discount for type of property, age of appraisal, and current status 0 - 28 (24) Other real estate owned 4.4 16.5 Appraisal Appraisal adjustment 17 - 40 (23) Long-lived assets to be disposed of by sale 1.0 1.0 Appraisal Appraisal adjustment 0 - 0 0 The Company is required to disclose the fair value of financial instruments for which it is practical to estimate fair value. The methodologies for estimating the fair value of financial instruments that are measured at fair value on a recurring or non-recurring basis are discussed above. The methodologies for estimating the fair value of other financial instruments are discussed below. For financial instruments bearing a variable interest rate where no credit risk exists, it is presumed that recorded book values are reasonable estimates of fair value. Financial Assets. Carrying values of cash, cash equivalents, and accrued interest receivable approximate fair values due to the liquid and/or short-term nature of these instruments. Fair values for investment securities held-to-maturity are obtained from an independent pricing service, which considers observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the investment’s terms and conditions, among other things. Fair values of fixed rate loans and variable rate loans that reprice on an infrequent basis are estimated by discounting future cash flows using current interest rates at which similar loans with similar terms would be made to borrowers of similar credit quality using an exit price notion. Carrying values of variable rate loans that reprice frequently, and with no change in credit risk, approximate the fair values of these instruments. Financial Liabilities. The fair values of demand deposits, savings accounts, securities sold under repurchase agreements, and accrued interest payable are the amounts that are payable on demand at the reporting date. The fair values of fixed-maturity certificates of deposit are estimated using external market rates that are currently offered for deposits that have similar remaining maturities. The fair values of derivative liabilities are obtained from an independent pricing service, which considers observable data that may include the United States Dollar – SOFR forward curve, the federal funds effective swap rate and cash flows, among other things. The fixed and floating rate subordinated debentures, floating rate subordinated term loan, other borrowed funds, fixed rate subordinated term debt, and capital lease obligation are estimated by discounting future cash flows using current rates for advances that have similar characteristics. Commitments to Extend Credit and Standby Letters of Credit. The fair value of commitments to extend credit and standby letters of credit, based on fees currently charged to enter into similar agreements, is not significant. The estimated fair values of financial instruments that are reported in the Company’s consolidated balance sheets, and are segregated by the level of the valuation inputs within the fair value hierarchy that are utilized to measure fair value, are as follows: Fair Value Measurements at Reporting Date Using As of September 30, 2024 Carrying Amount Estimated Quoted Prices in Active Markets for Significant Other Significant Financial assets: Cash and cash equivalents $ 698.6 $ 698.6 $ 698.6 $ — $ — Investment debt securities held-to-maturity 2,741.3 2,480.5 — 2,480.5 — Accrued interest receivable 127.3 127.3 — 127.3 — Mortgage servicing rights, net 26.3 37.2 — 37.2 — Loans held for sale 20.9 20.9 — 2.1 18.8 Net loans held for investment 17,801.7 17,257.5 — 17,147.9 109.6 Total financial assets $ 21,416.1 $ 20,622.0 $ 698.6 $ 19,795.0 $ 128.4 Financial liabilities: Total deposits, excluding time deposits $ 19,985.9 $ 19,985.9 $ 19,985.9 $ — $ — Time deposits 2,878.2 2,864.3 — 2,864.3 — Securities sold under repurchase agreements 557.2 557.2 — 557.2 — Other borrowed funds 2,080.0 2,080.0 — 2,080.0 — Accrued interest payable 87.7 87.7 — 87.7 — Long-term debt 137.3 132.1 — 132.1 — Subordinated debentures held by subsidiary trusts 163.1 151.0 — 151.0 — Total financial liabilities $ 25,889.4 $ 25,858.2 $ 19,985.9 $ 5,872.3 $ — Fair Value Measurements at Reporting Date Using As of December 31, 2023 Carrying Amount Estimated Quoted Prices in Active Markets for Significant Other Significant Financial assets: Cash and cash equivalents $ 578.0 $ 578.0 $ 578.0 $ — $ — Investment debt securities held-to-maturity 3,207.9 2,874.0 — 2,874.0 — Accrued interest receivable 129.1 129.1 — 129.1 — Mortgage servicing rights, net 28.3 38.8 — 38.8 — Loans held for sale 47.4 47.4 — 0.5 46.9 Net loans held for investment 18,051.9 17,334.4 — 17,281.8 52.6 Total financial assets $ 22,042.6 $ 21,001.7 $ 578.0 $ 20,324.2 $ 99.5 Financial liabilities: Total deposits, excluding time deposits $ 20,313.2 $ 20,313.2 $ 20,313.2 $ — $ — Time deposits 3,009.9 2,981.7 — 2,981.7 — Securities sold under repurchase agreements 782.7 782.7 — 782.7 — Other borrowed funds 2,603.0 2,603.0 — 2,603.0 — Accrued interest payable 52.2 52.2 — 52.2 — Long-term debt 120.8 115.6 — 115.6 — Subordinated debentures held by subsidiary trusts 163.1 151.1 — 151.1 — Total financial liabilities $ 27,044.9 $ 26,999.5 $ 20,313.2 $ 6,686.3 $ —

Recent Authoritative Accounting

Recent Authoritative Accounting Guidance	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Recent Authoritative Accounting Guidance	Recent Authoritative Accounting Guidance ASU 2023-02, “ Investments—Equity Method and Joint Ventures (Topic 323), Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method ” In March 2023, the FASB issued ASU 2023-02, Investments—Equity Method and Joint Ventures (Topic 323), Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method that permit reporting entities to elect to account for their tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. Previously, this method was only available for qualifying tax equity investments in low-income housing tax credit structures. The amendments also require that a reporting entity disclose certain information in annual and interim reporting periods that enable investors to understand certain information about its investments that generate income tax credits and other income tax benefits from a tax credit program. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. The Amendments in this ASU became effective for the Company on January 1, 2024. The Company elected the modified retrospective approach for qualifying New Market Tax Credits and adjusted beginning retained earnings by an increase of $1.2 million related to the previously recorded deferred taxes. Prospectively, both the amortization of the investment in Low Income Housing Tax Credits and the New Market Tax Credits are recorded net within income tax expense. ASU 2023-06, “ Disclosure Improvements—Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative ” In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements—Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative that amends the ASC to incorporate certain disclosure requirements from SEC Release No. 33-10532 - Disclosure Update and Simplification that was issued in 2018. The effective date for each amendment will be the date on which the SEC’s removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption prohibited. The Company does not anticipate the adoption of ASU 2023-06 will have a significant impact on the Company’s financial position, results of operations, or liquidity. ASU 2023-07, “ Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ” In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to improve disclosure requirements, primarily through enhanced disclosures about significant segment expenses. This update does not change how a public entity identifies its operating segments; however, it does require that an entity that has single reportable segment provide all the disclosures required by the amendments in this update. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. A public entity should apply the amendments in this update retrospectively to all prior periods presented in the consolidated financial statements. Early adoption is permitted. The Company currently has one reportable operating segment, Community Banking. This ASU will not impact the Company’s consolidated financial statements and will have minimal impact to the disclosures, requiring identification of the chief operating decision maker and the information used to make operating decisions and to allocate resources. ASU 2023-09, “ Income Taxes (Topic 740): Improvements to Income Tax Disclosures ” In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures that require public business entities to annually disclose (1) specific categories in their rate reconciliation; (2) additional information for reconciling items that meet a quantitative threshold; (3) the amount of income taxes paid (net of refunds received) disaggregated by federal, state, and foreign taxes; (4) the amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which the income taxes paid that meet a quantitative threshold; (5) income (or loss) from continuing operations before income tax expense (or benefit) disaggregated between domestic and foreign; and (6) income tax expense (or benefit) from continuing operations disaggregated by federal, state, and foreign. The ASU eliminates the requirement to disclose the nature and estimate of the range of the reasonably possible change in the unrecognized tax benefits balance in the next 12 months and to disclose the cumulative amount of each type of temporary difference when a deferred tax liability is not recognized because of the exceptions to comprehensive recognition of deferred taxes related to subsidiaries and corporate joint ventures. For public business entities, the amendments are effective for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The amendments should be applied on a prospective basis, but retrospective application is permitted. The Company is currently evaluating the impact of the standard and does not anticipate it will have a significant impact on the Company’s financial position, results of operations, or liquidity.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Subsequent events have been evaluated for potential recognition and disclosure through the date the Company’s financial statements were filed with the SEC. On October 23, 2024, the Company declared a quarterly dividend to common shareholders of $0.47 per share, to be paid on November 14, 2024 to shareholders of record as of November 4, 2024. No other undisclosed events requiring recognition or disclosure were identified.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Fair Value Measurements	Fair value is defined as the price that would be received to sell an asset or be paid to transfer a liability in an orderly transaction between market participants at the measurement date. There is a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The three levels of inputs to measure fair value are as follows: • Level 1 - Quoted prices in active markets for identical assets or liabilities • Level 2 - Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of assets or liabilities The methodologies used by the Company in determining the fair values of each class of financial instruments are based primarily on independent, market-based data to reflect a value that would be reasonably expected in an orderly transaction between market participants at the measurement date, and therefore, are classified within Level 2 of the valuation hierarchy. There have been no significant changes in the valuation techniques as of September 30, 2024. The Company’s policy is to recognize transfers between levels as of the end of the reporting period. Transfers in and out of Level 1, Level 2, and Level 3 are recognized on the actual transfer date. There were no significant transfers between fair value hierarchy levels as of September 30, 2024. Further details on the methods used to estimate the fair value of each class of financial instruments above are discussed below: Investment Debt Securities Available-for-Sale . The Company obtains fair value measurements for investment securities from an independent pricing service. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the investment’s terms and conditions, among others. Vendors chosen by the Company are widely recognized vendors whose evaluations support the pricing functions of financial institutions, investment and mutual funds, and portfolio managers. If needed, a broker may be utilized to determine the reported fair value of investment securities. Loans Held for Sale. Fair value measurements for residential mortgage loans held for sale are obtained from an independent pricing service. The fair value measurements consider observable data that may include binding contracts or quotes or bids from third party investors as well as loan level pricing adjustments. Commercial and agricultural loans held for sale are derived from quotes or bids from third party investors. Interest Rate Collars: The fair values of interest rate collars are obtained from an independent third party. The values are determined using the market standard methodology of discounting the future expected cash receipts that would occur if variable interest rates fell below (rise above) the strike rate of the floors (caps). The variable interest rates used in the calculation of projected receipts on the collars are based on an expectation of future interest rates derived from observable market interest rate curves and volatilities. The Company also compares the reasonableness of the pricing quarterly through a validation process involving additional independent third parties. Interest Rate Swap Contracts. Fair values for derivative interest rate swap contracts are obtained from an independent third party. The values are based upon the estimated amounts to settle the contracts considering current interest rates and are calculated using discounted cash flows that are observable, or that can be corroborated by observable market data. The inputs used to determine fair value include the United States Dollar – Secured Overnight Financing Rate (“SOFR”) forward curve to estimate variable rate cash inflows and SOFR to estimate the discount rate. The estimated variable rate cash inflows are compared to the fixed rate outflows and such difference is discounted to a present value to estimate the fair value of the interest rate swaps. The Company also compares the reasonableness of the pricing quarterly through a validation process involving additional independent third parties. For purposes of potential valuation adjustments to our derivative positions, we evaluate both our credit risk and the credit risk of our counterparties. Accordingly, we have considered factors such as the likelihood of our default and the default of our counterparties, our net exposures and remaining contractual life, among other things, in determining if any fair value adjustments related to credit risk are required. The change in value of derivative assets and derivative liabilities attributable to credit risk was not significant during the reported periods. Interest Rate Lock Commitments. Fair value measurements for interest rate lock commitments are obtained from an independent pricing service. The fair value measurements consider observable data that may include prices available from secondary market investors taking into consideration various characteristics of the loan, including the loan amount, interest rate, value of the servicing, and loan to value ratio, among other things. Observable data is then adjusted to reflect changes in interest rates, the Company’s estimated pull-through rate, and estimated direct costs necessary to complete the commitment into a closed loan net of origination, and processing fees collected from the borrower. Forward Loan Sales Contracts. The fair value measurements for forward loan sales contracts are obtained from an independent pricing service. The fair value measurements consider observable data that includes sales of similar loans. Deferred Compensation Plan Assets and Liabilities.
Recent Authoritative Accounting Guidance	Recent Authoritative Accounting Guidance ASU 2023-02, “ Investments—Equity Method and Joint Ventures (Topic 323), Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method ” In March 2023, the FASB issued ASU 2023-02, Investments—Equity Method and Joint Ventures (Topic 323), Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method that permit reporting entities to elect to account for their tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. Previously, this method was only available for qualifying tax equity investments in low-income housing tax credit structures. The amendments also require that a reporting entity disclose certain information in annual and interim reporting periods that enable investors to understand certain information about its investments that generate income tax credits and other income tax benefits from a tax credit program. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. The Amendments in this ASU became effective for the Company on January 1, 2024. The Company elected the modified retrospective approach for qualifying New Market Tax Credits and adjusted beginning retained earnings by an increase of $1.2 million related to the previously recorded deferred taxes. Prospectively, both the amortization of the investment in Low Income Housing Tax Credits and the New Market Tax Credits are recorded net within income tax expense. ASU 2023-06, “ Disclosure Improvements—Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative ” In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements—Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative that amends the ASC to incorporate certain disclosure requirements from SEC Release No. 33-10532 - Disclosure Update and Simplification that was issued in 2018. The effective date for each amendment will be the date on which the SEC’s removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption prohibited. The Company does not anticipate the adoption of ASU 2023-06 will have a significant impact on the Company’s financial position, results of operations, or liquidity. ASU 2023-07, “ Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ” In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to improve disclosure requirements, primarily through enhanced disclosures about significant segment expenses. This update does not change how a public entity identifies its operating segments; however, it does require that an entity that has single reportable segment provide all the disclosures required by the amendments in this update. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. A public entity should apply the amendments in this update retrospectively to all prior periods presented in the consolidated financial statements. Early adoption is permitted. The Company currently has one reportable operating segment, Community Banking. This ASU will not impact the Company’s consolidated financial statements and will have minimal impact to the disclosures, requiring identification of the chief operating decision maker and the information used to make operating decisions and to allocate resources. ASU 2023-09, “ Income Taxes (Topic 740): Improvements to Income Tax Disclosures ” In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures that require public business entities to annually disclose (1) specific categories in their rate reconciliation; (2) additional information for reconciling items that meet a quantitative threshold; (3) the amount of income taxes paid (net of refunds received) disaggregated by federal, state, and foreign taxes; (4) the amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which the income taxes paid that meet a quantitative threshold; (5) income (or loss) from continuing operations before income tax expense (or benefit) disaggregated between domestic and foreign; and (6) income tax expense (or benefit) from continuing operations disaggregated by federal, state, and foreign. The ASU eliminates the requirement to disclose the nature and estimate of the range of the reasonably possible change in the unrecognized tax benefits balance in the next 12 months and to disclose the cumulative amount of each type of temporary difference when a deferred tax liability is not recognized because of the exceptions to comprehensive recognition of deferred taxes related to subsidiaries and corporate joint ventures. For public business entities, the amendments are effective for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The amendments should be applied on a prospective basis, but retrospective application is permitted. The Company is currently evaluating the impact of the standard and does not anticipate it will have a significant impact on the Company’s financial position, results of operations, or liquidity.

Accounting Changes and Error Co

Accounting Changes and Error Corrections (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Changes and Error Corrections [Abstract]
Recent Authoritative Accounting Guidance	Recent Authoritative Accounting Guidance ASU 2023-02, “ Investments—Equity Method and Joint Ventures (Topic 323), Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method ” In March 2023, the FASB issued ASU 2023-02, Investments—Equity Method and Joint Ventures (Topic 323), Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method that permit reporting entities to elect to account for their tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. Previously, this method was only available for qualifying tax equity investments in low-income housing tax credit structures. The amendments also require that a reporting entity disclose certain information in annual and interim reporting periods that enable investors to understand certain information about its investments that generate income tax credits and other income tax benefits from a tax credit program. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. The Amendments in this ASU became effective for the Company on January 1, 2024. The Company elected the modified retrospective approach for qualifying New Market Tax Credits and adjusted beginning retained earnings by an increase of $1.2 million related to the previously recorded deferred taxes. Prospectively, both the amortization of the investment in Low Income Housing Tax Credits and the New Market Tax Credits are recorded net within income tax expense. ASU 2023-06, “ Disclosure Improvements—Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative ” In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements—Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative that amends the ASC to incorporate certain disclosure requirements from SEC Release No. 33-10532 - Disclosure Update and Simplification that was issued in 2018. The effective date for each amendment will be the date on which the SEC’s removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption prohibited. The Company does not anticipate the adoption of ASU 2023-06 will have a significant impact on the Company’s financial position, results of operations, or liquidity. ASU 2023-07, “ Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures ” In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to improve disclosure requirements, primarily through enhanced disclosures about significant segment expenses. This update does not change how a public entity identifies its operating segments; however, it does require that an entity that has single reportable segment provide all the disclosures required by the amendments in this update. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. A public entity should apply the amendments in this update retrospectively to all prior periods presented in the consolidated financial statements. Early adoption is permitted. The Company currently has one reportable operating segment, Community Banking. This ASU will not impact the Company’s consolidated financial statements and will have minimal impact to the disclosures, requiring identification of the chief operating decision maker and the information used to make operating decisions and to allocate resources. ASU 2023-09, “ Income Taxes (Topic 740): Improvements to Income Tax Disclosures ” In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures that require public business entities to annually disclose (1) specific categories in their rate reconciliation; (2) additional information for reconciling items that meet a quantitative threshold; (3) the amount of income taxes paid (net of refunds received) disaggregated by federal, state, and foreign taxes; (4) the amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which the income taxes paid that meet a quantitative threshold; (5) income (or loss) from continuing operations before income tax expense (or benefit) disaggregated between domestic and foreign; and (6) income tax expense (or benefit) from continuing operations disaggregated by federal, state, and foreign. The ASU eliminates the requirement to disclose the nature and estimate of the range of the reasonably possible change in the unrecognized tax benefits balance in the next 12 months and to disclose the cumulative amount of each type of temporary difference when a deferred tax liability is not recognized because of the exceptions to comprehensive recognition of deferred taxes related to subsidiaries and corporate joint ventures. For public business entities, the amendments are effective for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The amendments should be applied on a prospective basis, but retrospective application is permitted. The Company is currently evaluating the impact of the standard and does not anticipate it will have a significant impact on the Company’s financial position, results of operations, or liquidity.

