10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

___________________________________________________________________________________________________________________________________________________ 

FORM 10-Q

_____________________________________________________________________________________________________________________________________________________ 

☒    Quarterly report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the quarterly period ended September 30, 2023

OR

 ☐    Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the transition period from                   to                   

COMMISSION FILE NUMBER 001-34653

________________________________________________________________________________________________________ 

FIRST INTERSTATE BANCSYSTEM, INC.

(Exact name of registrant as specified in its charter)

________________________________________________________________________________________________________ 

Delaware		81-0331430
(State or other jurisdiction of incorporation or organization)		(IRS Employer Identification No.)
401 North 31st Street
Billings,	MT	59101
(Address of principal executive offices)		(Zip Code)

Registrant’s telephone number, including area code: (406) 255-5311

N/A

(Former name, former address and former fiscal year, if changed since last report)

_________________________________________________________________________________________________ 

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.00001 par value	FIBK	NASDAQ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files.)     Yes  ☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☒	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).  Yes  ☐ No  ☒

Indicate the number of shares outstanding of each of the registrant’s classes of common stock, as of the latest practicable date:

October 31, 2023 – Common stock 104,997,866 

Quarterly Report on Form 10-Q

	FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES
	Index
	September 30, 2023
		Page Nos.
	Part I - Financial Information
Item 1.	Financial Statements (Unaudited)
	Consolidated Balance Sheets	3
	Consolidated Statements of Income	4
	Consolidated Statements of Comprehensive Income (Loss)	5
	Consolidated Statements of Changes in Stockholders’ Equity	6
	Consolidated Statements of Cash Flows	8
	Notes to Unaudited Consolidated Financial Statements	10
Item 2.	Management's Discussion and Analysis of Financial Condition and Results of Operations	50
Item 3.	Quantitative and Qualitative Disclosures about Market Risk	67
Item 4.	Controls and Procedures	67
	Part II - Other Information
Item 1.	Legal Proceedings	67
Item 1A.	Risk Factors	67
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	68
Item 3.	Defaults Upon Senior Securities	68
Item 4.	Mine Safety Disclosures	68
Item 5.	Other Information	68
Item 6.	Exhibits	68
Signatures		69

2

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(In millions, except share data)

(Unaudited)

	September 30, 2023		December 31, 2022
Assets
Cash and due from banks	$	371.5	$	349.2
Interest bearing deposits in banks	219.5		521.2
Federal funds sold	2.1		0.1
Total cash and cash equivalents	593.1		870.5
Investment securities:
Available-for-sale, net of allowance for credit losses of $0 at September 30, 2023 and December 31, 2022 (amortized cost of $6,290.2 at September 30, 2023 and $7,573.5 at December 31, 2022)	5,627.7		6,946.1
Held-to-maturity, net of allowance for credit losses of $0.8 at September 30, 2023 and $1.9 at December 31, 2022 (estimated fair values of $2,796.1 at September 30, 2023 and $3,052.2 at December 31, 2022)	3,259.5		3,451.8
Total investment securities	8,887.2		10,397.9
FHLB and FRB stock, at cost	189.5		198.6
Loans held for sale	59.1		79.9
Loans held for investment, net of deferred fees and costs	18,213.3		18,099.2
Allowance for credit losses	(226.7)		(220.1)
Net loans held for investment	17,986.6		17,879.1
Goodwill	1,100.9		1,100.9
Company-owned life insurance	500.8		497.9
Premises and equipment, net of accumulated depreciation	446.3		444.7
Other intangibles, net of accumulated amortization	85.2		97.0
Accrued interest receivable	129.2		118.3
Mortgage servicing rights, net of accumulated amortization and impairment reserve	29.1		31.1
Other real estate owned	11.6		12.7
Deferred tax asset, net	215.3		210.5
Other assets	306.9		348.7
Total assets	$	30,540.8	$	32,287.8
Liabilities and Stockholders’ Equity
Deposits:
Non-interest bearing	$	6,402.6	$	7,560.0
Interest bearing	17,276.9		17,513.6
Total deposits	23,679.5		25,073.6
Securities sold under repurchase agreements	889.5		1,052.9
Accounts payable and accrued expenses	452.9		445.9
Accrued interest payable	63.7		14.5
Long-term debt	120.8		120.8
Other borrowed funds	2,067.0		2,327.0
Allowance for credit losses on off-balance sheet credit exposures	18.8		16.2
Subordinated debentures held by subsidiary trusts	163.1		163.1
Total liabilities	27,455.3		29,214.0
Stockholders’ equity:
Preferred stock, no par value; 100,000 shares authorized; none issued and outstanding	—		—
Common stock and additional paid-in-capital, $0.00001 par value; 150,000,000 shares authorized; 105,011,371 and 104,442,023 shares were issued and outstanding at September 30, 2023 and December 31, 2022	2,484.9		2,478.2
Retained earnings	1,122.3		1,072.7
Accumulated other comprehensive loss, net	(521.7)		(477.1)
Total stockholders’ equity	3,085.5		3,073.8
Total liabilities and stockholders’ equity	$	30,540.8	$	32,287.8

See accompanying notes to unaudited consolidated financial statements.

3

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(In millions, except per share data)

(Unaudited)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Interest income:
Interest and fees on loans	$	249.9	$	218.3	$	727.1	$	561.7
Interest and dividends on investment securities:
Taxable	66.0		64.3		203.3		142.4
Exempt from federal taxes	0.8		1.4		3.5		4.1
Interest and dividends on FHLB and FRB stock	2.9		1.3		9.3		2.8
Interest on deposits in banks	3.0		1.4		12.6		6.5
Total interest income	322.6		286.7		955.8		717.5
Interest expense:
Interest on deposits	68.8		13.3		162.7		20.6
Interest on securities sold under repurchase agreements	1.7		0.8		4.3		1.4
Interest on other borrowed funds	33.6		2.4		104.1		2.4
Interest on long-term debt	1.5		1.5		4.4		4.6
Interest on subordinated debentures held by subsidiary trusts	3.3		1.9		9.3		4.3
Total interest expense	108.9		19.9		284.8		33.3
Net interest income	213.7		266.8		671.0		684.2
(Reduction of) provision for credit losses	(0.1)		8.4		26.8		68.0
Net interest income after provision for credit losses	213.8		258.4		644.2		616.2
Non-interest income:
Payment services revenues	19.2		20.4		58.0		54.7
Mortgage banking revenues	2.0		2.7		6.9		16.1
Wealth management revenues	8.7		8.5		26.5		25.9
Service charges on deposit accounts	6.0		5.7		17.0		19.7
Other service charges, commissions, and fees	2.2		4.7		7.0		12.6
Investment securities losses, net	—		(24.2)		(23.5)		(24.4)
Other income	3.9		5.1		10.6		17.0
Total non-interest income	42.0		22.9		102.5		121.6
Non-interest expense:
Salaries and wages	65.4		71.9		199.1		206.7
Employee benefits	19.7		19.6		61.8		60.2
Outsourced technology services	14.5		15.9		44.5		40.0
Occupancy, net	11.7		11.3		35.9		32.5
Furniture and equipment	5.3		5.8		16.8		17.0
OREO expense, net of income	0.5		—		1.3		0.1
Professional fees	5.1		5.1		14.9		14.5
FDIC insurance premiums	5.0		4.1		15.4		10.2
Other intangibles amortization	3.9		4.1		11.8		11.8
Other expenses	30.0		31.4		89.3		82.7
Acquisition related expenses	—		4.0		—		115.0
Total non-interest expense	161.1		173.2		490.8		590.7
Income before income tax	94.7		108.1		255.9		147.1
Provision for income tax	22.0		22.4		59.9		30.7
Net income	$	72.7	$	85.7	$	196.0	$	116.4
Earnings per common share (Basic)	$	0.70	$	0.80	$	1.89	$	1.13
Earnings per common share (Diluted)	$	0.70	$	0.80	$	1.89	$	1.13
Weighted average common shares outstanding (Basic)	103,822,311		106,525,974		103,793,851		102,879,422
Weighted average common shares outstanding (Diluted)	103,826,427		106,589,699		103,824,276		102,935,360

See accompanying notes to unaudited consolidated financial statements.

4

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)

(In millions)

(Unaudited)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Net income	$	72.7	$	85.7	$	196.0	$	116.4
Other comprehensive income (loss), before tax:
Investment securities available-for sale:
Change in net unrealized losses during the period	(72.1)		(236.4)		(51.4)		(650.6)
Reclassification adjustment for net losses included in income	—		24.2		23.5		24.4
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	—		—		(7.2)		0.2
Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity	(0.3)		(1.7)		(1.1)		(25.6)
Change in unrealized gain on derivatives	(11.0)		(15.9)		(23.1)		(9.6)
Other comprehensive loss, before tax	(83.4)		(229.8)		(59.3)		(661.2)
Deferred tax benefit related to other comprehensive loss	20.7		51.9		14.7		164.5
Other comprehensive loss, net of tax	(62.7)		(177.9)		(44.6)		(496.7)
Comprehensive income (loss), net of tax	$	10.0	$	(92.2)	$	151.4	$	(380.3)

See accompanying notes to unaudited consolidated financial statements.

5

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY (In millions, except share and per share data) (Unaudited)
	Three Months Ended September 30,
	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at June 30, 2023	$	2,481.3	$	1,098.8	$	(459.0)	$	3,121.1
Net income	—		72.7		—		72.7
Other comprehensive loss, net of tax expense	—		—		(62.7)		(62.7)
Common stock transactions:
494 common shares purchased and retired	—		—		—		—
12,663 non-vested common shares issued	—		—		—		—
21,481 non-vested common shares forfeited or canceled	—		—		—		—
Stock-based compensation expense	3.6		—		—		3.6
Common stock cash dividends declared ($0.47 per share)	—		(49.2)		—		(49.2)
Balance at September 30, 2023	$	2,484.9	$	1,122.3	$	(521.7)	$	3,085.5
	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at June 30, 2022	$	2,607.9	$	993.8	$	(329.8)	$	3,271.9
Net income	—		85.7		—		85.7
Other comprehensive loss, net of tax expense	—		—		(177.9)		(177.9)
Common stock transactions:
3,280,042 common shares purchased and retired	(133.0)		—		—		(133.0)
251 non-vested common shares issued	—		—		—		—
27,443 non-vested common shares forfeited or canceled	—		—		—		—
Stock-based compensation expense	2.5		—		—		2.5
Common stock cash dividends declared ($0.41 per share)	—		(43.7)		—		(43.7)
Balance at September 30, 2022	$	2,477.4	$	1,035.8	$	(507.7)	$	3,005.5
See accompanying notes to unaudited consolidated financial statements.

6

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY (continued) (In millions, except share and per share data) (Unaudited)
	Nine Months Ended September 30,
	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at December 31, 2022	$	2,478.2	$	1,072.7	$	(477.1)	$	3,073.8
Net income	—		196.0		—		196.0
Other comprehensive loss, net of tax expense	—		—		(44.6)		(44.6)
Common stock transactions:
55,922 common shares purchased and retired	(1.9)		—		—		(1.9)
683,574 non-vested common shares issued	—		—		—		—
58,304 non-vested common shares forfeited or canceled	—		—		—		—
Stock-based compensation expense	8.6		—		—		8.6
Common cash dividends declared ($1.41 per share)	—		(146.4)		—		(146.4)
Balance at September 30, 2023	$	2,484.9	$	1,122.3	$	(521.7)	$	3,085.5
	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at December 31, 2021	$	945.0	$	1,052.6	$	(11.0)	$	1,986.6
Net income	—		116.4		—		116.4
Other comprehensive loss, net of tax expense	—		—		(496.7)		(496.7)
Common stock transactions:
5,039,784 common shares purchased and retired	(198.9)		—		—		(198.9)
46,913,370 common shares issued	1,722.5		—		—		1,722.5
453,690 non-vested common shares issued	—		—		—		—
94,735 non-vested common shares forfeited or canceled	—		—		—		—
17,807 stock options exercised, net of 4,877 shares tendered in payment of option price and income tax withholding amounts	0.1		—		—		0.1
Stock-based compensation expense	8.7		—		—		8.7
Common cash dividends declared ($1.23 per share)	—		(133.2)		—		(133.2)
Balance at September 30, 2022	$	2,477.4	$	1,035.8	$	(507.7)	$	3,005.5
See accompanying notes to unaudited consolidated financial statements.

7

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (In millions) (Unaudited)
	Nine Months Ended September 30,
	2023		2022
Cash flows from operating activities:
Net income	$	196.0	$	116.4
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	26.8		68.0
Net gain on disposal of premises and equipment	(1.7)		(2.3)
Depreciation and amortization	40.5		41.4
Net premium amortization on investment securities	1.7		16.7
Net loss on investment securities transactions	23.5		24.4
Realized and unrealized net gains on mortgage banking activities	(2.3)		(8.1)
Net gain on sale of OREO	(0.1)		(0.4)
Write-downs of OREO and other assets pending disposal	1.1		0.2
Net gain on extinguishment of debt	—		(1.4)
Mortgage servicing rights recovery	—		(3.4)
Deferred taxes	9.9		(4.8)
Net increase in cash surrender value of company-owned life insurance	(8.1)		(7.6)
Stock-based compensation expense	8.6		8.7
Originations of mortgage loans held for sale	(250.8)		(369.5)
Proceeds from sales of mortgage loans held for sale	255.9		387.2
Changes in operating assets and liabilities:
Increase in interest receivable	(10.9)		(25.9)
Decrease (increase) in other assets	38.5		(14.9)
Increase in accrued interest payable	49.2		1.3
(Decrease) increase in accounts payable and accrued expenses	(19.1)		212.6
Net cash provided by operating activities	358.7		438.6
Cash flows from investing activities:
Purchases of investment securities:
Held-to-maturity	—		(1,316.0)
Available-for-sale	—		(2,521.2)
Proceeds from sales, maturities, and pay-downs of investment securities:
Held-to-maturity	174.0		304.8
Available-for-sale	1,276.3		1,753.6
Purchases of FHLB and FRB stock	(187.3)		(115.8)
Proceeds from FHLB and FRB stock	196.4		53.3
Proceeds from bank-owned life insurance settlements	5.2		—
Extensions of credit to clients, net of repayments	(128.7)		(465.6)
Recoveries of loans charged-off	10.6		10.8
Proceeds from sale of OREO	2.6		2.0
Proceeds from the sale of Health Savings Accounts	—		1.4
Acquisition of bank and bank holding company, net of cash and cash equivalents received	—		2,006.9
Capital expenditures, net of sales	(19.4)		(27.2)
Net cash provided by (used in) investing activities	$	1,329.7	$	(313.0)

8

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (continued) (In millions) (Unaudited)
	Nine Months Ended September 30,
	2023		2022
Cash flows from financing activities:
Net decrease in deposits	$	(1,394.1)	$	(2,072.8)
Net (decrease) increase in securities sold under repurchase agreements	(163.4)		51.6
Net (decrease) increase in other borrowed funds	(260.0)		625.0
Repayments of long-term debt	(0.1)		(164.0)
Advances on long-term debt	—		14.4
Payment of stock issuance costs	—		(0.8)
Proceeds from issuance of common stock	—		0.1
Purchase and retirement of common stock	(1.8)		(198.9)
Dividends paid to common stockholders	(146.4)		(133.1)
Net cash used in financing activities	(1,965.8)		(1,878.5)
Net decrease in cash and cash equivalents	(277.4)		(1,752.9)
Cash and cash equivalents at beginning of period	870.5		2,344.8
Cash and cash equivalents at end of period	$	593.1	$	591.9
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$	39.0	$	42.2
Cash paid during the period for interest expense	235.6		32.0
Supplemental disclosures of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	$	6.4	$	22.9
Transfer of held-to-maturity to available-for sale securities	23.0		10.9
Transfer of available-for sale to held-to-maturity securities	—		463.6
Transfer of held-for-sale to held for investment loans	—		19.8
Transfer of held for investment loans to held-for-sale	3.1		12.4
Transfer of loans to OREO	2.5		0.4
Shares issued for acquisition	—		1,723.3
Capitalization of internally originated mortgage servicing rights	0.9		2.3

See accompanying notes to unaudited consolidated financial statements.

9

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(1)    Basis of Presentation

In the opinion of management, 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, 2023 and December 31, 2022, the results of operations, changes in stockholders’ equity, and cash flows for each of the three and the nine month periods ended September 30, 2023 and 2022, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2022 is derived from the audited consolidated financial statements. Certain reclassifications, none of which were material, have been made to conform the Company’s prior year financial statements to the September 30, 2023 presentation. These reclassifications did not change previously reported net income 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, 2022, which includes a description of significant accounting policies. Operating results for the three and the nine months ended September 30, 2023 are not necessarily indicative of the results that may be expected for the year ending December 31, 2023.

The below detailed discussion updates the accounting policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.

Change in Par Value

Unless otherwise noted, all capital values, and share and per share amounts, included in the consolidated financial statements have been retroactively adjusted to account for the change in the Company’s common stock par value from no par value per share to $0.00001 par value per share, which change became effective on May 25, 2023 in connection with the re-domestication of the Company from the State of Montana to the State of Delaware.

During the second quarter of 2023, the Company transitioned its Current Expected Credit Loss accounting standard (“CECL”), or ASC 326, model. The new model utilizes fewer portfolio loss segments than the old model due to limited observations of data within certain portfolio loss segments under the old model. The new model calculates historical loss rates by averaging quarterly net charge-offs for each loss segment. The loss rates are macroeconomic-conditioned and applied to loan-level expected cash flows based on contractual repayment terms. The loss rates also consider prepayment, utilization, interest rate, and probability of default assumptions. This change did not result in a material impact to the Company’s financial statements.

Allowance for Credit Losses - Loans held for investment

The allowance for credit losses is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected over the life of the loans. Loans are charged off against the allowance when management confirms that a loan balance is uncollectible. The Company applies recoveries when received and has elected not to forecast recoveries for purposes of calculating the allowance for credit losses.

Management estimates the allowance balance using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. Adjustments to historical loss information are made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix and trends, asset quality, or term. Other loan-specific risk characteristics may include changes in environmental and economic conditions, such as changes in unemployment rates, property values, or other relevant factors.

The allowance for credit losses is measured on a collective basis when similar risk characteristics exist.

10

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

Annualized loss rates are recalculated quarterly, with subsequent recoveries captured in the quarter a loan was charged off and are averaged across a look back period from 2009 to the current period. Expected future principal and interest cash flows are calculated using contractual repayment terms while considering prepayment, utilization, interest rate, and probability of default assumptions. Macroeconomic models calculate segment-specific multipliers using third party forecast data. The multipliers adjust the annual loss rates to the level expected under the economic conditions over the 2-year forecast period, followed by a 1-year straight-line reversion to the unadjusted historical average loss rates. The unadjusted loss rates then apply for the remaining life of the loan. Estimated losses are totaled and aggregated to the portfolio segment level.

The Company segments the loan portfolio into pools based on the following risk characteristics: financial asset type, collateral type, loan structure, credit characteristics, outstanding loan balances, contractual terms and prepayment assumptions, utilization assumptions, industry of borrower and concentrations, and historical or expected credit loss.

The Company has identified the following portfolio segments:

Real Estate loans. Include commercial real estate loans which are non-farm, non-residential real estate loans generally secured by first liens on income-producing real estate and generally mature in less than 10 years; construction development loans which are primarily to commercial builders for residential lot development and the construction of single-family residences and commercial real estate properties, commercial construction loans which are primarily made to commercial builders for the development of commercial real estate properties; and construction and development loans which are generally underwritten pursuant to credit worthiness or pre-qualification for permanent financing. During the construction phase for any of the above loans, the borrower pays interest only. In most cases, construction and development loans generally transition to a permanent real estate loans or otherwise mature in three years or less.

Real estate loans also include agricultural real estate loans that generally mature in ten years or less, secured by farmland or ranchland. These loans fund the construction of short, intermediate, and long-term structures and are made to experienced agriculturalists who have demonstrated management capabilities, established production and historical financial performance. Real estate loans also include consumer home equity and home equity lines of credit (“HELOC”) that are secured by residential property and generally mature in 25 years or less, and residential loans which are loans to finance the purchase or refinance of residential property which are typically secured by first liens or are construction loans to commercial builders or owner occupants for the construction of single-family residences. Residential 1-4 family loans generally mature within 15 years, and in some instances, could mature up to 30 years. Construction loans are generally underwritten pursuant to credit worthiness or pre-qualification for permanent financing. During the construction phase the borrower pays interest only. Residential construction loans generally transition to a permanent residential loan or otherwise mature in two years or less.

Consumer loans. Include indirect, direct advance lines, and credit cards. Indirect are loan contracts advanced for the purchase of automobiles, boats, and other consumer goods from the consumer product dealer networks within our market areas. Indirect dealer loans are generally secured by automobiles, recreational vehicles, boats, and other types of personal property and are made on an installment basis. Consumer indirect line loans generally mature in seven years or less. Consumer direct and advance line loans are originated for a variety of purposes including the purchase of automobiles, boats and other consumer goods, home improvements, medical expenses, vehicle repairs, debt consolidation, and planned expenses in addition to the purchase of automobiles, boats, and other consumer goods. Consumer direct and advance line loans generally mature in seven years or less. Consumer credit card loans are lines of credit offered to clients in our market areas that are generally floating rate loans and include both unsecured and secured lines. Consumer credit card loans generally do not have stated maturities but are reviewed periodically and are unconditionally cancellable.

Commercial loans. Include commercial and industrial loans through a mix of variable and fixed rate commercial loans, including loans to finance showroom floor inventories and other loans for commercial purposes that are secured by 1-4 family residential property. These loans are typically made to small and medium-sized manufacturing, wholesale, retail, and service businesses for working capital needs and business expansions. Floor plan loans and commercial purpose loans secured by 1-4 family residential property generally mature in seven years or less. Commercial loans also include secured and unsecured lines of credit, business credit cards, and loans with maturities of five years or less. Outstanding balances on these commercial loans tend to be cyclical in nature. These loans are generally made with business operations as the primary source of repayment, and are typically collateralized by inventory, accounts receivable, equipment, and/or personal guarantees.

11

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

Agricultural loans. Agricultural loans generally consist of short and medium-term loans and lines of credit that are primarily used for crops, livestock, equipment, and general operations. Agricultural loans are ordinarily secured by assets such as livestock or equipment and are repaid from the operations of the farm or ranch. Agricultural loans generally have maturities of seven years or less, with operating lines for one production season.

Contractual Term. Expected credit losses are estimated over the contractual term of the loans, adjusted for expected prepayments, defaults, interest rates, and utilization rates. The contractual term excludes expected extensions, renewals, and modifications unless either management has a reasonable expectation at the reporting date that a modification to borrowers experiencing financial difficulty will be executed or the extension or renewal options are included in the original or modified contract at the reporting date and are not unconditionally cancellable by the Company.

A loan for which the terms have been modified resulting in a concession, and for which the borrower is experiencing financial difficulties, is considered to be a modification to borrowers experiencing financial difficulty. The allowance for credit loss on a modification to borrowers experiencing financial difficulty is measured using the same method as all other loans held for investment, except when the loan is individually assessed for credit loss.

Allowance for Credit Losses on Off-Balance Sheet Credit Exposures. The Company estimates expected credit losses over the contractual period in which the Company is exposed to credit risk via a contractual obligation to extend credit unless that obligation is unconditionally cancellable by the Company. Management considers our unused credit card lines and federal fund lines, extended to others, to be unconditionally cancellable.

The allowance for credit losses on off-balance sheet credit exposures is adjusted as a provision for credit loss expense. The estimate considers the likelihood that funding will occur and an estimate of expected credit losses on commitments expected to be funded over the estimated life.

The Company has identified commitments to extend credit and standby letters of credit determined not to be unconditionally cancellable as categories with off-balance sheet credit exposures and uses the commitment balance, expected loss rate, expected cash flows, and utilization rate as primary assumptions to develop the allowance for credit losses on those exposures. The utilization rate represents management’s best estimate of the probability that the unfunded portion of the commitment will be funded given existing economic conditions.

(2)    Acquisition

Great Western Bank. On September 15, 2021, the Company entered into a definitive agreement (“Agreement”) to acquire 100% of the outstanding stock of Great Western Bancorp, Inc. (“Great Western”), the parent company of Great Western Bank (“GWB”), a Sioux Falls, South Dakota based community bank with 174 banking offices across Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota (“GWB acquisition”). The GWB acquisition expanded the Company’s geographical footprint with an enhanced platform for future growth. Consideration for the acquisition was $1,723.3 million, consisting of the issuance of 46.9 million shares of the Company’s Class A common stock valued at $36.76 per share, which was the opening price of the Company’s Class A common stock as quoted on the NASDAQ stock market on the acquisition date. The acquisition was completed on February 1, 2022.

The Company accounted for the transaction under the acquisition method of accounting in accordance with ASC 805, Business Combinations, which requires purchased assets and liabilities assumed and consideration exchanged to be recorded at their respective estimated fair values at the date of acquisition. The determination of estimated fair values required management to make certain estimates about discount rates, future expected cash flows, and market conditions at the time of the acquisition, as well as other future events that are highly subjective in nature.