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Amortized Cost and Approximate Fair Values of Investment Securities	The amortized cost and the approximate fair values of investment securities are summarized as follows: September 30, 2024 Amortized Gross Gross Estimated Available-for-Sale: U.S. Treasury notes $ 250.2 $ — $ (19.2) $ 231.0 State, county, and municipal securities 252.8 — (31.9) 220.9 Obligations of U.S. government agencies 171.9 — (6.5) 165.4 U.S. agency commercial mortgage-backed securities 1,164.1 1.4 (60.2) 1,105.3 U.S. agency residential mortgage-backed securities 1,354.2 2.4 (94.2) 1,262.4 Collateralized mortgage obligations 1,202.1 2.2 (87.7) 1,116.6 Private mortgage-backed securities 223.3 — (23.7) 199.6 Collateralized loan obligation 987.4 0.6 — 988.0 Corporate securities 260.0 — (14.9) 245.1 Total $ 5,866.0 $ 6.6 $ (338.3) $ 5,534.3 September 30, 2024 Amortized Cost 1 Allowance for Credit Losses Net Amortized Cost Gross Gross Estimated Held-to-Maturity: U.S. Treasury notes $ 99.6 $ — $ 99.6 $ — $ (0.4) $ 99.2 State, county, and municipal securities 176.7 — 176.7 0.3 (20.6) 156.4 Obligations of U.S. government agencies 356.4 — 356.4 — (32.0) 324.4 U.S. agency commercial mortgage-backed securities 493.0 — 493.0 — (41.8) 451.2 U.S. agency residential mortgage-backed securities 1,119.5 — 1,119.5 0.5 (106.2) 1,013.8 Collateralized mortgage obligations 439.8 — 439.8 0.8 (57.8) 382.8 Corporate securities 57.0 (0.7) 56.3 — (3.6) 52.7 Total $ 2,742.0 $ (0.7) $ 2,741.3 $ 1.6 $ (262.4) $ 2,480.5 (1) Amortized cost presented above includes $8.6 million of unamortized gains in U.S. agency residential and commercial mortgage-backed securities and collateralized mortgage obligations related to the 2021 transfer of securities from available-for-sale to held-to-maturity, and $16.5 million of unamortized losses in state, county, and municipal, obligations of U.S. government agencies and collateralized loan obligations related to the 2022 transfer of securities from available-for-sale to held-to-maturity. December 31, 2023 Amortized Gross Gross Estimated Available-for-Sale: U.S. Treasury notes $ 250.2 $ — $ (25.5) $ 224.7 State, county, and municipal securities 256.7 — (36.9) 219.8 Obligations of U.S. government agencies 179.4 — (10.9) 168.5 U.S. agency commercial mortgage-backed securities 1,192.7 0.6 (87.7) 1,105.6 U.S. agency residential mortgage-backed securities 1,496.3 1.2 (130.6) 1,366.9 Collateralized mortgage obligations 1,308.5 1.3 (120.3) 1,189.5 Private mortgage-backed securities 241.3 — (30.9) 210.4 Collateralized loan obligation 1,121.9 0.1 (2.3) 1,119.7 Corporate securities 260.8 — (24.4) 236.4 Total $ 6,307.8 $ 3.2 $ (469.5) $ 5,841.5 December 31, 2023 Amortized Cost 1 Allowance for Credit Losses Net Amortized Cost Gross Gross Estimated Held-to-Maturity: U.S. Treasury notes $ 399.0 $ — $ 399.0 $ — $ (2.8) $ 396.2 State, county, and municipal securities 179.2 — 179.2 0.2 (24.2) 155.2 Obligations of U.S. government agencies 354.5 — 354.5 — (42.4) 312.1 U.S. agency commercial mortgage-backed securities 510.5 — 510.5 — (52.9) 457.6 U.S. agency residential mortgage-backed securities 1,232.6 — 1,232.6 — (137.0) 1,095.6 Collateralized mortgage obligations 475.9 — 475.9 0.2 (69.0) 407.1 Corporate securities 57.0 (0.8) 56.2 — (6.0) 50.2 Total $ 3,208.7 $ (0.8) $ 3,207.9 $ 0.4 $ (334.3) $ 2,874.0 (1) Amortized cost presented above includes $10.7 million of unamortized gains and $18.1 million of unamortized losses related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity.
Gross Unrealized Losses and Fair Values of Investment Securities	The following tables show the gross unrealized losses and fair values of available-for-sale investment securities and the length of time individual investment securities have been in an unrealized loss position as of September 30, 2024 and December 31, 2023. Less than 12 Months 12 Months or More Total September 30, 2024 Fair Gross Fair Gross Fair Gross Available-for-Sale: U.S. Treasury notes $ — $ — $ 231.0 $ (19.2) $ 231.0 $ (19.2) State, county, and municipal securities — — 218.8 (31.9) 218.8 (31.9) Obligations of U.S. government agencies — — 165.1 (6.5) 165.1 (6.5) U.S. agency commercial mortgage-backed securities 0.1 — 1,048.8 (60.2) 1,048.9 (60.2) U.S. agency residential mortgage-backed securities — — 1,167.0 (94.2) 1,167.0 (94.2) Collateralized mortgage obligations 3.2 — 1,048.5 (87.7) 1,051.7 (87.7) Private mortgage-backed securities — — 199.5 (23.7) 199.5 (23.7) Corporate securities — — 217.0 (14.9) 217.0 (14.9) Total $ 3.3 $ — $ 4,295.7 $ (338.3) $ 4,299.0 $ (338.3) Less than 12 Months 12 Months or More Total December 31, 2023 Fair Gross Fair Gross Fair Gross Available-for-Sale: U.S. Treasury notes $ — $ — $ 224.7 $ (25.5) $ 224.7 $ (25.5) State, county, and municipal securities — — 217.1 (36.9) 217.1 (36.9) Obligations of U.S. government agencies — — 168.0 (10.9) 168.0 (10.9) U.S. agency commercial mortgage-backed securities 0.2 — 1,083.1 (87.7) 1,083.3 (87.7) U.S. agency residential mortgage-backed securities 0.7 — 1,287.5 (130.6) 1,288.2 (130.6) Collateralized mortgage obligations — — 1,142.4 (120.3) 1,142.4 (120.3) Private mortgage-backed securities — — 210.5 (30.9) 210.5 (30.9) Collateralized loan obligation — — 935.7 (2.3) 935.7 (2.3) Corporate securities — — 236.5 (24.4) 236.5 (24.4) Total $ 0.9 $ — $ 5,505.5 $ (469.5) $ 5,506.4 $ (469.5)
Debt Securities, Held-to-maturity, Credit Quality Indicator	The following table summarizes the credit quality indicators of held-to-maturity securities at amortized cost for the periods indicated: September 30, 2024 AAA AA A BBB BB Not Rated Total U.S. Treasury notes $ 99.6 $ — $ — $ — $ — $ — $ 99.6 State, county, and municipal securities 85.7 74.2 10.1 — — 6.7 176.7 Obligations of U.S. government agencies 356.4 — — — — — 356.4 U.S. agency commercial mortgage-backed securities FNMA/FHLMC 349.7 — — — — — 349.7 GNMA 143.3 — — — — — 143.3 U.S. agency residential mortgage-backed securities FNMA/FHLMC 1,080.7 — — — — — 1,080.7 GNMA 38.8 — — — — — 38.8 Collateralized mortgage obligations FNMA/FHLMC 308.5 — — — — — 308.5 GNMA 131.3 — — — — — 131.3 Corporate securities — — — 47.0 5.0 5.0 57.0 Total $ 2,594.0 $ 74.2 $ 10.1 $ 47.0 $ 5.0 $ 11.7 $ 2,742.0 December 31, 2023 AAA AA A BBB BB Not Rated Total U.S. Treasury notes $ 399.0 $ — $ — $ — $ — $ — $ 399.0 State, county, and municipal securities 69.0 92.3 10.6 — — 7.3 179.2 Obligations of U.S. government agencies 354.5 — — — — — 354.5 U.S. agency commercial mortgage-backed securities FNMA/FHLMC 359.7 — — — — — 359.7 GNMA 150.8 — — — — — 150.8 U.S. agency residential mortgage-backed securities FNMA/FHLMC 1,189.8 — — — — — 1,189.8 GNMA 42.8 — — — — — 42.8 Collateralized mortgage obligations FNMA/FHLMC 334.1 — — — — — 334.1 GNMA 141.8 — — — — — 141.8 Corporate securities — — — 47.0 5.0 5.0 57.0 Total $ 3,041.5 $ 92.3 $ 10.6 $ 47.0 $ 5.0 $ 12.3 $ 3,208.7
Maturities of Investment Securities	Available-for-Sale Held-to-Maturity September 30, 2024 Amortized Estimated Amortized Estimated Within one year $ 88.7 $ 87.5 $ 101.1 $ 100.6 After one year but within five years 1,326.9 1,265.9 416.0 396.8 After five years but within ten years 1,166.4 1,095.1 485.5 437.5 After ten years 3,284.0 3,085.8 1,739.4 1,545.6 Total $ 5,866.0 $ 5,534.3 $ 2,742.0 $ 2,480.5

Loans Held for Sale (Tables)

Loans Held for Sale (Tables)	9 Months Ended
	Sep. 30, 2024
Loans Held for Sale [Abstract]
Loans Held For Sale (Table)	The following table presents loans held for sale by class of receivable for the dates indicated: September 30, December 31, Loans held for sale: Agricultural, at lower of cost or market $ 18.8 $ 19.6 Commercial real estate, at lower of cost or market — 27.3 Residential mortgage, at fair value 2.1 0.5 Total loans held for sale $ 20.9 $ 47.4
Non-Residential Loans Held for Sale	The table below presents the non-residential mortgage loans held for sale activity for the 2024 period: Agricultural Commercial Beginning balance as of December 31, 2023 $ 19.6 $ 27.3 Repayments (0.8) — Loan disposals — (27.3) Ending balance as of September 30, 2024 $ 18.8 $ —

Loans Held for Investment (Tabl

Loans Held for Investment (Tables)	9 Months Ended
	Sep. 30, 2024
Receivables [Abstract]
Schedule of Loans by Class	The following table presents loans by class of receivable and portfolio segment as of the dates indicated: September 30, December 31, Real estate: Commercial $ 9,219.3 $ 8,869.2 Construction 1,307.9 1,826.5 Residential 2,217.8 2,244.3 Agricultural 726.4 716.8 Total real estate 13,471.4 13,656.8 Consumer: Indirect 742.2 740.9 Direct and advance lines 136.9 141.6 Credit card 76.4 76.5 Total consumer 955.5 959.0 Commercial 2,919.7 2,906.8 Agricultural 689.8 769.4 Other, including overdrafts 2.5 0.1 Loans held for investment 18,038.9 18,292.1 Deferred loan fees and costs (11.8) (12.5) Loans held for investment, net of deferred fees and costs 18,027.1 18,279.6 Allowance for credit losses (225.4) (227.7) Net loans held for investment $ 17,801.7 $ 18,051.9
Schedule of Allowance for Loan Losses by Portfolio Segment	The following tables represent, by loan portfolio segments, the activity in the allowance for credit losses for loans held for investment: Three Months Ended September 30, 2024 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 139.7 $ 18.3 $ (22.2) $ 0.2 $ 136.0 Consumer 18.5 1.5 (4.1) 1.3 17.2 Commercial 69.2 (0.1) (2.5) 0.2 66.8 Agricultural 5.4 0.3 (0.3) — 5.4 Total allowance for credit losses $ 232.8 $ 20.0 $ (29.1) $ 1.7 $ 225.4 Nine Months Ended September 30, 2024 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 160.1 $ 10.3 $ (35.5) $ 1.1 $ 136.0 Consumer 13.0 12.5 (11.9) 3.6 17.2 Commercial 50.2 23.2 (8.7) 2.1 66.8 Agricultural 4.4 1.0 (0.3) 0.3 5.4 Total allowance for credit losses $ 227.7 $ 47.0 $ (56.4) $ 7.1 $ 225.4 Three Months Ended September 30, 2023 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 158.7 $ 1.8 $ (1.8) $ 3.5 $ 162.2 Consumer 13.7 1.8 (3.7) 1.1 12.9 Commercial 49.5 (0.9) (0.7) 0.5 48.4 Agricultural 2.7 0.5 — — 3.2 Total allowance for credit losses $ 224.6 $ 3.2 $ (6.2) $ 5.1 $ 226.7 Nine Months Ended September 30, 2023 Beginning Balance Provision for (reversal of) Credit Losses Loans Charged-Off (2) Recoveries Collected Ending Balance Allowance for credit losses (1) Real estate $ 138.7 $ 35.6 $ (16.6) $ 4.5 $ 162.2 Consumer 23.3 (3.7) (10.4) 3.7 12.9 Commercial 54.9 (6.2) (2.2) 1.9 48.4 Agricultural 3.2 (0.4) — 0.4 3.2 Total allowance for credit losses $ 220.1 $ 25.3 $ (29.2) $ 10.5 $ 226.7 (1) Amounts presented exclude the allowance for credit losses related to unfunded commitments and investment securities. The allowance for credit losses related to unfunded commitments and investment securities are included in the “Financial Instruments with Off-Balance Sheet Risk” Note and “Investment Securities” Note, respectively. (2) Loans, or portions thereof, are charged-off against the allowance for credit losses when management believes the collectability of the principal is unlikely, or, with respect to consumer installment loans, according to an established delinquency schedule.
Schedule of Recorded Investment in Impaired Loans	The following tables present the principal balance of collateral-dependent loans by class of receivable as of the dates indicated: Collateral Type As of September 30, 2024 Business Assets Real Property Other Total Real estate: Commercial $ — $ 34.1 $ — $ 34.1 Construction — — — — Residential — 1.9 — 1.9 Agricultural — 1.0 — 1.0 Total real estate — 37.0 — 37.0 Commercial 71.2 0.1 0.7 72.0 Agricultural — 0.5 0.1 0.6 Total collateral-dependent loans $ 71.2 $ 37.6 $ 0.8 $ 109.6 Collateral Type As of December 31, 2023 Business Assets Real Property Other Total Real estate: Commercial $ — $ 26.6 $ — $ 26.6 Construction — 17.0 — 17.0 Residential — 0.5 — 0.5 Agricultural — 1.2 — 1.2 Total real estate — 45.3 — 45.3 Commercial 4.5 1.4 0.7 6.6 Agricultural 0.7 — — 0.7 Total collateral-dependent loans $ 5.2 $ 46.7 $ 0.7 $ 52.6
Schedule of Recorded Investment in Past Due Loans by Class	Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Loans classified in the following table as 90 days or more past due continue to accrue interest. The following tables present the contractual aging of the Company’s recorded principal balance of loans by class of receivable as of the dates indicated: Total Loans 30 - 59 60 - 89 90 or more 30 or More Days Days Days Days Current Non-accrual Total As of September 30, 2024 Past Due Past Due Past Due Past Due Loans Loans (1) Loans Real estate: Commercial $ 5.1 $ 6.8 $ — $ 11.9 $ 9,162.2 $ 45.2 $ 9,219.3 Construction 3.6 0.1 — 3.7 1,304.1 0.1 1,307.9 Residential 2.6 2.1 0.2 4.9 2,198.6 14.3 2,217.8 Agricultural 2.4 — — 2.4 719.3 4.7 726.4 Total real estate 13.7 9.0 0.2 22.9 13,384.2 64.3 13,471.4 Consumer: Indirect 6.4 1.6 0.1 8.1 730.7 3.4 742.2 Direct and advance lines 1.0 0.4 — 1.4 135.1 0.4 136.9 Credit card 0.7 0.5 0.7 1.9 74.5 — 76.4 Total consumer 8.1 2.5 0.8 11.4 940.3 3.8 955.5 Commercial 4.3 1.5 0.6 6.4 2,831.7 81.6 2,919.7 Agricultural 1.6 — 0.2 1.8 665.0 23.0 689.8 Other, including overdrafts — — — — 2.5 — 2.5 Loans held for investment $ 27.7 $ 13.0 $ 1.8 $ 42.5 $ 17,823.7 $ 172.7 $ 18,038.9 Total Loans 30 - 59 60 - 89 90 or more 30 or More Days Days Days Days Current Non-accrual Total As of December 31, 2023 Past Due Past Due Past Due Past Due Loans Loans (1) Loans Real estate: Commercial $ 12.7 $ 6.1 $ — $ 18.8 $ 8,822.2 $ 28.2 $ 8,869.2 Construction 3.1 0.4 — 3.5 1,805.8 17.2 1,826.5 Residential 11.9 3.1 0.6 15.6 2,218.0 10.7 2,244.3 Agricultural 1.8 — — 1.8 709.6 5.4 716.8 Total real estate 29.5 9.6 0.6 39.7 13,555.6 61.5 13,656.8 Consumer: Indirect 8.0 2.2 0.4 10.6 727.6 2.7 740.9 Direct and advance lines 0.9 0.2 — 1.1 140.2 0.3 141.6 Credit card 0.7 0.5 0.6 1.8 74.7 — 76.5 Total consumer 9.6 2.9 1.0 13.5 942.5 3.0 959.0 Commercial 14.5 1.1 0.3 15.9 2,879.4 11.5 2,906.8 Agricultural 0.1 — 3.0 3.1 735.9 30.4 769.4 Other, including overdrafts — — — — 0.1 — 0.1 Loans held for investment $ 53.7 $ 13.6 $ 4.9 $ 72.2 $ 18,113.5 $ 106.4 $ 18,292.1 (1) As of September 30, 2024 and December 31, 2023, none of our non-accrual loans were earning interest income. Additionally, no material interest income was recognized on non-accrual loans during the three and the nine months ended September 30, 2024 and 2023, respectively. There were $0.4 million and $2.4 million in reversals of accrued interest during the three and the nine months ended September 30, 2024, and $1.0 million and $1.9 million in reversals of accrued interest during the three and the nine months ended September 30, 2023.
Schedule of Recorded Credit Quality Indicator	The Company evaluates the credit quality and loan performance for the allowance for credit losses of the following class of receivables by origination year using the origination date or the loan’s subsequent renewal or modification date based on the aforementioned risk scale as of and for the periods ended: As of and for the nine months ended September 30, 2024 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2024 2023 2022 2021 2020 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Commercial real estate: Pass $ 1,026.8 $ 1,366.2 $ 1,981.5 $ 1,441.7 $ 1,137.3 $ 1,922.5 $ 48.2 $ 56.7 $ 8,980.9 Special mention 12.6 9.4 21.1 18.3 2.2 36.9 — — 100.5 Substandard 27.6 10.7 4.6 39.3 7.9 47.8 — — 137.9 Total $ 1,067.0 $ 1,386.3 $ 2,007.2 $ 1,499.3 $ 1,147.4 $ 2,007.2 $ 48.2 $ 56.7 $ 9,219.3 Current-period gross charge-offs — 5.7 — 15.8 — 0.1 — — 21.6 Construction real estate: Pass $ 256.1 $ 263.4 $ 484.4 $ 114.0 $ 19.7 $ 24.2 $ 129.3 $ 4.9 $ 1,296.0 Special mention 3.2 — 6.4 — — — — — 9.6 Substandard 1.9 — — — — 0.4 — — 2.3 Total $ 261.2 $ 263.4 $ 490.8 $ 114.0 $ 19.7 $ 24.6 $ 129.3 $ 4.9 $ 1,307.9 Current-period gross charge-offs — — 13.1 — 0.1 — — — 13.2 Agricultural real estate: Pass $ 92.2 $ 65.0 $ 113.6 $ 121.4 $ 79.9 $ 159.4 $ 25.8 $ — $ 657.3 Special mention 1.1 6.6 5.9 5.1 7.6 1.0 — — 27.3 Substandard 12.2 4.4 19.2 3.7 1.4 0.9 — — 41.8 Total $ 105.5 $ 76.0 $ 138.7 $ 130.2 $ 88.9 $ 161.3 $ 25.8 $ — $ 726.4 Current-period gross charge-offs — — — — — — — — — Commercial: Pass $ 386.0 $ 395.5 $ 406.9 $ 335.8 $ 176.1 $ 278.3 $ 783.5 $ 6.7 $ 2,768.8 Special mention 3.0 6.9 8.8 1.5 1.0 1.0 17.5 — 39.7 Substandard 28.9 4.2 5.6 5.2 8.1 3.6 7.1 — 62.7 Doubtful 1.2 1.7 2.5 — — — 43.1 — 48.5 Total $ 419.1 $ 408.3 $ 423.8 $ 342.5 $ 185.2 $ 282.9 $ 851.2 $ 6.7 $ 2,919.7 Current-period gross charge-offs 0.4 1.9 1.0 0.3 0.1 0.1 1.9 3.0 8.7 Agricultural: Pass $ 81.3 $ 52.5 $ 43.2 $ 20.5 $ 16.7 $ 7.4 $ 355.7 $ — $ 577.3 Special mention 0.5 3.6 0.7 0.1 1.0 0.2 5.2 0.1 11.4 Substandard 51.9 24.6 — 0.1 0.6 — 23.9 — 101.1 Total $ 133.7 $ 80.7 $ 43.9 $ 20.7 $ 18.3 $ 7.6 $ 384.8 $ 0.1 $ 689.8 Current-period gross charge-offs — — — 0.3 — — — — 0.3 December 31, 2023 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2023 2022 2021 2020 2019 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Commercial real estate: Pass $ 1,268.0 $ 2,065.0 $ 1,612.2 $ 1,200.1 $ 716.5 $ 1,660.5 $ 46.5 $ 28.1 $ 8,596.9 Special mention 4.2 9.1 42.6 12.9 27.5 17.1 0.3 — 113.7 Substandard 65.4 11.8 18.9 2.4 30.1 28.5 0.2 — 157.3 Doubtful — — 1.3 — — — — — 1.3 Total $ 1,337.6 $ 2,085.9 $ 1,675.0 $ 1,215.4 $ 774.1 $ 1,706.1 $ 47.0 $ 28.1 $ 8,869.2 Current-period gross charge-offs 1.7 0.3 1.7 2.6 — 1.3 — — 7.6 Construction: Pass $ 493.7 $ 735.3 $ 331.2 $ 36.7 $ 16.8 $ 36.2 $ 104.4 $ 13.7 $ 1,768.0 Special mention 0.5 6.6 1.3 — — 0.2 — 0.9 9.5 Substandard 7.0 4.0 24.4 0.2 — 0.4 — — 36.0 Doubtful — 13.0 — — — — — — 13.0 Total $ 501.2 $ 758.9 $ 356.9 $ 36.9 $ 16.8 $ 36.8 $ 104.4 $ 14.6 $ 1,826.5 Current-period gross charge-offs — — 0.1 — 0.6 — — 9.6 10.3 Agricultural real estate: Pass $ 86.2 $ 123.7 $ 126.2 $ 93.5 $ 56.7 $ 124.3 $ 31.8 $ 7.0 $ 649.4 Special mention 2.6 9.5 3.5 1.9 1.5 11.3 0.5 — 30.8 Substandard 8.1 20.8 3.6 2.6 0.4 1.1 — — 36.6 Total $ 96.9 $ 154.0 $ 133.3 $ 98.0 $ 58.6 $ 136.7 $ 32.3 $ 7.0 $ 716.8 Current-period gross charge-offs — — — — — — — — — Commercial: Pass $ 481.6 $ 507.7 $ 389.8 $ 215.1 $ 108.7 $ 272.9 $ 762.3 $ 7.6 $ 2,745.7 Special mention 7.3 4.7 6.6 3.1 0.9 1.9 14.8 0.2 39.5 Substandard 15.8 19.6 9.0 7.0 1.6 3.0 58.8 0.4 115.2 Doubtful 3.3 1.3 1.6 — — 0.1 0.1 — 6.4 Total $ 508.0 $ 533.3 $ 407.0 $ 225.2 $ 111.2 $ 277.9 $ 836.0 $ 8.2 $ 2,906.8 Current-period gross charge-offs 0.2 0.4 0.5 0.5 0.2 0.1 1.4 0.1 3.4 Agricultural: Pass $ 105.7 $ 57.7 $ 31.6 $ 22.4 $ 6.1 $ 7.2 $ 421.9 $ 3.4 $ 656.0 Special mention 2.6 0.8 0.5 0.2 0.1 0.1 9.0 3.1 16.4 Substandard 43.8 0.3 2.7 0.7 28.8 2.2 18.5 — 97.0 Total $ 152.1 $ 58.8 $ 34.8 $ 23.3 $ 35.0 $ 9.5 $ 449.4 $ 6.5 $ 769.4 Current-period gross charge-offs — — — — — — — — — As of and for the nine months ended September 30, 2024 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2024 2023 2022 2021 2020 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Residential: Performing $ 14.6 $ 70.5 $ 419.9 $ 489.5 $ 454.7 $ 264.6 $ 480.2 $ 9.3 $ 2,203.3 Nonperforming 1.0 0.8 3.6 1.8 1.6 5.4 — 0.3 14.5 Total $ 15.6 $ 71.3 $ 423.5 $ 491.3 $ 456.3 $ 270.0 $ 480.2 $ 9.6 $ 2,217.8 Current-period gross charge-offs — 0.2 0.1 0.1 0.2 0.1 — — 0.7 Consumer indirect: Performing $ 203.0 $ 146.9 $ 194.8 $ 83.0 $ 55.4 $ 55.6 $ — $ — $ 738.7 Nonperforming 0.3 0.8 1.0 0.5 0.4 0.5 — — 3.5 Total $ 203.3 $ 147.7 $ 195.8 $ 83.5 $ 55.8 $ 56.1 $ — $ — $ 742.2 Current-period gross charge-offs 0.2 1.7 2.9 0.9 0.3 0.9 — — 6.9 Consumer direct and advance lines: Performing $ 37.1 $ 29.8 $ 22.2 $ 12.0 $ 5.5 $ 5.9 $ 24.0 $ — $ 136.5 Nonperforming 0.1 0.1 0.1 — — 0.1 — — 0.4 Total $ 37.2 $ 29.9 $ 22.3 $ 12.0 $ 5.5 $ 6.0 $ 24.0 $ — $ 136.9 Current-period gross charge-offs 0.1 0.5 0.7 0.2 0.1 1.3 — — 2.9 Consumer credit card: Performing $ — $ — $ — $ — $ — $ — $ 75.7 $ — $ 75.7 Nonperforming — — — — — — 0.7 — 0.7 Total $ — $ — $ — $ — $ — $ — $ 76.4 $ — $ 76.4 Current-period gross charge-offs — — — — — — 2.1 — 2.1 December 31, 2023 Term Loans Amortized Cost Basis by Origination Year Risk by Collateral 2023 2022 2021 2020 2019 Prior Revolving Loans Amortized Cost Basis Revolving Loans Converted To Term Total Residential: Performing $ 44.7 $ 356.9 $ 521.3 $ 500.6 $ 88.5 $ 217.1 $ 471.8 $ 32.1 $ 2,233.0 Nonperforming 1.1 2.1 1.2 1.1 0.7 5.1 — — 11.3 Total $ 45.8 $ 359.0 $ 522.5 $ 501.7 $ 89.2 $ 222.2 $ 471.8 $ 32.1 $ 2,244.3 Current-period gross charge-offs 0.3 — 0.1 0.1 — 0.1 — — 0.6 Consumer indirect: Performing $ 194.9 $ 264.7 $ 115.4 $ 81.1 $ 32.9 $ 48.8 $ — $ — $ 737.8 Nonperforming 0.4 0.9 0.6 0.4 0.2 0.6 — — 3.1 Total $ 195.3 $ 265.6 $ 116.0 $ 81.5 $ 33.1 $ 49.4 $ — $ — $ 740.9 Current-period gross charge-offs 0.5 3.2 1.8 0.8 0.3 0.7 — — 7.3 Consumer direct and advance lines: Performing $ 44.5 $ 32.9 $ 18.5 $ 9.4 $ 3.6 $ 6.0 $ 26.2 $ 0.2 $ 141.3 Nonperforming 0.1 0.1 0.1 — — — — — 0.3 Total $ 44.6 $ 33.0 $ 18.6 $ 9.4 $ 3.6 $ 6.0 $ 26.2 $ 0.2 $ 141.6 Current-period gross charge-offs 0.2 0.5 0.2 0.4 0.1 2.6 0.1 — 4.1 Consumer credit card: Performing $ — $ — $ — $ — $ — $ — $ 75.9 $ — $ 75.9 Nonperforming — — — — — — 0.6 — 0.6 Total $ — $ — $ — $ — $ — $ — $ 76.5 $ — $ 76.5 Current-period gross charge-offs — — — — — — 2.6 — 2.6
Financing Receivable, Troubled Debt Restructuring	The following table presents the amortized cost basis of loans, by class and by type of modification, at September 30, 2024 and 2023 that were both experiencing financial difficulty and modified during the periods indicated. The percentage of the principal balance of loans that were modified to borrowers in financial distress as compared to the principal balance of each class of receivable is also presented below: Three Months Ended September 30, 2024 Principal Forgiveness Term Extension Term Extension and Interest Rate Reduction Total % of Total Class of Loans Held for Investment (1) Real estate: Commercial $ — $ 0.5 $ — $ 0.5 0.01 % Construction — 1.9 — 1.9 0.15 Agricultural — 6.5 — 6.5 0.89 Total real estate — 8.9 — 8.9 0.07 Commercial — 0.9 0.5 1.4 0.05 Agricultural — 21.4 — 21.4 3.10 Loans held for investment (2) $ — $ 31.2 $ 0.5 $ 31.7 0.18 Nine Months Ended September 30, 2024 Real estate: Commercial $ — $ 14.7 $ — $ 14.7 0.16 % Construction — 1.9 — 1.9 0.15 Residential — 0.1 0.3 0.4 0.02 Agricultural — 12.1 — 12.1 1.67 Total real estate — 28.8 0.3 29.1 0.22 Commercial — 14.4 0.5 14.9 0.51 Agricultural — 23.2 22.2 45.4 6.58 Loans held for investment (2) $ — $ 66.4 $ 23.0 $ 89.4 0.50 Three Months Ended September 30, 2023 Principal Forgiveness Term Extension Term Extension and Interest Rate Reduction Total % of Total Class of Loans Held for Investment (1) Real estate: Commercial $ — $ 10.9 $ 0.6 $ 11.5 0.13 % Construction — 13.1 — 13.1 0.68 Residential — 0.4 — 0.4 0.02 Agricultural — 6.1 — 6.1 0.83 Total real estate — 30.5 0.6 31.1 0.23 Commercial — 1.6 — 1.6 0.05 Agricultural — 0.5 — 0.5 0.07 Loans held for investment (2) $ — $ 32.6 $ 0.6 $ 33.2 0.18 Nine Months Ended September 30, 2023 Real estate: Commercial $ 1.6 $ 23.0 $ 0.6 $ 25.2 0.29 % Construction — 13.2 — 13.2 0.68 Residential 0.1 0.5 — 0.6 0.03 Agricultural — 6.4 — 6.4 0.87 Total real estate 1.7 43.1 0.6 45.4 0.33 Commercial — 9.4 — 9.4 0.32 Agricultural — 36.4 — 36.4 5.27 Loans held for investment (2) $ 1.7 $ 88.9 $ 0.6 $ 91.2 0.50 (1) Based on the principal balance as of period end, divided by the period end principal balance of the corresponding class of receivables. (2) As of September 30, 2024 and 2023, the Company excluded $1.1 million and $1.7 million, respectively, in accrued interest from the amortized cost of the identified loans. The following tables present the financial effect of the loan modifications presented above to borrowers experiencing financial difficulty during the periods indicated: Term Extension and Interest Rate Reduction Three Months Ended September 30, 2024 Principal Forgiveness Weighted-Average Months of Term Extension Weighted-Average Months of Term Extension Weighted-Average Interest Rate Reduction Real estate: Commercial $ — 5.9 0.0 — % Construction — 4.0 0.0 — Agricultural — 7.7 0.0 — Total real estate — Commercial — 5.3 59.0 0.8 Agricultural — 3.9 0.0 — Loans held for investment (1) $ — Nine Months Ended September 30, 2024 Real estate: Commercial $ — 6.8 0.0 — % Construction — 4.0 0.0 — Residential — 11.0 31.2 3.4 Agricultural — 7.4 0.0 — Total real estate — Commercial — 7.7 9.2 1.0 Agricultural — 4.1 55.2 1.1 Loans held for investment (1) $ — Term Extension and Interest Rate Reduction Three Months Ended September 30, 2023 Principal Forgiveness Weighted-Average Months of Term Extension Weighted-Average Months of Term Extension Weighted-Average Interest Rate Reduction Real estate: Commercial $ — 4.6 6.0 0.25 % Construction — 9.0 0.0 — Residential — 144.4 0.0 — Agricultural — 4.0 0.0 — Total real estate — Commercial — 7.8 0.0 — Agricultural — 3.5 0.0 — Loans held for investment (1) $ — Nine Months Ended September 30, 2023 Real estate: Commercial $ 1.3 5.7 6.0 0.25 % Construction — 9.0 0.0 — Residential 0.3 139.2 0.0 — Agricultural — 4.6 0.0 — Total real estate 1.6 Commercial — 8.8 0.0 — Agricultural — 9.2 0.0 — Loans held for investment (1) $ 1.6 (1) Balances based on loan original contractual terms.

Other Real Estate Owned (Tables

Other Real Estate Owned (Tables)	9 Months Ended
	Sep. 30, 2024
Repossessed Assets [Abstract]
Other Real Estate Owned Roll Forward	Other real estate owned (“OREO”) is a category of real estate owned by the Company resulting from a default by the borrower. Information with respect to the Company’s OREO is reflected in the following table: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Beginning balance $ 6.7 $ 14.4 $ 16.5 $ 12.7 Additions 0.9 — 4.6 2.5 Valuation adjustments — (0.3) (4.2) (1.1) Dispositions (3.2) (2.5) (12.5) (2.5) Ending balance $ 4.4 $ 11.6 $ 4.4 $ 11.6

Derivatives and Hedging Activ_2

Derivatives and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The following amounts were recorded on the consolidated balance sheets related to cumulative basis adjustment for fair value hedges for the periods indicated: September 30, 2024 December 31, 2023 Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Available-for-sale securities $ 194.3 $ 5.7 $ 193.3 $ 6.7
Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location	The following table summarizes the fair values of our derivative instruments on a gross and net basis for the periods indicated. The derivative asset and liability balances are presented on a gross basis, prior to the application of bilateral collateral and master netting agreements, but after the variation margin payments with central clearing organizations have been applied as settlement, as applicable. Total derivative assets and liabilities are adjusted to account for the impact of legally enforceable master netting agreements that allow us to settle all derivative contracts with a single counterparty on a net basis and to offset the net derivative position with the related cash collateral. Securities collateral related to legally enforceable master netting agreements is not offset on the consolidated balance sheets. September 30, 2024 December 31, 2023 Notional Amount Consolidated Balance Sheet Location Estimated Notional Amount Consolidated Balance Sheet Location Estimated Derivatives designated as accounting hedges: Interest rate swap contracts $ 300.0 $ 0.3 $ 550.0 $ 3.0 Derivatives not designated as accounting hedges: Interest rate swap contracts 1,468.5 28.3 1,589.0 34.3 Interest rate lock commitments 5.3 — 5.7 0.1 Derivative assets $ 1,773.8 Other assets $ 28.6 $ 2,144.7 Other assets $ 37.4 Derivatives designated as accounting hedges: Interest rate collars $ 300.0 $ 1.2 $ 300.0 $ 3.6 Interest rate swap contracts — — 300.0 2.4 Derivatives not designated as accounting hedges: Interest rate swap contracts 1,468.5 93.0 1,589.0 121.1 Risk participation agreements 95.5 — 101.1 0.1 Forward loan sales contracts 4.9 — 5.6 0.1 Derivative liabilities $ 1,868.9 Accounts payable and accrued expenses $ 94.2 $ 2,295.7 Accounts payable and accrued expenses $ 127.3
Derivatives Not Designated as Hedging Instruments	The table below presents the effect of the Company’s derivative financial instruments that are not designated as hedging instruments on the consolidated statements of income for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Location of Gain (Loss) Recognized in Income on Derivative Amount of Gain (Loss) Recognized in Income on Derivative Location of Gain (Loss) Recognized in Income on Derivative Amount of Gain (Loss) Recognized in Income on Derivative Interest rate lock commitments Mortgage banking revenues $ — $ 0.1 Mortgage banking revenues $ — $ (0.1)
Schedule of Derivative Instruments	The tables below present the gross presentation, the effects of offsetting, and a net presentation of the Company’s derivatives as of the dates indicated: September 30, 2024 Gross Assets Recognized Gross Assets Offset in the Balance Sheet Net Assets in the Balance Sheet Financial Instruments Cash Collateral Received (1) Net Amount Interest rate swap and collar contracts $ 28.6 $ — $ 28.6 $ — $ 25.8 $ 2.8 Total derivatives 28.6 — 28.6 — 25.8 2.8 Total assets $ 28.6 $ — $ 28.6 $ — $ 25.8 $ 2.8 (1) Netting adjustments represent the amounts recorded to convert derivatives assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The application of the collateral cannot reduce the net derivative position below zero. Therefore, excess collateral, if any, is not reflected above. Gross Liabilities Recognized Gross Liabilities Offset in the Balance Sheet Net Liabilities in the Balance Sheet Financial Instruments Cash Collateral Posted Net Amount Interest rate swap and collar contracts $ 94.2 $ — $ 94.2 $ — $ — $ 94.2 Total derivatives 94.2 — 94.2 — — 94.2 Repurchase agreements (2) 557.2 — 557.2 — — 557.2 Total liabilities $ 651.4 $ — $ 651.4 $ — $ — $ 651.4 (2) Repurchase agreements are fully collateralized by investment securities. December 31, 2023 Gross Assets Recognized Gross Assets Offset in the Balance Sheet Net Assets in the Balance Sheet Financial Instruments Cash Collateral Received (1) Net Amount Interest rate swap and collar contracts $ 37.3 $ — $ 37.3 $ — $ 32.7 $ 4.6 Interest rate lock commitments 0.1 — 0.1 — — 0.1 Total derivatives 37.4 — 37.4 — 32.7 4.7 Total assets $ 37.4 $ — $ 37.4 $ — $ 32.7 $ 4.7 (1) Netting adjustments represent the amounts recorded to convert derivatives assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The application of the collateral cannot reduce the net derivative position below zero. Therefore, excess collateral, if any, is not reflected above. Gross Liabilities Recognized Gross Liabilities Offset in the Balance Sheet Net Liabilities in the Balance Sheet Financial Instruments Cash Collateral Posted Net Amount Interest rate swap and collar contracts $ 127.1 $ — $ 127.1 $ — $ — $ 127.1 Risk participation agreements 0.1 — 0.1 — — 0.1 Forward loan sales contracts 0.1 — 0.1 — — 0.1 Total derivatives 127.3 — 127.3 — — 127.3 Repurchase agreements (2) 782.7 — 782.7 — — 782.7 Total liabilities $ 910.0 $ — $ 910.0 $ — $ — $ 910.0 (2) Repurchase agreements are fully collateralized by investment securities.

Schedule of Long-Term Debt (Tab

Schedule of Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Instruments	A summary of long-term debt follows: September 30, 2024 December 31, 2023 Parent Company: Fixed to floating subordinated notes, 5.25% fixed rate effective May 2020 through May 2025 $ 99.1 $ 99.0 Subsidiaries: 0.00% FHLB borrowings maturing in August 2029 3.9 — 8.00% finance lease obligation with term ending October 31, 2029 0.8 0.9 1.00% note payable maturing December 31, 2041, interest only payable quarterly until September 30, 2024 and then principal and interest until maturity 5.1 5.1 Note payable maturing March 31, 2038, interest only payable at 1.30% monthly until March 31, 2025 and then principal and interest at 3.25% until maturity 2.0 2.0 1.30% note payable maturing June 1, 2034, interest only payable monthly until March 31, 2025 and then principal and interest until maturity 0.6 0.6 1.12% note payable maturing December 31, 2045, interest only payable annually until December 31, 2028 and then principal and interest until maturity 6.8 6.8 1.35% note payable maturing December 31, 2046 interest only payable annually until December 31, 2025 and then principal and interest until maturity 6.4 6.4 1.26% note payable maturing December 31, 2051 interest only payable annually until December 31, 2031 and then principal and interest until maturity 12.6 — Total long-term debt $ 137.3 $ 120.8
Schedule of Debt	The following table presents outstanding FHLB and BTFP borrowings by original maturity classification for the dates indicated: As of September 30, 2024 Average Rate Outstanding Balance Fixed rate borrowings with tenors of up to twelve-months 4.87 % $ 1,830.0 Fixed rate borrowings with tenors over twelve-months 4.72 250.0 $ 2,080.0 As of December 31, 2023 Average Rate Outstanding Balance Fixed rate borrowings with tenors of up to three-months 5.52 % $ 2,603.0 $ 2,603.0

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings per Share	The following table sets forth the computation of basic and diluted earnings per share for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Net income $ 55.5 $ 72.7 $ 173.9 $ 196.0 Weighted average common shares outstanding for basic earnings per share computation 102,970,851 103,822,311 102,917,610 103,793,851 Dilutive effects of stock-based compensation 262,767 4,116 207,449 30,425 Weighted average common shares outstanding for diluted earnings per common share computation 103,233,618 103,826,427 103,125,059 103,824,276 Basic earnings per common share $ 0.54 $ 0.70 $ 1.69 $ 1.89 Diluted earnings per common share 0.54 0.70 1.69 1.89 Anti-dilutive unvested time restricted stock 5,841 162,231 47,854 162,231

Regulatory Capital (Tables)

Regulatory Capital (Tables)	9 Months Ended
	Sep. 30, 2024
Banking and Thrift, Other Disclosure [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	Actual capital amounts and ratios for the Company and its subsidiary Bank, as of September 30, 2024 and December 31, 2023 are presented in the following tables: Actual Minimum Required for Capital Adequacy Purposes For Capital Adequacy Purposes Plus Capital Conservation Buffer (1) Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements (2) September 30, 2024 Amount Ratio Amount Ratio Amount Ratio Amount Ratio Total risk-based capital: Consolidated $ 2,976.2 14.11 % $ 1,687.2 8.00 % $ 2,214.4 10.50 % $ 2,109.0 10.00 % FIB 2,701.2 12.84 1,683.6 8.00 2,209.7 10.50 2,104.5 10.00 Tier 1 risk-based capital: Consolidated 2,495.8 11.83 1,265.4 6.00 1,792.6 8.50 1,687.2 8.00 FIB 2,478.4 11.78 1,262.7 6.00 1,788.8 8.50 1,683.6 8.00 Common equity tier 1 risk-based capital: Consolidated 2,495.8 11.83 949.0 4.50 1,476.3 7.00 1,370.8 6.50 FIB 2,478.4 11.78 947.0 4.50 1,473.1 7.00 1,367.9 6.50 Leverage capital ratio: Consolidated 2,495.8 8.57 1,164.9 4.00 1,164.9 4.00 1,456.2 5.00 FIB 2,478.4 8.52 1,163.1 4.00 1,163.1 4.00 1,453.9 5.00 Actual Minimum Required for Capital Adequacy Purposes For Capital Adequacy Purposes Plus Capital Conservation Buffer (1) Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements (2) December 31, 2023 Amount Ratio Amount Ratio Amount Ratio Amount Ratio Total risk-based capital: Consolidated $ 2,941.1 13.28 % $ 1,771.6 8.00 % $ 2,325.2 10.50 % $ 2,214.5 10.00 % FIB 2,662.0 12.04 1,768.3 8.00 2,320.8 10.50 2,210.3 10.00 Tier 1 risk-based capital: Consolidated 2,454.4 11.08 1,328.7 6.00 1,882.3 8.50 1,771.6 8.00 FIB 2,433.0 11.01 1,326.2 6.00 1,878.8 8.50 1,768.3 8.00 Common equity tier 1 risk-based capital: Consolidated 2,454.4 11.08 996.5 4.50 1,550.1 7.00 1,439.4 6.50 FIB 2,433.0 11.01 994.6 4.50 1,547.2 7.00 1,436.7 6.50 Leverage capital ratio: Consolidated 2,454.4 8.22 1,193.9 4.00 1,193.9 4.00 1,492.3 5.00 FIB 2,433.0 8.16 1,192.2 4.00 1,192.2 4.00 1,490.2 5.00 (1) The capital conservation buffer is an additional 2.5% of the amount necessary to meet the minimum risk-based capital requirements for total, tier 1, and common equity tier 1 risk-based capital. (2) The ratios to meet the requirements to be deemed “well-capitalized” are only applicable to FIB. However, the Company manages its capital position as if the requirements apply to the consolidated company and has presented the ratios as if they also applied on a consolidated basis.