The following table provides the purchase price allocation as of the acquisition date and the Great Western assets acquired and liabilities assumed at their estimated fair value as of the acquisition date, as amended for measurement period adjustments. We recorded the estimate of fair value based on valuations at the acquisition date. The excess value of the consideration paid over the fair value of assets acquired and liabilities assumed was recorded as goodwill. The purchase price allocation resulted in goodwill of $479.3 million, of which $31.7 million is deductible for income tax purposes. Goodwill resulting from the acquisition was allocated to the Company’s one operating segment, community banking, and consists largely of the synergies and economies of scale expected from combining the operations of Great Western and the Company. All amounts reported were finalized during the fourth quarter of 2022.

12

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

As of February 1, 2022
Assets acquired:
Cash and cash equivalents	$	2,006.9
Investment securities	2,699.0
Securities purchased under agreement to resell	101.1
Loans held for sale	217.0
Loans held for investment	7,705.0
Allowance for credit losses	(59.5)
Premises and equipment, including right of use lease assets	144.7
Other real estate owned	15.8
Company-owned life insurance	186.6
Core deposit intangibles	50.1
Customer relationship intangible	22.8
Mortgage servicing rights	1.3
Deferred tax assets, net	60.2
Other assets	200.8
Total assets acquired	13,351.8
Liabilities assumed:
Deposits	11,688.0
Securities sold under repurchase agreements	74.0
Accrued expenses and other liabilities	110.4
FHLB advances	122.9
Subordinated debt	36.4
Subordinated debentures held by subsidiary trusts	76.1
Total liabilities assumed	12,107.8
Net assets acquired	$	1,244.0
Consideration paid:
Class A common stock	1,723.3
Total consideration paid (1)	$	1,723.3
Goodwill	$	479.3

(1) Includes $13 thousand of cash paid in lieu of fractional shares.

For a description of the fair value and unpaid principal balance of loans from the GWB acquisition, as well as the methods used to determine the fair values of significant assets and liabilities, see “Note 2 – Acquisitions” in Part IV, Item 15 “Notes to Consolidated Financial Statements” within our Annual Report on Form 10-K for the year ended December 31, 2022.

There were no acquisition related expenses related to the GWB acquisition for the three and the nine month periods ended September 30, 2023. There were $4.0 million and $115.0 million of acquisition related expenses related to the GWB acquisition for the three and the nine month periods ended September 30, 2022, respectively. During the three months ended March 31, 2022, the Company contributed $21.5 million to the First Interstate Foundation and reimbursed an aggregate of $8.2 million of the Scott family control group’s acquisition expenses pursuant to the Agreement.

The accompanying consolidated statements of income for the three and the nine months ended September 30, 2023 and 2022, include the results of operations of the acquired entity from the February 1, 2022 acquisition date. The disclosure of GWB post-acquisition revenue and net income is not practical due to the combining of certain GWB operations with and into FIB as of the acquisition date. GWB was merged with our existing bank subsidiary, FIB, contemporaneously with the closing of the parent company merger. The core system conversion was completed on May 23, 2022.

13

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following table presents certain unaudited pro forma financial information for illustrative purposes only, for the three and the nine month periods ended September 30, 2022 as if GWB had been acquired on January 1, 2021. This unaudited pro forma information combines the historical results of GWB with the Company’s consolidated historical results and includes certain adjustments reflecting the estimated impact of certain fair value adjustments for the respective periods. The pro forma information is not indicative of what would have occurred had the acquisition occurred at the beginning of the year prior to the acquisition. The unaudited pro forma information does not consider any changes to the provision for credit losses resulting from recording loan assets at fair value, cost savings, or business synergies. As a result, actual amounts would have differed from the unaudited pro forma information presented, and the differences could be significant.

	Three Months Ended September 30,		Nine Months Ended September 30,
	2022		2022
Total revenues	$	314.0	$	883.5
Net income	$	90.3	$	267.8
Earnings per common share (Basic)	$	0.85	$	2.60
Earnings per common share (Diluted)	$	0.85	$	2.60

(3)    Goodwill and Other Intangible Assets

Goodwill

The Company had goodwill of $1,100.9 million at both September 30, 2023 and December 31, 2022 and concluded during its annual impairment assessment as of July 1, 2023 that there was no impairment to goodwill. In addition, there were no events or circumstances that occurred during the third quarter of 2023 that would more-likely-than-not reduce the fair value of the Company’s reporting unit below its carrying value.

Other Intangible Assets

Other intangible assets are comprised of core deposit intangibles (“CDI”) and other customer relationship intangibles (“OCRI”) and amounted to the following at September 30, 2023 and December 31, 2022:

September 30, 2023	CDI		OCRI		Total
Gross other intangible assets, at January 1, 2023	$	154.7	$	22.8	$	177.5
Accumulated amortization	(89.1)		(3.2)		(92.3)
Net other intangible assets, at September 30, 2023	$	65.6	$	19.6	$	85.2
December 31, 2022
Gross other intangible assets, at January 1, 2022	$	106.0	$	—	$	106.0
Amounts established through acquisition	50.1		22.8		72.9
Reductions due to sale of health savings accounts	(1.4)		—		(1.4)
Accumulated amortization	(78.8)		(1.7)		(80.5)
Net other intangible assets, at December 31, 2022	$	75.9	$	21.1	$	97.0

The Company recorded $3.9 million and $4.1 million of other intangible asset amortization expense for the three months ended September 30, 2023 and 2022, respectively, and $11.8 million for the nine months ended September 30, 2023 and 2022.

CDI and OCRI are evaluated for impairment if events and circumstances indicate a possible impairment. CDI is amortized using an accelerated method based on the estimated weighted average useful lives of the related deposits, which is generally 10 years. OCRI is amortized using a straight-line method over its estimated useful life of 12 years based on customer revenue attrition on an annualized basis.

14

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following table provides the estimated aggregate future amortization expense of other intangible assets at September 30, 2023:

Years Ending December 31,	CDI		OCRI		Total
2023 remaining	$	3.4	$	0.4	$	3.8
2024	12.7		1.9		14.6
2025	11.8		1.9		13.7
2026	10.9		1.9		12.8
2027	8.2		1.9		10.1
Thereafter	18.6		11.6		30.2
Total	$	65.6	$	19.6	$	85.2

(4)    Investment Securities

The amortized cost and the approximate fair values of investment securities are summarized as follows:

September 30, 2023	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	250.1	$	—	$	250.1	$	—	$	(34.2)	$	215.9
State, county, and municipal securities	257.5		—		257.5		—		(54.9)		202.6
Obligations of U.S. government agencies	179.3		—		179.3		—		(17.3)		162.0
U.S. agency commercial mortgage-backed securities	1,191.9		—		1,191.9		0.1		(125.1)		1,066.9
U.S. agency residential mortgage-backed securities	1,474.3		—		1,474.3		—		(189.3)		1,285.0
Collateralized mortgage obligations	1,302.9		—		1,302.9		—		(159.2)		1,143.7
Private mortgage-backed securities	246.4		—		246.4		—		(39.1)		207.3
Collateralized loan obligations	1,126.7		—		1,126.7		—		(8.9)		1,117.8
Corporate securities	261.1		—		261.1		—		(34.6)		226.5
Total	$	6,290.2	$	—	$	6,290.2	$	0.1	$	(662.6)	$	5,627.7

September 30, 2023	Amortized Cost1		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	398.4	$	—	$	398.4	$	—	$	(6.8)	$	391.6
State, county, and municipal securities	179.0		—		179.0		—		(34.9)		144.1
Obligations of U.S. government agencies	353.8		—		353.8		—		(59.5)		294.3
U.S. agency commercial mortgage-backed securities	515.2		—		515.2		—		(71.9)		443.3
U.S. agency residential mortgage-backed securities	1,269.8		—		1,269.8		—		(197.2)		1,072.6
Collateralized mortgage obligations	487.1		—		487.1		—		(86.2)		400.9
Corporate securities	57.0		(0.8)		56.2		—		(6.9)		49.3
Total	$	3,260.3	$	(0.8)	$	3,259.5	$	—	$	(463.4)	$	2,796.1
(1) Amortized cost presented above includes $11.4 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 $18.6 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.

15

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

December 31, 2022	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	675.1	$	—	$	675.1	$	2.1	$	(34.5)	$	642.7
State, county, and municipal securities	314.3		—		314.3		—		(50.6)		263.7
Obligations of U.S. government agencies	216.2		—		216.2		—		(17.3)		198.9
U.S. agency commercial mortgage-backed securities	1,468.0		—		1,468.0		0.2		(117.0)		1,351.2
U.S. agency residential mortgage-backed securities	1,726.0		—		1,726.0		—		(167.7)		1,558.3
Collateralized mortgage obligations	1,491.5		—		1,491.5		—		(141.3)		1,350.2
Private mortgage-backed securities	264.9		—		264.9		—		(36.9)		228.0
Collateralized loan obligations	1,145.2		—		1,145.2		—		(33.6)		1,111.6
Corporate securities	272.3		—		272.3		—		(30.8)		241.5
Total	$	7,573.5	$	—	$	7,573.5	$	2.3	$	(629.7)	$	6,946.1

December 31, 2022	Amortized Cost1		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	396.6	$	—	$	396.6	$	—	$	(10.2)	$	386.4
State, county, and municipal securities	181.2		(0.1)		181.1		0.2		(31.6)		149.7
Obligations of U.S. government agencies	351.7		—		351.7		—		(49.6)		302.1
U.S. agency commercial mortgage-backed securities	526.8		—		526.8		—		(58.3)		468.5
U.S. agency residential mortgage-backed securities	1,391.5		—		1,391.5		—		(166.6)		1,224.9
Collateralized mortgage obligations	525.8		—		525.8		0.2		(76.7)		449.3
Corporate securities	80.1		(1.8)		78.3		—		(7.0)		71.3
Total	$	3,453.7	$	(1.9)	$	3,451.8	$	0.4	$	(400.0)	$	3,052.2
(1) Amortized cost presented above includes $20.2 million of unamortized losses and of $14.2 million unamortized gains 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, 2023 and December 31, 2022.

	Less than 12 Months				12 Months or More				Total
September 30, 2023	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	—	$	—	$	215.9	$	(34.2)	$	215.9	$	(34.2)
State, county, and municipal securities	1.0		—		199.7		(54.9)		200.7		(54.9)
Obligations of U.S. government agencies	—		—		161.5		(17.3)		161.5		(17.3)
U.S. agency commercial mortgage-backed securities	0.3		—		1,057.8		(125.1)		1,058.1		(125.1)
U.S. agency residential mortgage-backed securities	0.9		—		1,284.0		(189.3)		1,284.9		(189.3)
Collateralized mortgage obligations	—		—		1,143.7		(159.2)		1,143.7		(159.2)
Private mortgage-backed securities	—		—		207.3		(39.1)		207.3		(39.1)
Collateralized loan obligations	—		—		1,117.8		(8.9)		1,117.8		(8.9)
Corporate securities	—		—		226.6		(34.6)		226.6		(34.6)
Total	$	2.2	$	—	$	5,614.3	$	(662.6)	$	5,616.5	$	(662.6)

16

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

	Less than 12 Months				12 Months or More				Total
December 31, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	168.8	$	(4.7)	$	170.4	$	(29.8)	$	339.2	$	(34.5)
State, county, and municipal securities	104.9		(9.0)		146.1		(41.6)		251.0		(50.6)
Obligations of U.S. government agencies	152.2		(10.1)		46.1		(7.2)		198.3		(17.3)
U.S. agency commercial mortgage-backed securities	1,069.8		(59.9)		270.8		(57.0)		1,340.6		(116.9)
U.S. agency residential mortgage-backed securities	1,213.5		(112.3)		344.6		(55.4)		1,558.1		(167.7)
Collateralized mortgage obligations	1,016.4		(90.1)		333.0		(51.3)		1,349.4		(141.4)
Private mortgage-backed securities	133.1		(19.1)		94.9		(17.8)		228.0		(36.9)
Collateralized loan obligations	1,082.6		(33.1)		28.9		(0.5)		1,111.5		(33.6)
Corporate securities	130.6		(8.3)		110.8		(22.5)		241.4		(30.8)
Total	$	5,071.9	$	(346.6)	$	1,545.6	$	(283.1)	$	6,617.5	$	(629.7)

As of September 30, 2023 and December 31, 2022, there were no holdings of securities of any issuer, other than the U.S. government and its agencies, in an amount greater than 10% of stockholders’ equity.

The Company determines credit losses on both available-for-sale and held-to-maturity investment securities by a discounted cash flow approach using the 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. Credit losses on held-to-maturity investment securities are representative of current expected credit losses that management expects to be incurred over the life of the investment. The allowance for credit losses is established through a charge to provision for credit losses in current period earnings.

The available-for-sale 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 prepayment and 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, 2023 and December 31, 2022, the Company had 1,034 and 1,222 individual investment securities, respectively, that were in an unrealized loss position, which was related primarily to fluctuations in current interest rates. As of September 30, 2023, the Company had the intent and ability to hold these investment securities for a period of time sufficient to allow for an anticipated recovery. The Company does not intend to sell any of the available-for-sale securities in the above table, and the Company does not anticipate it will have to sell any securities before a recovery in cost.

The following table presents the activity in the allowance for credit losses related to available-for-sale investment securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Beginning balance	$	1.4	$	—	$	—	$	—
(Reduction of) provision for credit losses	(1.4)		—		—		—
Ending balance	$	—	$	—	$	—	$	—
The following table presents the activity in the allowance for credit losses related to held-to-maturity investment securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Beginning balance	$	0.7	$	1.6	$	1.9	$	—
Provision for (reduction of) credit losses	0.1		0.3		(1.1)		1.9
Ending balance	$	0.8	$	1.9	$	0.8	$	1.9

17

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company had no allowance for credit losses for available-for-sale corporate investment securities as of September 30, 2023 and December 31, 2022, respectively. The Company had a $0.8 million and a $1.9 million allowance for credit losses for held-to-maturity corporate and state, county, and municipal investment securities as of September 30, 2023 and December 31, 2022, respectively.

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, 2023	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	398.4	$	—	$	—	$	—	$	—	$	—	$	398.4
State, county, and municipal securities	68.1		92.3		10.6		—		—		8.0		179.0
Obligations of U.S. government agencies	353.8		—		—		—		—		—		353.8
U.S. agency commercial mortgage-backed securities
FNMA/FHLMC	360.9		—		—		—		—		—		360.9
GNMA	154.3		—		—		—		—		—		154.3
U.S. agency residential mortgage-backed securities
FNMA/FHLMC	1,225.6		—		—		—		—		—		1,225.6
GNMA	44.2		—		—		—		—		—		44.2
Collateralized mortgage obligations
FNMA/FHLMC	342.0		—		—		—		—		—		342.0
GNMA	145.1		—		—		—		—		—		145.1
Corporate securities	—		—		—		47.0		5.0		5.0		57.0
Total	$	3,092.4	$	92.3	$	10.6	$	47.0	$	5.0	$	13.0	$	3,260.3

December 31, 2022	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	396.6	$	—	$	—	$	—	$	—	$	—	$	396.6
State, county, and municipal securities	68.3		92.8		11.5		—		—		8.6		181.2
Obligations of U.S. government agencies	351.7		—		—		—		—		—		351.7
U.S. agency commercial mortgage-backed securities
FNMA/FHLMC	364.9		—		—		—		—		—		364.9
GNMA	161.9		—		—		—		—		—		161.9
U.S. agency residential mortgage-backed securities
FNMA/FHLMC	1,342.9		—		—		—		—		—		1,342.9
GNMA	48.6		—		—		—		—		—		48.6
Collateralized mortgage obligations
FNMA/FHLMC	525.8		—		—		—		—		—		525.8
Corporate securities	—		—		—		65.1		10.0		5.0		80.1
Total	$	3,260.7	$	92.8	$	11.5	$	65.1	$	10.0	$	13.6	$	3,453.7

As of September 30, 2023 and December 31, 2022, the Company had $36.5 million and $38.9 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, 2023 and December 31, 2022, 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, 2023 and December 31, 2022, there were no collateral-dependent available-for-sale or held-to-maturity securities.

18

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

There were no material gross realized gains and no material gross realized losses during the three months ended September 30, 2023. 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, as a result of the sale of $853.0 million in carrying value of investment securities. For the three and the nine month periods ended September 30, 2022, there were no material gross realized gains and $46.3 million of gross realized losses on the disposition of available-for-sale investment securities.

Maturities of securities do not reflect rate repricing opportunities present in adjustable-rate mortgage-backed securities. Maturities of mortgage-backed securities have been adjusted to reflect shorter maturities based upon estimated prepayments of principal. All other investment securities maturities are shown at contractual maturity dates.

	Available-for-Sale				Held-to-Maturity
September 30, 2023	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	1.6	$	1.5	$	308.7	$	304.5
After one year but within five years	1,036.0		941.3		346.4		320.2
After five years but within ten years	1,387.9		1,220.0		654.8		551.5
After ten years	3,864.7		3,464.9		1,950.4		1,619.9
Total	$	6,290.2	$	5,627.7	$	3,260.3	$	2,796.1

As of September 30, 2023, the Company held investment securities callable within one year having amortized costs and estimated fair values of $1,592.1 million and $1,514.4 million, respectively. These investment securities are primarily included in the “after ten years” category in the table above. As of September 30, 2023, the Company had no callable structured notes.

As of September 30, 2023 and December 31, 2022, the Company had amortized costs of $7,066.8 million and $4,998.9 million, respectively, for investment securities pledged to secure public deposits, securities sold under repurchase agreements, and as collateral for FHLB and the FRB term funding program line capacity that had estimated fair values of $6,169.7 million and $4,432.0 million, as of September 30, 2023 and December 31, 2022, 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, 2023 and December 31, 2022, the Company held $189.5 million and $198.6 million, respectively, in equity securities 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.

(5)     Loans Held for Sale

The following table presents loans held for sale by class of receivable for the dates indicated:

	September 30, 2023		December 31, 2022
Loans held for sale:
Agricultural1	$	49.5	$	62.5
Construction, at lower of cost or market	6.4		10.5
Residential mortgage, at fair value	3.2		6.9
Total loans held for sale	$	59.1	$	79.9

1 As of September 30, 2023 the agricultural loans held were at lower of cost or market. At December 31, 2022, the Company held $57.0 million of agricultural loans at lower of cost or market and $5.5 million of agricultural loans on accrual status at fair value with an unpaid principal balance of $7.7 million, of which $5.6 million is 90 days or more past due.

19

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The table below presents the non-residential mortgage loans held for sale activity for the 2023 period:

	Agricultural		Construction
Beginning balance	$	62.5	$	10.5
Loans held for investment transferred to loans held for sale	—		3.1
Repayments and discounted pay-offs	(15.2)		—
Loan disposals	—		(3.1)
Increase (decrease) in estimated fair value of the loans1	2.2		(4.1)
Ending balance	$	49.5	$	6.4

1 For the nine months ended September 30, 2023, the Company recorded a gain of $2.2 million and a loss of $4.1 million in other income within the consolidated statements of income related to fair value changes.

As of September 30, 2023, loans held for sale included nonaccrual loans of $31.6 million, of which $25.2 million were agricultural loans and $6.4 million was a construction loan. As of December 31, 2022, loans held for sale included nonaccrual loans of $39.8 million, of which $29.3 million were agricultural loans and $10.5 million was a construction loan.

(6)    Loans Held for Investment

The following table presents loans by class of receivable and portfolio segment as of the dates indicated:

	September 30, 2023		December 31, 2022
Real estate:
Commercial	$	8,766.2	$	8,528.6
Construction	1,930.3		1,944.4
Residential	2,212.2		2,188.3
Agricultural	731.5		794.9
Total real estate	13,640.2		13,456.2
Consumer:
Indirect	751.7		829.7
Direct and advance lines	142.3		152.9
Credit card	71.6		75.9
Total consumer	965.6		1,058.5
Commercial	2,925.1		2,882.6
Agricultural	690.5		708.3
Other, including overdrafts	5.0		9.2
Loans held for investment	18,226.4		18,114.8
Deferred loan fees and costs	(13.1)		(15.6)
Loans held for investment, net of deferred fees and costs	18,213.3		18,099.2
Allowance for credit losses	(226.7)		(220.1)
Net loans held for investment	$	17,986.6	$	17,879.1

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, 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

20

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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

Three Months Ended September 30, 2022	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	29.5	$	(5.5)	$	(0.1)	$	—	$	23.9
Owner occupied	26.6		(3.7)		—		1.8		24.7
Multi-family	33.4		(2.6)		(5.7)		—		25.1
Total commercial real estate	89.5		(11.8)		(5.8)		1.8		73.7
Construction:
Land acquisition & development	0.8		(0.2)		—		0.1		0.7
Residential construction	3.4		(0.3)		—		—		3.1
Commercial construction	14.9		16.4		(6.6)		—		24.7
Total construction	19.1		15.9		(6.6)		0.1		28.5
Residential real estate:
Residential 1-4 family	18.2		0.9		—		—		19.1
Home equity and HELOC	1.5		0.1		(0.1)		0.1		1.6
Total residential real estate	19.7		1.0		(0.1)		0.1		20.7
Agricultural real estate	5.4		0.4		—		—		5.8
Total real estate	133.7		5.5		(12.5)		2.0		128.7
Consumer:
Indirect	13.1		1.6		(1.2)		0.6		14.1
Direct and advance lines	5.0		1.3		(1.4)		0.4		5.3
Credit card	2.2		0.3		(0.3)		0.2		2.4
Total consumer	20.3		3.2		(2.9)		1.2		21.8
Commercial:
Commercial and floor plans	54.1		(2.2)		(0.5)		1.0		52.4
Commercial purpose secured by 1-4 family	5.5		0.4		—		—		5.9
Credit card	0.3		0.2		(0.3)		—		0.2
Total commercial	59.9		(1.6)		(0.8)		1.0		58.5
Agricultural:
Agricultural	6.5		(2.5)		—		—		4.0
Total agricultural	6.5		(2.5)		—		—		4.0
Total allowance for credit losses	$	220.4	$	4.6	$	(16.2)	$	4.2	$	213.0

21

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

Nine Months Ended September 30, 2022	Beginning Balance		ACL for PCD Loans		Provision for Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	17.3	$	17.2	$	(7.6)	$	(3.0)	$	—	$	23.9
Owner occupied	13.3		9.5		2.3		(2.2)		1.8		24.7
Multi-family	13.3		10.9		5.9		(5.7)		0.7		25.1
Total commercial real estate	43.9		37.6		0.6		(10.9)		2.5		73.7
Construction:
Land acquisition & development	0.5		3.4		(0.8)		(2.7)		0.3		0.7
Residential construction	2.4		—		0.7		—		—		3.1
Commercial construction	6.0		0.2		25.1		(6.6)		—		24.7
Total construction	8.9		3.6		25.0		(9.3)		0.3		28.5
Residential real estate:
Residential 1-4 family	13.4		0.1		5.4		(0.1)		0.3		19.1
Home equity and HELOC	1.2		—		0.1		(0.1)		0.4		1.6
Total residential real estate	14.6		0.1		5.5		(0.2)		0.7		20.7
Agricultural real estate	1.9		2.3		1.7		(0.2)		0.1		5.8
Total real estate	69.3		43.6		32.8		(20.6)		3.6		128.7
Consumer:
Indirect	14.3		—		0.9		(2.9)		1.8		14.1
Direct and advance lines	4.6		—		1.7		(2.8)		1.8		5.3
Credit card	2.2		—		1.6		(1.8)		0.4		2.4
Total consumer	21.1		—		4.2		(7.5)		4.0		21.8
Commercial:
Commercial and floor plans	27.1		11.2		18.1		(5.8)		1.8		52.4
Commercial purpose secured by 1-4 family	4.4		0.2		1.2		—		0.1		5.9
Credit card	0.1		—		0.6		(0.5)		—		0.2
Commercial	31.6		11.4		19.9		(6.3)		1.9		58.5
Agricultural:
Agricultural	0.3		4.5		3.3		(5.4)		1.3		4.0
Total agricultural	0.3		4.5		3.3		(5.4)		1.3		4.0
Total allowance for credit losses	$	122.3	$	59.5	$	60.2	$	(39.8)	$	10.8	$	213.0
(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 Financial Loans

A collateral-dependent financial 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.