Comprehensive Text Block List (

Comprehensive Text Block List (Tables)	9 Months Ended
	Sep. 30, 2024
Text Block [Abstract]
financial instruments with off-balance sheet risk	The following table presents our financial instruments with off-balance sheet risk, as well as the activity in the allowance for off-balance sheet credit losses related to those financial instruments: Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Beginning balance $ 5.8 $ 20.8 $ 18.4 $ 16.2 Provision for credit loss expense (0.2) (2.0) (12.8) 2.6 Ending balance $ 5.6 $ 18.8 $ 5.6 $ 18.8 September 30, 2024 December 31, 2023 Unused credit card lines $ 861.4 $ 814.0 Commitments to extend credit 3,290.7 4,069.2 Standby letters of credit 88.7 97.1

Other Comprehensive Income_Lo_2

Other Comprehensive Income/Loss (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Other Comprehensive Income and Related Tax Effects	The gross amounts of each component of other comprehensive loss and the related tax effects are as follows: Pre-tax Tax (Expense) Benefit Net of Tax Three Months Ended September 30, 2024 2023 2024 2023 2024 2023 Investment securities available-for sale: Change in net unrealized gains (losses) during the period $ 158.5 $ (72.1) $ (39.4) $ 17.9 $ 119.1 $ (54.2) Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity (0.2) (0.3) — 0.1 (0.2) (0.2) Cash flow hedge: Change in unrealized gains (losses) on derivatives 12.4 (13.1) (3.0) 3.2 9.4 (9.9) Reclassification adjustment for derivatives net losses included in income 3.1 2.1 (0.8) (0.5) 2.3 1.6 Total other comprehensive income (loss) $ 173.8 $ (83.4) $ (43.2) $ 20.7 $ 130.6 $ (62.7) Pre-tax Tax (Expense) Benefit Net of Tax Nine Months Ended September 30, 2024 2023 2024 2023 2024 2023 Investment securities available-for sale: Change in net unrealized gains (losses) during the period $ 134.6 $ (51.4) $ (33.5) $ 12.7 $ 101.1 $ (38.7) Reclassification adjustment for net losses included in income — 23.5 — (5.8) — 17.7 Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale — (7.2) — 1.8 — (5.4) Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity (0.5) (1.1) — 0.3 (0.5) (0.8) Cash flow hedge: Change in unrealized gains on derivatives (10.1) (27.2) 2.8 6.7 (7.3) (20.5) Reclassification adjustment for derivatives net losses included in income 11.2 4.1 (2.9) (1.0) 8.3 3.1 Total other comprehensive income (loss) $ 135.2 $ (59.3) $ (33.6) $ 14.7 $ 101.6 $ (44.6)
Schedule of Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive loss, net of related tax effects, are as follows: September 30, 2024 December 31, 2023 Net unrealized loss on investment securities available-for-sale $ (249.0) $ (350.1) Net unrealized loss on investment securities transferred to held-to-maturity (5.9) (5.6) Net unrealized loss on derivatives — (0.8) Net accumulated other comprehensive loss $ (254.9) $ (356.5)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis	Financial assets and financial liabilities measured at fair value on a recurring basis are as follows: Fair Value Measurements at Reporting Date Using As of September 30, 2024 Fair Value Quoted Prices in Significant Other Significant Investment debt securities available-for-sale: U.S. Treasury notes $ 231.0 $ — $ 231.0 $ — State, county, and municipal securities 220.9 — 220.9 — Obligations of U.S. government agencies 165.4 — 165.4 — U.S. agency commercial mortgage-backed securities 1,105.3 — 1,105.3 — U.S. agency residential mortgage-backed securities 1,262.4 — 1,262.4 — Collateralized mortgage obligations 1,116.6 — 1,116.6 — Private mortgage-backed securities 199.6 — 199.6 — Collateralized loan obligations 988.0 — 988.0 — Corporate securities 245.1 — 245.1 — Loans held for sale 2.1 — 2.1 — Derivative assets: Interest rate swap contracts 28.6 — 28.6 — Derivative liabilities: Interest rate collars 1.2 — 1.2 — Interest rate swap contracts 93.0 — 93.0 — Deferred compensation plan assets 21.8 21.8 — — Deferred compensation plan liabilities 21.8 21.8 — — Fair Value Measurements at Reporting Date Using As of December 31, 2023 Fair Value Quoted Prices in Significant Other Significant Investment debt securities available-for-sale: U.S. Treasury notes $ 224.7 $ — $ 224.7 $ — State, county and municipal securities 219.8 — 219.8 — Obligations of U.S. government agencies 168.5 — 168.5 — U.S. agency commercial mortgage-backed securities 1,105.6 — 1,105.6 — U.S. agency residential mortgage-backed securities 1,366.9 — 1,366.9 — Collateralized mortgage obligations 1,189.5 — 1,189.5 — Private mortgage-backed securities 210.4 — 210.4 — Collateralized loan obligations 1,119.7 — 1,119.7 — Corporate securities 236.4 — 236.4 — Loans held for sale 0.5 — 0.5 — Derivative assets: Interest rate swap contracts 37.3 — 37.3 — Forward loan sales contracts 0.1 — 0.1 — Derivative liabilities Interest rate collars 3.6 — 3.6 — Interest rate swap contracts 123.5 — 123.5 — Risk participation agreements 0.1 — 0.1 — Forward loan sales contracts 0.1 — 0.1 — Deferred compensation plan assets 19.2 19.2 — — Deferred compensation plan liabilities 19.2 19.2 — —
Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Non-Recurring Basis	The following table presents information about the Company’s assets and liabilities measured at fair value on a non-recurring basis: Fair Value Measurements at Reporting Date Using As of September 30, 2024 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Significant Collateral-dependent loans $ 109.6 $ — $ — $ 109.6 Loans held for sale 18.8 — — 18.8 Other real estate owned 4.4 — — 4.4 Long-lived assets to be disposed of by sale 1.0 — — 1.0 Fair Value Measurements at Reporting Date Using As of December 31, 2023 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Significant Collateral-dependent loans $ 52.6 $ — $ — $ 52.6 Loans held for sale 46.9 — — 46.9 Other real estate owned 16.5 — — 16.5 Long-lived assets to be disposed of by sale 1.0 — — 1.0
Fair Value Inputs, Assets, Quantitative Information	The following table presents additional quantitative information about assets measured at fair value on a non-recurring basis and for which the Company has utilized Level 3 inputs to determine fair values: Fair Value As of September 30, 2024 December 31, 2023 Valuation Unobservable Range Collateral-dependent loans $ 109.6 $ 52.6 Appraisal Appraisal adjustment 0% - 71% (41%) Loans held for sale 18.8 46.9 Fair value of collateral Discount for type of property, age of appraisal, and current status 0 - 28 (24) Other real estate owned 4.4 16.5 Appraisal Appraisal adjustment 17 - 40 (23) Long-lived assets to be disposed of by sale 1.0 1.0 Appraisal Appraisal adjustment 0 - 0 0
Fair Value, by Balance Sheet Grouping	The estimated fair values of financial instruments that are reported in the Company’s consolidated balance sheets, and are segregated by the level of the valuation inputs within the fair value hierarchy that are utilized to measure fair value, are as follows: Fair Value Measurements at Reporting Date Using As of September 30, 2024 Carrying Amount Estimated Quoted Prices in Active Markets for Significant Other Significant Financial assets: Cash and cash equivalents $ 698.6 $ 698.6 $ 698.6 $ — $ — Investment debt securities held-to-maturity 2,741.3 2,480.5 — 2,480.5 — Accrued interest receivable 127.3 127.3 — 127.3 — Mortgage servicing rights, net 26.3 37.2 — 37.2 — Loans held for sale 20.9 20.9 — 2.1 18.8 Net loans held for investment 17,801.7 17,257.5 — 17,147.9 109.6 Total financial assets $ 21,416.1 $ 20,622.0 $ 698.6 $ 19,795.0 $ 128.4 Financial liabilities: Total deposits, excluding time deposits $ 19,985.9 $ 19,985.9 $ 19,985.9 $ — $ — Time deposits 2,878.2 2,864.3 — 2,864.3 — Securities sold under repurchase agreements 557.2 557.2 — 557.2 — Other borrowed funds 2,080.0 2,080.0 — 2,080.0 — Accrued interest payable 87.7 87.7 — 87.7 — Long-term debt 137.3 132.1 — 132.1 — Subordinated debentures held by subsidiary trusts 163.1 151.0 — 151.0 — Total financial liabilities $ 25,889.4 $ 25,858.2 $ 19,985.9 $ 5,872.3 $ — Fair Value Measurements at Reporting Date Using As of December 31, 2023 Carrying Amount Estimated Quoted Prices in Active Markets for Significant Other Significant Financial assets: Cash and cash equivalents $ 578.0 $ 578.0 $ 578.0 $ — $ — Investment debt securities held-to-maturity 3,207.9 2,874.0 — 2,874.0 — Accrued interest receivable 129.1 129.1 — 129.1 — Mortgage servicing rights, net 28.3 38.8 — 38.8 — Loans held for sale 47.4 47.4 — 0.5 46.9 Net loans held for investment 18,051.9 17,334.4 — 17,281.8 52.6 Total financial assets $ 22,042.6 $ 21,001.7 $ 578.0 $ 20,324.2 $ 99.5 Financial liabilities: Total deposits, excluding time deposits $ 20,313.2 $ 20,313.2 $ 20,313.2 $ — $ — Time deposits 3,009.9 2,981.7 — 2,981.7 — Securities sold under repurchase agreements 782.7 782.7 — 782.7 — Other borrowed funds 2,603.0 2,603.0 — 2,603.0 — Accrued interest payable 52.2 52.2 — 52.2 — Long-term debt 120.8 115.6 — 115.6 — Subordinated debentures held by subsidiary trusts 163.1 151.1 — 151.1 — Total financial liabilities $ 27,044.9 $ 26,999.5 $ 20,313.2 $ 6,686.3 $ —

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Business Acquisition [Line Items]
Goodwill	$ 1,100.9	$ 1,100.9

Acquisitions - Schedule of Reco

Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Liabilities assumed:
Goodwill	$ 1,100.9	$ 1,100.9

Goodwill and Core Deposit Intan

Goodwill and Core Deposit Intangibles - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Goodwill [Line Items]
Amortization of intangible assets	$ 3.6	$ 3.9	$ 11	$ 11.8

Goodwill and Core Deposit Int_2

Goodwill and Core Deposit Intangibles - Goodwill Carrying Value (Details) $ in Millions	Sep. 30, 2024 USD ($)
Goodwill [Roll Forward]
Net carrying value at beginning of the period	$ 1,100.9
Net carrying value at end of period	$ 1,100.9

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Approximate Fair Values of Investment Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Sep. 30, 2024
Available-for-Sale:
Gross Unrealized Gains	$ 3.2	$ 6.6
Gross Unrealized Losses	(469.5)	(338.3)
Held-to-Maturity:
Investment securities classified as held to maturity	3,208.7	2,742
Allowance for Credit Losses	(0.8)	(0.7)
Net Amortized Cost	3,207.9	2,741.3
Gross Unrealized Gains	0.4	1.6
Gross Unrealized Losses	(334.3)	(262.4)
Investment debt securities held-to-maturity	2,874	2,480.5
Debt Securities, Held-To-Maturity, Transfer, Unamortized Gain	10.7
Debt Securities, Held-To-Maturity, Transfer, Unamortized Loss	(18.1)
Estimated Fair Value	5,841.5	5,534.3
Allowance for Credit Losses		0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	6,307.8	5,866
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Fair Value		1,478
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Amortized Cost Basis		1,514.6
U.S. Treasury notes
Available-for-Sale:
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(25.5)	(19.2)
Held-to-Maturity:
Investment securities classified as held to maturity	399	99.6
Allowance for Credit Losses	0	0
Net Amortized Cost	399	99.6
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2.8)	(0.4)
Investment debt securities held-to-maturity	396.2	99.2
Estimated Fair Value	224.7	231
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	250.2	250.2
State, county, and municipal securities
Available-for-Sale:
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(36.9)	(31.9)
Held-to-Maturity:
Investment securities classified as held to maturity	179.2	176.7
Allowance for Credit Losses	0	0
Net Amortized Cost	179.2	176.7
Gross Unrealized Gains	0.2	0.3
Gross Unrealized Losses	(24.2)	(20.6)
Investment debt securities held-to-maturity	155.2	156.4
Estimated Fair Value	219.8	220.9
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	256.7	252.8
Obligations of U.S. government agencies
Available-for-Sale:
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(10.9)	(6.5)
Held-to-Maturity:
Investment securities classified as held to maturity	354.5	356.4
Allowance for Credit Losses	0	0
Net Amortized Cost	354.5	356.4
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(42.4)	(32)
Investment debt securities held-to-maturity	312.1	324.4
Estimated Fair Value	168.5	165.4
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	179.4	171.9
Corporate Debt Securities
Available-for-Sale:
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(24.4)	(14.9)
Held-to-Maturity:
Investment securities classified as held to maturity	57	57
Allowance for Credit Losses	(0.8)	(0.7)
Net Amortized Cost	56.2	56.3
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(6)	(3.6)
Investment debt securities held-to-maturity	50.2	52.7
Estimated Fair Value	236.4	245.1
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	260.8	260
Collateralized Mortgage Obligations
Available-for-Sale:
Gross Unrealized Gains	1.3	2.2
Gross Unrealized Losses	(120.3)	(87.7)
Held-to-Maturity:
Investment securities classified as held to maturity	475.9	439.8
Allowance for Credit Losses	0	0
Net Amortized Cost	475.9	439.8
Gross Unrealized Gains	0.2	0.8
Gross Unrealized Losses	(69)	(57.8)
Investment debt securities held-to-maturity	407.1	382.8
Estimated Fair Value	1,189.5	1,116.6
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,308.5	1,202.1
Commercial Mortgage-Backed Securities
Available-for-Sale:
Gross Unrealized Gains	0.6	1.4
Gross Unrealized Losses	(87.7)	(60.2)
Held-to-Maturity:
Investment securities classified as held to maturity	510.5	493
Allowance for Credit Losses	0	0
Net Amortized Cost	510.5	493
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(52.9)	(41.8)
Investment debt securities held-to-maturity	457.6	451.2
Estimated Fair Value	1,105.6	1,105.3
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,192.7	1,164.1
Residential Mortgage Backed Securities
Available-for-Sale:
Gross Unrealized Gains	1.2	2.4
Gross Unrealized Losses	(130.6)	(94.2)
Held-to-Maturity:
Investment securities classified as held to maturity	1,232.6	1,119.5
Allowance for Credit Losses	0	0
Net Amortized Cost	1,232.6	1,119.5
Gross Unrealized Gains	0	0.5
Gross Unrealized Losses	(137)	(106.2)
Investment debt securities held-to-maturity	1,095.6	1,013.8
Estimated Fair Value	1,366.9	1,262.4
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,496.3	1,354.2
Private mortgage-backed securities
Available-for-Sale:
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(30.9)	(23.7)
Held-to-Maturity:
Estimated Fair Value	210.4	199.6
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	241.3	223.3
Collateralized Loan Obligations
Available-for-Sale:
Gross Unrealized Gains	0.1	0.6
Gross Unrealized Losses	(2.3)	0
Held-to-Maturity:
Estimated Fair Value	1,119.7	988
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	$ 1,121.9	$ 987.4

Investment Securities - Gross U

Investment Securities - Gross Unrealized Losses and Fair Values of Investment Securities (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Available-for-Sale:
Fair Value, Less than 12 Months	$ 3.3	$ 0.9
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	4,295.7	5,505.5
Gross Unrealized Losses, 12 Months or Longer	(338.3)	(469.5)
Fair Value, Total	4,299	5,506.4
Gross Unrealized Losses, Total	(338.3)	(469.5)
Allowance for Credit Losses	0
Gross Unrealized Gains	6.6	3.2
Gross Unrealized Losses	(338.3)	(469.5)
Estimated Fair Value	5,534.3	5,841.5
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	5,866	6,307.8
Investment securities classified as held to maturity	2,742	3,208.7
Allowance for Credit Losses	(0.7)	(0.8)
Net Amortized Cost	2,741.3	3,207.9
Gross Unrealized Gains	1.6	0.4
Gross Unrealized Losses	(262.4)	(334.3)
Investment debt securities held-to-maturity	2,480.5	2,874
Debt Securities, Held-To-Maturity, Transfer, Unamortized Loss		18.1
Debt Securities, Held-To-Maturity, Transfer, Unamortized Gain		(10.7)
US Treasury Notes Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0
Gross Unrealized Losses, Less than 12 Months	0
Fair Value, 12 Months or Longer	231
Gross Unrealized Losses, 12 Months or Longer	(19.2)
Fair Value, Total	231
Gross Unrealized Losses, Total	(19.2)
U.S. Treasury notes
Available-for-Sale:
Fair Value, Less than 12 Months		0
Gross Unrealized Losses, Less than 12 Months		0
Fair Value, 12 Months or Longer		224.7
Gross Unrealized Losses, 12 Months or Longer		(25.5)
Fair Value, Total		224.7
Gross Unrealized Losses, Total		(25.5)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(19.2)	(25.5)
Estimated Fair Value	231	224.7
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	250.2	250.2
Investment securities classified as held to maturity	99.6	399
Allowance for Credit Losses	0	0
Net Amortized Cost	99.6	399
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.4)	(2.8)
Investment debt securities held-to-maturity	99.2	396.2
State, county, and municipal securities
Available-for-Sale:
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	218.8	217.1
Gross Unrealized Losses, 12 Months or Longer	(31.9)	(36.9)
Fair Value, Total	218.8	217.1
Gross Unrealized Losses, Total	(31.9)	(36.9)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(31.9)	(36.9)
Estimated Fair Value	220.9	219.8
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	252.8	256.7
Investment securities classified as held to maturity	176.7	179.2
Allowance for Credit Losses	0	0
Net Amortized Cost	176.7	179.2
Gross Unrealized Gains	0.3	0.2
Gross Unrealized Losses	(20.6)	(24.2)
Investment debt securities held-to-maturity	156.4	155.2
Obligations of U.S. government agencies
Available-for-Sale:
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	165.1	168
Gross Unrealized Losses, 12 Months or Longer	(6.5)	(10.9)
Fair Value, Total	165.1	168
Gross Unrealized Losses, Total	(6.5)	(10.9)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(6.5)	(10.9)
Estimated Fair Value	165.4	168.5
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	171.9	179.4
Investment securities classified as held to maturity	356.4	354.5
Allowance for Credit Losses	0	0
Net Amortized Cost	356.4	354.5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(32)	(42.4)
Investment debt securities held-to-maturity	324.4	312.1
Private mortgage-backed securities
Available-for-Sale:
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	199.5	210.5
Gross Unrealized Losses, 12 Months or Longer	(23.7)	(30.9)
Fair Value, Total	199.5	210.5
Gross Unrealized Losses, Total	(23.7)	(30.9)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(23.7)	(30.9)
Estimated Fair Value	199.6	210.4
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	223.3	241.3
Collateralized Loan Obligations
Available-for-Sale:
Fair Value, Less than 12 Months		0
Gross Unrealized Losses, Less than 12 Months		0
Fair Value, 12 Months or Longer		935.7
Gross Unrealized Losses, 12 Months or Longer		(2.3)
Fair Value, Total		935.7
Gross Unrealized Losses, Total		(2.3)
Gross Unrealized Gains	0.6	0.1
Gross Unrealized Losses	0	(2.3)
Estimated Fair Value	988	1,119.7
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	987.4	1,121.9
Corporate Debt Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	217	236.5
Gross Unrealized Losses, 12 Months or Longer	(14.9)	(24.4)
Fair Value, Total	217	236.5
Gross Unrealized Losses, Total	(14.9)	(24.4)
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(14.9)	(24.4)
Estimated Fair Value	245.1	236.4
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	260	260.8
Investment securities classified as held to maturity	57	57
Allowance for Credit Losses	(0.7)	(0.8)
Net Amortized Cost	56.3	56.2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(3.6)	(6)
Investment debt securities held-to-maturity	52.7	50.2
Commercial Mortgage-Backed Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0.1	0.2
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	1,048.8	1,083.1
Gross Unrealized Losses, 12 Months or Longer	(60.2)	(87.7)
Fair Value, Total	1,048.9	1,083.3
Gross Unrealized Losses, Total	(60.2)	(87.7)
Gross Unrealized Gains	1.4	0.6
Gross Unrealized Losses	(60.2)	(87.7)
Estimated Fair Value	1,105.3	1,105.6
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,164.1	1,192.7
Investment securities classified as held to maturity	493	510.5
Allowance for Credit Losses	0	0
Net Amortized Cost	493	510.5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(41.8)	(52.9)
Investment debt securities held-to-maturity	451.2	457.6
Residential Mortgage Backed Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0	0.7
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	1,167	1,287.5
Gross Unrealized Losses, 12 Months or Longer	(94.2)	(130.6)
Fair Value, Total	1,167	1,288.2
Gross Unrealized Losses, Total	(94.2)	(130.6)
Gross Unrealized Gains	2.4	1.2
Gross Unrealized Losses	(94.2)	(130.6)
Estimated Fair Value	1,262.4	1,366.9
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,354.2	1,496.3
Investment securities classified as held to maturity	1,119.5	1,232.6
Allowance for Credit Losses	0	0
Net Amortized Cost	1,119.5	1,232.6
Gross Unrealized Gains	0.5	0
Gross Unrealized Losses	(106.2)	(137)
Investment debt securities held-to-maturity	1,013.8	1,095.6
Collateralized Mortgage Obligations
Available-for-Sale:
Fair Value, Less than 12 Months	3.2	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Longer	1,048.5	1,142.4
Gross Unrealized Losses, 12 Months or Longer	(87.7)	(120.3)
Fair Value, Total	1,051.7	1,142.4
Gross Unrealized Losses, Total	(87.7)	(120.3)
Gross Unrealized Gains	2.2	1.3
Gross Unrealized Losses	(87.7)	(120.3)
Estimated Fair Value	1,116.6	1,189.5
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,202.1	1,308.5
Investment securities classified as held to maturity	439.8	475.9
Allowance for Credit Losses	0	0
Net Amortized Cost	439.8	475.9
Gross Unrealized Gains	0.8	0.2
Gross Unrealized Losses	(57.8)	(69)
Investment debt securities held-to-maturity	382.8	$ 407.1
US agency, residential and commercial MBS and CMOs
Available-for-Sale:
Debt Securities, Held-To-Maturity, Transfer, Unamortized Gain	(8.6)
State, county & municipal, obligations of US govt agencies and CLOs
Available-for-Sale:
Debt Securities, Held-To-Maturity, Transfer, Unamortized Loss	$ 16.5

Investment Securities - Narrati

Investment Securities - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) Investments	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) Investments	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) Investments
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 0.7		$ 0.7		$ 0.8
Interest Receivable	127.3		127.3		129.1
Debt Securities, Available-for-sale, Realized Gain	0	$ 0
Debt Securities, Available-for-sale, Realized Loss	0	0		$ (23.5)
Callable structured notes amortized costs	0		0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	3,159.8		3,159.8		3,858.6
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	$ 2,888		$ 2,888		$ 3,462.2
Investment securities in an unrealized loss position (securities) | Investments	648		648		704
Debt Securities, Current		853		853
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Amortized Cost Basis	$ 1,514.6		$ 1,514.6
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Fair Value	1,478		1,478
Accrued interest reversal	(0.4)	$ (1)	(2.4)	$ (1.9)
Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Interest Receivable	$ 33.1		$ 33.1		$ 38.5

Investment Securities - Availab

Investment Securities - Available-for-Sale Allowance for Credit loss (Details) $ in Millions	Sep. 30, 2024 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	$ 0

Investment Securities - Held-To

Investment Securities - Held-To-Maturity Allowance For Credit Loss (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 0.7	$ 0.8

Investment Securities - Credit

Investment Securities - Credit Quality Indicators (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	$ 2,742	$ 3,208.7
AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	2,594	3,041.5
AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	74.2	92.3
A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	10.1	10.6
BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	47	47
Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	11.7	12.3
BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5	5
U.S. Treasury notes
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	99.6	399
U.S. Treasury notes | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	99.6	399
U.S. Treasury notes | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
U.S. Treasury notes | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
U.S. Treasury notes | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
U.S. Treasury notes | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
U.S. Treasury notes | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
State, county, and municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	176.7	179.2
State, county, and municipal securities | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	85.7	69
State, county, and municipal securities | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	74.2	92.3
State, county, and municipal securities | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	10.1	10.6
State, county, and municipal securities | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
State, county, and municipal securities | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	6.7	7.3
State, county, and municipal securities | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Obligations of U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	356.4	354.5
Obligations of U.S. government agencies | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	356.4	354.5
Obligations of U.S. government agencies | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Obligations of U.S. government agencies | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Obligations of U.S. government agencies | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Obligations of U.S. government agencies | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Obligations of U.S. government agencies | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Corporate securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	57	57
Corporate securities | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Corporate securities | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Corporate securities | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Corporate securities | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	47	47
Corporate securities | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5	5
Corporate securities | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5	5
Commercial Mortgage-Backed Securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	493	510.5
Commercial Mortgage-Backed Securities | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	349.7	359.7
Commercial Mortgage-Backed Securities | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	349.7	359.7
Commercial Mortgage-Backed Securities | FNMA/FHLMC | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | FNMA/FHLMC | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | FNMA/FHLMC | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | FNMA/FHLMC | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | FNMA/FHLMC | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	143.3	150.8
Commercial Mortgage-Backed Securities | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	143.3	150.8
Commercial Mortgage-Backed Securities | GNMA | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | GNMA | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | GNMA | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | GNMA | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Commercial Mortgage-Backed Securities | GNMA | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	1,119.5	1,232.6
Residential Mortgage Backed Securities | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	1,080.7	1,189.8
Residential Mortgage Backed Securities | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	1,080.7	1,189.8
Residential Mortgage Backed Securities | FNMA/FHLMC | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | FNMA/FHLMC | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | FNMA/FHLMC | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | FNMA/FHLMC | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | FNMA/FHLMC | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	38.8	42.8
Residential Mortgage Backed Securities | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	38.8	42.8
Residential Mortgage Backed Securities | GNMA | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | GNMA | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | GNMA | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | GNMA | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Residential Mortgage Backed Securities | GNMA | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	439.8	475.9
Collateralized Mortgage Obligations | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	308.5	334.1
Collateralized Mortgage Obligations | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	308.5	334.1
Collateralized Mortgage Obligations | FNMA/FHLMC | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | FNMA/FHLMC | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | FNMA/FHLMC | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | FNMA/FHLMC | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | FNMA/FHLMC | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	131.3	141.8
Collateralized Mortgage Obligations | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	131.3	141.8
Collateralized Mortgage Obligations | GNMA | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | GNMA | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | GNMA | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | GNMA | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0	0
Collateralized Mortgage Obligations | GNMA | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	$ 0	$ 0

Investment Securities - Maturit

Investment Securities - Maturities of Investment Securities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Available-for-Sale, Amortized Cost
Available-for-Sale Amortized Cost, Within One Year	$ 88.7
Available-for-Sale Amortized Cost, After One Year but Within Five Years	1,326.9
Available-for-Sale Amortized Cost, After Five Years but Within Ten Years	1,166.4
Available-for-Sale Amortized Cost, After Ten Years	3,284
Amortized Cost	5,866	$ 6,307.8
Available-for-Sale, Estimated Fair Value
Available-for-Sale Estimated Fair Value, Within One Year	87.5
Available-for-Sale Estimated Fair Value, After One Year but Within Five Years	1,265.9
Available-for-Sale Estimated Fair Value, After Five Years but Within Ten Years	1,095.1
Available-for-Sale Estimated Fair Value, After Ten Years	3,085.8
Estimated Fair Value	5,534.3	5,841.5
Held-to-Maturity, Amortized Cost
Held-to-Maturity Amortized Cost, Within One Year	101.1
Held-to-Maturity Amortized Cost, After One Year but Within Five Years	416
Held-to-Maturity Amortized Cost, After Five Years but Within Ten Years	485.5
Held-to-Maturity Amortized Cost, After Ten Years	1,739.4
Amortized Cost1	2,742	3,208.7
Held-to-Maturity, Estimated Fair Value
Held-to-Maturity Estimated Fair Value, Within One Year	100.6
Held-to-Maturity Estimated Fair Value, After One Year but Within Five Years	396.8
Held-to-Maturity Estimated Fair Value, After Five Years but Within Ten Years	437.5
Held-to-Maturity Estimated Fair Value, After Ten Years	1,545.6
Investment debt securities held-to-maturity	2,480.5	2,874
Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	3,159.8	3,858.6
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	2,888	$ 3,462.2
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Fair Value	1,478
Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Amortized Cost Basis	$ 1,514.6

Loans Held for Sale - By Segmen

Loans Held for Sale - By Segment (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	$ 20.9		$ 47.4
Transfer of loans to held-for-sale	0	$ 3.1
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	20.9		47.4
Agricultural
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	18.8		19.6
Commercial Real Estate Portfolio
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	0		27.3
Residential
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	2.1		0.5
Agricultural
Debt Securities, Available-for-sale [Line Items]
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	18.8		19.6
Proceeds from Collection of Loans Held-for-sale	(0.8)
Commercial Real Estate Portfolio
Debt Securities, Available-for-sale [Line Items]
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	0		$ 27.3
Proceeds from Collection of Loans Held-for-sale	$ 0

Non-Residential Loans Held for

Non-Residential Loans Held for Sale (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	$ 20.9		$ 47.4
Transfer of loans to held-for-sale	0	$ 3.1
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	20.9		47.4
Agricultural
Debt Securities, Available-for-sale [Line Items]
Proceeds from Collection of Loans Held-for-sale	(0.8)
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	18.8		19.6
Proceeds from Sale of Loans Held-for-sale	0
Commercial Real Estate Portfolio
Debt Securities, Available-for-sale [Line Items]
Proceeds from Collection of Loans Held-for-sale	0
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	0		$ 27.3
Proceeds from Sale of Loans Held-for-sale	$ (27.3)

Loans Held for Sale - Narrative

Loans Held for Sale - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	$ 20.9		$ 47.4
Transfer of loans to held-for-sale	0	$ 3.1
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	20.9		47.4
Agricultural
Debt Securities, Available-for-sale [Line Items]
Nonaccrual loans	18.8
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	18.8		19.6
Proceeds from Collection of Loans Held-for-sale	0.8
Commercial Real Estate Portfolio
Debt Securities, Available-for-sale [Line Items]
Nonaccrual loans			27.3
Loans held for sale ($2.1 and $0.5 of which is recorded at fair value at September 30, 2024 December 31, 2023)	0		$ 27.3
Proceeds from Collection of Loans Held-for-sale	$ 0

Loans Held for Investment - Sch

Loans Held for Investment - Schedule of Loans by Segment (Details) - USD ($) $ in Millions	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Deferred loan fees and costs	$ (11.8)		$ (12.5)
Loans held for investment, net of deferred fees and costs	18,027.1		18,279.6
Allowance for credit losses	(225.4)	$ (232.8)	(227.7)	$ (226.7)	$ (224.6)	$ (220.1)
Net loans held for investment	17,801.7		18,051.9
Financing Receivable, Loan in Process	0.5
Commercial real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	11.9		18.8
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	9,219.3		8,869.2
Nonaccrual loans	45.2		28.2
Commercial real estate | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	5.1		12.7
Commercial real estate | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.8		6.1
Commercial real estate | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Commercial real estate | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	9,162.2		8,822.2
Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	3.7		3.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,307.9		1,826.5
Nonaccrual loans	0.1		17.2
Total construction loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	3.6		3.1
Total construction loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		0.4
Total construction loans | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Total construction loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1,304.1		1,805.8
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	4.9		15.6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,217.8		2,244.3
Nonaccrual loans	14.3		10.7
Residential | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.6		11.9
Residential | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.1		3.1
Residential | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		0.6
Residential | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,198.6		2,218
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.4		1.8
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	726.4		716.8
Nonaccrual loans	4.7		5.4
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.4		1.8
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Agricultural | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	719.3		709.6
Total real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(136)	(139.7)	(160.1)	(162.2)	(158.7)	(138.7)
Financing Receivable, Loan in Process	22.9		39.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,471.4		13,656.8
Nonaccrual loans	64.3		61.5
Total real estate | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13.7		29.5
Total real estate | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	9		9.6
Total real estate | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		0.6
Total real estate | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13,384.2		13,555.6
Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	8.1		10.6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	742.2		740.9
Nonaccrual loans	3.4		2.7
Indirect consumer | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.4		8
Indirect consumer | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.6		2.2
Indirect consumer | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		0.4
Indirect consumer | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	730.7		727.6
Direct and advance lines
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.4		1.1
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	136.9		141.6
Nonaccrual loans	0.4		0.3
Direct and advance lines | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1		0.9
Direct and advance lines | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		0.2
Direct and advance lines | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Direct and advance lines | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	135.1		140.2
Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.9		1.8
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	76.4		76.5
Nonaccrual loans	0		0
Credit card | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.7		0.7
Credit card | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.5		0.5
Credit card | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.7		0.6
Credit card | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	74.5		74.7
Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(17.2)	(18.5)	(13)	(12.9)	(13.7)	(23.3)
Financing Receivable, Loan in Process	11.4		13.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	955.5		959
Nonaccrual loans	3.8		3
Total consumer loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	8.1		9.6
Total consumer loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.5		2.9
Total consumer loans | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.8		1
Total consumer loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	940.3		942.5
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(66.8)	(69.2)	(50.2)	(48.4)	(49.5)	(54.9)
Financing Receivable, Loan in Process	6.4		15.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,919.7		2,906.8
Nonaccrual loans	81.6		11.5
Commercial | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	4.3		14.5
Commercial | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.5		1.1
Commercial | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.6		0.3
Commercial | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,831.7		2,879.4
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(5.4)	$ (5.4)	(4.4)	$ (3.2)	$ (2.7)	$ (3.2)
Financing Receivable, Loan in Process	1.8		3.1
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	689.8		769.4
Nonaccrual loans	23		30.4
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.6		0.1
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Agricultural | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		3
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	665		735.9
Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2.5		0.1
Nonaccrual loans	0		0
Other, including overdrafts | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Other, including overdrafts | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Other, including overdrafts | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0
Other, including overdrafts | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.5		0.1
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	42.5		72.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	18,038.9		18,292.1
Nonaccrual loans	172.7		106.4
Loans And Leases Held For Investment [Member] | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	27.7		53.7
Loans And Leases Held For Investment [Member] | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13		13.6
Loans And Leases Held For Investment [Member] | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.8		4.9
Loans And Leases Held For Investment [Member] | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	$ 17,823.7		$ 18,113.5

Loans Held for Investment - S_2

Loans Held for Investment - Schedule of Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 232.8	$ 224.6	$ 227.7	$ 220.1	$ 220.1
Provision for credit losses	19.8	(0.1)	34.1	26.8
Loans Charged-Off(2)	(29.1)	(6.2)	(56.4)	(29.2)
Recoveries Collected	1.7	5.1	7.1	10.5
Ending balance	225.4	226.7	225.4	226.7	227.7
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	20	3.2	47	25.3
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loans Charged-Off(2)			(21.6)		(7.6)
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5.4	2.7	4.4	3.2	3.2
Provision for credit losses	0.3	0.5	1	(0.4)
Loans Charged-Off(2)	(0.3)	0	(0.3)	0	0
Recoveries Collected	0	0	0.3	0.4
Ending balance	5.4	3.2	5.4	3.2	4.4
Residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loans Charged-Off(2)			(0.7)		(0.6)
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loans Charged-Off(2)			0		0
Total real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	139.7	158.7	160.1	138.7	138.7
Provision for credit losses	18.3	1.8	10.3	35.6
Loans Charged-Off(2)	(22.2)	(1.8)	(35.5)	(16.6)
Recoveries Collected	0.2	3.5	1.1	4.5
Ending balance	136	162.2	136	162.2	160.1
Indirect consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loans Charged-Off(2)			(6.9)		(7.3)
Direct and advance lines
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loans Charged-Off(2)			(2.9)		(4.1)
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Loans Charged-Off(2)			(2.1)		(2.6)
Total consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	18.5	13.7	13	23.3	23.3
Provision for credit losses	1.5	1.8	12.5	(3.7)
Loans Charged-Off(2)	(4.1)	(3.7)	(11.9)	(10.4)
Recoveries Collected	1.3	1.1	3.6	3.7
Ending balance	17.2	12.9	17.2	12.9	13
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	69.2	49.5	50.2	54.9	54.9
Provision for credit losses	(0.1)	(0.9)	23.2	(6.2)
Loans Charged-Off(2)	(2.5)	(0.7)	(8.7)	(2.2)	(3.4)
Recoveries Collected	0.2	0.5	2.1	1.9
Ending balance	$ 66.8	$ 48.4	$ 66.8	$ 48.4	$ 50.2

Loans Held for Investment - S_3

Loans Held for Investment - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	$ (19.8)	$ 0.1	$ (34.1)	$ (26.8)
Accounts Receivable, Allowance for Credit Loss	225.4	226.7	225.4	226.7	$ 232.8	$ 227.7	$ 224.6	$ 220.1
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	20	3.2	47	25.3
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	(18.3)	(1.8)	(10.3)	(35.6)
Accounts Receivable, Allowance for Credit Loss	136	162.2	136	162.2	139.7	160.1	158.7	138.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,471.4		13,471.4			13,656.8
Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	0.1	0.9	(23.2)	6.2
Accounts Receivable, Allowance for Credit Loss	66.8	48.4	66.8	48.4	69.2	50.2	49.5	54.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,919.7		2,919.7			2,906.8
Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	(0.3)	(0.5)	(1)	0.4
Accounts Receivable, Allowance for Credit Loss	5.4	$ 3.2	5.4	$ 3.2	$ 5.4	4.4	$ 2.7	$ 3.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	689.8		689.8			769.4
Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	9,219.3		9,219.3			8,869.2
Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,217.8		2,217.8			2,244.3
Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	726.4		726.4			716.8
Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,307.9		1,307.9			1,826.5
Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	109.6		109.6			52.6
Collateral [Member] | Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	37		37			45.3
Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	72		72			6.6
Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.6		0.6			0.7
Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	34.1		34.1			26.6
Collateral [Member] | Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1.9		1.9			0.5
Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1		1			1.2
Collateral [Member] | Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			17
Business Assets [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	71.2		71.2			5.2
Business Assets [Member] | Collateral [Member] | Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Business Assets [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	71.2		71.2			4.5
Business Assets [Member] | Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0.7
Business Assets [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Business Assets [Member] | Collateral [Member] | Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Business Assets [Member] | Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Business Assets [Member] | Collateral [Member] | Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Real Property [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	37.6		37.6			46.7
Real Property [Member] | Collateral [Member] | Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	37		37			45.3
Real Property [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.1		0.1			1.4
Real Property [Member] | Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.5		0.5			0
Real Property [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	34.1		34.1			26.6
Real Property [Member] | Collateral [Member] | Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1.9		1.9			0.5
Real Property [Member] | Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1		1			1.2
Real Property [Member] | Collateral [Member] | Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			17
Other Property [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.8		0.8			0.7
Other Property [Member] | Collateral [Member] | Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Other Property [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.7		0.7			0.7
Other Property [Member] | Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.1		0.1			0
Other Property [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Other Property [Member] | Collateral [Member] | Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Other Property [Member] | Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0		0			0
Other Property [Member] | Collateral [Member] | Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 0		$ 0			$ 0

Loans Held for Investment - S_4

Loans Held for Investment - Schedule of Recorded Investment in Past Due Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	$ 0.5		$ 0.5
Accrued interest reversal	(0.4)	$ (1)	(2.4)	$ (1.9)
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	11.9		11.9		$ 18.8
Nonaccrual loans	45.2		45.2		28.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	9,219.3		9,219.3		8,869.2
Commercial | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	5.1		5.1		12.7
Commercial | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.8		6.8		6.1
Commercial | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Commercial | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	9,162.2		9,162.2		8,822.2
Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	3.7		3.7		3.5
Nonaccrual loans	0.1		0.1		17.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,307.9		1,307.9		1,826.5
Total construction loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	3.6		3.6		3.1
Total construction loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		0.1		0.4
Total construction loans | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Total construction loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1,304.1		1,304.1		1,805.8
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	4.9		4.9		15.6
Nonaccrual loans	14.3		14.3		10.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,217.8		2,217.8		2,244.3
Residential | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.6		2.6		11.9
Residential | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.1		2.1		3.1
Residential | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		0.6
Residential | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,198.6		2,198.6		2,218
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.4		2.4		1.8
Nonaccrual loans	4.7		4.7		5.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	726.4		726.4		716.8
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.4		2.4		1.8
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Agricultural | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	719.3		719.3		709.6
Total real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	22.9		22.9		39.7
Nonaccrual loans	64.3		64.3		61.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,471.4		13,471.4		13,656.8
Total real estate | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13.7		13.7		29.5
Total real estate | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	9		9		9.6
Total real estate | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		0.6
Total real estate | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13,384.2		13,384.2		13,555.6
Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	8.1		8.1		10.6
Nonaccrual loans	3.4		3.4		2.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	742.2		742.2		740.9
Indirect consumer | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.4		6.4		8
Indirect consumer | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.6		1.6		2.2
Indirect consumer | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		0.1		0.4
Indirect consumer | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	730.7		730.7		727.6
Direct and advance lines
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.4		1.4		1.1
Nonaccrual loans	0.4		0.4		0.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	136.9		136.9		141.6
Direct and advance lines | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1		1		0.9
Direct and advance lines | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		0.4		0.2
Direct and advance lines | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Direct and advance lines | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	135.1		135.1		140.2
Credit Card Receivable [Member]
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.9		1.9		1.8
Nonaccrual loans	0		0		0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	76.4		76.4		76.5
Credit Card Receivable [Member] | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.7		0.7		0.7
Credit Card Receivable [Member] | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.5		0.5		0.5
Credit Card Receivable [Member] | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.7		0.7		0.6
Credit Card Receivable [Member] | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	74.5		74.5		74.7
Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	11.4		11.4		13.5
Nonaccrual loans	3.8		3.8		3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	955.5		955.5		959
Total consumer loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	8.1		8.1		9.6
Total consumer loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.5		2.5		2.9
Total consumer loans | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.8		0.8		1
Total consumer loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	940.3		940.3		942.5
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.4		6.4		15.9
Nonaccrual loans	81.6		81.6		11.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,919.7		2,919.7		2,906.8
Commercial | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	4.3		4.3		14.5
Commercial | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.5		1.5		1.1
Commercial | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.6		0.6		0.3
Commercial | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,831.7		2,831.7		2,879.4
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.8		1.8		3.1
Nonaccrual loans	23		23		30.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	689.8		689.8		769.4
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.6		1.6		0.1
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Agricultural | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		3
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	665		665		735.9
Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Nonaccrual loans	0		0		0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2.5		2.5		0.1
Other, including overdrafts | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Other, including overdrafts | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Other, including overdrafts | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0		0		0
Other, including overdrafts | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.5		2.5		0.1
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	42.5		42.5		72.2
Nonaccrual loans	172.7		172.7		106.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	18,038.9		18,038.9		18,292.1
Loans And Leases Held For Investment [Member] | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	27.7		27.7		53.7
Loans And Leases Held For Investment [Member] | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13		13		13.6
Loans And Leases Held For Investment [Member] | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.8		1.8		4.9
Loans And Leases Held For Investment [Member] | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	$ 17,823.7		$ 17,823.7		$ 18,113.5