22

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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, 2023	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	—	$	29.6	$	—	$	29.6
Construction	—		17.1		—		17.1
Residential	—		0.5		—		0.5
Agricultural	—		1.5		—		1.5
Total real estate	—		48.7		—		48.7
Commercial	4.4		1.6		0.9		6.9
Agricultural	0.7		—		—		0.7
Total collateral-dependent loans	$	5.1	$	50.3	$	0.9	$	56.3

	Collateral Type
As of December 31, 2022	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	1.7	$	15.8	$	—	$	17.5
Construction	—		3.2		—		3.2
Residential	—		0.5		—		0.5
Agricultural	0.2		5.8		—		6.0
Total real estate	1.9		25.3		—		27.2
Commercial	3.1		1.5		—		4.6
Agricultural	2.1		5.2		—		7.3
Total collateral-dependent loans	$	7.1	$	32.0	$	—	$	39.1

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, 2023	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate:
Commercial	$	1.2	$	0.4	$	—	$	1.6	$	8,733.6	$	31.0	$	8,766.2
Construction	6.5		7.5		0.5		14.5		1,898.4		17.4		1,930.3
Residential	2.4		1.8		1.0		5.2		2,197.5		9.5		2,212.2
Agricultural	0.4		1.5		—		1.9		724.2		5.4		731.5
Total real estate	10.5		11.2		1.5		23.2		13,553.7		63.3		13,640.2
Consumer:
Indirect	6.4		2.2		0.4		9.0		739.7		3.0		751.7
Direct	0.6		0.2		—		0.8		141.3		0.2		142.3
Credit card	0.6		0.4		0.5		1.5		70.1		—		71.6
Total consumer	7.6		2.8		0.9		11.3		951.1		3.2		965.6
Commercial	2.3		16.1		0.5		18.9		2,894.2		12.0		2,925.1
Agricultural	0.7		—		0.3		1.0		686.6		2.9		690.5
Other, including overdrafts	—		—		—		—		5.0		—		5.0
Loans held for investment	$	21.1	$	30.1	$	3.2	$	54.4	$	18,090.6	$	81.4	$	18,226.4

23

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

							Total Loans
	30 - 59		60 - 89		90 or more		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2022	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate:
Commercial	$	5.6	$	0.8	$	1.1	$	7.5	$	8,501.5	$	19.6	$	8,528.6
Construction	10.4		0.6		0.6		11.6		1,929.1		3.7		1,944.4
Residential	9.9		2.1		1.2		13.2		2,168.7		6.4		2,188.3
Agricultural	1.1		6.1		—		7.2		780.1		7.6		794.9
Total real estate	27.0		9.6		2.9		39.5		13,379.4		37.3		13,456.2
Consumer:
Indirect	9.3		2.4		0.6		12.3		814.7		2.7		829.7
Direct	0.8		0.3		0.1		1.2		151.4		0.3		152.9
Credit card	0.8		0.4		0.6		1.8		74.1		—		75.9
Total consumer	10.9		3.1		1.3		15.3		1,040.2		3.0		1,058.5
Commercial	7.1		1.7		2.1		10.9		2,861.5		10.2		2,882.6
Agricultural	0.8		2.2		0.1		3.1		696.5		8.7		708.3
Other, including overdrafts	—		—		—		—		9.2		—		9.2
Loans held for investment	$	45.8	$	16.6	$	6.4	$	68.8	$	17,986.8	$	59.2	$	18,114.8

(1) As of September 30, 2023 and December 31, 2022, 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, 2023 and 2022, respectively. There were $1.0 million and $1.9 million in reversals of accrued interest during the three and the nine months ended September 30, 2023, respectively, and no material reversals of accrued interest during the three and the nine months ended September 30, 2022.

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 borrowers payment relief. Effective January 1, 2023, the Company adopted ASU 2022-02, which eliminated accounting guidance for troubled debt restructurings while requiring disclosures of borrowers experiencing financial difficulty for modifications related to principal reductions, interest rate reductions, term extensions, and more than insignificant payment delay. See “Note 17 – Recent Authoritative Accounting Guidance” of these Notes to Unaudited Consolidated Financial Statements” for further discussion of the amendments in this update.

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, or a term extension or a combination thereof, among other things.

24

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following table presents the amortized cost basis of loans at September 30, 2023 that were both experiencing financial difficulty and modified during the three and the nine month periods ended September 30, 2023, by class and by type of modification. 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, 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, 2023, the Company excluded $1.7 million in accrued interest from the amortized cost of the identified loans.

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 nine months ended September 30, 2023, there were $0.1 million of loans classified as past due 30 days or more, with the remaining loans performing in accordance with the modified terms and are classified as current at September 30, 2023.

There were no commitments to lend additional funds to borrowers experiencing financial difficulty whose terms have been modified during the three and the nine month periods ended September 30, 2023 through either principal forgiveness, interest rate reduction, term extension, or other than insignificant payment delay.

25

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following table presents the financial effect of the loan modifications presented above to borrowers experiencing financial difficulty during the three and the nine month periods ended September 30, 2023:

				Term Extension and Interest Rate Reduction
Three Months Ended September 30, 2023	Principal Forgiveness		Weighted-Average Months of Term Extension	Weighted-Average Interest Rate Reduction		Weighted-Average Months of Term Extension
Real estate:
Commercial	$	—	4.6	0.25	%	6.0
Construction	—		9.0	—		—
Residential	—		144.4	—		—
Agricultural	—		4.0	—		—
Total real estate	—
Commercial	—		7.8	—		—
Agricultural	—		3.5	—		—
Loans held for investment (1)	$	—
Nine Months Ended September 30, 2023
Real estate:
Commercial	$	1.3	5.7	0.25	%	6.0
Construction	—		9.0	—		—
Residential	0.3		139.2	—		—
Agricultural	—		4.6	—		—
Total real estate	1.6
Commercial	—		8.8	—		—
Agricultural	—		9.2	—		—
Loans held for investment (1)	$	1.6

(1) Balances based on loan original contractual terms.

There were no payment defaults on these loans subsequent to their modifications during the three and the nine month periods ended September 30, 2023. 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 on the basis of 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.

Purchased Credit Deteriorated Loans (“PCD”)

The Company analyzes all acquired loans at the time of acquisition for more-than-insignificant deterioration in credit quality since their origination date. Such loans are classified as PCD, also referred to as PCD loans. Acquired loans classified as PCD are recorded at an initial amortized cost, which is comprised of the purchase price of the loans plus the initial allowance for credit losses for the loans, and any resulting discount or premium related to factors other than credit. The Company accounts for interest income on PCD loans using the interest method, whereby any purchase discounts or premiums are accreted or amortized into interest income as an adjustment of the loan’s yield.

The following table reconciles the par value, or initial amortized cost, of PCD loans acquired in the GWB acquisition as of February 1, 2022, or the date of the acquisition, with the purchase price (or initial fair value of the loans) as amended for measurement period adjustments:

Purchase price (initial fair value)	$	623.3
Allowance for credit losses (1)	298.2
Discount attributable to other factors (2)	57.7
Par value (unpaid principal balance)	$	979.2

26

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(1) For acquired PCD loans, an allowance of $298.2 million was required with a corresponding increase to the amortized cost basis as of the acquisition date. For PCD loans where all or a portion of the loan balance had been previously written-off by GWB, or would be subject to write-off under the Company’s charge-off policy, a CECL allowance of $238.7 million, included as part of the grossed-up loan balance at acquisition was immediately written-off. The net impact to the allowance for PCD assets on the acquisition date was $59.5 million.

(2) Non-credit discount includes the difference between the amortized cost basis and the unpaid principal balance of $39.6 million established on PCD loans acquired from GWB and interest applied to principal of $18.1 million.

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.

27

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company evaluates the credit quality and loan performance for the allowance for credit losses of the following class of receivables based on the aforementioned risk scale as of and for the periods ended:

	As of and for the nine months ended September 30, 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	$	845.8	$	2,240.2	$	1,649.9	$	1,245.7	$	732.7	$	1,741.5	$	42.8	$	21.6	$	8,520.2
Special mention	2.9		5.0		41.3		4.7		26.9		20.5		—		—		101.3
Substandard	28.0		26.0		19.6		9.6		30.4		28.4		1.0		—		143.0
Doubtful	—		0.3		1.4		—		—		—		—		—		1.7
Total	$	876.7	$	2,271.5	$	1,712.2	$	1,260.0	$	790.0	$	1,790.4	$	43.8	$	21.6	$	8,766.2
Current-period gross charge-offs	1.7		0.3		1.7		2.6		—		—		—		—		6.3
Construction real estate:
Pass	$	444.9	$	806.1	$	413.3	$	39.4	$	16.5	$	38.7	$	102.8	$	2.6	$	1,864.3
Special mention	4.1		11.4		6.5		—		—		0.2		—		0.8		23.0
Substandard	1.4		3.3		24.5		0.2		—		0.5		—		—		29.9
Doubtful	—		13.1		—		—		—		—		—		—		13.1
Total	$	450.4	$	833.9	$	444.3	$	39.6	$	16.5	$	39.4	$	102.8	$	3.4	$	1,930.3
Current-period gross charge-offs	—		—		0.1		—		—		—		—		9.6		9.7
Agricultural real estate:
Pass	$	60.5	$	133.1	$	158.8	$	95.9	$	59.4	$	130.1	$	27.8	$	0.1	$	665.7
Special mention	3.5		6.6		1.4		2.1		1.8		5.9		0.5		—		21.8
Substandard	8.1		19.8		4.8		2.2		0.5		8.6		—		—		44.0
Total	$	72.1	$	159.5	$	165.0	$	100.2	$	61.7	$	144.6	$	28.3	$	0.1	$	731.5
Current-period gross charge-offs	—		—		—		—		—		—		—		—		—
Commercial:
Pass	$	383.8	$	537.2	$	408.5	$	224.5	$	116.4	$	317.0	$	765.8	$	9.5	$	2,762.7
Special mention	2.3		4.9		6.7		4.7		2.5		1.4		14.8		0.1		37.4
Substandard	5.0		23.3		10.9		7.2		4.6		5.0		62.4		0.4		118.8
Doubtful	4.7		0.2		1.2		—		—		—		0.1		—		6.2
Total	$	395.8	$	565.6	$	427.3	$	236.4	$	123.5	$	323.4	$	843.1	$	10.0	$	2,925.1
Current-period gross charge-offs	—		0.3		0.3		0.4		0.1		0.1		0.9		0.1		2.2
Agricultural:
Pass	$	77.2	$	74.8	$	35.9	$	25.5	$	7.7	$	9.6	$	374.0	$	6.0	$	610.7
Special mention	0.9		1.1		0.8		0.2		0.2		0.2		9.7		—		13.1
Substandard	45.0		0.7		1.4		1.4		0.5		1.3		16.4		—		66.7
Total	$	123.1	$	76.6	$	38.1	$	27.1	$	8.4	$	11.1	$	400.1	$	6.0	$	690.5
Current-period gross charge-offs	—		—		—		—		—		—		—		—		—

28

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial real estate non-owner occupied:
Pass	$	1,162.6	$	861.3	$	661.1	$	467.6	$	241.5	$	890.4	$	29.2	$	4,313.7
Special mention	1.0		6.8		2.3		4.6		—		7.4		—		22.1
Substandard	0.1		13.9		10.8		18.2		19.6		9.8		—		72.4
Total	$	1,163.7	$	882.0	$	674.2	$	490.4	$	261.1	$	907.6	$	29.2	$	4,408.2
Commercial real estate owner occupied:
Pass	$	793.0	$	718.7	$	533.9	$	266.3	$	165.8	$	551.3	$	18.2	$	3,047.2
Special mention	10.9		14.2		12.3		6.1		5.6		5.5		1.1		55.7
Substandard	8.4		3.0		2.3		8.9		8.5		17.2		0.5		48.8
Doubtful	0.4		1.4		—		—		—		—		—		1.8
Total	$	812.7	$	737.3	$	548.5	$	281.3	$	179.9	$	574.0	$	19.8	$	3,153.5
Commercial multi-family:
Pass	$	369.2	$	204.9	$	189.0	$	52.1	$	35.0	$	113.7	$	1.0	$	964.9
Special mention	—		—		—		—		—		1.7		—		1.7
Substandard	—		—		—		—		—		0.3		—		0.3
Total	$	369.2	$	204.9	$	189.0	$	52.1	$	35.0	$	115.7	$	1.0	$	966.9
Land, acquisition and development:
Pass	$	152.5	$	114.4	$	29.5	$	17.0	$	10.9	$	28.4	$	22.2	$	374.9
Special mention	6.7		—		—		—		0.2		0.3		—		7.2
Substandard	—		0.3		0.2		—		—		0.4		—		0.9
Doubtful	—		3.2		—		—		—		—		—		3.2
Total	$	159.2	$	117.9	$	29.7	$	17.0	$	11.1	$	29.1	$	22.2	$	386.2
Residential construction:
Pass	$	118.4	$	119.9	$	0.4	$	0.3	$	0.4	$	5.8	$	270.1	$	515.3
Substandard	—		0.5		—		—		—		0.4		—		0.9
Total	$	118.4	$	120.4	$	0.4	$	0.3	$	0.4	$	6.2	$	270.1	$	516.2
Commercial construction:
Pass	$	442.7	$	374.8	$	89.7	$	45.9	$	0.4	$	—	$	10.6	$	964.1
Special mention	2.3		—		23.1		—		—		—		11.3		36.7
Substandard	16.8		24.4		—		—		—		—		—		41.2
Total	$	461.8	$	399.2	$	112.8	$	45.9	$	0.4	$	—	$	21.9	$	1,042.0
Agricultural real estate:
Pass	$	180.0	$	172.8	$	109.5	$	64.8	$	46.6	$	105.1	$	31.4	$	710.2
Special mention	22.4		0.7		1.2		2.6		10.0		3.2		11.0		51.1
Substandard	1.8		12.3		3.5		0.6		2.7		11.3		0.1		32.3
Doubtful	—		—		1.3		—		—		—		—		1.3
Total	$	204.2	$	185.8	$	115.5	$	68.0	$	59.3	$	119.6	$	42.5	$	794.9
Commercial and floor plans:
Pass	$	501.7	$	358.9	$	214.4	$	124.3	$	120.3	$	171.1	$	631.6	$	2,122.3
Special mention	15.9		6.8		1.3		4.4		0.9		4.9		18.5		52.7
Substandard	9.8		3.3		3.7		3.4		3.2		2.1		47.2		72.7
Doubtful	0.3		1.3		—		—		—		—		0.1		1.7
Total	$	527.7	$	370.3	$	219.4	$	132.1	$	124.4	$	178.1	$	697.4	$	2,249.4

29

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial purpose secured by 1-4 family:
Pass	$	191.7	$	134.5	$	69.8	$	30.4	$	29.9	$	39.5	$	28.9	$	524.7
Special mention	0.1		1.2		2.1		0.2		1.4		0.2		—		5.2
Substandard	0.2		0.3		0.1		0.3		0.9		1.2		—		3.0
Total	$	192.0	$	136.0	$	72.0	$	30.9	$	32.2	$	40.9	$	28.9	$	532.9
Agricultural:
Pass	$	127.2	$	59.7	$	31.8	$	10.6	$	8.6	$	3.1	$	375.1	$	616.1
Special mention	26.1		2.8		0.4		1.0		0.3		—		26.2		56.8
Substandard	22.8		4.6		2.8		0.6		1.2		0.2		0.8		33.0
Doubtful	—		0.5		—		—		—		—		—		0.5
Total	$	176.1	$	67.6	$	35.0	$	12.2	$	10.1	$	3.3	$	402.1	$	706.4

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, 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	$	38.6	$	317.5	$	513.2	$	512.8	$	92.3	$	227.2	$	475.6	$	24.5	$	2,201.7
Nonperforming	0.7		1.6		1.0		0.6		0.8		5.8		—		—		10.5
Total	$	39.3	$	319.1	$	514.2	$	513.4	$	93.1	$	233.0	$	475.6	$	24.5	$	2,212.2
Current-period gross charge-offs	0.3		—		0.1		0.1		—		0.1		—		—		0.6
Consumer indirect:
Performing	$	142.5	$	292.4	$	128.3	$	92.3	$	38.5	$	54.3	$	—	$	—	$	748.3
Nonperforming	0.4		1.2		0.7		0.4		0.2		0.5		—		—		3.4
Total	$	142.9	$	293.6	$	129.0	$	92.7	$	38.7	$	54.8	$	—	$	—	$	751.7
Current-period gross charge-offs	0.2		2.0		1.6		0.6		0.2		0.6		—		—		5.2
Consumer direct and advance lines:
Performing	$	35.3	$	36.8	$	21.1	$	10.8	$	4.4	$	7.0	$	26.5	$	0.2	$	142.1
Nonperforming	—		0.1		0.1		—		—		—		—		—		0.2
Total	$	35.3	$	36.9	$	21.2	$	10.8	$	4.4	$	7.0	$	26.5	$	0.2	$	142.3
Current-period gross charge-offs	0.1		0.3		0.2		0.3		0.1		2.1		0.1		—		3.2
Consumer credit card:
Performing	$	—	$	—	$	—	$	—	$	—	$	—	$	71.1	$	—	$	71.1
Nonperforming	—		—		—		—		—		—		0.5		—		0.5
Total	$	—	$	—	$	—	$	—	$	—	$	—	$	71.6	$	—	$	71.6
Current-period gross charge-offs	—		—		—		—		—		—		2.0		—		2.0

30

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Residential 1-4 family:
Performing	$	258.9	$	490.3	$	541.6	$	98.0	$	32.0	$	213.8	$	—	$	1,634.6
Nonperforming	—		0.2		0.1		0.5		0.3		3.7		—		4.8
Total	$	258.9	$	490.5	$	541.7	$	98.5	$	32.3	$	217.5	$	—	$	1,639.4
Consumer home equity and HELOC:
Performing	$	23.8	$	8.0	$	5.2	$	5.5	$	5.6	$	15.2	$	482.8	$	546.1
Nonperforming	0.6		0.3		0.2		0.2		0.1		1.2		0.2		2.8
Total	$	24.4	$	8.3	$	5.4	$	5.7	$	5.7	$	16.4	$	483.0	$	548.9
Consumer indirect:
Performing	$	380.3	$	176.4	$	130.0	$	59.7	$	33.6	$	46.3	$	—	$	826.3
Nonperforming	1.0		0.9		0.6		0.3		0.2		0.4		—		3.4
Total	$	381.3	$	177.3	$	130.6	$	60.0	$	33.8	$	46.7	$	—	$	829.7
Consumer direct and advance lines:
Performing	$	52.6	$	31.9	$	18.2	$	8.5	$	6.5	$	8.9	$	25.8	$	152.4
Nonperforming	0.1		0.1		0.1		—		—		0.1		0.1		0.5
Total	$	52.7	$	32.0	$	18.3	$	8.5	$	6.5	$	9.0	$	25.9	$	152.9

While the Company considers the performance of the loan portfolio on the allowance for credit losses, for certain credit card loan classes, the Company also evaluates credit quality based on the aging status of the loan, which was previously presented, and by payment activity of the credit card holder. The following table presents the recorded investment in credit card loans based on payment activity for the periods indicated:

As of December 31, 2022	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	75.4	$	100.0	$	1.9	$	177.3
Nonperforming	0.5		0.3		—		0.8
Total credit card	$	75.9	$	100.3	$	1.9	$	178.1

In the normal course of business, there were no material purchases of portfolio loans and no material sales of loans held for investment during the three and the nine months ended September 30, 2023 or 2022.

(7)    Other Real Estate Owned

Other real estate owned (“OREO”) is a category of real estate owned by the Company as a result of 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,
	2023		2022		2023		2022
Beginning balance	$	14.4	$	16.8	$	12.7	$	2.0
Acquired through acquisition	—		—		—		15.8
Additions	—		0.3		2.5		0.4
Valuation adjustments	(0.3)		(0.2)		(1.1)		(0.2)
Dispositions	(2.5)		(0.5)		(2.5)		(1.6)
Ending balance	$	11.6	$	16.4	$	11.6	$	16.4

The carrying value of foreclosed residential real estate properties included in OREO was not material as of September 30, 2023 and December 31, 2022. The Company had $0.4 million and no material 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, 2023 and December 31, 2022, respectively.

31

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(8)    Derivatives 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 through the use of 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.

In the normal course of business, the Company enters into interest rate lock commitments to finance residential mortgage loans that are not designated as accounting hedges. These commitments, which contain fixed expiration dates, offer the borrower an interest rate guarantee, provided the loan meets underwriting guidelines, and closes within the timeframe established by the Company. Interest rate risk arises on these commitments and subsequently on closed loans if interest rates change between the time of the interest rate lock and the delivery of the loan to the investor. Loan commitments related to residential mortgage loans intended to be sold are considered derivatives and are recorded at fair value with changes in fair value recorded through earnings.

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 (loss).

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 for the most part 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. Interest rate swaps that were designated as cash flow hedges on the variable-rate borrowings (trust preferred securities) involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. During 2021 and the first quarter of 2022, such derivatives were used to hedge the variable cash flows associated with the existing trust preferred securities. The trades that the Company had in place on its trust preferred securities matured during the first and second quarters of 2022.

As part of the Company’s overall asset and liability management strategy, in August 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. Each of the collars designated as cash flow hedges synthetically fixes the interest income received by the Company when the collar index falls below a floor rate on a rate reset during the term of the collar and when the collar index exceeds the cap rate on a rate reset during the term of the collar without exchange of the underlying notional amount.

In October 2022, the Company 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. Each of these swaps designated as cash flow hedges synthetically fixes the interest income received by the Company without exchange of the underlying notional amount. Of the six trades with a total notional amount of $1.15 billion, four are effective with a total notional of $600.0 million. Of these effective trades, the two collars and one swap are related to variable-rate loans and the other swap is related to variable-rate securities.

32

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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 (expense) 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 (expense) when interest payments are made on the Company’s variable-rate liabilities. During the next twelve months, the Company estimates that $15.0 million will be reclassified as an increase to interest expense.

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.

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, 2023				December 31, 2022
	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	$	192.9	$	7.1	$	191.9	$	8.1

Non-designated Hedge Derivatives

Derivatives 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 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 GWB 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 take into account 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.

33

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

	September 30, 2023					December 31, 2022
	Notional Amount		Consolidated Balance Sheet Location	Estimated Fair Value		Notional Amount		Consolidated Balance Sheet Location	Estimated Fair Value
Derivatives designated as accounting hedges:
Interest rate swap contracts	$	—		$	—	$	550.0		$	3.5
Derivatives not designated as accounting hedges:
Interest rate swap contracts	1,638.8			57.4		1,728.1			41.6
Forward loan sales contracts	8.0			—		12.6			0.1
Derivative assets	$	1,646.8	Other assets	$	57.4	$	2,290.7	Other assets	$	45.2
Derivatives designated as accounting hedges:
Interest rate collars	$	300.0		$	7.3	$	300.0		$	5.4
Interest rate swap contracts	850.0			18.6		300.0			0.3
Derivatives not designated as accounting hedges:
Interest rate swap contracts	1,638.8			184.1		1,728.1			153.9
Risk participation agreements	102.2			—		106.1			—
Interest rate lock commitments	7.0			—		14.8			—
Derivative liabilities	$	2,898.0	Accounts payable and accrued expenses	$	210.0	$	2,449.0	Accounts payable and accrued expenses	$	159.6

There was an unrealized fair value loss on cash flow hedging derivative instruments in accumulated other comprehensive income of $25.1 million and $31.2 million during the three and the nine months ended September 30, 2023. There were $5.6 million effects of derivative instruments in fair value or cash flow hedge accounting on accumulated other comprehensive loss during the three and the nine months ended September 30, 2022.

There were no material effects from the Company’s fair value or cash flow hedged derivative financial instruments on the consolidated statements of income during the three and the nine months ended September 30, 2023 or 2022.

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,
		2023		2022			2023		2022
	Location of Gain (Loss) Recognized in Income on Derivative	Amount of Gain (Loss) Recognized in Income on Derivative				Location of Loss Recognized in Income on Derivative	Amount of Loss Recognized in Income on Derivative
Interest rate lock commitments	Mortgage banking revenues	$	0.1	$	(0.2)	Mortgage banking revenues	$	(0.1)	$	(1.7)

The Company recorded swap fee revenues of $0.1 million and $2.5 million for the three months ended September 30, 2023 and September 30, 2022, and $0.7 million and $5.6 million for the nine months ended September 30, 2023 and September 30, 2022. The Company includes swap fee revenues in other service charges, commissions, and fees on the consolidated statements of income.

34

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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, 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 contracts	$	57.4	$	—	$	57.4	$	—	$	38.6	$	18.8
Total derivatives	57.4		—		57.4		—		38.6		18.8
Total assets	$	57.4	$	—	$	57.4	$	—	$	38.6	$	18.8
(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	$	210.0	$	—	$	210.0	$	—	$	1.0	$	209.0
Total derivatives	210.0		—		210.0		—		1.0		209.0
Repurchase agreements	889.5		—		889.5		—		889.5		—
Total liabilities	$	1,099.5	$	—	$	1,099.5	$	—	$	890.5	$	209.0

	December 31, 2022
	Gross Assets Recognized		Gross Assets Offset in the Balance Sheet		Net Assets in the Balance Sheet		Financial Instruments		Cash Collateral Received		Net Amount
Interest rate swap contracts	$	45.1	$	—	$	45.1	$	—	$	45.1	$	—
Mortgage related derivatives	0.1		—		0.1		—		—		0.1
Total derivatives	45.2		—		45.2		—		45.1		0.1
Total assets	$	45.2	$	—	$	45.2	$	—	$	45.1	$	0.1
	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 contracts	$	159.6	$	—	$	159.6	$	—	$	—	$	159.6
Total derivatives	159.6		—		159.6		—		—		159.6
Repurchase agreements	1,052.9		—		1,052.9		—		1,052.9		—
Total liabilities	$	1,212.5	$	—	$	1,212.5	$	—	$	1,052.9	$	159.6

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 each of its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company's default on the indebtedness.

35

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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, 2023 or December 31, 2022, it could have been required to settle its obligations under the agreements at the termination value.

As of September 30, 2023, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, was $0.9 million related to these agreements. As of September 30, 2023, the Company has minimum collateral posting thresholds with certain of its derivative counterparties and has $0.1 million posted excess collateral. If the Company had breached any of these provisions at September 30, 2023, it could have been required to settle its obligations under the agreements at their termination value.

(9)    Other Borrowed Funds            

At September 30, 2023, the Company had $2,067.0 million in outstanding FHLB borrowings, as compared to $2,327.0 million outstanding borrowings with the FHLB at December 31, 2022. At September 30, 2023, the Company has remaining available lines of credit with the FHLB of approximately $4,764.4 million, subject to collateral availability. The borrowings are collateralized by certain loans and securities with an advance equivalent collateral value of $6,831.4 million. As of September 30, 2023 and December 31, 2022, there were no long or short-term advances outstanding with the FHLB. As of September 30, 2023 and December 31, 2022, the Company had no other material outstanding borrowings classified as other borrowed funds.

The following table presents outstanding FHLB borrowings by maturity buckets for the dates indicated:

As of September 30, 2023	Average Rate		Outstanding Balance
Fixed rate borrowings with tenors of up to one week	5.52	%	$	106.0
Fixed rate borrowings with tenors of up to two weeks	5.51		100.0
Fixed rate borrowings with tenors of up to one month	5.50		925.0
Two-month fixed rate borrowings	5.56		500.0
Five-month fixed rate borrowings	5.56		436.0
			$	2,067.0
As of December 31, 2022	Rate		Outstanding Balance
Variable rate overnight borrowings	4.60	%	$	827.0
Fixed rate borrowings in tenors of up to one month	4.48		1,500.0
			$	2,327.0

(10)    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. At the effective time of the conversion, each outstanding share of the 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. Accordingly, all references to Class A common stock in these financial statements and notes refer to the role of the Class A common stock in the GWB acquisition while all other references to the Company’s common capital stock have been retroactively changed to reference common stock.

The Company had 105,011,371 shares and 104,442,023 shares of common stock outstanding as of September 30, 2023 and December 31, 2022, respectively.

36

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company completed the stock repurchase program adopted by the Company’s board of directors in 2022 and the Company’s board of directors has not authorized a stock repurchase program for 2023. There were 3,729,300 shares repurchased and retired under the stock repurchase program during the three months ended September 30, 2022 at a total cost of $133.1 million, including costs and commissions, at an average cost of $40.59 per share. There were 5.0 million shares repurchased and retired during the nine months ended September 30, 2022 at a total cost of $197.4 million, including costs and commissions, at an average cost of $39.48.

Other stock repurchases during the nine months ended September 30, 2023 and 2022, were redemptions of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants in the Company’s equity compensation plans.

During the nine months ended September 30, 2023, the Company issued 54,414 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.

On May 25, 2023, the Company filed a Registration Statement on Form S-8 to register an additional 2,000,000 shares of common stock to be issued pursuant to the Company's 2023 Equity and Incentive Plan.

On May 26, 2023, the Company filed a universal shelf registration statement on Form S-3, which was subsequently declared effective by the SEC. The shelf registration statement allows the Company to raise additional capital from time to time through offers and sales of registered securities consisting of debt securities, preferred stock, depositary shares, common stock, warrants, purchase contracts, and units or units consisting of any combination of the foregoing securities. The Company may sell these securities using the prospectus in the shelf registration statement, together with applicable prospectus supplements, from time to time, in one or more offerings.

(11)    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,
	2023		2022		2023		2022
Net income	$	72.7	$	85.7	$	196.0	$	116.4
Weighted average common shares outstanding for basic earnings per share computation	103,822,311		106,525,974		103,793,851		102,879,422
Dilutive effects of stock-based compensation	4,116		63,725		30,425		55,938
Weighted average common shares outstanding for diluted earnings per common share computation	103,826,427		106,589,699		103,824,276		102,935,360
Basic earnings per common share	$	0.70	$	0.80	$	1.89	$	1.13
Diluted earnings per common share	0.70		0.80		1.89		1.13
Anti-dilutive unvested time restricted stock	162,231		48,871		162,231		51,161

The Company had 967,996 and 481,567 shares of unvested restricted stock as of September 30, 2023 and 2022, respectively, that were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met.

37

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(12)    Regulatory Capital

As of September 30, 2023 and December 31, 2022, 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, 2023 and December 31, 2022 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, 2023	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,957.6	13.19	%	$	1,794.5	8.00	%	$	2,355.3	10.50	%	$	2,243.1	10.00	%
FIB	2,782.1		12.43		1,790.8		8.00		2,350.5		10.50		2,238.6		10.00
Tier 1 risk-based capital:
Consolidated	2,471.6		11.02		1,345.9		6.00		1,906.6		8.50		1,794.5		8.00
FIB	2,553.7		11.41		1,343.1		6.00		1,902.8		8.50		1,790.8		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,471.6		11.02		1,009.4		4.50		1,570.2		7.00		1,458.0		6.50
FIB	2,553.7		11.41		1,007.3		4.50		1,567.0		7.00		1,455.1		6.50
Leverage capital ratio:
Consolidated	2,471.6		8.22		1,202.8		4.00		1,202.8		4.00		1,503.5		5.00
FIB	2,553.7		8.50		1,201.1		4.00		1,201.1		4.00		1,501.3		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, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,875.8	12.48	%	$	1,843.2	8.00	%	$	2,419.2	10.50	%	$	2,304.0	10.00	%
FIB	2,713.5		11.80		1,839.6		8.00		2,414.5		10.50		2,299.5		10.00
Tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,382.4		6.00		1,958.4		8.50		1,843.2		8.00
FIB	2,504.1		10.89		1,379.7		6.00		1,954.6		8.50		1,839.6		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,036.8		4.50		1,612.8		7.00		1,497.6		6.50
FIB	2,504.1		10.89		1,034.8		4.50		1,609.7		7.00		1,494.7		6.50
Leverage capital ratio:
Consolidated	2,408.8		7.75		1,242.9		4.00		1,242.9		4.00		1,553.6		5.00
FIB	2,504.1		8.07		1,241.1		4.00		1,241.1		4.00		1,551.4		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.

38

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

In connection with the adoption of CECL on January 1, 2020, the Company recognized an after-tax cumulative effect reduction to retained earnings 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 ASC 326 on their regulatory capital computations. This interim rule is in addition to the three-year transition period already in place under the capital transition rule previously issued in February 2019. Banking organizations can elect to mitigate the estimated cumulative regulatory capital effects for an additional two years. This rule allows an institution to defer incorporating the impact of ASC 326 into its regulatory capital calculation, including ratios, over an extended period. Additionally, the interim rule extends the transition period whereby an institution can defer the impact from ASC 326 on the current period, determined based on the difference between the new ASC 326 allowance for credit losses and the allowance for loan losses under the incurred loss method from previous GAAP, for up to two years. The total impact related to ASC 326 would then be transitioned into regulatory capital and the associated ratios over a three-year transition period, beginning after the initial two-year deferral period, for a total transition period of five years. The Company elected to opt into the transition election and adopted transition relief over the permissible five-year period.

(13)    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, 2023, the Company had commitments under construction contracts of $7.0 million.

Residential mortgage loans sold to investors in the secondary market are sold with varying recourse provisions. Essentially all the loan sales agreements require the repurchase of a mortgage loan by the seller in situations such as breach of representation, warranty, or covenant; untimely document delivery; false or misleading statements; failure to obtain certain certificates or insurance; or unmarketability. Certain loan sales agreements contain repurchase requirements based on payment-related defects that are defined in terms of the number of days or months since the purchase, the sequence number of the payment, and/or the number of days of payment delinquency. Based on the specific terms stated in the agreements, the Company had $0.8 million of sold residential mortgage loans with recourse provisions still in effect as of September 30, 2023.

(14)    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.    

39

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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,
	2023		2022		2023		2022
Beginning balance	$	20.8	$	6.2	$	16.2	$	3.8
Provision for credit loss expense	(2.0)		3.5		2.6		5.9
Ending balance	$	18.8	$	9.7	$	18.8	$	9.7

	September 30, 2023		December 31, 2022
Unused credit card lines	$	805.1	$	827.6
Commitments to extend credit	4,441.0		5,173.3
Standby letters of credit	94.7		93.8

(15)    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,	2023		2022		2023		2022		2023		2022
Investment securities available-for sale:
Change in net unrealized losses during the period	$	(72.1)	$	(236.4)	$	(17.9)	$	(53.4)	$	(54.2)	$	(183.0)
Reclassification adjustment for net losses included in income	—		24.2		—		5.5		—		18.7
Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity	(0.3)		(1.7)		(0.1)		(0.4)		(0.2)		(1.3)
Change in net unrealized loss on derivatives	(11.0)		(15.9)		(2.7)		(3.6)		(8.3)		(12.3)
Total other comprehensive loss	$	(83.4)	$	(229.8)	$	(20.7)	$	(51.9)	$	(62.7)	$	(177.9)

	Pre-tax				Tax Expense (Benefit)				Net of Tax
Nine Months Ended September 30,	2023		2022		2023		2022		2023		2022
Investment securities available-for sale:
Change in net unrealized losses during period	$	(51.4)	$	(650.6)	$	(12.7)	$	(161.3)	$	(38.7)	$	(489.3)
Reclassification adjustment for net losses included in net income	23.5		24.4		5.8		5.5		17.7		18.9
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(7.2)		0.2		(1.8)		0.1		(5.4)		0.1
Net change in unamortized losses on available-for-sale securities transferred into held-to-maturity	(1.1)		(25.6)		(0.3)		(6.3)		(0.8)		(19.3)
Change in net unrealized loss on derivatives	(23.1)		(9.6)		(5.7)		(2.5)		(17.4)		(7.1)
Total other comprehensive loss	$	(59.3)	$	(661.2)	$	(14.7)	$	(164.5)	$	(44.6)	$	(496.7)

The components of accumulated other comprehensive loss, net of related tax effects, are as follows:

	September 30, 2023		December 31, 2022
Net unrealized loss on investment securities available-for-sale	$	(497.4)	$	(471.0)
Net unrealized loss on investment securities transferred to held-to-maturity	(5.4)		(4.5)
Net unrealized loss on derivatives	(18.9)		(1.6)
Net accumulated other comprehensive loss	$	(521.7)	$	(477.1)

(16)    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.

40

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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 during the three and the nine months ended September 30, 2023 and 2022.

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 during the three and the nine months ended September 30, 2023 and 2022.

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 change in the value of derivative assets attributable to basis risk, or the risk that offsetting investments in a hedging strategy will not experience price changes in entirely opposite directions, was not significant in the reported periods. The Company also compares the reasonableness of the pricing semi-annually 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 the 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 change in the value of derivative assets attributable to basis risk, or the risk that offsetting investments in a hedging strategy will not experience price changes in entirely opposite directions, was not significant in the reported periods. The Company also compares the reasonableness of the pricing semi-annually through a validation process involving additional independent third parties.

41

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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, 2023	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Investment debt securities available-for-sale:
U.S. Treasury notes	$	215.9	$	—	$	215.9	$	—
State, county, and municipal securities	202.6			—	202.6			—
Obligations of U.S. government agencies	162.0			—	162.0			—
U.S. agency commercial mortgage-backed securities	1,066.9			—	1,066.9			—
U.S. agency residential mortgage-backed securities	1,285.0			—	1,285.0			—
Collateralized mortgage obligations	1,143.7			—	1,143.7			—
Private mortgage-backed securities	207.3			—	207.3			—
Collateralized loan obligations	1,117.8			—	1,117.8			—
Corporate securities	226.5			—	226.5			—
Loans held for sale	3.2			—	3.2			—
Derivative assets:
Interest rate swap contracts	57.4			—	57.4			—
Derivative liabilities:
Interest rate collars	7.3			—	7.3			—
Interest rate swap contracts	202.7			—	202.7			—
Interest rate lock commitments	—			—	—			—
Deferred compensation plan assets	19.2			—	19.2			—
Deferred compensation plan liabilities	19.2			—	19.2			—

42

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

			Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Investment debt securities available-for-sale:
U.S. Treasury notes	$	642.7	$	—	$	642.7	$	—
State, county and municipal securities	263.7			—	263.7			—
Obligations of U.S. government agencies	198.9			—	198.9			—
U.S. agency commercial mortgage-backed securities	1,351.2			—	1,351.2			—
U.S. agency residential mortgage-backed securities	1,558.3			—	1,558.3			—
Collateralized mortgage obligations	1,350.2			—	1,350.2			—
Private mortgage-backed securities	228.0			—	228.0			—
Collateralized loan obligations	1,111.6			—	1,111.6			—
Corporate securities	241.5			—	241.5			—
Loans held for sale	12.4			—	6.9			5.5
Derivative assets:
Interest rate swap contracts	45.1			—	45.1			—
Forward loan sales contracts	0.1			—	0.1			—
Derivative liabilities
Interest rate collars	5.4			—	5.4			—
Interest rate swap contracts	154.2			—	154.2			—
Deferred compensation plan assets	18.7			—	18.7			—
Deferred compensation plan liabilities	18.7			—	18.7			—

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, 2023	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral-dependent loans	$	56.3	$	—	$	—	$	56.3
Loans held for sale	55.9			—		—	55.9
Other real estate owned	11.6			—		—	11.6
Long-lived assets to be disposed of by sale	4.5			—		—	4.5
				Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral-dependent loans	$	39.1	$	—	$	—	$	39.1
Loans held for sale	67.5			—		—	67.5
Other real estate owned	12.7			—		—	12.7
Long-lived assets to be disposed of by sale	5.5			—		—	5.5

43

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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, 2023 and December 31, 2022, the Company had collateral-dependent loans with a carrying and fair value of $56.3 million and $39.1 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. The Company had $1.1 million and $0.2 million of write downs on OREO properties during the nine months ended September 30, 2023 and 2022, respectively.

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, 2023, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $9.1 million, reduced by write-downs of $4.6 million charged to other expense, and fair values aggregating $4.5 million. As of December 31, 2022, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $5.7 million, reduced by write-downs of $0.2 million charged to other expense, and fair values aggregating $5.5 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, 2023		December 31, 2022		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Collateral-dependent loans	$	56.3	$	39.1	Appraisal	Appraisal adjustment	0%	-	45%	(7%)
Loans held for sale	55.9		67.5		Fair value of collateral	Discount for type of property, age of appraisal, and current status	11%	-	23%	(17%)
Other real estate owned	11.6		12.7		Appraisal	Appraisal adjustment	15%	-	36%	(22%)
Long-lived assets to be disposed of by sale	4.5		5.5		Appraisal	Appraisal adjustment	0%	-	6%	(3%)

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.        

44

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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, 2023	Carrying Amount		Estimated Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	$	593.1	$	593.1	$	593.1	$	—	$	—
Investment debt securities available-for-sale	5,627.7		5,627.7		—		5,627.7		—
Investment debt securities held-to-maturity	3,259.5		2,796.1		—		2,796.1		—
Accrued interest receivable	129.2		129.2		—		129.2		—
Mortgage servicing rights, net	29.1		35.6		—		35.6		—
Loans held for sale	59.1		59.1		—		3.2		55.9
Net loans held for investment	17,986.6		17,226.1		—		17,169.8		56.3
Derivative assets	57.4		57.4		—		57.4		—
Deferred compensation plan assets	19.2		19.2		—		19.2		—
Total financial assets	$	27,760.9	$	26,543.5	$	593.1	$	25,838.2	$	112.2
Financial liabilities:
Total deposits, excluding time deposits	$	20,516.8	$	20,516.8	$	20,516.8	$	—	$	—
Time deposits	3,162.7		3,126.2		—		3,126.2		—
Securities sold under repurchase agreements	889.5		889.5		—		889.5		—
Other borrowed funds	2,067.0		2,067.0		—		2,067.0		—
Accrued interest payable	63.7		63.7		—		63.7		—
Long-term debt	120.8		114.4		—		114.4		—
Subordinated debentures held by subsidiary trusts	163.1		152.5		—		152.5		—
Derivative liabilities	210.0		210.0		—		210.0		—
Deferred compensation plan liabilities	19.2		19.2		—		19.2		—
Total financial liabilities	$	27,212.8	$	27,159.3	$	20,516.8	$	6,642.5	$	—

45

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

					Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Carrying Amount		Estimated Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	$	870.5	$	870.5	$	870.5	$	—	$	—
Investment debt securities available-for-sale	6,946.1		6,946.1		—		6,946.1		—
Investment debt securities held-to-maturity	3,451.8		3,052.2		—		3,052.2		—
Accrued interest receivable	118.3		118.3		—		118.3		—
Mortgage servicing rights, net	31.1		37.4		—		37.4		—
Loans held for sale	79.9		79.9		—		6.9		73.0
Net loans held for investment	17,879.1		17,552.1		—		17,513.0		39.1
Derivative assets	45.2		45.2		—		45.2		—
Deferred compensation plan assets	18.7		18.7		—		18.7		—
Total financial assets	$	29,440.7	$	28,720.4	$	870.5	$	27,737.8	$	112.1
Financial liabilities:
Total deposits, excluding time deposits	$	23,145.2	$	23,145.2	$	23,145.2	$	—	$	—
Time deposits	1,928.4		1,876.1		—		1,876.1		—
Securities sold under repurchase agreements	1,052.9		1,052.9		—		1,052.9		—
Other borrowed funds	2,327.0		2,327.0		—		2,327.0		—
Accrued interest payable	14.5		14.5		—		14.5		—
Long-term debt	120.8		116.3		—		116.3		—
Subordinated debentures held by subsidiary trusts	163.1		155.8		—		155.8		—
Derivative liabilities	159.6		159.6		—		159.6		—
Deferred compensation plan liabilities	18.7		18.7		—		18.7		—
Total financial liabilities	$	28,930.2	$	28,866.1	$	23,145.2	$	5,720.9	$	—

(17)    Recent Authoritative Accounting Guidance

ASU 2020-04, “Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Accounting.” In March 2020, the FASB issued ASU 2020-04, which provides temporary exceptions that are optional for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. For transactions that are modified because of reference rate reform and that meet certain scope guidance (i) modifications of loan agreements should be accounted for by prospectively adjusting the effective interest rate, with such modification considered to be "minor" so that any existing unamortized origination fees/costs will carry forward and continue to be amortized and (ii) modifications of lease agreements should be accounted for as a continuation of the existing agreement with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required for modifications will not be accounted for as separate contracts. ASU 2020-04 is effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within the Codification, the amendments in this ASU must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company adopted certain elections related to cash flow hedges which did not have a significant impact on the Company’s financial position or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2020-04 can generally be applied through December 31, 2024.

46

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

ASU 2021-01, “Reference Rate Reform (Topic 848)” In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform Topic 848, that clarifies certain exceptions that are optional in Topic 848 for contract modifications and hedge accounting and apply those exceptions to derivatives that are affected by the discounting transition. An entity may elect to apply the amendments in this ASU on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to the date of the issuance of a final ASU. If an entity elects to apply any of the amendments in this ASU for an eligible hedging relationship, any adjustments as a result of those elections must be reflected as of the date the entity applies the election. The amendments in this ASU do not apply to contract modifications made, new hedging relationships entered into, or existing hedging relationships evaluated for effectiveness in periods after December 31, 2022, except for hedging relationships existing as of December 31, 2022, that apply certain exceptions that are optional in which the accounting effects of the hedging activity are recorded through the end of the hedging relationship. 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 or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2021-01 can generally be applied through December 31, 2024.

ASU 2021-08, “Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers” In October 2021, the FASB issued ASU 2021-08, Business Combinations Topic 805, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, to address diversity in practice and inconsistency related to the accounting for revenue contracts with customers acquired in a business combination. The amendments require that an entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606 as if it had originated the contracts. The amendments also provide certain practical expedients for acquirers when recognizing and measuring acquired contract assets and contract liabilities from revenue contracts in a business combination and applies to contract assets and contract liabilities from other contracts to which the provisions of Topic 606 apply. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. Entities should apply the amendments prospectively to business combinations that occur after the effective date. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-01, “Derivatives and Hedging (Topic 815), Fair Value Hedging—Portfolio Layer Method” In March 2022, the FASB issued ASU 2022-01, Derivatives and Hedging Topic 815, Fair Value Hedging—Portfolio Layer Method that clarifies the accounting for and promotes consistency in the reporting of hedge basis adjustments applicable to both a single hedged layer and multiple hedged layers. The amendments allow nonprepayable financial assets also to be included in a closed portfolio hedged using the portfolio layer method. That expanded scope permits an entity to apply the same portfolio hedging method to both prepayable and nonprepayable financial assets, thereby allowing consistent accounting for similar hedges. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

47

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings and Vintage Disclosures” In March 2022, the FASB issued ASU 2022-02, Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings (TDRs) and Vintage Disclosures that eliminate the accounting guidance for TDRs by creditors in Subtopic 310-40, Receivables—Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Rather than applying the recognition and measurement guidance for TDRs, an entity must apply the loan refinancing and restructuring guidance to determine whether a modification results in a new loan or a continuation of an existing loan. The amendment also requires an entity disclose current-period gross writeoffs by year of origination for financing receivables and net investments in leases within the scope of Subtopic 326. The amendments are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 on a prospective basis, and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity. Prior to the adoption of ASU 2022-02, a TDR occurred when a loan to a borrower experiencing financial difficulty was restructured with a concession provided that a creditor would not otherwise consider. For the Company’s accounting policy related to TDRs granted prior to the adoption of ASU 2022-02, see “Note 1 – Summary of Significant Accounting Policies” in Part IV, Item 15 “Notes to Consolidated Financial Statements” within our Annual Report on Form 10-K for the year ended December 31, 2022. See “Note 6 – Loans Held For Investment” of these Notes to the Unaudited Consolidated Financial Statements” for further details of the amendments in this update.

ASU 2022-06, “Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848” In December 2022, the FASB issued ASU 2022-06, Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848 that extends the period of time preparers can utilize the reference rate reform relief guidance provided by ASU 2020-04 and ASU 2021-01, which are discussed above. ASU 2022-06, which was effective upon issuance, defers the sunset date of this prior guidance from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief guidance in Topic 848. The adoption of ASU 2022-06 did not have a significant impact on the Company’s financial position, results of operations, or liquidity.

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. Early adoption is permitted for all entities in any interim period. If an entity adopts the amendments in an interim period, it shall adopt them as of the beginning of the fiscal year that includes that interim period. The amendments must be applied on either a modified retrospective or a retrospective basis (except for certain LIHTC investments not accounted for using the proportional amortization method). 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.

ASU 2023-05, “Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement” In August 2023, the FASB issued ASU 2023-05, Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement that requires certain joint ventures to apply a new basis of accounting upon formation by recognizing and initially measuring most of their assets and liabilities at fair value. The objectives of the amendments are to provide decision-useful information to investors and other allocators of capital in a joint venture's financial statements and also to reduce diversity in practice. These amendments are effective prospectively for all joint venture formations with a formation date on or after January 1, 2025. The Company does not anticipate the adoption of ASU 2023-05 will have a significant impact on the Company’s financial position, results of operations, or liquidity.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

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.

(18)    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 24, 2023, the Company declared a quarterly dividend to common shareholders of $0.47 per share, to be paid on November 16, 2023 to shareholders of record as of November 6, 2023.

No other undisclosed events requiring recognition or disclosure were identified.

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Item 2.

MANAGEMENT’S DISCUSSION AND ANALYSIS OF

FINANCIAL CONDITION AND RESULTS OF OPERATIONS

When we refer to “we,” “our,” “us,” “First Interstate,” or the “Company” in this report, we mean First Interstate BancSystem, Inc. and our consolidated subsidiaries, including our wholly-owned subsidiary, First Interstate Bank, unless the context indicates that we refer only to the parent company, First Interstate BancSystem, Inc. When we refer to the “Bank” or “FIB” in this report, we mean only First Interstate Bank.

The following discussion of our consolidated financial data reflects our historical results of operations and financial condition and should be read in conjunction with our financial statements and related notes thereto presented elsewhere in this Quarterly Report on Form 10-Q and in our Annual Report on Form 10-K for the year ended December 31, 2022, including the audited financial statements and related notes contained therein, as previously filed with the Securities and Exchange Commission, or SEC.

Cautionary Note Regarding Forward-Looking Statements and Factors that Could Affect Future Results

This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Rule 175 promulgated thereunder, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and Rule 3b-6 promulgated thereunder, that involve inherent risks and uncertainties. Any statements about our plans, objectives, expectations, strategies, beliefs, or future performance or events constitute forward-looking statements. Such statements are identified by words or phrases such as “believes,” “expects,” “anticipates,” “plans,” “trends,” “objectives,” “views,” “continues” or similar expressions, or future or conditional verbs such as “will,” “would,” “should,” “could,” “might,” “may,” or similar expressions. Forward-looking statements involve known and unknown risks, uncertainties, assumptions, estimates and other important factors that could cause actual results to differ materially from any results, performance or events expressed or implied by such forward-looking statements. A detailed discussion of risks that may cause actual results to differ materially from current expectations in the forward-looking statements is included below in this report under the caption “Risk Factors” and in our Annual Report on Form 10-K for the year ended December 31, 2022, under the captions “Cautionary Note Regarding Forward-Looking Statements” and “Risk Factors”. These factors and the other risk factors described in our periodic and current reports filed with the SEC from time to time, however, are not necessarily all of the important factors that could cause our actual results, performance, or achievements to differ materially from those expressed in or implied by any of our forward-looking statements. Other unknown or unpredictable factors also could harm our results.