Loans Held for Investment - S_5

Loans Held for Investment - Schedule of Modifications to Borrowers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 31.7	$ 33.2	$ 89.4	$ 91.2
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.18%	0.18%	0.50%	0.50%
Interest Receivable	$ 127.3		$ 127.3		$ 129.1
Financing Receivable, Loan in Process	0.5		0.5
Financing Receivable, Modified in Period, Accrued Interest, Amount			1.1	$ 1.7
Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	$ 0	0	1.7
Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	31.2	32.6	66.4	88.9
Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0.5	0.6	23	0.6
Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0	0	1.6
Agricultural
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 6.5	$ 6.1	$ 12.1	$ 6.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.89%	0.83%	1.67%	0.87%
Financing Receivable, Loan in Process	$ 2.4		$ 2.4		1.8
Financing Receivable, Modified, Weighted Average Term Increase from Modification	7 years 8 months 12 days	4 years	7 years 4 months 24 days	4 years 7 months 6 days
Agricultural | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Agricultural | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	6.5	6.1	12.1	6.4
Agricultural | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0	0	0
Agricultural | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Agricultural | Weighted-Average Months of Term Extension
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	0 years	0 years	0 years	0 years
Agricultural | Weighted-Average Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Combination Term Extension and Interest Rate Reduction Percent	0%	0%	0%	0%
Agricultural
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 21.4	$ 0.5	$ 45.4	$ 36.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	3.10%	0.07%	6.58%	5.27%
Financing Receivable, Loan in Process	$ 1.8		$ 1.8		3.1
Financing Receivable, Modified, Weighted Average Term Increase from Modification	3 years 10 months 24 days	3 years 6 months	4 years 1 month 6 days	9 years 2 months 12 days
Agricultural | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Agricultural | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	21.4	0.5	23.2	36.4
Agricultural | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0	22.2	0
Agricultural | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Agricultural | Weighted-Average Months of Term Extension
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	0 years	0 years	55 years 2 months 12 days	0 years
Agricultural | Weighted-Average Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Combination Term Extension and Interest Rate Reduction Percent	0%	0%	1.10%	0%
Other, including overdrafts
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 0		$ 0		0
Commercial
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0.5	$ 11.5	$ 14.7	$ 25.2
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.01%	0.13%	0.16%	0.29%
Financing Receivable, Loan in Process	$ 11.9		$ 11.9		18.8
Financing Receivable, Modified, Weighted Average Term Increase from Modification	5 years 10 months 24 days	4 years 7 months 6 days	6 years 9 months 18 days	5 years 8 months 12 days
Commercial | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 1.6
Commercial | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0.5	10.9	14.7	23
Commercial | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0.6	0	0.6
Commercial | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 1.3
Commercial | Weighted-Average Months of Term Extension
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	0 years	6 years	0 years	6 years
Commercial | Weighted-Average Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Combination Term Extension and Interest Rate Reduction Percent	0%	0.25%	0%	0.25%
Total construction loans
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 1.9	$ 13.1	$ 1.9	$ 13.2
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.15%	0.68%	0.15%	0.68%
Financing Receivable, Loan in Process	$ 3.7		$ 3.7		3.5
Financing Receivable, Modified, Weighted Average Term Increase from Modification	4 years	9 years	4 years	9 years
Total construction loans | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Total construction loans | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	1.9	13.1	1.9	13.2
Total construction loans | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0	0	0
Total construction loans | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Total construction loans | Weighted-Average Months of Term Extension
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	0 years	0 years	0 years	0 years
Total construction loans | Weighted-Average Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Combination Term Extension and Interest Rate Reduction Percent	0%	0%	0%	0%
Residential
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period		$ 0.4	$ 0.4	$ 0.6
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent		0.02%	0.02%	0.03%
Financing Receivable, Loan in Process	$ 4.9		$ 4.9		15.6
Financing Receivable, Modified, Weighted Average Term Increase from Modification		144 years 4 months 24 days	11 years	139 years 2 months 12 days
Residential | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period		$ 0	$ 0	$ 0.1
Residential | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period		0.4	0.1	0.5
Residential | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period		0	0.3	0
Residential | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period		$ 0	$ 0	$ 0.3
Residential | Weighted-Average Months of Term Extension
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months		0 years	31 years 2 months 12 days	0 years
Residential | Weighted-Average Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Combination Term Extension and Interest Rate Reduction Percent		0%	3.40%	0%
Total real estate
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 8.9	$ 31.1	$ 29.1	$ 45.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.07%	0.23%	0.22%	0.33%
Financing Receivable, Loan in Process	$ 22.9		$ 22.9		39.7
Total real estate | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	$ 0	0	$ 1.7
Total real estate | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	8.9	30.5	28.8	43.1
Total real estate | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0.6	0.3	0.6
Total real estate | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0	0	0	1.6
Commercial
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 1.4	$ 1.6	$ 14.9	$ 9.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.05%	0.05%	0.51%	0.32%
Financing Receivable, Loan in Process	$ 6.4		$ 6.4		15.9
Financing Receivable, Modified, Weighted Average Term Increase from Modification	5 years 3 months 18 days	7 years 9 months 18 days	7 years 8 months 12 days	8 years 9 months 18 days
Commercial | Principal Forgiveness
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Commercial | Extended Maturity [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0.9	1.6	14.4	9.4
Commercial | Extended Maturity and Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	0.5	0	0.5	0
Commercial | Principal Forgiven
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period	$ 0	$ 0	$ 0	$ 0
Commercial | Weighted-Average Months of Term Extension
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	59 years	0 years	9 years 2 months 12 days	0 years
Commercial | Weighted-Average Interest Rate Reduction
Financing Receivable, Modifications to Borrowers [Line Items]
Combination Term Extension and Interest Rate Reduction Percent	0.80%	0%	1%	0%
Indirect consumer
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 8.1		$ 8.1		10.6
Direct and advance lines
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	1.4		1.4		1.1
Credit Card Receivable [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	1.9		1.9		1.8
Total consumer loans
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 11.4		$ 11.4		$ 13.5

Loans Held for Investment - S_6

Loans Held for Investment - Schedule of Contractual Aging of Loans by Portfolio (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	$ 0.5		$ 0.5
Less loans charged-off	29.1	$ 6.2	56.4	$ 29.2
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11.9		11.9		$ 18.8
Nonaccrual loans	45.2		45.2		28.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	9,219.3		9,219.3		8,869.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,067		1,067		1,337.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,386.3		1,386.3		2,085.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	2,007.2		2,007.2		1,675
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,499.3		1,499.3		1,215.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,147.4		1,147.4		774.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	2,007.2		2,007.2		1,706.1
Financing Receivable, Excluding Accrued Interest, Revolving	48.2		48.2		47
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	56.7		56.7		28.1
Total	9,219.3		9,219.3		8,869.2
Less loans charged-off			21.6		7.6
Commercial real estate | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,026.8		1,026.8		1,268
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,366.2		1,366.2		2,065
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,981.5		1,981.5		1,612.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,441.7		1,441.7		1,200.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,137.3		1,137.3		716.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,922.5		1,922.5		1,660.5
Financing Receivable, Excluding Accrued Interest, Revolving	48.2		48.2		46.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	56.7		56.7		28.1
Total	8,980.9		8,980.9		8,596.9
Commercial real estate | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	12.6		12.6		4.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	9.4		9.4		9.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21.1		21.1		42.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	18.3		18.3		12.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	2.2		2.2		27.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	36.9		36.9		17.1
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	100.5		100.5		113.7
Commercial real estate | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	27.6		27.6		65.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	10.7		10.7		11.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	4.6		4.6		18.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39.3		39.3		2.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.9		7.9		30.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	47.8		47.8		28.5
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	137.9		137.9		157.3
Commercial real estate | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					1.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Revolving					0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan					0
Total					1.3
Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3.7		3.7		3.5
Nonaccrual loans	0.1		0.1		17.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,307.9		1,307.9		1,826.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	261.2		261.2		501.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	263.4		263.4		758.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	490.8		490.8		356.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	114		114		36.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	19.7		19.7		16.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	24.6		24.6		36.8
Financing Receivable, Excluding Accrued Interest, Revolving	129.3		129.3		104.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	4.9		4.9		14.6
Total	1,307.9		1,307.9		1,826.5
Less loans charged-off			13.2		10.3
Total construction loans | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	256.1		256.1		493.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	263.4		263.4		735.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	484.4		484.4		331.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	114		114		36.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	19.7		19.7		16.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	24.2		24.2		36.2
Financing Receivable, Excluding Accrued Interest, Revolving	129.3		129.3		104.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	4.9		4.9		13.7
Total	1,296		1,296		1,768
Total construction loans | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3.2		3.2		0.5
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		6.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6.4		6.4		1.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0.2
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.9
Total	9.6		9.6		9.5
Total construction loans | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.9		1.9		7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		24.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.4		0.4		0.4
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	2.3		2.3		36
Total construction loans | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					13
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Revolving					0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan					0
Total					13
Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	4.9		4.9		15.6
Nonaccrual loans	14.3		14.3		10.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,217.8		2,217.8		2,244.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	15.6		15.6		45.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	71.3		71.3		359
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	423.5		423.5		522.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	491.3		491.3		501.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	456.3		456.3		89.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	270		270		222.2
Financing Receivable, Excluding Accrued Interest, Revolving	480.2		480.2		471.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9.6		9.6		32.1
Total	2,217.8		2,217.8		2,244.3
Less loans charged-off			0.7		0.6
Residential | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	14.6		14.6		44.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	70.5		70.5		356.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	419.9		419.9		521.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	489.5		489.5		500.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	454.7		454.7		88.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	264.6		264.6		217.1
Financing Receivable, Excluding Accrued Interest, Revolving	480.2		480.2		471.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9.3		9.3		32.1
Total	2,203.3		2,203.3		2,233
Residential | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1		1		1.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.8		0.8		2.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	3.6		3.6		1.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1.8		1.8		1.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.6		1.6		0.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.4		5.4		5.1
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.3		0.3		0
Total	14.5		14.5		11.3
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.4		2.4		1.8
Nonaccrual loans	4.7		4.7		5.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	726.4		726.4		716.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	105.5		105.5		96.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	76		76		154
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	138.7		138.7		133.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	130.2		130.2		98
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	88.9		88.9		58.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	161.3		161.3		136.7
Financing Receivable, Excluding Accrued Interest, Revolving	25.8		25.8		32.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		7
Total	726.4		726.4		716.8
Less loans charged-off			0		0
Agricultural | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	92.2		92.2		86.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	65		65		123.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	113.6		113.6		126.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	121.4		121.4		93.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	79.9		79.9		56.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	159.4		159.4		124.3
Financing Receivable, Excluding Accrued Interest, Revolving	25.8		25.8		31.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		7
Total	657.3		657.3		649.4
Agricultural | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.1		1.1		2.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.6		6.6		9.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	5.9		5.9		3.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	5.1		5.1		1.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.6		7.6		1.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1		1		11.3
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	27.3		27.3		30.8
Agricultural | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	12.2		12.2		8.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.4		4.4		20.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	19.2		19.2		3.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	3.7		3.7		2.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.4		1.4		0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.9		0.9		1.1
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	41.8		41.8		36.6
Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	22.9		22.9		39.7
Nonaccrual loans	64.3		64.3		61.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,471.4		13,471.4		13,656.8
Less loans charged-off	22.2	1.8	35.5	16.6
Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	8.1		8.1		10.6
Nonaccrual loans	3.4		3.4		2.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	742.2		742.2		740.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	203.3		203.3		195.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	147.7		147.7		265.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	195.8		195.8		116
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	83.5		83.5		81.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	55.8		55.8		33.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	56.1		56.1		49.4
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	742.2		742.2		740.9
Less loans charged-off			6.9		7.3
Indirect consumer | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	203		203		194.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	146.9		146.9		264.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	194.8		194.8		115.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	83		83		81.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	55.4		55.4		32.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	55.6		55.6		48.8
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	738.7		738.7		737.8
Indirect consumer | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.3		0.3		0.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.8		0.8		0.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1		1		0.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.5		0.5		0.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.4		0.4		0.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.5		0.5		0.6
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	3.5		3.5		3.1
Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.4		1.4		1.1
Nonaccrual loans	0.4		0.4		0.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	136.9		136.9		141.6
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	37.2		37.2		44.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	29.9		29.9		33
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	22.3		22.3		18.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	12		12		9.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	5.5		5.5		3.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	6		6		6
Financing Receivable, Excluding Accrued Interest, Revolving	24		24		26.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.2
Total	136.9		136.9		141.6
Less loans charged-off			2.9		4.1
Direct and advance lines | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	37.1		37.1		44.5
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	29.8		29.8		32.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	22.2		22.2		18.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	12		12		9.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	5.5		5.5		3.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.9		5.9		6
Financing Receivable, Excluding Accrued Interest, Revolving	24		24		26.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.2
Total	136.5		136.5		141.3
Direct and advance lines | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.1		0.1		0.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.1		0.1		0.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.1		0.1		0.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.1		0.1		0
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	0.4		0.4		0.3
Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.9		1.9		1.8
Nonaccrual loans	0		0		0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	76.4		76.4		76.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving	76.4		76.4		76.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	76.4		76.4		76.5
Less loans charged-off			2.1		2.6
Credit card | Performing Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving	75.7		75.7		75.9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	75.7		75.7		75.9
Credit card | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving	0.7		0.7		0.6
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	0.7		0.7		0.6
Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11.4		11.4		13.5
Nonaccrual loans	3.8		3.8		3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	955.5		955.5		959
Less loans charged-off	4.1	3.7	11.9	10.4
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6.4		6.4		15.9
Nonaccrual loans	81.6		81.6		11.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,919.7		2,919.7		2,906.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	419.1		419.1		508
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	408.3		408.3		533.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	423.8		423.8		407
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	342.5		342.5		225.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	185.2		185.2		111.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	282.9		282.9		277.9
Financing Receivable, Excluding Accrued Interest, Revolving	851.2		851.2		836
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.7		6.7		8.2
Total	2,919.7		2,919.7		2,906.8
Less loans charged-off	2.5	0.7	8.7	2.2	3.4
Commercial | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	386		386		481.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	395.5		395.5		507.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	406.9		406.9		389.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	335.8		335.8		215.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	176.1		176.1		108.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	278.3		278.3		272.9
Financing Receivable, Excluding Accrued Interest, Revolving	783.5		783.5		762.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.7		6.7		7.6
Total	2,768.8		2,768.8		2,745.7
Commercial | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3		3		7.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.9		6.9		4.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	8.8		8.8		6.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1.5		1.5		3.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1		1		0.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1		1		1.9
Financing Receivable, Excluding Accrued Interest, Revolving	17.5		17.5		14.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.2
Total	39.7		39.7		39.5
Commercial | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	28.9		28.9		15.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.2		4.2		19.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	5.6		5.6		9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	5.2		5.2		7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	8.1		8.1		1.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	3.6		3.6		3
Financing Receivable, Excluding Accrued Interest, Revolving	7.1		7.1		58.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.4
Total	62.7		62.7		115.2
Commercial | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.2		1.2		3.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.7		1.7		1.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	2.5		2.5		1.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	43.1		43.1		0.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	48.5		48.5		6.4
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.8		1.8		3.1
Nonaccrual loans	23		23		30.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	689.8		689.8		769.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	133.7		133.7		152.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	80.7		80.7		58.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	43.9		43.9		34.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	20.7		20.7		23.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	18.3		18.3		35
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.6		7.6		9.5
Financing Receivable, Excluding Accrued Interest, Revolving	384.8		384.8		449.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1		6.5
Total	689.8		689.8		769.4
Less loans charged-off	0.3	$ 0	0.3	$ 0	0
Agricultural | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	81.3		81.3		105.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	52.5		52.5		57.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	43.2		43.2		31.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	20.5		20.5		22.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16.7		16.7		6.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.4		7.4		7.2
Financing Receivable, Excluding Accrued Interest, Revolving	355.7		355.7		421.9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		3.4
Total	577.3		577.3		656
Agricultural | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.5		0.5		2.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	3.6		3.6		0.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.7		0.7		0.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.1		0.1		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1		1		0.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.2		0.2		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	5.2		5.2		9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1		3.1
Total	11.4		11.4		16.4
Agricultural | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	51.9		51.9		43.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	24.6		24.6		0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		2.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.1		0.1		0.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.6		0.6		28.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		2.2
Financing Receivable, Excluding Accrued Interest, Revolving	23.9		23.9		18.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Total	101.1		101.1		97
Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Nonaccrual loans	0		0		0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2.5		2.5		0.1
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	42.5		42.5		72.2
Nonaccrual loans	172.7		172.7		106.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	18,038.9		18,038.9		18,292.1
30 to 59 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	5.1		5.1		12.7
30 to 59 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3.6		3.6		3.1
30 to 59 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.6		2.6		11.9
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.4		2.4		1.8
30 to 59 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13.7		13.7		29.5
30 to 59 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6.4		6.4		8
30 to 59 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1		1		0.9
30 to 59 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.7		0.7		0.7
30 to 59 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	8.1		8.1		9.6
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	4.3		4.3		14.5
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.6		1.6		0.1
30 to 59 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
30 to 59 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	27.7		27.7		53.7
60 to 89 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6.8		6.8		6.1
60 to 89 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.1		0.1		0.4
60 to 89 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.1		2.1		3.1
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
60 to 89 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9		9		9.6
60 to 89 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.6		1.6		2.2
60 to 89 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.4		0.4		0.2
60 to 89 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.5		0.5		0.5
60 to 89 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.5		2.5		2.9
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.5		1.5		1.1
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
60 to 89 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
60 to 89 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13		13		13.6
Equal to or Greater than 90 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Equal to or Greater than 90 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Equal to or Greater than 90 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		0.6
Equal to or Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Equal to or Greater than 90 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		0.6
Equal to or Greater than 90 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.1		0.1		0.4
Equal to or Greater than 90 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Equal to or Greater than 90 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.7		0.7		0.6
Equal to or Greater than 90 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.8		0.8		1
Equal to or Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.6		0.6		0.3
Equal to or Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0.2		0.2		3
Equal to or Greater than 90 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Equal to or Greater than 90 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1.8		1.8		4.9
Financial Asset, Not Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9,162.2		9,162.2		8,822.2
Financial Asset, Not Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,304.1		1,304.1		1,805.8
Financial Asset, Not Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,198.6		2,198.6		2,218
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	719.3		719.3		709.6
Financial Asset, Not Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13,384.2		13,384.2		13,555.6
Financial Asset, Not Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	730.7		730.7		727.6
Financial Asset, Not Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	135.1		135.1		140.2
Financial Asset, Not Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	74.5		74.5		74.7
Financial Asset, Not Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	940.3		940.3		942.5
Financial Asset, Not Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,831.7		2,831.7		2,879.4
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	665		665		735.9
Financial Asset, Not Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2.5		2.5		0.1
Financial Asset, Not Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	$ 17,823.7		17,823.7		18,113.5
Year One, Originated, Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		1.7
Year One, Originated, Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year One, Originated, Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0.3
Year One, Originated, Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year One, Originated, Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0.5
Year One, Originated, Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.2
Year One, Originated, Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year One, Originated, Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.4		0.2
Year One, Originated, Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			5.7		0.3
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.7		3.2
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.5		0.5
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.9		0.4
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Three, Originated, Two Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		1.7
Year Three, Originated, Two Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			13.1		0.1
Year Three, Originated, Two Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Year Three, Originated, Two Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Three, Originated, Two Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			2.9		1.8
Year Three, Originated, Two Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.7		0.2
Year Three, Originated, Two Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Three, Originated, Two Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1		0.5
Year Three, Originated, Two Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Four, Originated, Three Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			15.8		2.6
Year Four, Originated, Three Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Four, Originated, Three Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Year Four, Originated, Three Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Four, Originated, Three Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.9		0.8
Year Four, Originated, Three Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0.4
Year Four, Originated, Three Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Four, Originated, Three Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.3		0.5
Year Four, Originated, Three Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.3		0
Year Five, Originated, Four Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Five, Originated, Four Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.6
Year Five, Originated, Four Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.2		0
Year Five, Originated, Four Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Five, Originated, Four Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.3		0.3
Year Five, Originated, Four Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Year Five, Originated, Four Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Year Five, Originated, Four Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.2
Year Five, Originated, Four Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Originated, More than Five Years before Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		1.3
Originated, More than Five Years before Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Originated, More than Five Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Originated, More than Five Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Originated, More than Five Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.9		0.7
Originated, More than Five Years before Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.3		2.6
Originated, More than Five Years before Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Originated, More than Five Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0.1		0.1
Originated, More than Five Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0.1
Revolving | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			2.1		2.6
Revolving | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1.9		1.4
Revolving | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		9.6
Revolving, Converted to Term | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0		0
Revolving, Converted to Term | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			3		0.1
Revolving, Converted to Term | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			$ 0		$ 0