All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the cautionary statements set forth above. Interested parties are urged to read in their entirety the referenced risk factors prior to making any investment decision with respect to the Company. Forward-looking statements speak only as of the date they are made and we do not undertake or assume any obligation to update publicly any of these statements to reflect actual results, new information or future events, changes in assumptions or changes in other factors affecting forward-looking statements, except to the extent required by applicable law. If we update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

Non-GAAP Financial Measures

In addition to financial measures presented in accordance with GAAP, this document contains GAAP financial measures and non-GAAP financial measures where management believes it to be helpful in understanding our results of operations or financial position. Where non-GAAP financial measures are used, the comparable GAAP financial measure, as well as the reconciliation to the comparable GAAP financial measure, can be found herein.

Fully-Taxable Equivalent Basis. Interest income, yields, and ratios on an FTE basis are considered non-GAAP financial measures. Management believes net interest income on an FTE basis provides an insightful picture of the interest margin for comparison purposes. The FTE basis also allows management to assess the comparability of revenue arising from both taxable and tax-exempt sources. The FTE basis assumes a federal statutory tax rate of 21 percent. We encourage readers to consider the Unaudited Consolidated Financial Statements and other financial information contained in this Form 10-Q in their entirety, and not to rely on any single financial measure.

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Executive Overview

We are a financial and bank holding company focused on community banking. Since our incorporation in Montana in 1971, we have grown both organically and through strategic acquisitions. We operate 305 banking offices, including detached drive-up facilities, in communities across fourteen states—Arizona, Colorado, Idaho, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, North Dakota, Oregon, South Dakota, Washington, and Wyoming. Through our bank subsidiary, First Interstate Bank, we deliver a comprehensive range of banking products and services—including online and mobile banking—to individuals, businesses, municipalities, and others throughout our market areas. We are proud to provide lending opportunities to clients that participate in a wide variety of industries, including:

•Agriculture	•Governmental services	•Professional services	•Tourism
•Construction	•Healthcare	•Real Estate Development	•Wholesale trade
•Education	•Hospitality	•Retail
•Energy	•Housing	•Technology

Our principal business activity is lending to, accepting deposits from, and conducting financial transactions with and for individuals, businesses, municipalities, and other entities located in the communities we serve. We derive our income principally from interest charged on loans and, to a lesser extent, from interest and dividends earned on fixed income investments.

We also derive income from non-interest sources such as: (i) fees received in connection with various lending and deposit services; (ii) wealth management services, such as trust, employee benefit, investment, and insurance services; (iii) mortgage loan originations, sales, and servicing; (iv) merchant and electronic banking services; and (v) from time-to-time, gains on sales of assets and securities.

Our principal expenses include: (i) interest expense on deposit accounts and other borrowings; (ii) salaries and employee benefits; (iii) data processing and communication costs primarily associated with maintaining loan and deposit functions; (iv) furniture, equipment, and occupancy expenses for maintaining our facilities; (v) professional fees, including FDIC insurance assessments; (vi) income tax expense; (vii) provisions for credit losses; (viii) intangible amortization; and (ix) other real estate owned expenses. From time to time, we also incur acquisition costs related to our strategic acquisitions.

Recent Trends and Developments

Our community banking footprint spans across the Rocky Mountain and Pacific Northwest regions and has also expanded into the Midwest and Southwest regions, in large part due to our acquisition activity. As part of our normal course of business, we continue to evaluate bank acquisitions and other strategic opportunities on an on-going basis.

During the first half of 2023, the banking industry experienced significant volatility with multiple high-profile bank failures leading to broader industry concerns related to funding and liquidity. Despite these developments, the Company’s liquidity position and balance sheet remains strong and the capital ratios continue to exceed all regulatory well-capitalized requirements as of September 30, 2023. Our deposit base is diversified, including by depositor, which includes from individuals, businesses across multiple industries, municipalities, and other entities, as well as geographically, across the communities we serve. As of September 30, 2023, our FDIC insured deposits were 66.78% of total deposits, including accounts eligible for pass-through insurance. However, in light of these events, the Company took a number of pro-active actions which included outreach to clients and collateral optimization actions to maximize its availability to various liquidity sources.

Beginning in the third quarter of 2022, the Bank began borrowing from the FHLB to fund loan growth and cushion the Bank further against the outflow of deposits. Although decreasing since December 31, 2022, total deposits increased over the three months ended September 30, 2023. As a result, and due to investment portfolio cash flows, during the three months ended September 30, 2023, FHLB advances were paid down, and other borrowed funds decreased $0.5 billion to $2.1 billion at September 30, 2023, from $2.6 billion at June 30, 2023 at an average rate of 5.56% and 5.31%, respectively.

As of October 26, 2023, the Bank had available borrowing capacity of $4.9 billion with the FHLB and $3.1 billion with the Federal Reserve Bank based on pledged investment securities and loan collateral.

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U.S. inflation data hit a multi-decade high in June 2022, climbing to 9.1%, as reported by the Bureau of Labor Statistics, decreasing to 3.0% in June 2023, with a modest increase to 3.7% in September 2023. While our operating expenses are affected by general inflation, the asset and liability structure of the Company largely consists of monetary items. Monetary items, such as cash, investments, loans, deposits and other borrowings, are assets and liabilities which are or will be converted into a fixed number of dollars regardless of changes in prices. As a result, changes in interest rates have a more significant impact on a financial institution’s performance than does general inflation. However, inflation may have negative impacts on the Company’s clients and their customers, impacting their ability or willingness to repay loans or maintain deposits.

The Federal Reserve stated its current objective is to return the rate of inflation to 2% and it has been aggressively acting to achieve this goal. In response to sustained inflationary pressures, the Federal Reserve increased short-term interest rates 525 basis points between March 16, 2022 and July 26, 2023. Although the general inflationary pressures are easing, the Federal Reserve has continued to raise interest rates into the third quarter of 2023 and has reduced its ownership of agency mortgage-backed securities and U.S. Treasury securities. With the recent interest rate increases, the short end (up to two years) of the yield curve on U.S. Treasuries has increased, which has resulted in increased returns on our interest earning assets. The Company’s quarterly yield on interest earning assets increased to 4.63% as of September 30, 2023 from 4.52% as of June 30, 2023, and 3.99% as of September 30, 2022.

However, increases in short-term interest rates have also impacted the Company’s cost of funds, primarily as a result of the shift of non-interest-bearing deposits into higher-cost interest-bearing and time deposit balances and variable rate debt. The Company’s cost of funds increased to 1.59% during the three months ended September 30, 2023, from 1.43% during the three months ended June 30, 2023, and 0.28% during the three months ended September 30, 2022. Overall, the change in the mix and cost of funds has offset the changes in the mix and yield on earning assets, resulting in compression of the Company’s FTE net interest margin to 3.07% during the three months ended September 30, 2023, from 3.12% during the three months ended June 30, 2023, and 3.71% during the three months ended September 30, 2022.

Gross domestic product declined 2.6% during the first half of 2022, increased 5.3% in the second half of 2022, increased 4.3% in the first half of 2023, with the recent advance estimate released for the third quarter of 2023 suggesting growth at a seasonally- and inflation-adjusted rate of 4.9% for the quarter ending September 30, 2023. While gross domestic product has expanded at or above 2.0% since the second quarter of 2022, it is unclear whether the volatility of 2022 in the economic performance of the U.S. economy will re-emerge leading to an economic slowdown, downturn, or recession or whether its regular pattern of growth will continue. Any economic slowdown, downturn, or recession could impact the Company and one of its primary lending sources, by impacting the level of deposits held by our clients, whether through a higher volume of withdrawals or through a lower volume of deposits. The credit quality of the Company’s loans may also be impacted if clients must weather adverse economic conditions which could result in an increase in credit losses or other related expenses.

Primary Factors Used in Evaluating Our Business

As a banking institution, we manage and evaluate various aspects of both our financial condition and our results of operations. We monitor our financial condition and performance and evaluate the levels and trends of line items included in our consolidated balance sheets, consolidated statements of income, and comprehensive (loss) income. We also utilize various financial ratios that are commonly used in our industry. We analyze these ratios and financial trends against our own historical performance and the financial condition and performance of comparable banking institutions in our region and across the nation.

As discussed in our Annual Report on Form 10-K for the year ended December 31, 2022, our financial performance is impacted by a number of external factors outside our control, as well as our ability to execute on the key components of our strategy for continued success and future growth. See Part II – Other Information “Item 1A – Risk Factors” for an update of the risk factors disclosed in our Annual Report on Form 10-K for the year ended December 31, 2022.

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Critical Accounting Estimates and Significant Accounting Policies

Our consolidated financial statements are prepared in accordance with generally accepted accounting principles (“GAAP”) in the United States and follow general practices within the banking industry. Application of these principles requires management to make estimates, assumptions, and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. The most significant accounting policies we follow are summarized in Note 1 of the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2022, as referenced in Note 1 to the unaudited financial statements in this quarterly report. There have been no material changes in our critical accounting estimates and policies described in our Annual Report on Form 10-K for the year ended December 31, 2022, during the quarterly period covered by this quarterly report, except for the transition to new CECL modeling tools during the second quarter of 2023 and the adoption of ASU 2022-02 on January 1, 2023. Refer to “Note – Basis of Presentation” in the accompanying “Notes to Unaudited Consolidated Financial Statements” for further discussion of the CECL model transition and “Note – Recent Authoritative Accounting Guidance” in the accompanying “Notes to Unaudited Consolidated Financial Statements” for further discussion of the adoption.

The preparation of financial statements in conformity with GAAP requires management to measure the Company’s financial position and operating results primarily in terms of historic dollars. Changes in the relative value of money due to inflation or recession are generally not considered. The primary effect of inflation on our operations is reflected in increased operating expenses. Management considers changes in interest rates to impact our financial condition and results of operations to a far greater degree than changes in prices due to inflation. We manage our interest rate risk in several ways. Refer to “Note – Derivatives and Hedging Activities” in the accompanying “Notes to Unaudited Consolidated Financial Statements” for further discussion on how we manage interest rate risk. There can be no assurance that we will not be materially adversely affected by future changes in interest rates, as interest rates are highly sensitive to many factors that are beyond our control.

Results of Operations

The following discussion and analysis is intended to provide detail about the results of our operations and financial condition.

Net income decreased $13.0 million to $72.7 million, or $0.70 per share, during the three months ended September 30, 2023, as compared to net income of $85.7 million, or $0.80 per share, for the same period in 2022. The decrease during the quarter ended September 30, 2023 compared to the same period in 2022 was primarily attributable to lower net interest income as a result of higher interest expense on deposits and other borrowed funds. Lower net interest income was partially offset by lower non-interest expenses and an increase in non-interest income related to the $24.2 million loss on investment securities during the 2022 period.

Net income increased $79.6 million to $196.0 million, or $1.89 per share during the nine months ended September 30, 2023, as compared to net income of $116.4 million, or $1.13 per share for the same period in 2022. The increase during the nine months ended September 30, 2023 was primarily attributable to an increase in net interest income after the reduction of provision for credit losses of $28.0 million, which was largely related to the non-PCD provision expense in 2022 associated with the GWB acquisition, and lower non-interest expenses of $99.9 million, related to the acquisition related expenses of $115.0 million in 2022. These impacts were partially offset by a decrease in non-interest income and an increase in income tax expense in 2023.

Net Interest Income

Our operating results depend primarily on our net interest income, which is the difference between the interest the Company earns on its interest-earning assets, such as loans and investment securities, and the expense the Company pays on interest-bearing liabilities, such as deposits and borrowings. Net interest income depends on both the volume of our interest-earning assets and interest-bearing liabilities and the interest rates the Company earns or pays on them.

Changes in interest rate spread, which is the difference between interest earned on assets and interest paid on liabilities, has the most significant impact on net interest income. Other factors like volume of loans, investment securities, and other interest-earning assets compared to the volume of interest-bearing deposits and indebtedness also cause changes in our net interest income between periods. Non-interest-bearing sources of funds, such as demand deposits and stockholders’ equity, help to support earning assets.

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For the periods indicated, the following table presents condensed average balance sheet information, together with interest income and yields earned on average interest-earning assets and interest expense and rates paid on average interest-bearing liabilities.

Average Balance Sheets, Yields and Rates	Three Months Ended
(Dollars in millions)	September 30, 2023						September 30, 2022
	Average Balance		Interest(2)		Average Rate		Average Balance		Interest(2)		Average Rate
Interest-earning assets:
Loans (1)	$	18,317.4	$	251.5	5.45	%	$	17,543.8	$	220.2	4.98	%
Investment securities:
Taxable	8,877.6		66.0		2.95		10,581.1		64.7		2.43
Tax-exempt	190.4		0.9		1.88		238.5		1.2		2.00
Investment in FHLB and FRB stock	202.6		2.9		5.68		121.7		1.3		4.24
Interest-bearing deposits in banks	208.5		3.0		5.71		244.4		1.4		2.27
Federal funds sold	0.3		—		—		1.7		—		—
Total interest-earning assets	$	27,796.8	$	324.3	4.63	%	$	28,731.2	$	288.8	3.99	%
Non-interest-earning assets	2,955.5						2,922.5
Total assets	$	30,752.3					$	31,653.7
Interest-bearing liabilities:
Demand deposits	$	6,361.5	$	13.3	0.83	%	$	7,824.3	$	5.1	0.26	%
Savings deposits	7,838.4		33.6		1.70		8,689.0		7.0		0.32
Time deposits	2,938.0		21.9		2.96		1,502.3		1.2		0.32
Repurchase agreements	895.2		1.7		0.75		1,107.7		0.8		0.29
Other borrowed funds	2,396.3		33.6		5.56		370.9		2.4		2.57
Long-term debt	120.8		1.5		4.93		120.4		1.5		4.94
Subordinated debentures held by subsidiary trusts	163.1		3.3		8.03		163.1		1.9		4.62
Total interest-bearing liabilities	$	20,713.3	$	108.9	2.09	%	$	19,777.7	$	19.9	0.40	%
Non-interest-bearing deposits	6,401.2						8,212.6
Other non-interest-bearing liabilities	504.0						423.7
Stockholders’ equity	3,133.8						3,239.7
Total liabilities and stockholders’ equity	$	30,752.3					$	31,653.7
Net FTE interest income (non-GAAP)(3)			$	215.4					$	268.9
Less FTE adjustments(2)			(1.7)						(2.1)
Net interest income from consolidated statements of income			$	213.7					$	266.8
Interest rate spread					2.54	%					3.59	%
Net interest margin					3.05						3.68
Net FTE interest margin (non-GAAP)(3)					3.07						3.71
Cost of funds, including non-interest-bearing demand deposits (4)					1.59						0.28
(1) Average loan balances include loans held for sale and loans held for investment, net of deferred fees and costs, which include non-accrual loans. Interest income includes amortization of deferred loan fees net of deferred loan costs, which is not material.
(2) The Company adjusts interest income and average rates for tax exempt loans and securities to a FTE basis utilizing a 21.00% and 26.25% tax rate for 2023 and 2022, respectively.
(3) Management believes fully taxable equivalent, or FTE, interest income is useful to investors in evaluating the Company’s performance as a comparison of the returns between a tax-free investment and a taxable alternative. Net FTE interest income and net FTE interest margin are non-GAAP financial measure - see Non-GAAP Financial Measures included herein for a reconciliation to GAAP measures.
(4) Calculated by dividing total annualized interest on interest-bearing liabilities by the sum of total interest-bearing liabilities plus non-interest-bearing deposits.

Net interest income decreased $53.1 million during the three months ended September 30, 2023, as compared to the same period in 2022, primarily due to an increase in interest expense as a result of higher levels and costs of interest-bearing liabilities.

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Net interest income included interest accretion related to the fair valuation of acquired loans of $5.2 million during the three months ended September 30, 2023, compared to interest accretion of $17.7 million during the three months ended September 30, 2022.

Our net FTE interest margin ratio, a non-GAAP financial measure, decreased 64 basis points for the three months ended September 30, 2023, as compared to the same period in 2022. Exclusive of the impact of interest accretion on acquired loans, the net FTE interest margin ratio, decreased 47 basis points to 3.00% during the three months ended September 30, 2023, as compared to 3.47% for the same period in 2022.

Average Balance Sheets, Yields and Rates	Nine Months Ended
(Dollars in millions)	September 30, 2023						September 30, 2022
	Average Balance		Interest(2)		Average Rate		Average Balance		Interest(2)		Average Rate
Interest earning assets:
Loans (1)	$	18,314.3	$	731.9	5.34	%	$	16,425.3	$	566.7	4.61	%
Investment securities
Taxable	9,329.3		204.3		2.93		9,588.3		143.4		1.50
Tax-exempt	202.9		3.0		1.98		246.7		3.9		1.58
Investment in FHLB and FRB stock	212.7		9.3		5.85		103.2		2.8		3.63
Interest-bearing deposits in banks	330.6		12.6		5.10		1,841.5		6.5		0.47
Federal funds sold	0.6		—		—		0.6		—		—
Total interest-earning assets	$	28,390.4	$	961.1	4.53	%	$	28,205.6	$	723.3	3.43	%
Non-earning assets	2,955.3						2,726.5
Total assets	$	31,345.7					$	30,932.1
Interest-bearing liabilities:
Demand deposits	$	6,581.8	$	31.9	0.65	%	$	7,596.0	$	7.8	0.14	%
Savings deposits	8,063.4		84.8		1.41		8,829.1		9.7		0.15
Time deposits	2,506.8		46.0		2.45		1,485.4		3.1		0.28
Repurchase agreements	973.4		4.3		0.59		1,122.4		1.4		0.17
Other borrowed funds	2,658.5		104.1		5.24		125.0		2.4		2.57
Long-term debt	120.8		4.4		4.87		122.7		4.6		5.01
Subordinated debentures held by subsidiary trusts	163.1		9.3		7.62		154.4		4.3		3.72
Total interest-bearing liabilities	$	21,067.8	$	284.8	1.81	%	$	19,435.0	$	33.3	0.23	%
Non-interest-bearing deposits	6,660.2						7,925.0
Other non-interest-bearing liabilities	463.2						335.7
Stockholders’ equity	3,154.5						3,236.4
Total liabilities and stockholders’ equity	$	31,345.7					$	30,932.1
Net FTE interest income (non-GAAP)(3)			$	676.3					$	690.0
Less FTE adjustments’(2)			(5.3)						(5.8)
Net interest income from consolidated statements of income			$	671.0					$	684.2
Interest rate spread					2.72	%					3.20	%
Net interest margin					3.16						3.24
Net FTE interest margin (non-GAAP)(3)					3.18						3.27
Cost of funds, including non-interest-bearing demand deposits (4)					1.37						0.16
(1) Average loan balances include loans held for sale and loans held for investment, net of deferred fees and costs, which include non-accrual loans. Interest income on loans includes amortization of deferred loan fees, net of deferred loan costs of $1.1 million and $6.3 million at September 30, 2023 and September 30, 2022, respectively.
(2) The Company adjusts interest income and average rates for tax exempt loans and securities to a FTE basis utilizing a 21.00% and 26.25% tax rate for 2023 and 2022, respectively.
(3) Management believes fully taxable equivalent, or FTE, interest income is useful to investors in evaluating the Company’s performance as a comparison of the returns between a tax-free investment and a taxable alternative. Net FTE interest income and net FTE interest margin are non-GAAP financial measure - see Non-GAAP Financial Measures included herein for a reconciliation to GAAP measures.
(4) Calculated by dividing total annualized interest on interest-bearing liabilities by the sum of total interest-bearing liabilities plus non-interest-bearing deposits.

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Net interest income decreased $13.2 million during the nine months ended September 30, 2023 as compared the same period in 2022, primarily due to a decrease in interest accretion related to the fair valuation of acquired loans and an increase in interest expense as a result of higher levels and costs of interest-bearing liabilities.

Net interest income included interest accretion related to the fair valuation of acquired loans of $15.0 million during the nine months ended September 30, 2023, compared to interest accretion of $42.0 million for the same period in 2022.

Our net FTE interest margin ratio, a non-GAAP measure, increased 9 basis points for the nine months ended September 30, 2023, as compared to the same period in 2022. Exclusive of the impact of interest accretion on acquired loans, the net FTE interest margin ratio, increased 5 basis points to 3.11% during the nine months ended September 30, 2023, as compared to 3.06% for the same period in 2022.

The table below sets forth a summary of the changes in interest income and interest expense resulting from estimated changes in average asset and liability balances (volume) and estimated changes in average interest rates (referred to as “rate”) for the three and the nine month periods ended September 30, 2023 and 2022. Changes which are not due solely to volume or rate have been allocated to these categories based on the respective percent changes in average volume and average rate as they compare to each other.    

Analysis of Interest Changes Due to Volume and Rates
(Dollars in millions)	Three Months Ended September 30, 2023 compared with Three Months Ended September 30, 2022						Nine Months Ended September 30, 2023 compared with Nine Months Ended September 30, 2022
	Volume		Rate		Net		Volume		Rate		Net
Interest earning assets:
Loans (1)	$	9.7	$	21.6	$	31.3	$	65.1	$	100.1	$	165.2
Investment securities (1)	(10.7)		11.7		1.0		(4.5)		64.5		60.0
Investment in FHLB and FRB stock	0.9		0.7		1.6		3.0		3.5		6.5
Interest bearing deposits in banks	(0.2)		1.8		1.6		(5.3)		11.4		6.1
Total change	(0.3)		35.8		35.5		58.3		179.5		237.8
Interest bearing liabilities:
Demand deposits	(1.0)		9.2		8.2		(1.1)		25.2		24.1
Savings deposits	(0.7)		27.3		26.6		(0.9)		76.0		75.1
Time deposits	1.1		19.6		20.7		2.1		40.8		42.9
Repurchase agreements	(0.2)		1.1		0.9		(0.2)		3.1		2.9
Other borrowed funds	13.1		18.1		31.2		48.7		53.0		101.7
Long-term debt	—		—		—		(0.1)		(0.1)		(0.2)
Subordinated debentures held by subsidiary trusts	—		1.4		1.4		0.2		4.8		5.0
Total change	12.3		76.7		89.0		48.7		202.8		251.5
Increase in FTE net interest income (1)	$	(12.6)	$	(40.9)	$	(53.5)	$	9.6	$	(23.3)	$	(13.7)

(1)Interest income and average rates for tax exempt loans and securities are presented on a FTE basis.

(Reduction of) provision for Credit Losses

The Company had a $0.1 million reduction of credit losses, which included a provision for credit losses of $3.2 million on loans held for investment, reduction of credit losses for unfunded commitments of $2.0 million, and a reduction of credit losses for investment securities of $1.3 million during the three months ended September 30, 2023, as compared to an $8.4 million provision for credit losses during same period in 2022. The provision incorporated the impact of net charge-offs of $1.1 million, or an annualized 0.02% of average loans outstanding, for the third quarter of 2023, compared to $12.0 million, or an annualized 0.27% of average loans outstanding during the same period in 2022. Net loan charge-offs in the third quarter of 2023 were composed of charge-offs of $6.2 million and recoveries of $5.1 million.

The provision during the nine months ended September 30, 2023 of $26.8 million included a provision for credit losses on loans held for investment of $25.3 million, provision for credit losses on unfunded commitments of $2.6 million, and a provision reduction of credit losses for investment securities of $1.1 million. This compares to a provision for credit losses of $68.0 million which included a provision for credit losses on loans held for investment of $60.2 million that included the CECL day-2 impact from the Great Western acquisition, provision for credit losses on unfunded commitments of $5.9 million, and a provision for credit losses on held-to-maturity investment securities of $1.9 million during the same period in 2022.

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For information regarding our non-performing loans, see “Financial Condition – Non-Performing Assets” included herein. For more information on our allowance for credit losses, see “Financial Condition – Allowance for Credit Losses” included herein.             

Non-Interest Income

Non-interest income also contributes to our operating results with fee-based revenues such as payment services, mortgage banking and wealth management revenues, service charges on deposit accounts and other service charges, commissions and fees being our principal source of non-interest income. The following table presents the composition of our non-interest income as of the periods indicated:

Non-Interest Income	Three Months Ended September 30,				$ Change		% Change		Nine Months Ended September 30,				$ Change		% Change
(Dollars in millions)	2023		2022						2023		2022
Payment services revenues	$	19.2	$	20.4	$	(1.2)	(5.9)	%	$	58.0	$	54.7	$	3.3	6.0	%
Mortgage banking revenues	2.0		2.7		(0.7)		(25.9)		6.9		16.1		(9.2)		(57.1)
Wealth management revenues	8.7		8.5		0.2		2.4		26.5		25.9		0.6		2.3
Service charges on deposit accounts	6.0		5.7		0.3		5.3		17.0		19.7		(2.7)		(13.7)
Other service charges, commissions and fees	2.2		4.7		(2.5)		(53.2)		7.0		12.6		(5.6)		(44.4)
Investment securities losses, net	—		(24.2)		24.2		(100.0)		(23.5)		(24.4)		0.9		(3.7)
Other income	3.9		5.1		$	(1.2)	(23.5)		10.6		17.0		(6.4)		(37.6)
Total non-interest income	$	42.0	$	22.9	$	19.1	83.4	%	$	102.5	$	121.6	$	(19.1)	(15.7)	%

Total non-interest income increased $19.1 million for the three months ended September 30, 2023, as compared to the same period in 2022 and decreased $19.1 million for the nine months ended September 30, 2023, as compared to the same period in 2022. Significant components of this fluctuation are discussed below.

 Payment services revenues consist of interchange fees that merchants pay for processing electronic payment transactions and ATM service fees. Payment services revenues decreased $1.2 million during the three months ended September 30, 2023 and increased $3.3 million during the nine months ended September 30, 2023, as compared to the same periods in 2022. The increase during the nine months ended September 30, 2023 reflects higher credit and debit card volume in addition to an additional month of revenues related to the acquisition of GWB on February 1, 2022.

Mortgage banking revenues include gains on residential real estate loans sold, net mortgage servicing revenues and direct costs related to loans sold (including amortization, mortgage servicing rights impairment and recoveries and other expenses), and origination and processing fees on residential real estate loans held for sale. Mortgage banking revenues decreased $0.7 million during the three months ended September 30, 2023 compared to the same period in 2022. For the nine months ended September 30, 2023, mortgage banking revenues decreased $9.2 million compared to the same period in 2022. Included in the nine months ended September 30, 2022 was a $3.4 million recovery of mortgage servicing rights impairment. Excluding the 2022 impairment recovery, mortgage banking revenues decreased $5.8 million during the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022. The decrease in mortgage banking revenues was driven by a decline in home loan production volume, largely as a result of higher interest rates during the nine months ended September 30, 2023, and tighter gain-on-sale spreads.

Service charges on deposit accounts are primarily driven by service fees and overdraft charges on deposit accounts. Service charges on deposit accounts increased $0.3 million during the three months ended September 30, 2023 compared to the same period in 2022. For the nine months ended September 30, 2023, service charges on deposit accounts decreased $2.7 million, as compared to the same period in 2022, primarily due to the company’s discontinuance of assessing non-sufficient fund fees and a reduction of overdraft fees on April 1, 2022 for the legacy footprint and as of May 23, 2022 for the acquired GWB footprint.

Other service charges, commissions, and fees primarily include fees earned on certain derivative interest rate contracts, insurance commissions, and safe deposit boxes. Other service charges, commissions, and fees decreased $2.5 million during the three months ended September 30, 2023 compared to the same period in 2022. For the nine months ended September 30, 2023, other service charges, commissions and fees decreased $5.6 million as compared to the same period in 2022. The decreases during the three and the nine months ended September 30, 2023 were primarily the result of decreased swap fee revenues earned on derivative interest rate swap contracts offered to clients.

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Investment securities losses, net includes realized gains and losses associated with the sales of investment securities. Investment securities losses, net was zero during the three months ended September 30, 2023 compared to a net loss of $24.2 million in the same period in 2022. The 2022 period included the loss of $46.3 million incurred on the sale of $500 million in U.S. treasury notes previously swapped. The loss incurred on the sale was offset by the recognition of a deferred swap termination gain of $22.1 million. During the nine months ended September 30, 2023, investment securities losses, net increased $0.9 million as compared to the same period in 2022 due to the disposition of $853.0 million in carrying value of available-for-sale investment securities during the first quarter of 2023 compared to the aforementioned loss in 2022.

Other income primarily includes company-owned life insurance revenues, check printing income, agency stock dividends, and gains on sales of miscellaneous assets. Other income decreased $1.2 million during the three months ended September 30, 2023 compared to the same period in 2022, primarily due to a loss on the sale of loans held for sale during the three months ended September 30, 2023. Other income decreased $6.4 million during the nine months ended September 30, 2023, as compared to the same period in 2022, primarily due a decrease in the credit valuation discount on derivatives acquired in the GWB acquisition, gain on the disposition of the GWB acquired subordinated debt, and gains on the sale of premises and equipment during the nine months ended September 30, 2022 compared to an increase in life insurance proceeds offset by a loss on the sale of loans held for sale during the nine months ended September 30, 2023.

Non-Interest Expense

Non-interest expense decreased $12.1 million during the three months ended September 30, 2023 compared to the same period in 2022. The decrease was primarily the result of a decrease in incentive compensation accrued during the three months ended September 30, 2023 and a decrease in acquisition expenses related to the GWB acquisition incurred during the three months ended September 30, 2022.

Non-interest expense decreased $99.9 million during the nine months ended September 30, 2023 as compared to the same period in 2022. The decrease was the result of lower incentive compensation accruals and a decrease in acquisition expenses related to the GWB acquisition incurred during the nine months ended September 30, 2022, partially offset by increased expenses in 2023 as a result of three full quarters of combined operations, post-GWB acquisition. Expenses related to acquisitions include legal fees, consulting fees, investment banking fees, conversion and contract termination costs, and retention and severance compensation costs. Other significant components of non-interest expense are discussed below. For additional information regarding acquisitions, see “Note 2 – Acquisitions” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report.

The following table presents the composition of our non-interest expense as of the periods indicated:

Non-Interest Expense	Three Months Ended September 30,				$ Change		% Change		Nine Months Ended September 30,				$ Change		% Change
(Dollars in millions)	2023		2022						2023		2022
Salaries and wages	$	65.4	$	71.9	$	(6.5)	(9.0)	%	$	199.1	$	206.7	$	(7.6)	(3.7)	%
Employee benefits	19.7		19.6		0.1		0.5		61.8		60.2		1.6		2.7
Outsourced technology services	14.5		15.9		(1.4)		(8.8)		44.5		40.0		4.5		11.3
Occupancy, net	11.7		11.3		0.4		3.5		35.9		32.5		3.4		10.5
Furniture and equipment	5.3		5.8		(0.5)		(8.6)		16.8		17.0		(0.2)		(1.2)
OREO expense, net of income	0.5		—		0.5		NM		1.3		0.1		1.2		NM
Professional fees	5.1		5.1		—		—		14.9		14.5		0.4		2.8
FDIC insurance premiums	5.0		4.1		0.9		22.0		15.4		10.2		5.2		51.0
Other intangibles amortization	3.9		4.1		(0.2)		(4.9)		11.8		11.8		—		—
Other expenses	30.0		31.4		(1.4)		(4.5)		89.3		82.7		6.6		8.0
Acquisition related expenses	—		4.0		(4.0)		(100.0)		—		115.0		(115.0)		NM
Total non-interest expense	$	161.1	$	173.2	$	(12.1)	(7.0)	%	$	490.8	$	590.7	$	(99.9)	(16.9)	%

The increases in employee benefits, outsourced technology services, and occupancy, net, during the nine-month period ended September 30, 2023, as compared to the same period in 2022, are primarily due to having a full first quarter 2023 of expenses from additional costs resulting from the GWB acquisition.

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Salaries and wages expense decreased $6.5 million during the three months ended September 30, 2023, as compared to the same period in 2022. Salaries and wages decreased $7.6 million during the nine months ended September 30, 2023 as compared to the same period in 2022. The decreases during the three and the nine months ended September 30, 2023 are the result of lower mortgage loan originator commissions and lower levels of incentive accruals during the 2023 periods as compared to 2022, partially offset by inflationary wage pressure and severance costs primarily related to permanent staffing reductions within the mortgage group during the second quarter of 2023.

FDIC insurance premiums increased $0.9 million during the three months ended September 30, 2023 compared to the same period in 2022 and increased $5.2 million during the nine months ended September 30, 2023, as compared to the same period in 2022, primarily attributable to the incremental two basis point assessment fee imposed by the FDIC which began in the first quarter of 2023. The Company is expecting additional FDIC expenses related to the Notice of Proposed Rulemaking by the FDIC in May 2023. To recover the cost associated with protecting uninsured depositors during the recent bank failures, the proposal would implement a 12.5 basis point annual special assessment on uninsured deposits reported in bank’s call reports as of December 31, 2022, excluding the first $5.0 billion of uninsured deposits. The FDIC is proposing to collect the special assessment for an estimated eight consecutive quarters beginning with the first quarter 2024. A final rule is not expected until later in 2023 after a public comment period and the FDIC's final deliberations have concluded. As proposed, the estimated impact of the special assessment is approximately $9.8 million, which is expected to be recognized upon the rule's final issuance. The ultimate impact and timing of recognition will depend on the final outcome of the ongoing FDIC deliberations.

Other expenses primarily include advertising and public relations costs; office supply, postage, freight, telephone, and travel expenses; donations expense; debit and credit card expenses; board of director fees; legal expenses; and other losses. Other expenses decreased $1.4 million during the three months ended September 30, 2023 compared to the same period in 2022, primarily due to an increase in credit card rewards. Other expenses increased $6.6 million during the nine months ended September 30, 2023, as compared to the same period in 2022, mainly attributable to swap servicing fees, sales and use taxes, credit and debit card processing, credit card rewards, and increases in fraud losses.

Income Tax Expense

Our effective tax rate was 23.2% for the three months ended September 30, 2023 compared to 20.7% for the three months ended September 30, 2022 and 23.4% for the nine months ended September 30, 2023 compared to 20.9% for the same period in 2022.

Financial Condition        

Total Assets

Total assets decreased $1,747.0 million, or 5.4%, to $30,540.8 million as of September 30, 2023, from $32,287.8 million as of December 31, 2022, primarily due to a decrease in cash and cash equivalents and investment securities as a result of a decline in deposits and securities sold under repurchase agreements, partially offset by an increase in loans held for investment. Significant fluctuations in balance sheet accounts are discussed below. More information regarding the results as of December 31, 2022 can be found in our Annual Report on Form 10-K for the year ended December 31, 2022.

Investment Securities

We manage our investment portfolio primarily as a source of liquidity. In doing so, we seek to obtain the highest yield possible within our risk tolerance and liquidity guidelines, while satisfying the pledging requirements for deposits of state and political subdivisions and securities sold under repurchase agreements. Our portfolio principally comprises U.S. treasuries, U.S. government agency residential and commercial mortgage-backed securities and collateralized mortgage obligations, U.S. government agency, collateralized loan obligations, corporate securities, and tax-exempt securities. Federal funds sold and interest-bearing deposits in the Bank are additional investments that are classified as cash equivalents rather than as investment securities. Investment securities classified as available-for-sale are recorded at fair value, while investment securities classified as held-to-maturity are recorded at amortized cost. Unrealized gains or losses, net of the deferred tax effect, on available-for-sale securities are reported as increases or decreases in accumulated other comprehensive income or loss, a component of stockholders’ equity.

Investment securities decreased $1,510.7 million, or 14.5%, to $8,887.2 million, or 29.1% of total assets, as of September 30, 2023, from $10,397.9 million, or 32.2% of total assets, as of December 31, 2022. The decrease was the result of the disposition of $853.0 million of investment securities during the first quarter of 2023, normal amortization of the portfolio that was used to pay down short-term borrowings, and declines in fair market values during the period. There have been no new purchases during the nine months ended September 30, 2023.

As of September 30, 2023 and December 31, 2022, the estimated duration of our investment portfolio was 3.7 years.

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As of September 30, 2023 and December 31, 2022, we had $8,317.5 million and $2,620.8 million, respectively, of investment securities that had been in a continuous loss position for more than twelve months. At September 30, 2023 and December 31, 2022, the Company had no allowance for credit losses on available-for-sale securities and an allowance for credit losses on held-to maturity securities classified as corporate and municipal securities of $0.8 million and $1.9 million, respectively.

Loans Held for Investment, Net of Deferred Fees and Costs

Loans held for investment, net of deferred fees and costs, increased $114.1 million as of September 30, 2023 as compared to December 31, 2022.

The following table presents the composition and comparison of loans held for investment for the periods indicated:

	September 30, 2023		December 31, 2022		$ Change		% Change
Real estate:
Commercial	$	8,766.2	$	8,528.6	$	237.6	2.8	%
Construction	1,930.3		1,944.4		(14.1)		(0.7)
Residential	2,212.2		2,188.3		23.9		1.1
Agricultural	731.5		794.9		(63.4)		(8.0)
Total real estate	13,640.2		13,456.2		184.0		1.4
Consumer:
Indirect	751.7		829.7		(78.0)		(9.4)
Direct and advance lines	142.3		152.9		(10.6)		(6.9)
Credit card	71.6		75.9		(4.3)		(5.7)
Total consumer	965.6		1,058.5		(92.9)		(8.8)
Commercial	2,925.1		2,882.6		42.5		1.5
Agricultural	690.5		708.3		(17.8)		(2.5)
Other, including overdrafts	5.0		9.2		(4.2)		(45.7)
Deferred loan fees and costs	(13.1)		(15.6)		2.5		(16.0)
Loans held for investment, net of deferred loan fees and costs	$	18,213.3	$	18,099.2	$	114.1	0.6	%

Non-Performing Assets

Non-performing assets include non-performing loans and OREO.

Non-Performing Loans. Non-performing loans include non-accrual loans and loans contractually past due 90 days or more and still accruing interest.

Non-accrual loans. We generally place loans on non-accrual status when they become 90 days past due unless they are well secured and in the process of collection. When a loan is placed on non-accrual status, any interest previously accrued but not collected is reversed from income. Non-accrual loans increased approximately $22.2 million, or 37.5%, to $81.4 million, as of September 30, 2023, from $59.2 million as of December 31, 2022, primarily due to construction and commercial real estate loans. As of September 30, 2023 there were approximately $37.4 million of non-accrual loans for which there was no related allowance for credit losses, as these loans had sufficient collateral securing the loan for repayment.

Loans contractually past due 90 days or more and still accruing interest. Loans past due 90 days or more accruing interest were $3.2 million as of September 30, 2023, a decrease of $3.2 million, or 50.0%, from $6.4 million as of December 31, 2022.

Other Real Estate Owned (OREO). OREO consists of real property acquired through foreclosure on the collateral underlying defaulted loans. We initially record OREO at fair value less estimated selling costs. Any excess of loan carrying value over the fair value of the real estate acquired is recorded as a charge against the allowance for credit losses. Estimated losses that result from the ongoing periodic valuation of these properties are charged to earnings in the period in which they are identified. OREO decreased $1.1 million, or 8.7%, to $11.6 million as of September 30, 2023, from $12.7 million as of December 31, 2022 as a result of valuation adjustments to OREO properties.

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The following table sets forth information regarding non-performing assets as of the dates indicated:

Non-Performing Assets
(Dollars in millions)	September 30, 2023			December 31, 2022
Non-performing loans:
Non-accrual loans	$	81.4		$	59.2
Accruing loans past due 90 days or more	3.2			6.4
Total non-performing loans	84.6			65.6
OREO	11.6			12.7
Total non-performing assets	$	96.2		$	78.3
Non-accrual loans to loans held for investment	0.45		%	0.33		%
Non-performing loans to loans held for investment	0.46			0.36
Non-performing assets to loans held for investment and OREO	0.53			0.43
Non-performing assets to total assets	0.31			0.24

The following table sets forth the allocation of our non-performing loans among our various loan categories as of the dates indicated.

Non-Performing Loans by Loan Type
(Dollars in millions)	September 30, 2023		Percent of Total		December 31, 2022		Percent of Total
Real estate:
Commercial	$	31.0	36.6	%	$	20.7	31.5	%
Construction	17.9		21.2		4.3		6.6
Residential	10.5		12.4		7.6		11.6
Agricultural	5.4		6.4		7.6		11.6
Total real estate	64.8		76.6		40.2		61.3
Consumer	4.1		4.8		4.3		6.6
Commercial	12.5		14.8		12.3		18.7
Agricultural	3.2		3.8		8.8		13.4
Total non-performing loans	$	84.6	100.0	%	$	65.6	100.0	%

Allowance for Credit Losses

The Company performs a quarterly assessment of the appropriateness of its allowance for credit losses in accordance with GAAP. The allowance for credit losses is established through a provision for credit losses based on our evaluation of quantitative and qualitative risk factors in our loan portfolio at each balance sheet date. In determining the allowance for credit losses, we estimate losses on specific loans, or groups of loans, where the expected loss can be identified and reasonably determined over the life of the loans. The balance of the allowance for credit losses is based on internally assigned risk classifications of loans, historical loan loss rates, changes in the nature or tenure of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends, current environmental and economic factors, and the estimated impact of forecasted economic conditions on historical loan loss rates.    

The allowance for credit losses is increased by provisions charged against earnings and net recoveries of charged-off loans and is reduced by negative provisions credited to earnings and net loan charge-offs. The allowance for credit losses consists of three elements:    

(1)Specific valuation allowances associated with collateral-dependent and other individually evaluated loans. Specific valuation allowances are determined based on assessment of the fair value of the collateral underlying the loans as determined through independent appraisals, the present value of future cash flows, observable market prices, and any relevant qualitative or environmental factors impacting loans.

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(2)Collective valuation allowances based on loan loss experience and future expectations for similar loans with similar characteristics and trends. The Company applies open pool methodologies for all portfolio segments. The open pool methodology averages quarterly loss rates by modeling segment, calculated as quarter-to-date net charge off balance divided by the end of period balance. Loss rates are recalculated quarterly with recoveries captured in the quarter a loan was charged off, are averaged across a look back period from 2009 to the current period, and are annualized. Macroeconomic-conditioned historical loss rates are applied to loan-level cash flows. Expected future principal and interest cash flows are calculated using contractual repayment terms and prepayment, utilization, interest rate, and probability of default assumptions. Macroeconomic sensitivity models calculate segment-specific multipliers using third party forecast data. The multipliers condition the annual loss rates over the 2-year forecast period, followed by a 1-year straight-line reversion to the unadjusted historical average loss rates. The unadjusted loss rates then apply for the remaining life of the loan. Estimated losses are totaled and aggregated to the segment level.

(3)General valuation allowances determined based on asset quality trends, industry concentrations, environmental risks, changes in portfolio composition, and other qualitative risk factors, both internal and external to the Company. Other qualitative factors, including changes in loan and lending policies, collateral quality, underwriting standards and personnel, credit review quality, and model imprecision, are also considered.     

Based on the assessment of the appropriateness of the allowance for credit losses, the Company records provisions for credit losses to maintain the allowance for credit losses at appropriate levels.

Loans acquired in business combinations are initially recorded at fair value as adjusted for credit risk and an allowance for credit losses at the date of acquisition. For loans with no significant evidence of credit deterioration since origination, the difference between the fair value and the unpaid principal balance of the loan at the acquisition date is amortized into interest income using the effective interest method over the remaining period to contractual maturity. An allowance for credit loss is recorded for the expected credit losses over the life of the loan. Subsequent changes to the allowance for credit losses are recorded through provision expense using the same methodology as other loans held for investment.

For loans acquired in business combinations with evidence of deterioration in credit quality since origination, the Company determines the fair value of the loans by estimating the amount and timing of principal and interest cash flows initially expected to be collected on the loans and discounting those cash flows at an appropriate market rate of interest. An allowance for credit losses is recognized by estimating the expected credit losses of the purchased asset and recording an adjustment to the acquisition date fair value to establish the initial amortized cost basis of the asset. Differences between the established amortized cost basis, and the unpaid principal balance of the asset, is considered to be a non-credit discount/premium and is accreted/amortized into interest income using the level yield interest method. Subsequent changes to the allowance for credit losses are recorded through provision expense using the same methodology as other loans held for investment.

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. Generally, loans are charged-off when (1) there has been no material principal reduction within the previous 90 days and there is no pending sale of collateral or other assets, (2) there is no significant or pending event which will result in principal reduction within the upcoming 90 days, (3) it is clear that we will not be able to collect all or a portion of the loan, (4) payments on the loan are sporadic, will result in an excessive amortization, or are not consistent with the collateral held, or (5) foreclosure or repossession actions are pending. Loan charge-offs do not directly correspond with the receipt of independent appraisals or the use of observable market data if the collateral value is determined to be sufficient to repay the principal balance of the loan.

If a collateral-dependent loan is adequately collateralized, a specific valuation allowance for credit losses is not recorded. As such, significant changes in collateral-dependent and non-performing loans do not necessarily correspond proportionally with changes in the specific valuation component of the allowance for credit losses. Additionally, the Company expects the timing of charge-offs will vary between quarters and will not necessarily correspond proportionally to changes in the allowance for credit losses or changes in non-performing or collateral-dependent loans due to timing differences among the initial identification of a collateral-dependent loan, recording of a specific valuation allowance for collateral-dependent loans, and any resulting charge-off of uncollectible principal.

Our allowance for credit losses was $226.7 million, or 1.24% of loans held for investment as of September 30, 2023 compared to $220.1 million, or 1.22% of loans held for investment, as of December 31, 2022. The increase in the percentage from December 31, 2022 is primarily a result of loan growth and credit migration. The Company’s allowance for off-balance sheet credit losses was $18.8 million as of September 30, 2023, compared to $16.2 million as of December 31, 2022.

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Although we have established our allowance for credit losses in accordance with GAAP in the United States and we believe that the allowance for credit losses is appropriate to provide for known and expected losses in the portfolio at all times, future provisions will be subject to on-going evaluations of the risks in the loan portfolio. If the economy declines or asset quality deteriorates, material additional provisions could be required.

The following table sets forth information regarding our allowance for credit losses as of and for the periods indicated:

Allowance for Credit Losses	Three Months Ended
(Dollars in millions)	Sep 30, 2023			Jun 30, 2023			Mar 31, 2023			Dec 31, 2022			Sep 30, 2022
Beginning balance	$	224.6		$	226.1		$	220.1		$	213.0		$	220.4
Provision for credit losses	3.2			9.9			12.2			8.2			4.6
Charge offs:
Real estate
Commercial	1.7			0.3			4.3			0.8			5.8
Construction	—			9.7			—			(0.1)			6.6
Residential	0.1			—			0.5			0.1			0.1
Consumer	3.7			3.3			3.4			2.6			2.9
Commercial	0.7			0.8			0.7			1.8			0.8
Total charge-offs	6.2			14.1			8.9			5.2			16.2
Recoveries:
Real estate
Commercial	3.4			0.6			0.1			0.5			1.8
Construction	—			—			—			0.2			0.1
Residential	0.1			—			—			0.1			0.1
Agricultural	—			0.2			0.1			0.3			—
Consumer	1.1			1.4			1.2			1.0			1.2
Commercial	0.5			0.4			1.0			0.4			1.0
Agricultural	—			0.1			0.3			1.6			—
Total recoveries	5.1			2.7			2.7			4.1			4.2
Net charge-offs	1.1			11.4			6.2			1.1			12.0
Ending balance	$	226.7		$	224.6		$	226.1		$	220.1		$	213.0
Allowance for off-balance sheet credit losses:
Beginning balance	$	20.8		$	17.8		$	16.2		$	9.7		$	6.2
(Reversal of) provision for credit losses	(2.0)			3.0			1.6			6.5			3.5
Ending balance	$	18.8		$	20.8		$	17.8		$	16.2		$	9.7
Allowance for credit losses on investment securities:
Beginning balance	$	2.1		$	3.3		$	1.9		$	1.9		$	1.6
(Reversal of) provision for investment securities	(1.3)			(1.2)			1.4			—			0.3
Ending balance	$	0.8		$	2.1		$	3.3		$	1.9		$	1.9
Total allowance for credit losses	$	246.3		$	247.5		$	247.2		$	238.2		$	224.6
Total (reversal of) provision for credit losses	(0.1)			11.7			15.2			14.7			8.4
Loans held for investment	18,213.3			18,263.4			18,245.7			18,099.2			17,603.5
Average loans	18,317.4			18,351.5			18,273.6			17,920.5			17,543.8
Net loans charged-off to average loans, annualized	0.02		%	0.25		%	0.14		%	0.02		%	0.27		%
Allowance to non-accrual loans	278.50			260.86			279.83			371.79			268.26
Allowance to loans held for investment	1.24			1.23			1.24			1.22			1.21

Total Liabilities

Total liabilities decreased $1,758.7 million, or 6.0%, to $27,455.3 million as of September 30, 2023, from $29,214.0 million as of December 31, 2022, primarily due to decreases in deposits, securities sold under repurchase agreements, and other borrowed funds, partially offset by an increase in accrued interest payable. Significant fluctuations in liability accounts are discussed below.

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Deposits

Our deposits consist of non-interest-bearing and interest-bearing demand, savings, individual retirement, and time deposit accounts. Total deposits decreased $1,394.1 million, or 5.6%, to $23,679.5 million as of September 30, 2023, from $25,073.6 million as of December 31, 2022, primarily due to a decrease in business-related non-interest-bearing balances and interest-bearing demand and savings deposits, partially offset by increases in time deposits.