Loans Held for Investment - S_7

Loans Held for Investment - Schedule of Recorded Credit Quality Indicator (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Commitments to purchase or sell	$ 0	$ 0	$ 0	$ 0
Proceeds from sale of loans held-for-investment	0	0	0	0
Less loans charged-off	(29.1)	(6.2)	(56.4)	(29.2)
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	9,219.3		9,219.3		$ 8,869.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,067		1,067		1,337.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,386.3		1,386.3		2,085.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	2,007.2		2,007.2		1,675
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,499.3		1,499.3		1,215.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,147.4		1,147.4		774.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	2,007.2		2,007.2		1,706.1
Financing Receivable, Excluding Accrued Interest, Revolving	48.2		48.2		47
Less loans charged-off			(21.6)		(7.6)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	56.7		56.7		28.1
Commercial | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		(1.7)
Commercial | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(5.7)		(0.3)
Commercial | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		(1.7)
Commercial | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(15.8)		(2.6)
Commercial | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Commercial | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(1.3)
Commercial | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Commercial | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,217.8		2,217.8		2,244.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	15.6		15.6		45.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	71.3		71.3		359
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	423.5		423.5		522.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	491.3		491.3		501.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	456.3		456.3		89.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	270		270		222.2
Financing Receivable, Excluding Accrued Interest, Revolving	480.2		480.2		471.8
Less loans charged-off			(0.7)		(0.6)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9.6		9.6		32.1
Residential | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		(0.3)
Residential | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.2)		0
Residential | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.1)
Residential | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.1)
Residential | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.2)		0
Residential | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.1)
Residential | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Residential | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	1,307.9		1,307.9		1,826.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	261.2		261.2		501.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	263.4		263.4		758.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	490.8		490.8		356.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	114		114		36.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	19.7		19.7		16.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	24.6		24.6		36.8
Financing Receivable, Excluding Accrued Interest, Revolving	129.3		129.3		104.4
Less loans charged-off			(13.2)		(10.3)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	4.9		4.9		14.6
Total construction loans | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total construction loans | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total construction loans | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(13.1)		(0.1)
Total construction loans | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total construction loans | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.6)
Total construction loans | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total construction loans | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total construction loans | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		(9.6)
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	726.4		726.4		716.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	105.5		105.5		96.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	76		76		154
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	138.7		138.7		133.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	130.2		130.2		98
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	88.9		88.9		58.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	161.3		161.3		136.7
Financing Receivable, Excluding Accrued Interest, Revolving	25.8		25.8		32.3
Less loans charged-off			0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		7
Agricultural | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total real estate
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off	(22.2)	(1.8)	(35.5)	(16.6)
Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	742.2		742.2		740.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	203.3		203.3		195.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	147.7		147.7		265.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	195.8		195.8		116
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	83.5		83.5		81.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	55.8		55.8		33.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	56.1		56.1		49.4
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Less loans charged-off			(6.9)		(7.3)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Indirect consumer | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.2)		(0.5)
Indirect consumer | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(1.7)		(3.2)
Indirect consumer | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(2.9)		(1.8)
Indirect consumer | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.9)		(0.8)
Indirect consumer | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.3)		(0.3)
Indirect consumer | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.9)		(0.7)
Indirect consumer | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Indirect consumer | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	136.9		136.9		141.6
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	37.2		37.2		44.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	29.9		29.9		33
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	22.3		22.3		18.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	12		12		9.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	5.5		5.5		3.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	6		6		6
Financing Receivable, Excluding Accrued Interest, Revolving	24		24		26.2
Less loans charged-off			(2.9)		(4.1)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.2
Direct consumer | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.2)
Direct consumer | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.5)		(0.5)
Direct consumer | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.7)		(0.2)
Direct consumer | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.2)		(0.4)
Direct consumer | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.1)
Direct consumer | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(1.3)		(2.6)
Direct consumer | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		(0.1)
Direct consumer | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	76.4		76.4		76.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving	76.4		76.4		76.5
Less loans charged-off			(2.1)		(2.6)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Credit card | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Credit card | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(2.1)		(2.6)
Credit card | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Total consumer loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off	(4.1)	(3.7)	(11.9)	(10.4)
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,919.7		2,919.7		2,906.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	419.1		419.1		508
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	408.3		408.3		533.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	423.8		423.8		407
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	342.5		342.5		225.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	185.2		185.2		111.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	282.9		282.9		277.9
Financing Receivable, Excluding Accrued Interest, Revolving	851.2		851.2		836
Less loans charged-off	(2.5)	(0.7)	(8.7)	(2.2)	(3.4)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.7		6.7		8.2
Commercial | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.4)		(0.2)
Commercial | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(1.9)		(0.4)
Commercial | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(1)		(0.5)
Commercial | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.3)		(0.5)
Commercial | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.2)
Commercial | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)		(0.1)
Commercial | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(1.9)		(1.4)
Commercial | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(3)		(0.1)
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	689.8		689.8		769.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	133.7		133.7		152.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	80.7		80.7		58.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	43.9		43.9		34.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	20.7		20.7		23.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	18.3		18.3		35
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.6		7.6		9.5
Financing Receivable, Excluding Accrued Interest, Revolving	384.8		384.8		449.4
Less loans charged-off	(0.3)	$ 0	(0.3)	$ 0	0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1		6.5
Agricultural | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Three, Originated, Two Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.3)		0
Agricultural | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Originated, More than Five Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Agricultural | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0		0
Pass | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	8,980.9		8,980.9		8,596.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,026.8		1,026.8		1,268
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,366.2		1,366.2		2,065
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,981.5		1,981.5		1,612.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,441.7		1,441.7		1,200.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,137.3		1,137.3		716.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,922.5		1,922.5		1,660.5
Financing Receivable, Excluding Accrued Interest, Revolving	48.2		48.2		46.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	56.7		56.7		28.1
Pass | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	1,296		1,296		1,768
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	256.1		256.1		493.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	263.4		263.4		735.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	484.4		484.4		331.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	114		114		36.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	19.7		19.7		16.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	24.2		24.2		36.2
Financing Receivable, Excluding Accrued Interest, Revolving	129.3		129.3		104.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	4.9		4.9		13.7
Pass | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	657.3		657.3		649.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	92.2		92.2		86.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	65		65		123.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	113.6		113.6		126.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	121.4		121.4		93.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	79.9		79.9		56.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	159.4		159.4		124.3
Financing Receivable, Excluding Accrued Interest, Revolving	25.8		25.8		31.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		7
Pass | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,768.8		2,768.8		2,745.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	386		386		481.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	395.5		395.5		507.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	406.9		406.9		389.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	335.8		335.8		215.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	176.1		176.1		108.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	278.3		278.3		272.9
Financing Receivable, Excluding Accrued Interest, Revolving	783.5		783.5		762.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.7		6.7		7.6
Pass | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	577.3		577.3		656
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	81.3		81.3		105.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	52.5		52.5		57.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	43.2		43.2		31.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	20.5		20.5		22.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16.7		16.7		6.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.4		7.4		7.2
Financing Receivable, Excluding Accrued Interest, Revolving	355.7		355.7		421.9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		3.4
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	100.5		100.5		113.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	12.6		12.6		4.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	9.4		9.4		9.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21.1		21.1		42.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	18.3		18.3		12.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	2.2		2.2		27.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	36.9		36.9		17.1
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0.3
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Other Assets Especially Mentioned | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	9.6		9.6		9.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3.2		3.2		0.5
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		6.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6.4		6.4		1.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0.2
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.9
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	27.3		27.3		30.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.1		1.1		2.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.6		6.6		9.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	5.9		5.9		3.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	5.1		5.1		1.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.6		7.6		1.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1		1		11.3
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	39.7		39.7		39.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3		3		7.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.9		6.9		4.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	8.8		8.8		6.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1.5		1.5		3.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1		1		0.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1		1		1.9
Financing Receivable, Excluding Accrued Interest, Revolving	17.5		17.5		14.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.2
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	11.4		11.4		16.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.5		0.5		2.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	3.6		3.6		0.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.7		0.7		0.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.1		0.1		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1		1		0.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.2		0.2		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	5.2		5.2		9
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1		3.1
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	137.9		137.9		157.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	27.6		27.6		65.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	10.7		10.7		11.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	4.6		4.6		18.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39.3		39.3		2.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.9		7.9		30.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	47.8		47.8		28.5
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Substandard | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2.3		2.3		36
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.9		1.9		7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0		4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		24.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.4		0.4		0.4
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	41.8		41.8		36.6
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	12.2		12.2		8.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.4		4.4		20.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	19.2		19.2		3.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	3.7		3.7		2.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.4		1.4		0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.9		0.9		1.1
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	62.7		62.7		115.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	28.9		28.9		15.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.2		4.2		19.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	5.6		5.6		9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	5.2		5.2		7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	8.1		8.1		1.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	3.6		3.6		3
Financing Receivable, Excluding Accrued Interest, Revolving	7.1		7.1		58.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0.4
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	101.1		101.1		97
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	51.9		51.9		43.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	24.6		24.6		0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0		2.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.1		0.1		0.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.6		0.6		28.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		2.2
Financing Receivable, Excluding Accrued Interest, Revolving	23.9		23.9		18.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0		0
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					1.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Revolving					0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan					0
Doubtful | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					13
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					13
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Revolving					0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan					0
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	48.5		48.5		6.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.2		1.2		3.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.7		1.7		1.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	2.5		2.5		1.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	43.1		43.1		0.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	$ 0		$ 0		$ 0

Loans Held for Investment - Nar

Loans Held for Investment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Dec. 31, 2023
Receivables [Abstract]
Commitments to purchase or sell	$ 0	$ 0	$ 0	$ 0
Proceeds from sale of loans held-for-investment	0	0	0	0
Interest Receivable	127.3		127.3		$ 127.3	$ 129.1
Financing Receivable, Loan in Process	0.5		0.5		0.5
Financing Receivable, Excluding Accrued Interest, Modified, Subsequent Default					$ 1.3
Accrued interest reversal	$ (0.4)	$ (1)	$ (2.4)	$ (1.9)

Other Real Estate Owned (Detail

Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Repossessed Assets [Abstract]
Balance at beginning of year	$ 6.7	$ 14.4	$ 16.5	$ 12.7
Additions	0.9	0	4.6	2.5
Write-down of OREO	0	(0.3)	(4.2)	(1.1)
Dispositions	(3.2)	(2.5)	(12.5)	(2.5)
Balance at end of year	$ 4.4	$ 11.6	$ 4.4	$ 11.6

Other Real Estate Owned - Narra

Other Real Estate Owned - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Balance at beginning of year
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 1.7	$ 0.5

Derivatives and Hedging Activ_3

Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	$ 1,773.8	$ 2,144.7
Derivative Asset, Estimated Fair Value	28.6	37.4
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	1,868.9	2,295.7
Derivative Liabilities, Estimated Fair Value	94.2	127.3
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	1,468.5	1,589
Derivative Asset, Estimated Fair Value	28.3	34.3
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	1,468.5	1,589
Derivative Liabilities, Estimated Fair Value	93	121.1
Not Designated as Hedging Instrument | Interest rate lock commitments
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	5.3	5.7
Derivative Asset, Estimated Fair Value	0	0.1
Not Designated as Hedging Instrument | Forward loan sales contracts
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	4.9	5.6
Derivative Liabilities, Estimated Fair Value	0	0.1
Designated as Hedging Instrument [Member] | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	300	550
Derivative Asset, Estimated Fair Value	0.3	3
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	0	300
Derivative Liabilities, Estimated Fair Value	$ 0	$ 2.4

Derivatives and Hedging Activ_4

Derivatives and Hedging Activities - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financial Assets
Gross Amounts Recognized	$ 28.6		$ 28.6		$ 37.4
Gross Amounts Offset in the Balance Sheet	0		0		0
Net Amounts in the Balance Sheet	28.6		28.6		37.4
Financial Instruments	0		0		0
Fair Value of Financial Collateral in the Balance Sheet	25.8		25.8		32.7
Net Amount	2.8		2.8		4.7
Financial Liabilities
Gross Amounts Recognized	94.2		94.2		127.3
Gross Amounts Offset in the Balance Sheet	0		0		0
Net Amounts in the Balance Sheet	94.2		94.2		127.3
Financial Instruments	0		0		0
Fair Value of Financial Collateral in the Balance Sheet	0		0		0
Net Amount	94.2		94.2		127.3
Repurchase agreements
Gross Amounts Recognized	557.2		557.2		782.7
Gross Amounts Offset in the Balance Sheet	0		0		0
Net Amounts in the Balance Sheet	557.2		557.2		782.7
Financial Instruments	0		0		0
Fair Value of Financial Collateral in the Balance Sheet	0		0		0
Net Amount	557.2		557.2		782.7
Total assets and liabilities
Gross Amounts Recognized	651.4		651.4		910
Gross Amounts Offset in the Balance Sheet	0		0		0
Net Amounts in the Balance Sheet	651.4		651.4		910
Financial Instruments	0		0		0
Fair Value of Financial Collateral in the Balance Sheet	0		0		0
Net Amount	651.4		651.4		910
Derivative Liability, Notional Amount	1,868.9		1,868.9		2,295.7
Not Designated as Hedging Instrument
Total assets and liabilities
Amount of net gains recognized in mortgage banking revenues	0	$ 0.1	0	$ (0.1)
Interest Rate Swap
Financial Assets
Gross Amounts Recognized	28.6		28.6		37.3
Gross Amounts Offset in the Balance Sheet	0		0		0
Net Amounts in the Balance Sheet	28.6		28.6		37.3
Financial Instruments	0		0		0
Fair Value of Financial Collateral in the Balance Sheet	25.8		25.8		32.7
Net Amount	2.8		2.8		4.6
Interest Rate Swap | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	1,468.5		1,468.5		1,589
Risk Participation Agreements
Financial Liabilities
Gross Amounts Recognized					0.1
Gross Amounts Offset in the Balance Sheet					0
Net Amounts in the Balance Sheet					0.1
Financial Instruments					0
Fair Value of Financial Collateral in the Balance Sheet					0
Net Amount					0.1
Risk Participation Agreements | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	95.5		95.5		101.1
Interest Rate Lock Commitments
Financial Assets
Gross Amounts Recognized					0.1
Gross Amounts Offset in the Balance Sheet					0
Net Amounts in the Balance Sheet					0.1
Financial Instruments					0
Fair Value of Financial Collateral in the Balance Sheet					0
Net Amount					0.1
Interest Rate Swap and Interest Rate Collar
Financial Liabilities
Gross Amounts Recognized	94.2		94.2		127.1
Gross Amounts Offset in the Balance Sheet	0		0		0
Net Amounts in the Balance Sheet	94.2		94.2		127.1
Financial Instruments	0		0		0
Fair Value of Financial Collateral in the Balance Sheet	0		0		0
Net Amount	94.2		94.2		127.1
Forward Contracts
Financial Liabilities
Gross Amounts Recognized					0.1
Gross Amounts Offset in the Balance Sheet					0
Net Amounts in the Balance Sheet					0.1
Financial Instruments					0
Fair Value of Financial Collateral in the Balance Sheet					0
Net Amount					0.1
Forward Contracts | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	$ 4.9		$ 4.9		$ 5.6

Derivatives and Hedging Activ_5

Derivatives and Hedging Activities - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ 3	$ (3.2)	$ (2.8)	$ (6.7)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	1.7		1.7
Derivative Instruments and Hedges, Assets	194.3		194.3		$ 193.3
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	5.7		5.7		6.7
Financial Instruments	0		0		0
Derivative Asset, Notional Amount	1,773.8		1,773.8		2,144.7
Derivative Asset, Estimated Fair Value	28.6		28.6		37.4
Derivative Liability, Notional Amount	1,868.9		1,868.9		2,295.7
Derivative Liabilities, Estimated Fair Value	94.2		94.2		127.3
Collateral Pledged
Derivative [Line Items]
Derivative, Fair Value, Net	0		0
Financial Instruments	0		0
Not Designated as Hedging Instrument
Derivative [Line Items]
Amount of net fee income recognized in other non-interest income	0		0
Amount of net gains recognized in mortgage banking revenues	0	0.1	0	(0.1)
Interest Rate Swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	850		850
Interest Rate Swap | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	300		300		550
Derivative Asset, Estimated Fair Value	0.3		0.3		3
Derivative Liability, Notional Amount	0		0		300
Derivative Liabilities, Estimated Fair Value	0		0		2.4
Interest Rate Swap | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	1,468.5		1,468.5		1,589
Derivative Asset, Estimated Fair Value	28.3		28.3		34.3
Derivative Liability, Notional Amount	1,468.5		1,468.5		1,589
Derivative Liabilities, Estimated Fair Value	93		93		121.1
Risk Participation Agreements
Derivative [Line Items]
Financial Instruments					0
Risk Participation Agreements | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Notional Amount	95.5		95.5		101.1
Derivative Liabilities, Estimated Fair Value	0		0		0.1
Forward Contracts
Derivative [Line Items]
Financial Instruments					0
Forward Contracts | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Notional Amount	4.9		4.9		5.6
Derivative Liabilities, Estimated Fair Value	0		0		0.1
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	5.3		5.3		5.7
Derivative Asset, Estimated Fair Value	0		0		0.1
Interest Rate Collars
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	300		300
Interest Rate Collars | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	300		300		300
Derivative Liabilities, Estimated Fair Value	1.2		1.2		$ 3.6
Cash Flow Hedging [Member] | Interest Rate Swap | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ (12.4)	$ 13.1	$ 10.1	$ 27.2

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	$ 194.3		$ 194.3		$ 193.3
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	5.7		5.7		$ 6.7
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	3	$ (3.2)	(2.8)	$ (6.7)
Interest Income, Hedge Basis Adjustment, Portfolio Layer Method, Increase (Decrease)	0.4
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(3.1)	(2.1)	(11.2)	(4.1)
Not Designated as Hedging Instrument
Derivative [Line Items]
Amount of net fee income recognized in other non-interest income	0		0
Interest Rate Swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	850		850
Interest Rate Swap | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	(12.4)	13.1	10.1	27.2
Interest Rate Collars
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	300		300
Interest Rate Floor [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	$ (3.1)	$ (2.1)	$ (11.2)	$ (4.1)
three-year forward starting, four-year pay fixed interest rate swap [Member]
Derivative [Line Items]
Derivative Instruments and Hedges, Assets						$ 200
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)						$ 8.5

Schedule of Long-Term Debt (Det

Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Long-Term Debt and Lease Obligation	$ 137.3	$ 120.8
Parent
Fixed-to-floating rate (percent)	5.25%
Long-Term Debt	$ 99.1	99
FHLB Borrowing maturing July 2025 | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	0%
Long-Term Debt	$ 3.9	0
Capital Lease Obligation, 8.00% | Subsidiaries | Capital Lease Obligations
Fixed-to-floating rate (percent)	8%
Finance Lease, Liability	$ 0.8	0.9
Note Payable, maturing December 31, 2041, 1.00% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1%
Long-Term Debt	$ 5.1	5.1
Note Payable maturing March 31, 2038, 1.30% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.30%
Long-Term Debt	$ 2	2
Note Payable maturing June 1, 2034, 1.30% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.30%
Long-Term Debt	$ 0.6	0.6
Note Payable maturing December 31, 2045, 1.12% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.12%
Long-Term Debt	$ 6.8	6.8
Note Payable maturing December 31, 2046, 1.35% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.35%
Long-Term Debt	$ 6.4	6.4
Note Payable maturing March 31, 2038, 3.25% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	3.25%
Note Payable maturing December 31, 2051, 1.26% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.26%
Long-Term Debt	$ 12.6	$ 0

Long-Term Debt and Other Borr_2

Long-Term Debt and Other Borrowed Funds - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Long-Term Debt and Lease Obligation	$ 137.3	$ 120.8
Advance from Federal Home Loan Bank		2,603
Other Short-term Borrowings	$ 2,080	2,603
Parent
Fixed-to-floating rate (percent)	5.25%
Long-Term Debt	$ 99.1	$ 99
Notes Payable to FHLB | Subsidiaries | Federal Home Loan Bank Advances
Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds	4,885.2
Federal Home Loan Bank, Advances, General Debt Obligations, Maximum Amount Available	$ 5,969
5.01% fixed rate borrowings in tenors up to one-month
Fixed-to-floating rate (percent)	4.86%	5.52%
Capital Lease Obligation, 8.00% | Subsidiaries | Capital Lease Obligations
Fixed-to-floating rate (percent)	8%
Finance Lease, Liability	$ 0.8	$ 0.9
Note Payable, maturing December 31, 2041, 1.00% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1%
Long-Term Debt	$ 5.1	5.1
Note Payable maturing March 31, 2038, 1.30% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.30%
Long-Term Debt	$ 2	2
Note Payable maturing June 1, 2034, 1.30% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.30%
Long-Term Debt	$ 0.6	0.6
Note Payable maturing December 31, 2045, 1.12% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.12%
Long-Term Debt	$ 6.8	6.8
Note Payable maturing December 31, 2046, 1.35% | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	1.35%
Long-Term Debt	$ 6.4	6.4
FHLB Borrowing maturing July 2025 | Subsidiaries | Notes Payable, Other Payables
Fixed-to-floating rate (percent)	0%
Long-Term Debt	$ 3.9	$ 0

Other Borrowed Funds (Details)

Other Borrowed Funds (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
Other Short-term Borrowings	$ 2,080	$ 2,603
Short-Term Debt [Line Items]
Other Short-term Borrowings	2,080	2,603
Average fixed rate borrowings in tenors up to one-week
Debt Disclosure [Abstract]
Other Short-term Borrowings		$ 2,603
Fixed-to-floating rate (percent)		5.52%
Short-Term Debt [Line Items]
Fixed-to-floating rate (percent)		5.52%
Other Short-term Borrowings		$ 2,603
Average fixed rate borrowings in tenors of 12-months
Debt Disclosure [Abstract]
Other Short-term Borrowings	$ 1,830
Fixed-to-floating rate (percent)	4.87%
Short-Term Debt [Line Items]
Fixed-to-floating rate (percent)	4.87%
Other Short-term Borrowings	$ 1,830
Average fixed rate borrowings in tenors over twelve-months
Debt Disclosure [Abstract]
Other Short-term Borrowings	$ 250
Fixed-to-floating rate (percent)	4.72%
Short-Term Debt [Line Items]
Fixed-to-floating rate (percent)	4.72%
Other Short-term Borrowings	$ 250