The following table summarizes our deposits as of the dates indicated:

Deposits
(Dollars in millions)	September 30, 2023		Percent of Total		December 31, 2022		Percent of Total
Non-interest-bearing demand	$	6,402.6	27.0	%	$	7,560.0	30.2	%
Interest bearing:
Demand	6,317.9		26.7		7,205.9		28.7
Savings	7,796.3		32.9		8,379.3		33.4
Time, $250k and over	817.1		3.5		438.0		1.8
Time, other (1)	2,345.6		9.9		1,490.4		5.9
Total interest-bearing	17,276.9		73.0		17,513.6		69.8
Total deposits	$	23,679.5	100.0	%	$	25,073.6	100.0	%

(1)Included in “Time, other” are Certificate of Deposit Account Registry Service, or CDARS, deposits of $50.9 million and $36.6 million as of September 30, 2023 and December 31, 2022, respectively.

Deposit Insurance

The deposits of the Bank are insured up to the applicable limits by the Deposit Insurance Fund (“DIF”) of the FDIC, generally up to $250,000 per insured depositor. The Bank pays deposit insurance premiums based on assessment rates established by the FDIC. The estimated amount of deposits in excess of the FDIC insurance limit at September 30, 2023 was $7.9 billion, or 33.2% of total deposits. Estimates of uninsured deposits are based on the methodologies and assumptions used in the Bank’s call reports and do not necessarily reflect an evaluation of all scenarios that potentially would determine the availability of deposit insurance to customer accounts based on FDIC regulations.

Securities Sold Under Repurchase Agreements

In addition to deposits, repurchase agreements with commercial depositors, which include municipalities, provide an additional source of funds. Under repurchase agreements, deposit balances are invested in short-term U.S. government agency securities overnight and are then repurchased the following day. All outstanding repurchase agreements are due in one day and balances fluctuate in the normal course of our client’s business. Securities sold under repurchase agreement balances decreased $163.4 million, or 15.5%, to $889.5 million as of September 30, 2023, from $1,052.9 million as of December 31, 2022.

Other Borrowed Funds

Other borrowed funds decreased $260.0 million as of September 30, 2023 compared to December 31, 2022, primarily due to the repayment of advances by the Company resulting in the Company’s lower outstanding borrowings with the FHLB during 2023.

Capital Resources and Liquidity Management

Capital Resources. Stockholders’ equity is influenced primarily by earnings, dividends, sales and redemptions of common stock, and changes in the unrealized holding gains or losses, net of taxes, on available-for-sale investment securities. Stockholders’ equity increased $11.7 million, or 0.4%, to $3,085.5 million as of September 30, 2023, from $3,073.8 million as of December 31, 2022, due to the retention of earnings, which was partially offset by a modest increase to the unrealized losses on available-for-sale securities through other comprehensive income, by stock repurchases of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants, and by cash dividends paid.

On October 24, 2023, the Company’s board of directors declared a dividend of $0.47 per common share, payable on November 16, 2023, to common stockholders of record as of November 6, 2023. The dividend equates to a 7.2% annual yield based on the $26.10 average closing pricing of the Company’s common stock during the third quarter of 2023.

64

As a bank holding company, the Company must comply with the capital requirements established by the Federal Reserve, and our subsidiary Bank must comply with the capital requirements established by the FDIC. The current risk-based guidelines applicable to us and our Bank are based on the Basel III framework, as implemented by the federal bank regulators. As of September 30, 2023 and December 31, 2022, the Company had capital levels that, in all cases, exceeded the guidelines to be deemed “well-capitalized.” For additional information regarding our capital levels, see “Note – Regulatory Capital” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report.

Liquidity. Liquidity measures our ability to meet current and future cash flow needs on a timely basis and at a reasonable cost. We manage our liquidity position to meet the daily cash flow needs of clients, while maintaining an appropriate balance between assets and liabilities to meet the return-on-investment objectives of our shareholders. Our liquidity position is supported by management of liquid assets and liabilities and access to alternative sources of funds. Liquid assets include cash, interest-bearing deposits in banks, federal funds sold, available-for-sale investment securities, and maturing or prepaying balances in our held-to-maturity investment and loan portfolios. Liquid liabilities include core deposits, federal funds purchased, securities sold under repurchase agreements, and borrowings. Other sources of liquidity include the sale of loans, the ability to acquire additional national market funds through non-core deposits, the issuance of additional collateralized borrowings such as FHLB advances, the issuance of debt securities, additional borrowings through the Federal Reserve’s discount window, Federal Reserve’s Bank Term Funding Program (“BTFP”), and the issuance of preferred or common securities. Our short-term and long-term liquidity requirements are primarily to fund on-going operations, including payment of interest on deposits and debt, extensions of credit to borrowers, capital expenditures, and shareholder dividends. These liquidity requirements are met primarily through cash flow from operations, redeployment of prepaying and maturing balances in our loan and investment portfolios, the issuance of securities, borrowings and other debt financing, and increases in client deposits.

For the nine months ended September 30, 2023, net cash provided by operating activities was $358.7 million, net cash provided by investing activities was $1,329.7 million and net cash used in financing activities was $1,965.8 million. Major uses of cash were $1,394.1 million in outflows of deposits, $260.0 million in repayment of other borrowed funds, and the extension of credit to clients of $128.7 million. A major source of cash included $1,276.3 million in repayment of loans at maturity, exercise of call options, principal pay downs, and sales of available-for-sale securities. Total cash and cash equivalents were $593.1 million as of September 30, 2023, compared to $870.5 million as of December 31, 2022 and $591.9 million as of September 30, 2022. For additional information regarding our operating, investing, and financing cash flows, see the unaudited “Consolidated Statements of Cash Flows,” included in Part I, Item 1. For additional information regarding our deposits, see “Financial Condition – Deposits,” include in Part I, Item 2.

As a holding company, we are a corporation separate and apart from our subsidiary Bank and, therefore, we provide for our own liquidity. Our primary sources of funding include management fees and dividends declared and paid by the Bank and access to capital markets. There are statutory, regulatory, and debt covenant limitations that affect the ability of our Bank to pay dividends to us. Management believes that such limitations will not impact our ability to meet our ongoing short-term cash obligations.    

The Company continuously monitors our liquidity position and adjustments are made to the balance between sources and uses of funds as deemed appropriate. We are not aware of any events that are reasonably likely to have a material adverse effect on our liquidity, capital resources, or operations. In addition, we are not aware of any regulatory recommendations regarding liquidity, which if implemented, would have a material adverse effect on us. The Bank satisfies incremental liquidity needs with either liquid assets or external funding sources. Available liquidity includes cash, FHLB advances and Federal Reserve Bank (FRB) borrowings, through either the discount window or the newly established BTFP. The Bank has pledged its investment securities portfolio to access wholesale funding as needed and does not intend to sell or restructure securities at this time.

Through the Bank’s relationship with the FHLB, the Bank owns $93.3 million of FHLB stock and has access to additional liquidity and funding sources through FHLB advances. The Bank’s borrowing capacity is dependent upon the amount of collateral the Bank places at the FHLB. As of September 30, 2023, the Bank had no short-term advances outstanding at FHLB and $2,067.0 million in outstanding FHLB borrowings consisting of fixed rate borrowings with tenors of up to five months. The Bank’s remaining borrowing capacity with the FHLB was $4,764.4 million as of September 30, 2023.

The Bank had no short-term borrowings outstanding with the Federal Reserve Bank's BTFP as of September 30, 2023. As of September 30, 2023, the Bank’s remaining borrowing capacity with the BTFP was $2.5 billion and its remaining borrowing capacity at the Federal Reserve Discount Window was $0.7 billion.

In addition to borrowing capacity with the FHLB and at the Federal Reserve Discount Window as described above, the Bank had additional liquidity of $2.5 billion available via cash, unpledged bond collateral, and the federal funds market as of September 30, 2023.

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Recent Accounting Pronouncements    

See “Note – Recent Authoritative Accounting Guidance” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report for details of recently issued accounting pronouncements and their expected impact on our financial statements.    

Non-GAAP Reconciliation

	Three Months Ended						Nine Months Ended
(Dollars in millions)	September 30, 2023			September 30, 2022			September 30, 2023			September 30, 2022
Net interest income	$	213.7		$	266.8		$	671.0		$	684.2
Add tax exempt securities	0.1			0.2			0.5			0.8
Add tax exempt loans	1.6			1.9			4.8			5.0
Net FTE interest income (non-GAAP)	215.4			268.9			676.3			690.0
Less purchase accounting accretion (non-GAAP)	5.2			17.7			15.0			42.0
Adjusted net FTE interest income (non-GAAP)	$	210.2		$	251.2		$	661.3		$	648.0
Total interest-earning assets	$	27,796.8		$	28,731.2		$	28,390.4		$	28,205.6
Net interest margin	3.05		%	3.68		%	3.16		%	3.24		%
Net FTE interest margin (non-GAAP)	3.07		%	3.71		%	3.18		%	3.27		%
Adjusted net FTE interest margin (non-GAAP)	3.00		%	3.47		%	3.11		%	3.06		%

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Item 3.

QUANTITATIVE AND QUALITATIVE DISCLOSURES

ABOUT MARKET RISK

Based on the changes in interest rates and the composition of the Company’s balance sheet subsequent to December 31, 2022, the following update of the Company’s assessment of market risk as of September 30, 2023 is being provided. These updates and changes should be read in conjunction with the additional quantitative and qualitative disclosures in our Annual Report on Form 10-K for the year ended December 31, 2022.

As of September 30, 2023, our income simulation model predicted net interest income would decrease by 3.28% on an immediate upward 100 basis point parallel shock over the following twelve months, assuming a static balance sheet, which was lower than the previous increase of 0.17% as of December 31, 2022, and increase 5.22% on an immediate downward 100 basis point parallel shock. Assuming a 2.0% gradual reduction in interest rates during each of the next four consecutive quarters, net interest income would increase 5.81%.

Item 4.

CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

Our management is responsible for establishing and maintaining effective disclosure controls and procedures, as defined under Rules 13a-15(e) and 15d-15(e) of the Exchange Act. As of September 30, 2023, an evaluation was performed, under the supervision and with the participation of management, including the Chief Executive Officer and Chief Financial Officer, of the effectiveness of the design and operation of our disclosure controls and procedures. Based on that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures as of September 30, 2023 were effective in ensuring that information required to be disclosed in our reports filed or submitted under the Exchange Act is recorded, processed, summarized, and reported within the time periods required by the SEC’s rules and forms, and is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.

Changes in Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting for the quarter ended September 30, 2023 that have materially affected, or are reasonably likely to materially affect, such control.

Limitations on Controls and Procedures

The effectiveness of our disclosure controls and procedures and our internal control over financial reporting is subject to various inherent limitations, including cost limitations, judgments used in decision making, assumptions about the likelihood of future events, the soundness of our systems, the possibility of human error, and the risk of fraud. Moreover, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions and the risk that the degree of compliance with policies or procedures may deteriorate over time. Because of these limitations, any system of disclosure controls and procedures or internal control over financial reporting may not be successful in preventing all errors or fraud or in making all material information known in a timely manner to the appropriate levels of management.

PART II.

OTHER INFORMATION

Item 1.    Legal Proceedings

The Company is involved in various claims, legal actions, and complaints which arise in the ordinary course of business. In the Company’s opinion, all such matters are adequately covered by insurance, are without merit, or are of such kind, or involve such amounts, that unfavorable disposition would not have a material adverse effect on the financial condition or results of operations of the Company.

Item 1A.    Risk Factors

There have been no material changes in risk factors described in our Annual Report on Form 10-K for the year ended December 31, 2022 during the period covered by this quarterly report.

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Item 2.    Unregistered Sales of Equity Securities and Use of Proceeds

(a) There were no unregistered sales of equity securities during the three months ended September 30, 2023.

(b) Not applicable.

(c) The following table provides information with respect to purchases made of our common stock by or on behalf of us or any “affiliated purchasers” (as defined in Rule 10b-18(a)(3) under the Exchange Act), during the three months ended September 30, 2023. 

				Total Number of	Maximum Number
				Shares Purchased as Part	of Shares That May
	Total Number of	Average Price		of Publicly Announced	Yet Be Purchased Under
Period	Shares Purchased (1)	Paid Per Share		Plans or Programs	the Plans or Programs
July 1, 2023 to July 31, 2023	295	$	25.79	—	—
August 1, 2023 to August 31, 2023	19	28.30		—	—
Sept 1, 2023 to Sept 30, 2023	180	25.65		—	—
Total	494	$	25.84	—	—

(1)    Stock repurchases were redemptions of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants of the Company’s 2015 Equity Compensation Plan.

Item 3.    Defaults upon Senior Securities

None.

Item 4.    Mine Safety Disclosures

Not applicable.

Item 5.    Other Information

Information Required by Item 407(c)(3) of Regulation S-K. During the quarter ended September 30, 2023, none of the Company’s directors or executive officers adopted, modified or terminated any contract, instruction or written plan for the purchase or sale of Company securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any “non-Rule 10b5-1 trading arrangement.”

Item 6.    Exhibits

Exhibit Number		Description
10.1		Employment Agreement by and between Lorrie Asker, First Interstate BancSystem, Inc. and First Interstate Bank, effective August 24, 2023 (incorporated herein by reference to Exhibit 10.1 to the Company’s Current Report on Form 8-K, File No. 001-34653, filed on August 28, 2023).
31.1*		Certification by Chief Executive Officer pursuant to Rule 13a-14(a) and Rule 15d-14(a) under the Securities Exchange Act of 1934, as amended
31.2*		Certification by Chief Financial Officer pursuant to Rule 13a-14(a) and Rule 15d-14(a) under the Securities Exchange Act of 1934, as amended.
32**		18 U.S.C. Section 1350 Certifications.
101.INS*		Interactive Data File - The instance document does not appear in the interactive data file because its XBRL tags are embedded within the inline XBRL document.
101.SCH*		Inline XBRL Taxonomy Extension Schema Document
101.CAL*		Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF*		Inline XBRL Taxonomy Extension Definition Linkbase Document
101.LAB*		Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE*		Inline XBRL Taxonomy Extension Presentation Linkbase Document
104*		Cover Page Interactive Data File - The cover page XBRL tags are embedded within the inline XBRL document (included in Exhibit 101)
*	Filed herewith.
**	Furnished herewith.

68

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		FIRST INTERSTATE BANCSYSTEM, INC.
Date:	November 3, 2023	By:	/S/  KEVIN P. RILEY
			Kevin P. Riley President and Chief Executive Officer
Date:	November 3, 2023	By:	/S/  MARCY D. MUTCH
			Marcy D. Mutch Executive Vice President and Chief Financial Officer

69

EX-31.1

Exhibit 31.1

CERTIFICATION BY CHIEF EXECUTIVE OFFICER

PURSUANT TO RULE 13a-14(a) AND RULE 15d-14(a)

UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED

I, Kevin P. Riley, certify that :

1.I have reviewed this quarterly report on Form 10-Q of First Interstate BancSystem, Inc.

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a.designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b.designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes, in accordance with generally accepted accounting principles;

c.evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d.disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of registrant’s board of directors (or persons performing the equivalent functions);

a.all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b.any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

DATE: November 3, 2023

/s/ KEVIN P. RILEY

Kevin P. Riley

President and Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION BY CHIEF FINANCIAL OFFICER

PURSUANT TO RULE 13a-14(a) AND RULE 15d-14(a)

UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED

I, Marcy D. Mutch, certify that :

1.I have reviewed this quarterly report on Form 10-Q of First Interstate BancSystem, Inc;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a.designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b.designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes, in accordance with generally accepted accounting principles;

c.evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d.disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of registrant’s board of directors (or persons performing the equivalent functions);

a.all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b.any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

DATE: November 3, 2023

/s/ MARCY D. MUTCH

Marcy D. Mutch

Executive Vice President and Chief Financial Officer

EX-32

Exhibit 32

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350

The undersigned are the Chief Executive Officer and the Chief Financial Officer of First Interstate BancSystem, Inc. (the “Registrant”). This Certification is made pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. This Certification accompanies the Quarterly Report on Form 10-Q of the Registrant for the quarter ended September 30, 2023.

We certify that, based on our knowledge, such Quarterly Report on Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 and that the information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Registrant.

This Certification is executed as of November 3, 2023.

/s/ KEVIN P. RILEY

Kevin P. Riley

President and Chief Executive Officer

/s/ MARCY D. MUTCH

Marcy D. Mutch

Executive Vice President and Chief Financial Officer

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Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 31, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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	2023
Document Fiscal Period Focus	Q3
Entity Common Stock, Shares Outstanding		104,997,866

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Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets
Cash and due from banks	$ 371.5	$ 349.2
Interest bearing deposits in banks	219.5	521.2
Federal funds sold	2.1	0.1
Total cash and cash equivalents	593.1	870.5
Investment securities:
Available-for-sale, net of allowance for credit losses of $0 at September 30, 2023 and December 31, 2022 (amortized cost of $6,290.2 at September 30, 2023 and $7,573.5 at December 31, 2022)	5,627.7	6,946.1
Held-to-maturity, net of allowance for credit losses of $0.8 at September 30, 2023 and $1.9 at December 31, 2022 (estimated fair values of $2,796.1 at September 30, 2023 and $3,052.2 at December 31, 2022)	3,259.5	3,451.8
Total investment securities	8,887.2	10,397.9
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	189.5	198.6
Loans held for sale	59.1	79.9
Loans held for investment, net of deferred fees and costs	18,213.3	18,099.2
Allowance for credit losses	(226.7)	(220.1)
Net loans held for investment	17,986.6	17,879.1
Goodwill	1,100.9	1,100.9
Bank Owned Life Insurance	500.8	497.9
Premises and equipment, net of accumulated depreciation	446.3	444.7
Other intangibles, net of accumulated amortization	85.2	97.0
Accrued interest receivable	129.2	118.3
Mortgage servicing rights, net of accumulated amortization and impairment reserve	29.1	31.1
Real Estate Acquired Through Foreclosure	11.6	12.7
Deferred tax assets	215.3	210.5
Other assets	306.9	348.7
Total assets	30,540.8	32,287.8
Deposits:
Non-interest bearing	6,402.6	7,560.0
Interest bearing	17,276.9	17,513.6
Total deposits	23,679.5	25,073.6
Securities sold under repurchase agreements	889.5	1,052.9
Accounts payable and accrued expenses	452.9	445.9
Accrued interest payable	63.7	14.5
Long-term debt	120.8	120.8
Other Short-term Borrowings	2,067.0	2,327.0
Allowance for credit losses on off-balance sheet credit exposures	18.8	16.2
Subordinated debentures held by subsidiary trusts	163.1	163.1
Total liabilities	27,455.3	29,214.0
Stockholders’ equity:
Preferred stock, no par value; 100,000 shares authorized; none issued and outstanding	0.0	0.0
Common stock and additional paid-in-capital, $0.00001 par value; 150,000,000 shares authorized; 105,011,371 and 104,442,023 shares were issued and outstanding at September 30, 2023 and December 31, 2022	2,484.9	2,478.2
Retained earnings	1,122.3	1,072.7
Accumulated other comprehensive loss, net	(521.7)	(477.1)
Total stockholders’ equity	3,085.5	3,073.8
Total liabilities and stockholders’ equity	$ 30,540.8	$ 32,287.8
Common Stock, Shares Authorized	150,000,000	150,000,000

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Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investment securities:
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 0.8	$ 1.9
Estimated fair value	$ 2,796.1	$ 3,052.2
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)	105,011,371	104,442,023
Common Stock, Shares, Issued	105,011,371	104,442,023
Common Stock, Shares Authorized	150,000,000	150,000,000
Common Stock, Par or Stated Value Per Share	$ 0.00001	$ 0.00001
Preferred Stock, No Par Value	$ 0	$ 0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	$ 6,290.2	$ 7,573.5
Estimated Fair Value	5,627.7	6,946.1
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	$ 0.0	$ 0.0
Class A Common Stock
Stockholders' equity:
Shares outstanding (in shares)		104,442,023
Common Stock, Shares, Issued		104,442,023

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Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Interest income:
Interest and fees on loans	$ 249.9	$ 218.3	$ 727.1	$ 561.7
Interest and dividends on investment securities:
Taxable	66.0	64.3	203.3	142.4
Exempt from federal taxes	0.8	1.4	3.5	4.1
Other Interest and Dividend Income	2.9	1.3	9.3	2.8
Interest on deposits in banks	3.0	1.4	12.6	6.5
Total interest income	322.6	286.7	955.8	717.5
Interest expense:
Interest on deposits	68.8	13.3	162.7	20.6
Interest on securities sold under repurchase agreements	1.7	0.8	4.3	1.4
Interest Expense, Other Short-term Borrowings	33.6	2.4	104.1	2.4
Interest on long-term debt	1.5	1.5	4.4	4.6
Interest on subordinated debentures held by subsidiary trusts	3.3	1.9	9.3	4.3
Total interest expense	108.9	19.9	284.8	33.3
Net interest income	213.7	266.8	671.0	684.2
(Reduction of) provision for credit losses	(0.1)	8.4	26.8	68.0
Net interest income after provision for credit losses	213.8	258.4	644.2	616.2
Non-interest income:
Payment Services Revenues	19.2	20.4	58.0	54.7
Mortgage banking revenues	2.0	2.7	6.9	16.1
Wealth management revenues	8.7	8.5	26.5	25.9
Service Charges on Deposit Accounts	6.0	5.7	17.0	19.7
Non-interest income	2.2	4.7	7.0	12.6
Debt Securities, Available-for-sale, Gain (Loss)	0.0	(24.2)	(23.5)	(24.4)
Other income	3.9	5.1	10.6	17.0
Total non-interest income	42.0	22.9	102.5	121.6
Non-interest expense:
Salaries and wages	65.4	71.9	199.1	206.7
Employee benefits	19.7	19.6	61.8	60.2
Outsourced technology services	14.5	15.9	44.5	40.0
Occupancy, net	11.7	11.3	35.9	32.5
Furniture and equipment	5.3	5.8	16.8	17.0
OREO expense, net of income	0.5	0.0	1.3	0.1
Professional fees	5.1	5.1	14.9	14.5
FDIC insurance premiums	5.0	4.1	15.4	10.2
Other intangibles amortization	3.9	4.1	11.8	11.8
Other expenses	30.0	31.4	89.3	82.7
Acquisition related expenses	0.0	4.0	0.0	115.0
Noninterest Expense	161.1	173.2	490.8	590.7
Income before income tax	94.7	108.1	255.9	147.1
Provision for income tax	22.0	22.4	59.9	30.7
Net income	$ 72.7	$ 85.7	$ 196.0	$ 116.4
Earnings per common share, basic (in dollars per share)	$ 0.70	$ 0.80	$ 1.89	$ 1.13
Earnings per common share, diluted (in dollars per share)	$ 0.70	$ 0.80	$ 1.89	$ 1.13
Weighted average common shares outstanding, basic (in shares)	103,822,311	106,525,974	103,793,851	102,879,422
Weighted average common shares outstanding, diluted (in shares)	103,826,427	106,589,699	103,824,276	102,935,360

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Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 72.7	$ 85.7	$ 196.0	$ 116.4
Other comprehensive income (loss), before tax:
Change in net unrealized losses during the period	(72.1)	(236.4)	(51.4)	(650.6)
Reclassification adjustment for net losses included in income	0.0	24.2	23.5	24.4
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0.0	0.0	(7.2)	0.2
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax	(0.3)	(1.7)	(1.1)	(25.6)
Change in unrealized gain on derivatives	(11.0)	(15.9)	(23.1)	(9.6)
Other comprehensive loss, before tax	(83.4)	(229.8)	(59.3)	(661.2)
Deferred tax benefit related to other comprehensive loss	20.7	51.9	14.7	164.5
Other comprehensive loss, net of tax	(62.7)	(177.9)	(44.6)	(496.7)
Comprehensive income (loss), net of tax	$ 10.0	$ (92.2)	$ 151.4	$ (380.3)

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Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Retained earnings	Accumulated other comprehensive loss
Equity, beginning balance at Dec. 31, 2021	$ 1,986.6	$ 945.0	$ 1,052.6	$ (11.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	116.4	0.0	116.4	0.0
Other comprehensive income (loss), net of tax expense	$ (496.7)	0.0	0.0	(496.7)
Stock repurchased and retired (in shares)	5,039,784
Common shares issued (in shares)	46,913,370
Non-vested common shares issued (in shares)	453,690
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	94,735
Stock Issued During Period, Value, Stock Options Exercised	$ 0.1	0.1	0.0	0.0
Common stock transactions:
Common shares purchased and retired	(198.9)	(198.9)	0.0	0.0
Common shares issued	1,722.5	1,722.5	0.0	0.0
Non-vested common shares issued	0.0	0.0	0.0	0.0
Non-vested common shares forfeited or canceled	0.0	0.0	0.0	0.0
Stock-based compensation expense	$ 8.7	8.7	0.0	0.0
Common dividends (in dollars per share)	$ 1.23
Common cash dividend declared	$ (133.2)	0.0	(133.2)	0.0
Equity, ending balance at Sep. 30, 2022	3,005.5	2,477.4	1,035.8	(507.7)
Equity, beginning balance at Jun. 30, 2022	3,271.9	2,607.9	993.8	(329.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	85.7	0.0	85.7	0.0
Other comprehensive income (loss), net of tax expense	$ (177.9)	0.0	0.0	(177.9)
Stock repurchased and retired (in shares)	3,280,042
Non-vested common shares issued (in shares)	251
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	27,443
Common stock transactions:
Common shares purchased and retired	$ (133.0)	(133.0)	0.0	0.0
Non-vested common shares issued	0.0	0.0	0.0	0.0
Non-vested common shares forfeited or canceled	0.0	0.0	0.0	0.0
Stock-based compensation expense	$ 2.5	2.5	0.0	0.0
Common dividends (in dollars per share)	$ 0.41
Common cash dividend declared	$ (43.7)	0.0	(43.7)	0.0
Equity, ending balance at Sep. 30, 2022	3,005.5	2,477.4	1,035.8	(507.7)
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	0.0	196.0	0.0
Other comprehensive income (loss), net of tax expense	$ (44.6)	0.0	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	0.0
Non-vested common shares issued	0.0	0.0	0.0	0.0
Non-vested common shares forfeited or canceled	0.0	0.0	0.0	0.0
Stock-based compensation expense	$ 8.6	8.6	0.0	0.0
Common dividends (in dollars per share)	$ 1.41
Common cash dividend declared	$ (146.4)	0.0	(146.4)	0.0
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	(459.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	72.7	0.0	72.7	0.0
Other comprehensive income (loss), net of tax expense	$ (62.7)	0.0	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	0.0	0.0
Non-vested common shares issued	0.0	0.0	0.0	0.0
Non-vested common shares forfeited or canceled	0.0	0.0	0.0	0.0
Stock-based compensation expense	$ 3.6	3.6	0.0	0.0
Common dividends (in dollars per share)	$ 0.47
Common cash dividend declared	$ (49.2)	0.0	(49.2)	0.0
Equity, ending balance at Sep. 30, 2023	$ 3,085.5	$ 2,484.9	$ 1,122.3	$ (521.7)