Capital Stock (Details)

Capital Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Class of Stock [Line Items]
Shares outstanding (in shares)					103,941,626
Stock repurchased and retired (in shares)	3,972	494	49,420	55,922
Stock Repurchased and Retired During Period, Value	$ 0.1	$ 0	$ 1.2	$ 1.9
Common Stock, Shares, Issued					103,941,626
Capital Stock, Authorized	150,100,000		150,100,000
Common Stock, Shares Authorized	150,000,000		150,000,000
Preferred Stock, Shares Authorized	100,000		100,000		100,000
Class A Common Stock
Class of Stock [Line Items]
Shares outstanding (in shares)					103,941,626
Common Stock, Shares, Issued					103,941,626
Common Stock, Voting Rights, Votes Per Share			$ 1
Director [Member]
Class of Stock [Line Items]
Common shares issued (in shares)			43,514
Director [Member] | Class A Common Stock
Class of Stock [Line Items]
Dividend, Share-based Payment Arrangement, Paid-in-Kind			$ 1.2

Earnings per Common Share (Deta

Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 55.5	$ 72.7	$ 173.9	$ 196
Weighted average common shares outstanding for basic earnings per share computation (in shares)	102,970,851	103,822,311	102,917,610	103,793,851
Dilutive effects of stock-based compensation (in shares)	262,767	4,116	207,449	30,425
Weighted average common shares outstanding for diluted earnings per common share computation (in shares)	103,233,618	103,826,427	103,125,059	103,824,276
Basic earnings per common share (in dollars per share)	$ 0.54	$ 0.70	$ 1.69	$ 1.89
Diluted earnings per common share (in dollars per share)	$ 0.54	$ 0.70	$ 1.69	$ 1.89
Restricted Stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)	5,841	162,231	47,854	162,231
Unvested restricted stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)			773,563	967,996

Regulatory Capital (Details)

Regulatory Capital (Details) $ in Millions	Jan. 01, 2020 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained Earnings (Accumulated Deficit)		$ 1,163.3	$ 1,135.1
Total risk-based capital:
Actual, Amount		$ 2,976.2	$ 2,941.1
Actual, Ratio		0.1411	0.1328
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,687.2	$ 1,771.6
Minimum Required for Capital Adequacy Purposes, Ratio		0.0800	0.0800
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 2,214.4	$ 2,325.2
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		10.50%	10.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 2,109	$ 2,214.5
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.1000	0.1000
Banking Regulation, Common Equity Tier One Risk-Based Capital, Capital Adequacy, Minimum		$ 949	$ 996.5
Tier 1 risk-based capital:
Actual, Amount		$ 2,495.8	$ 2,454.4
Actual, Ratio		0.1183	0.1108
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,265.4	$ 1,328.7
Minimum Required for Capital Adequacy Purposes, Ratio		0.0600	0.0600
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,792.6	$ 1,882.3
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		8.50%	8.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,687.2	$ 1,771.6
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.0800	0.0800
Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Well Capitalized, Minimum		0.0650	0.0650
Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Capital Adequacy, Minimum		0.0450	0.0450
Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Actual		0.1183	0.1108
Banking Regulation, Common Equity Tier One Risk-Based Capital, Well Capitalized, Minimum		$ 1,370.8	$ 1,439.4
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		2,495.8	2,454.4
Common equity tier 1 risk-based capital:
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,476.3	$ 1,550.1
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		7%	7%
Leverage capital ratio:
Actual, Amount		$ 2,495.8	$ 2,454.4
Actual, Ratio		0.0857	0.0822
Banking Regulation, Tier One Leverage Capital, Capital Adequacy, Minimum		$ 1,164.9	$ 1,193.9
Capital Adequacy Purposes and Conservation Buffer, Ratio		0.0400	0.0400
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,456.2	$ 1,492.3
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.0500	0.0500
Income Tax Effects Allocated Directly to Equity, Cumulative Effect of Change in Accounting Principle	$ 24.1
FIB
Total risk-based capital:
Actual, Amount		$ 2,701.2	$ 2,662
Actual, Ratio		0.1284	0.1204
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,683.6	$ 1,768.3
Minimum Required for Capital Adequacy Purposes, Ratio		0.0800	0.0800
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 2,209.7	$ 2,320.8
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		10.50%	10.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 2,104.5	$ 2,210.3
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.1000	0.1000
Banking Regulation, Common Equity Tier One Risk-Based Capital, Capital Adequacy, Minimum		$ 947	$ 994.6
Tier 1 risk-based capital:
Actual, Amount		$ 2,478.4	$ 2,433
Actual, Ratio		0.1178	0.1101
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,262.7	$ 1,326.2
Minimum Required for Capital Adequacy Purposes, Ratio		0.0600	0.0600
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,788.8	$ 1,878.8
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		8.50%	8.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,683.6	$ 1,768.3
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.0800	0.0800
Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Well Capitalized, Minimum		0.0650	0.0650
Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Capital Adequacy, Minimum		0.0450	0.0450
Banking Regulation, Common Equity Tier One Risk-Based Capital Ratio, Actual		0.1178	0.1101
Banking Regulation, Common Equity Tier One Risk-Based Capital, Well Capitalized, Minimum		$ 1,367.9	$ 1,436.7
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		2,478.4	2,433
Common equity tier 1 risk-based capital:
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,473.1	$ 1,547.2
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		7%	7%
Leverage capital ratio:
Actual, Amount		$ 2,478.4	$ 2,433
Actual, Ratio		0.0852	0.0816
Banking Regulation, Tier One Leverage Capital, Capital Adequacy, Minimum		$ 1,163.1	$ 1,192.2
Capital Adequacy Purposes and Conservation Buffer, Ratio		0.0400	0.0400
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,453.9	$ 1,490.2
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.0500	0.0500

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Shares outstanding (in shares)		103,941,626
Class A Common Stock
Loss Contingencies [Line Items]
Shares outstanding (in shares)		103,941,626
Mortgage Loans Held For Sale [Member]
Loss Contingencies [Line Items]
Mortgage loans with recourse provision in effect	$ 0.7
Construction Contracts
Loss Contingencies [Line Items]
Commitments under construction contracts	$ 5.5

Financial Instruments with Of_2

Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Entity Information [Line Items]
Off-Balance Sheet, Credit Loss, Liability	$ 5.6	$ 18.8	$ 5.6	$ 18.8	$ 5.8	$ 18.4	$ 20.8	$ 16.2
Provision for credit loss expense	(20)	(3.2)	(47)	(25.3)
Credit Extension Commitments	3,290.7		3,290.7			4,069.2
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	861.4		861.4			814
Standby Letter of Credit
Entity Information [Line Items]
Credit Extension Commitments	88.7		88.7			$ 97.1
Cumulative effect, period of adoption, adjusted balance
Entity Information [Line Items]
Provision for credit loss expense	$ (0.2)	$ (2)	$ (12.8)	$ 2.6

Other Comprehensive Income_Lo_3

Other Comprehensive Income/Loss - Schedule of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Investment securities available-for sale:
Change in net unrealized gain during period, pre-tax	$ 158.5	$ (72.1)	$ 134.6	$ (51.4)
Change in net unrealized gain during period, tax expense (benefit)	(39.4)	17.9	(33.5)	12.7
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	119.1	(54.2)	101.1	(38.7)
Reclassification adjustment for net gains included in income, pre-tax	0	0	0	23.5
Reclassification adjustment for net gains included in income, tax expense (benefit)			0	(5.8)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			0	17.7
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax			0	(5.4)
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, Tax			0	1.8
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), after Tax	(0.2)	(0.2)	(0.5)	(0.8)
Unrealized loss on derivatives, tax expense (benefit)	(0.8)	(0.5)	(2.9)	(1)
Unrealized loss on derivatives, net of tax	9.4	(9.9)	(7.3)	(20.5)
Other comprehensive income (loss), before tax	173.8	(83.4)	135.2	(59.3)
Other Comprehensive Income (Loss), tax expense (benefit)	(43.2)	20.7	(33.6)	14.7
Other Comprehensive Income (Loss), Net of Tax	130.6	(62.7)	101.6	(44.6)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	12.4	(13.1)	(10.1)	(27.2)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	3.1	2.1	11.2	4.1
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	2.3	1.6	8.3	3.1
Total stockholders’ equity	3,365.8	3,085.5	3,365.8	3,085.5	$ 3,225.3	$ 3,227.5	$ 3,121.1	$ 3,073.8
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0	0	0	(7.2)
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax	(0.2)	(0.3)	(0.5)	(1.1)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	0	0.1	0	0.3
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ (3)	$ 3.2	$ 2.8	$ 6.7

Other Comprehensive Income_Lo_4

Other Comprehensive Income/Loss - Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ 3,365.8	$ 3,085.5	$ 3,365.8	$ 3,085.5	$ 3,227.5	$ 3,225.3	$ 3,121.1	$ 3,073.8
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax			0	(5.4)
Change in net unrealized gain during period, pre-tax	158.5	(72.1)	134.6	(51.4)
Change in net unrealized gain during period, tax expense (benefit)	39.4	(17.9)	33.5	(12.7)
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	119.1	(54.2)	101.1	(38.7)
Reclassification adjustment for net losses included in income	0	0	0	23.5
Reclassification adjustment for net gains included in income, tax expense (benefit)			0	5.8
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			0	17.7
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax	(0.2)	(0.3)	(0.5)	(1.1)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	0	(0.1)	0	(0.3)
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), after Tax	(0.2)	(0.2)	(0.5)	(0.8)
Unrealized loss on derivatives, tax expense (benefit)	0.8	0.5	2.9	1
Other comprehensive income (loss), before tax	173.8	(83.4)	135.2	(59.3)
Other Comprehensive Income (Loss), tax expense (benefit)	43.2	(20.7)	33.6	(14.7)
Other Comprehensive Income (Loss), Net of Tax	130.6	(62.7)	101.6	(44.6)
Net unrealized loss on investment securities available-for-sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	(249)		(249)		(350.1)
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax			(5.9)		(5.6)
Net unrealized loss on derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on derivatives			0		(0.8)
Net accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ (254.9)	$ (521.7)	$ (254.9)	$ (521.7)	$ (356.5)	$ (385.5)	$ (459)	$ (477.1)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring and Non-Recurring Basis (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	$ 2.1		$ 2.1		$ 0.5
Deferred compensation plan assets	21.8		21.8		19.2
Deferred compensation plan liabilities	21.8		21.8		19.2
Estimated Fair Value | U.S. Treasury notes | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	231		231		224.7
Estimated Fair Value | State, county, and municipal securities | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	220.9		220.9		219.8
Estimated Fair Value | Obligations of U.S. government agencies | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	165.4		165.4		168.5
Estimated Fair Value | Private mortgage-backed securities | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	199.6		199.6		210.4
Estimated Fair Value | Corporate securities | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	245.1		245.1		236.4
Estimated Fair Value | Collateral-dependent loans | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	109.6		109.6		52.6
Estimated Fair Value | Collateralized Loan Obligations | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	988		988		1,119.7
Estimated Fair Value | Commercial Mortgage-Backed Securities | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,105.3		1,105.3		1,105.6
Estimated Fair Value | Residential Mortgage Backed Securities | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,262.4		1,262.4		1,366.9
Estimated Fair Value | Collateralized Mortgage Obligations | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,116.6		1,116.6		1,189.5
Carrying Amount | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	109.6		$ 109.6		$ 52.6
Long-Lived Assets Held-for-sale, Description			1.0 million		1.0 million
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net			$ 0
Derivative assets	28.6		28.6		$ 37.4
Derivative liabilities	94.2		94.2		127.3
Write downs	0	$ (0.3)	(4.2)	$ (1.1)
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0		0		0
Deferred compensation plan assets	21.8		21.8		19.2
Deferred compensation plan liabilities	21.8		21.8		19.2
Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	2.1		2.1		0.5
Deferred compensation plan assets	0		0		0
Deferred compensation plan liabilities	0		0		0
Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	0		0		0
Deferred compensation plan assets	0		0		0
Deferred compensation plan liabilities	0		0		0
U.S. Treasury notes | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
U.S. Treasury notes | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	231		231		224.7
U.S. Treasury notes | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
State, county, and municipal securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
State, county, and municipal securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	220.9		220.9		219.8
State, county, and municipal securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Obligations of U.S. government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Obligations of U.S. government agencies | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	165.4		165.4		168.5
Obligations of U.S. government agencies | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Private mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Private mortgage-backed securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	199.6		199.6		210.4
Private mortgage-backed securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Corporate securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	245.1		245.1		236.4
Corporate securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Collateral-dependent loans | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	0		0		0
Collateral-dependent loans | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	0		0		0
Collateral-dependent loans | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral-dependent loans	109.6		109.6		52.6
Collateralized Loan Obligations | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Collateralized Loan Obligations | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	988		988		1,119.7
Collateralized Loan Obligations | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Commercial Mortgage-Backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Commercial Mortgage-Backed Securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,105.3		1,105.3		1,105.6
Commercial Mortgage-Backed Securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Residential Mortgage Backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Residential Mortgage Backed Securities | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,262.4		1,262.4		1,366.9
Residential Mortgage Backed Securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Collateralized Mortgage Obligations | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Collateralized Mortgage Obligations | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	1,116.6		1,116.6		1,189.5
Collateralized Mortgage Obligations | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value	0		0		0
Interest Rate Swap | Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	28.6		28.6		37.3
Derivative liabilities	93		93		123.5
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	28.6		28.6		37.3
Interest Rate Swap | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0		0
Derivative liabilities	0		0		0
Interest Rate Swap | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	28.6		28.6		37.3
Derivative liabilities	93		93		123.5
Interest Rate Swap | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0		0		0
Derivative liabilities	0		0		0
Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0.1
Forward Contracts | Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0.1
Derivative liabilities					0.1
Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities					0.1
Forward Contracts | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0
Derivative liabilities					0
Forward Contracts | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0.1
Derivative liabilities					0.1
Forward Contracts | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0
Derivative liabilities					0
Risk Participation Agreements | Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities					0.1
Risk Participation Agreements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities					0.1
Risk Participation Agreements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities					0
Risk Participation Agreements | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities					0.1
Risk Participation Agreements | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities					0
Interest Rate Collars | Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	1.2		1.2		3.6
Interest Rate Collars | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0		0
Interest Rate Collars | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	1.2		1.2		3.6
Interest Rate Collars | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0		0		0
Long-lived assets to be disposed of by sale | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets to be disposed of by sale	1		1		1
Long-lived assets to be disposed of by sale | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets to be disposed of by sale	0		0		0
Long-lived assets to be disposed of by sale | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets to be disposed of by sale	0		0		0
Long-lived assets to be disposed of by sale | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets to be disposed of by sale	$ 1		$ 1		$ 1

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Inputs, Quantitative Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Real Estate Acquired Through Foreclosure	$ 4.4	$ 11.6	$ 4.4	$ 11.6	$ 6.7	$ 16.5	$ 14.4	$ 12.7
Material write downs	0	$ 0.3	4.2	$ 1.1
Significant Unobservable Inputs (Level 3) | Carrying Amount | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Collateral-dependent loans	109.6		109.6			52.6
Collateral-dependent loans | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Collateral-dependent loans	109.6		109.6			52.6
Collateral-dependent loans | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Collateral-dependent loans	0		0			0
Collateral-dependent loans | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Collateral-dependent loans	0		0			0
Collateral-dependent loans | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Collateral-dependent loans	$ 109.6		$ 109.6			52.6
Collateral-dependent loans | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0
Collateral-dependent loans | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0.71		0.71
Collateral-dependent loans | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	(0.41)		(0.41)
Other real estate owned | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Other real estate owned	$ 4.4		$ 4.4			16.5
Other real estate owned | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Other real estate owned	0		0			0
Other real estate owned | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Other real estate owned	0		0			0
Other real estate owned | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Other real estate owned	$ 4.4		$ 4.4			16.5
Other real estate owned | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0.17		0.17
Other real estate owned | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0.40		0.40
Other real estate owned | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	(0.23)		(0.23)
Loans held for sale | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financing Receivable, Held-for-Sale, Nor Part of Disposal Group, after Valuation Allowance, Fair Value Disclosure	$ 18.8		$ 18.8			46.9
Loans held for sale | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financing Receivable, Held-for-Sale, Nor Part of Disposal Group, after Valuation Allowance, Fair Value Disclosure	0		0			0
Loans held for sale | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financing Receivable, Held-for-Sale, Nor Part of Disposal Group, after Valuation Allowance, Fair Value Disclosure	0		0			0
Loans held for sale | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financing Receivable, Held-for-Sale, Nor Part of Disposal Group, after Valuation Allowance, Fair Value Disclosure	$ 18.8		$ 18.8
Loans held for sale | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financing Receivable, Held-for-Sale, Nor Part of Disposal Group, after Valuation Allowance, Fair Value Disclosure						46.9
Loans held for sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0
Loans held for sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0.28		0.28
Loans held for sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	(0.24)		(0.24)
Long-lived assets to be disposed of by sale | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Long-lived assets to be disposed of by sale	$ 1		$ 1			1
Long-lived assets to be disposed of by sale | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Long-lived assets to be disposed of by sale	0		0			0
Long-lived assets to be disposed of by sale | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Long-lived assets to be disposed of by sale	0		0			0
Long-lived assets to be disposed of by sale | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Long-lived assets to be disposed of by sale	$ 1		$ 1			$ 1
Long-lived assets to be disposed of by sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0
Long-lived assets to be disposed of by sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0
Long-lived assets to be disposed of by sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments by Level of Valuation Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Estimated Fair Value
Financial assets:
Cash and cash equivalents	$ 698.6	$ 578
Investment debt securities held-to-maturity	2,480.5	2,874
Accrued interest receivable	127.3	129.1
Mortgage servicing rights, net	37.2	38.8
Loans held for sale	20.9	47.4
Net loans held for investment	17,257.5	17,334.4
Total financial assets	20,622	21,001.7
Financial liabilities:
Time deposits	2,864.3	2,981.7
Securities sold under repurchase agreements	557.2	782.7
Other Borrowings	2,080	2,603
Accrued interest payable	87.7	52.2
Long-term debt	132.1	115.6
Subordinated debentures held by subsidiary trusts	151	151.1
Total financial liabilities	25,858.2	26,999.5
Deposits, Excluding Time Deposits, Fair Value Disclosure	19,985.9	20,313.2
Carrying Amount
Financial assets:
Cash and cash equivalents	698.6	578
Investment debt securities held-to-maturity	2,741.3	3,207.9
Accrued interest receivable	127.3	129.1
Mortgage servicing rights, net	26.3	28.3
Loans held for sale	20.9	47.4
Net loans held for investment	17,801.7	18,051.9
Total financial assets	21,416.1	22,042.6
Financial liabilities:
Time deposits	2,878.2	3,009.9
Securities sold under repurchase agreements	557.2	782.7
Other Borrowings	2,080	2,603
Accrued interest payable	87.7	52.2
Long-term debt	137.3	120.8
Subordinated debentures held by subsidiary trusts	163.1	163.1
Total financial liabilities	25,889.4	27,044.9
Deposits, Excluding Time Deposits, Fair Value Disclosure	19,985.9	20,313.2
Investment debt securities held-to-maturity	2,480.5	2,874
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	698.6	578
Investment debt securities held-to-maturity	0	0
Accrued interest receivable	0	0
Mortgage servicing rights, net	0	0
Loans held for sale	0	0
Net loans held for investment	0	0
Total financial assets	698.6	578
Financial liabilities:
Time deposits	0	0
Securities sold under repurchase agreements	0	0
Other Borrowings	0	0
Accrued interest payable	0	0
Long-term debt	0	0
Subordinated debentures held by subsidiary trusts	0	0
Total financial liabilities	19,985.9	20,313.2
Deposits, Excluding Time Deposits, Fair Value Disclosure	19,985.9	20,313.2
Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Investment debt securities held-to-maturity	2,480.5	2,874
Accrued interest receivable	127.3	129.1
Mortgage servicing rights, net	37.2	38.8
Loans held for sale	2.1	0.5
Net loans held for investment	17,147.9	17,281.8
Total financial assets	19,795	20,324.2
Financial liabilities:
Time deposits	2,864.3	2,981.7
Securities sold under repurchase agreements	557.2	782.7
Other Borrowings	2,080	2,603
Accrued interest payable	87.7	52.2
Long-term debt	132.1	115.6
Subordinated debentures held by subsidiary trusts	151	151.1
Total financial liabilities	5,872.3	6,686.3
Deposits, Excluding Time Deposits, Fair Value Disclosure	0	0
Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Investment debt securities held-to-maturity	0	0
Accrued interest receivable	0	0
Mortgage servicing rights, net	0	0
Loans held for sale	18.8	46.9
Net loans held for investment	109.6	52.6
Total financial assets	128.4	99.5
Financial liabilities:
Time deposits	0	0
Securities sold under repurchase agreements	0	0
Other Borrowings	0	0
Accrued interest payable	0	0
Long-term debt	0	0
Subordinated debentures held by subsidiary trusts	0	0
Total financial liabilities	0	0
Deposits, Excluding Time Deposits, Fair Value Disclosure	$ 0	$ 0

Subsequent Events (Details)

Subsequent Events (Details)	Oct. 23, 2024 $ / shares
Class A Common Stock | Subsequent Event
Subsequent Event [Line Items]
Dividend amount per share (in dollars)	$ 0.47