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Consolidated Statement of Changes in Stockholders' Equity (Parenthetical)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Statement of Stockholders' Equity [Abstract]
Stock repurchased and retired (in shares)	5,039,784
Common shares issued (in shares)	46,913,370
Non-vested common shares issued (in shares)	453,690
Non-vested common shares forfeited (in shares)	94,735
stock options exercised (in shares)	17,807
Shares tendered (in shares)	4,877
Common dividends (in dollars per share) | $ / shares	$ 1.23

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Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	$ 196.0	$ 116.4
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
(Reduction of) provision for credit losses	26.8	68.0
Gain (Loss) on Disposition of Property Plant Equipment	(1.7)	(2.3)
Depreciation, Depletion and Amortization	40.5	41.4
Accretion (Amortization) of Discounts and Premiums, Investments	1.7	16.7
Debt and Equity Securities, Gain (Loss)	23.5	24.4
Gain (Loss) on Sale of Loans and Leases	(2.3)	(8.1)
Impairment of Real Estate and Other Assets Pending Disposal	1.1	0.2
Gain (Loss) on Extinguishment of Debt	0.0	(1.4)
Mortgage Servicing Rights (MSR) Impairment (Recovery)	0.0	(3.4)
Deferred Income Tax Expense (Benefit)	9.9	(4.8)
Life Insurance, Corporate or Bank Owned, Change in Value	(8.1)	(7.6)
Share-Based Payment Arrangement, Noncash Expense	8.6	8.7
Payments for Origination of Mortgage Loans Held-for-sale	(250.8)	(369.5)
Proceeds from Sale of Mortgage Loans Held-for-sale	255.9	387.2
Increase (Decrease) in Operating Capital [Abstract]
Increase (Decrease) in Accrued Interest Receivable, Net	(10.9)	(25.9)
Increase (Decrease) in Other Operating Assets	38.5	(14.9)
Increase (Decrease) in Interest Payable, Net	49.2	1.3
Increase (Decrease) in Accounts Payable and Accrued Liabilities	(19.1)	212.6
Net Cash Provided by (Used in) Operating Activities, Total	358.7	438.6
Payments to Acquire Investments [Abstract]
Payments to Acquire Held-to-Maturity Securities	0.0	(1,316.0)
Payments to Acquire Debt Securities, Available-for-Sale	0.0	(2,521.2)
Proceeds from Sale, Maturity and Collection of Investments [Abstract]
Proceeds from Sale and Maturity of Held-to-Maturity Securities	174.0	304.8
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	1,276.3	1,753.6
Purchases of Federal Home Loan Bank and Federal Reserve Bank stock	187.3	115.8
Proceeds from Federal Home Loan Bank and Federal Reserve Bank stock	196.4	53.3
Proceeds from Life Insurance Policy	5.2	0.0
Payments for (Proceeds from) Other Loans and Leases	(128.7)	(465.6)
Payments For (Proceeds From) Recoveries of Loans Previously Charged off	10.6	10.8
Proceeds from Sale of Wholly Owned Real Estate and Real Estate Acquired in Settlement of Loans	2.6	2.0
Proceeds From The Sale Of Health Savings Accounts	0.0	1.4
Cash Acquired from Acquisition	0.0	2,006.9
Payments for (Proceeds from) Productive Assets	(19.4)	(27.2)
Net Cash Provided by (Used in) Investing Activities, Total	1,329.7	(313.0)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Increase (Decrease) in Deposits	(1,394.1)	(2,072.8)
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	(163.4)	51.6
Proceeds from (Repayments of) Other Debt	(260.0)	625.0
Repayments of Other Long-Term Debt	(0.1)	(164.0)
Proceeds from Issuance of Unsecured Debt	0.0	14.4
Payments of Stock Issuance Costs	0.0	(0.8)
Proceeds from Issuance of Common Stock	0.0	0.1
Payments for Repurchase of Common Stock	(1.8)	(198.9)
Payments of Ordinary Dividends, Common Stock	(146.4)	(133.1)
Net Cash Provided by (Used in) Financing Activities, Total	(1,965.8)	(1,878.5)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(277.4)	(1,752.9)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Beginning Balance	870.5	2,344.8
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Ending Balance	593.1	591.9
Supplemental Cash Flow Information [Abstract]
Income Taxes Paid	39.0	42.2
Interest Paid, Excluding Capitalized Interest, Operating Activities	235.6	32.0
Supplemental Cash Flow Elements [Abstract]
Asset Acquisition, Consideration Transferred, Equity Interest Issued and Issuable	0.0	1,723.3
Capitalization Of Internally Originated Mortgage Servicing Rights, Noncash Supplemental Disclosures	0.9	2.3
Finance Lease, Right-of-Use Asset, Amortization	6.4	22.9
Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity	23.0	10.9
Debt Securities, Available-For-Sale, Transfer, Unrealized Gain (Loss)	0.0	463.6
Transfer of loans to held-for-sale	3.1	12.4
Transfer of loans from held-for-sale to held for investment	0.0	19.8
Real Estate Owned, Transfer to Real Estate Owned	2.5	0.4
Gains (Losses) on Sales of Other Real Estate	$ (0.1)	$ (0.4)

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Basis of Presentation

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

In the opinion of management, 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, 2023 and December 31, 2022, the results of operations, changes in stockholders’ equity, and cash flows for each of the three and the nine month periods ended September 30, 2023 and 2022, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2022 is derived from the audited consolidated financial statements. Certain reclassifications, none of which were material, have been made to conform the Company’s prior year financial statements to the September 30, 2023 presentation. These reclassifications did not change previously reported net income 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, 2022, which includes a description of significant accounting policies. Operating results for the three and the nine months ended September 30, 2023 are not necessarily indicative of the results that may be expected for the year ending December 31, 2023.

The below detailed discussion updates the accounting policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.

Change in Par Value

Unless otherwise noted, all capital values, and share and per share amounts, included in the consolidated financial statements have been retroactively adjusted to account for the change in the Company’s common stock par value from no par value per share to $0.00001 par value per share, which change became effective on May 25, 2023 in connection with the re-domestication of the Company from the State of Montana to the State of Delaware.

During the second quarter of 2023, the Company transitioned its Current Expected Credit Loss accounting standard (“CECL”), or ASC 326, model. The new model utilizes fewer portfolio loss segments than the old model due to limited observations of data within certain portfolio loss segments under the old model. The new model calculates historical loss rates by averaging quarterly net charge-offs for each loss segment. The loss rates are macroeconomic-conditioned and applied to loan-level expected cash flows based on contractual repayment terms. The loss rates also consider prepayment, utilization, interest rate, and probability of default assumptions. This change did not result in a material impact to the Company’s financial statements.

Allowance for Credit Losses - Loans held for investment

The allowance for credit losses is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected over the life of the loans. Loans are charged off against the allowance when management confirms that a loan balance is uncollectible. The Company applies recoveries when received and has elected not to forecast recoveries for purposes of calculating the allowance for credit losses.

Management estimates the allowance balance using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. Adjustments to historical loss information are made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix and trends, asset quality, or term. Other loan-specific risk characteristics may include changes in environmental and economic conditions, such as changes in unemployment rates, property values, or other relevant factors.

The allowance for credit losses is measured on a collective basis when similar risk characteristics exist.

Annualized loss rates are recalculated quarterly, with subsequent recoveries captured in the quarter a loan was charged off and are averaged across a look back period from 2009 to the current period. Expected future principal and interest cash flows are calculated using contractual repayment terms while considering prepayment, utilization, interest rate, and probability of default assumptions. Macroeconomic models calculate segment-specific multipliers using third party forecast data. The multipliers adjust the annual loss rates to the level expected under the economic conditions over the 2-year forecast period, followed by a 1-year straight-line reversion to the unadjusted historical average loss rates. The unadjusted loss rates then apply for the remaining life of the loan. Estimated losses are totaled and aggregated to the portfolio segment level.

The Company segments the loan portfolio into pools based on the following risk characteristics: financial asset type, collateral type, loan structure, credit characteristics, outstanding loan balances, contractual terms and prepayment assumptions, utilization assumptions, industry of borrower and concentrations, and historical or expected credit loss.

The Company has identified the following portfolio segments:

Real Estate loans. Include commercial real estate loans which are non-farm, non-residential real estate loans generally secured by first liens on income-producing real estate and generally mature in less than 10 years; construction development loans which are primarily to commercial builders for residential lot development and the construction of single-family residences and commercial real estate properties, commercial construction loans which are primarily made to commercial builders for the development of commercial real estate properties; and construction and development loans which are generally underwritten pursuant to credit worthiness or pre-qualification for permanent financing. During the construction phase for any of the above loans, the borrower pays interest only. In most cases, construction and development loans generally transition to a permanent real estate loans or otherwise mature in three years or less.

Real estate loans also include agricultural real estate loans that generally mature in ten years or less, secured by farmland or ranchland. These loans fund the construction of short, intermediate, and long-term structures and are made to experienced agriculturalists who have demonstrated management capabilities, established production and historical financial performance. Real estate loans also include consumer home equity and home equity lines of credit (“HELOC”) that are secured by residential property and generally mature in 25 years or less, and residential loans which are loans to finance the purchase or refinance of residential property which are typically secured by first liens or are construction loans to commercial builders or owner occupants for the construction of single-family residences. Residential 1-4 family loans generally mature within 15 years, and in some instances, could mature up to 30 years. Construction loans are generally underwritten pursuant to credit worthiness or pre-qualification for permanent financing. During the construction phase the borrower pays interest only. Residential construction loans generally transition to a permanent residential loan or otherwise mature in two years or less.

Consumer loans. Include indirect, direct advance lines, and credit cards. Indirect are loan contracts advanced for the purchase of automobiles, boats, and other consumer goods from the consumer product dealer networks within our market areas. Indirect dealer loans are generally secured by automobiles, recreational vehicles, boats, and other types of personal property and are made on an installment basis. Consumer indirect line loans generally mature in seven years or less. Consumer direct and advance line loans are originated for a variety of purposes including the purchase of automobiles, boats and other consumer goods, home improvements, medical expenses, vehicle repairs, debt consolidation, and planned expenses in addition to the purchase of automobiles, boats, and other consumer goods. Consumer direct and advance line loans generally mature in seven years or less. Consumer credit card loans are lines of credit offered to clients in our market areas that are generally floating rate loans and include both unsecured and secured lines. Consumer credit card loans generally do not have stated maturities but are reviewed periodically and are unconditionally cancellable.

Commercial loans. Include commercial and industrial loans through a mix of variable and fixed rate commercial loans, including loans to finance showroom floor inventories and other loans for commercial purposes that are secured by 1-4 family residential property. These loans are typically made to small and medium-sized manufacturing, wholesale, retail, and service businesses for working capital needs and business expansions. Floor plan loans and commercial purpose loans secured by 1-4 family residential property generally mature in seven years or less. Commercial loans also include secured and unsecured lines of credit, business credit cards, and loans with maturities of five years or less. Outstanding balances on these commercial loans tend to be cyclical in nature. These loans are generally made with business operations as the primary source of repayment, and are typically collateralized by inventory, accounts receivable, equipment, and/or personal guarantees.

Agricultural loans. Agricultural loans generally consist of short and medium-term loans and lines of credit that are primarily used for crops, livestock, equipment, and general operations. Agricultural loans are ordinarily secured by assets such as livestock or equipment and are repaid from the operations of the farm or ranch. Agricultural loans generally have maturities of seven years or less, with operating lines for one production season.

Contractual Term. Expected credit losses are estimated over the contractual term of the loans, adjusted for expected prepayments, defaults, interest rates, and utilization rates. The contractual term excludes expected extensions, renewals, and modifications unless either management has a reasonable expectation at the reporting date that a modification to borrowers experiencing financial difficulty will be executed or the extension or renewal options are included in the original or modified contract at the reporting date and are not unconditionally cancellable by the Company.

A loan for which the terms have been modified resulting in a concession, and for which the borrower is experiencing financial difficulties, is considered to be a modification to borrowers experiencing financial difficulty. The allowance for credit loss on a modification to borrowers experiencing financial difficulty is measured using the same method as all other loans held for investment, except when the loan is individually assessed for credit loss.

Allowance for Credit Losses on Off-Balance Sheet Credit Exposures. The Company estimates expected credit losses over the contractual period in which the Company is exposed to credit risk via a contractual obligation to extend credit unless that obligation is unconditionally cancellable by the Company. Management considers our unused credit card lines and federal fund lines, extended to others, to be unconditionally cancellable.

The allowance for credit losses on off-balance sheet credit exposures is adjusted as a provision for credit loss expense. The estimate considers the likelihood that funding will occur and an estimate of expected credit losses on commitments expected to be funded over the estimated life.

The Company has identified commitments to extend credit and standby letters of credit determined not to be unconditionally cancellable as categories with off-balance sheet credit exposures and uses the commitment balance, expected loss rate, expected cash flows, and utilization rate as primary assumptions to develop the allowance for credit losses on those exposures. The utilization rate represents management’s best estimate of the probability that the unfunded portion of the commitment will be funded given existing economic conditions.

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Acquisitions

9 Months Ended

Sep. 30, 2023

Business Combinations [Abstract]

Acquisitions

Great Western Bank. On September 15, 2021, the Company entered into a definitive agreement (“Agreement”) to acquire 100% of the outstanding stock of Great Western Bancorp, Inc. (“Great Western”), the parent company of Great Western Bank (“GWB”), a Sioux Falls, South Dakota based community bank with 174 banking offices across Arizona, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota (“GWB acquisition”). The GWB acquisition expanded the Company’s geographical footprint with an enhanced platform for future growth. Consideration for the acquisition was $1,723.3 million, consisting of the issuance of 46.9 million shares of the Company’s Class A common stock valued at $36.76 per share, which was the opening price of the Company’s Class A common stock as quoted on the NASDAQ stock market on the acquisition date. The acquisition was completed on February 1, 2022.

The Company accounted for the transaction under the acquisition method of accounting in accordance with ASC 805, Business Combinations, which requires purchased assets and liabilities assumed and consideration exchanged to be recorded at their respective estimated fair values at the date of acquisition. The determination of estimated fair values required management to make certain estimates about discount rates, future expected cash flows, and market conditions at the time of the acquisition, as well as other future events that are highly subjective in nature.

The following table provides the purchase price allocation as of the acquisition date and the Great Western assets acquired and liabilities assumed at their estimated fair value as of the acquisition date, as amended for measurement period adjustments. We recorded the estimate of fair value based on valuations at the acquisition date. The excess value of the consideration paid over the fair value of assets acquired and liabilities assumed was recorded as goodwill. The purchase price allocation resulted in goodwill of $479.3 million, of which $31.7 million is deductible for income tax purposes. Goodwill resulting from the acquisition was allocated to the Company’s one operating segment, community banking, and consists largely of the synergies and economies of scale expected from combining the operations of Great Western and the Company. All amounts reported were finalized during the fourth quarter of 2022.

As of February 1, 2022
Assets acquired:
Cash and cash equivalents	$	2,006.9
Investment securities	2,699.0
Securities purchased under agreement to resell	101.1
Loans held for sale	217.0
Loans held for investment	7,705.0
Allowance for credit losses	(59.5)
Premises and equipment, including right of use lease assets	144.7
Other real estate owned	15.8
Company-owned life insurance	186.6
Core deposit intangibles	50.1
Customer relationship intangible	22.8
Mortgage servicing rights	1.3
Deferred tax assets, net	60.2
Other assets	200.8
Total assets acquired	13,351.8
Liabilities assumed:
Deposits	11,688.0
Securities sold under repurchase agreements	74.0
Accrued expenses and other liabilities	110.4
FHLB advances	122.9
Subordinated debt	36.4
Subordinated debentures held by subsidiary trusts	76.1
Total liabilities assumed	12,107.8
Net assets acquired	$	1,244.0
Consideration paid:
Class A common stock	1,723.3
Total consideration paid (1)	$	1,723.3
Goodwill	$	479.3

(1) Includes $13 thousand of cash paid in lieu of fractional shares.

For a description of the fair value and unpaid principal balance of loans from the GWB acquisition, as well as the methods used to determine the fair values of significant assets and liabilities, see “Note 2 – Acquisitions” in Part IV, Item 15 “Notes to Consolidated Financial Statements” within our Annual Report on Form 10-K for the year ended December 31, 2022.

There were no acquisition related expenses related to the GWB acquisition for the three and the nine month periods ended September 30, 2023. There were $4.0 million and $115.0 million of acquisition related expenses related to the GWB acquisition for the three and the nine month periods ended September 30, 2022, respectively. During the three months ended March 31, 2022, the Company contributed $21.5 million to the First Interstate Foundation and reimbursed an aggregate of $8.2 million of the Scott family control group’s acquisition expenses pursuant to the Agreement.

The accompanying consolidated statements of income for the three and the nine months ended September 30, 2023 and 2022, include the results of operations of the acquired entity from the February 1, 2022 acquisition date. The disclosure of GWB post-acquisition revenue and net income is not practical due to the combining of certain GWB operations with and into FIB as of the acquisition date. GWB was merged with our existing bank subsidiary, FIB, contemporaneously with the closing of the parent company merger. The core system conversion was completed on May 23, 2022.

The following table presents certain unaudited pro forma financial information for illustrative purposes only, for the three and the nine month periods ended September 30, 2022 as if GWB had been acquired on January 1, 2021. This unaudited pro forma information combines the historical results of GWB with the Company’s consolidated historical results and includes certain adjustments reflecting the estimated impact of certain fair value adjustments for the respective periods. The pro forma information is not indicative of what would have occurred had the acquisition occurred at the beginning of the year prior to the acquisition. The unaudited pro forma information does not consider any changes to the provision for credit losses resulting from recording loan assets at fair value, cost savings, or business synergies. As a result, actual amounts would have differed from the unaudited pro forma information presented, and the differences could be significant.

	Three Months Ended September 30,		Nine Months Ended September 30,
	2022		2022
Total revenues	$	314.0	$	883.5
Net income	$	90.3	$	267.8
Earnings per common share (Basic)	$	0.85	$	2.60
Earnings per common share (Diluted)	$	0.85	$	2.60

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Goodwill and Core Deposit Intangibles

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

Goodwill

The Company had goodwill of $1,100.9 million at both September 30, 2023 and December 31, 2022 and concluded during its annual impairment assessment as of July 1, 2023 that there was no impairment to goodwill. In addition, there were no events or circumstances that occurred during the third quarter of 2023 that would more-likely-than-not reduce the fair value of the Company’s reporting unit below its carrying value.

Other Intangible Assets

Other intangible assets are comprised of core deposit intangibles (“CDI”) and other customer relationship intangibles (“OCRI”) and amounted to the following at September 30, 2023 and December 31, 2022:

September 30, 2023	CDI		OCRI		Total
Gross other intangible assets, at January 1, 2023	$	154.7	$	22.8	$	177.5
Accumulated amortization	(89.1)		(3.2)		(92.3)
Net other intangible assets, at September 30, 2023	$	65.6	$	19.6	$	85.2
December 31, 2022
Gross other intangible assets, at January 1, 2022	$	106.0	$	—	$	106.0
Amounts established through acquisition	50.1		22.8		72.9
Reductions due to sale of health savings accounts	(1.4)		—		(1.4)
Accumulated amortization	(78.8)		(1.7)		(80.5)
Net other intangible assets, at December 31, 2022	$	75.9	$	21.1	$	97.0

The Company recorded $3.9 million and $4.1 million of other intangible asset amortization expense for the three months ended September 30, 2023 and 2022, respectively, and $11.8 million for the nine months ended September 30, 2023 and 2022.

CDI and OCRI are evaluated for impairment if events and circumstances indicate a possible impairment. CDI is amortized using an accelerated method based on the estimated weighted average useful lives of the related deposits, which is generally 10 years. OCRI is amortized using a straight-line method over its estimated useful life of 12 years based on customer revenue attrition on an annualized basis.

The following table provides the estimated aggregate future amortization expense of other intangible assets at September 30, 2023:

Years Ending December 31,	CDI		OCRI		Total
2023 remaining	$	3.4	$	0.4	$	3.8
2024	12.7		1.9		14.6
2025	11.8		1.9		13.7
2026	10.9		1.9		12.8
2027	8.2		1.9		10.1
Thereafter	18.6		11.6		30.2
Total	$	65.6	$	19.6	$	85.2

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Investment Securities

9 Months Ended

Sep. 30, 2023

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, 2023	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	250.1	$	—	$	250.1	$	—	$	(34.2)	$	215.9
State, county, and municipal securities	257.5		—		257.5		—		(54.9)		202.6
Obligations of U.S. government agencies	179.3		—		179.3		—		(17.3)		162.0
U.S. agency commercial mortgage-backed securities	1,191.9		—		1,191.9		0.1		(125.1)		1,066.9
U.S. agency residential mortgage-backed securities	1,474.3		—		1,474.3		—		(189.3)		1,285.0
Collateralized mortgage obligations	1,302.9		—		1,302.9		—		(159.2)		1,143.7
Private mortgage-backed securities	246.4		—		246.4		—		(39.1)		207.3
Collateralized loan obligations	1,126.7		—		1,126.7		—		(8.9)		1,117.8
Corporate securities	261.1		—		261.1		—		(34.6)		226.5
Total	$	6,290.2	$	—	$	6,290.2	$	0.1	$	(662.6)	$	5,627.7

September 30, 2023	Amortized Cost1		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	398.4	$	—	$	398.4	$	—	$	(6.8)	$	391.6
State, county, and municipal securities	179.0		—		179.0		—		(34.9)		144.1
Obligations of U.S. government agencies	353.8		—		353.8		—		(59.5)		294.3
U.S. agency commercial mortgage-backed securities	515.2		—		515.2		—		(71.9)		443.3
U.S. agency residential mortgage-backed securities	1,269.8		—		1,269.8		—		(197.2)		1,072.6
Collateralized mortgage obligations	487.1		—		487.1		—		(86.2)		400.9
Corporate securities	57.0		(0.8)		56.2		—		(6.9)		49.3
Total	$	3,260.3	$	(0.8)	$	3,259.5	$	—	$	(463.4)	$	2,796.1
(1) Amortized cost presented above includes $11.4 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 $18.6 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, 2022	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	675.1	$	—	$	675.1	$	2.1	$	(34.5)	$	642.7
State, county, and municipal securities	314.3		—		314.3		—		(50.6)		263.7
Obligations of U.S. government agencies	216.2		—		216.2		—		(17.3)		198.9
U.S. agency commercial mortgage-backed securities	1,468.0		—		1,468.0		0.2		(117.0)		1,351.2
U.S. agency residential mortgage-backed securities	1,726.0		—		1,726.0		—		(167.7)		1,558.3
Collateralized mortgage obligations	1,491.5		—		1,491.5		—		(141.3)		1,350.2
Private mortgage-backed securities	264.9		—		264.9		—		(36.9)		228.0
Collateralized loan obligations	1,145.2		—		1,145.2		—		(33.6)		1,111.6
Corporate securities	272.3		—		272.3		—		(30.8)		241.5
Total	$	7,573.5	$	—	$	7,573.5	$	2.3	$	(629.7)	$	6,946.1

December 31, 2022	Amortized Cost1		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	396.6	$	—	$	396.6	$	—	$	(10.2)	$	386.4
State, county, and municipal securities	181.2		(0.1)		181.1		0.2		(31.6)		149.7
Obligations of U.S. government agencies	351.7		—		351.7		—		(49.6)		302.1
U.S. agency commercial mortgage-backed securities	526.8		—		526.8		—		(58.3)		468.5
U.S. agency residential mortgage-backed securities	1,391.5		—		1,391.5		—		(166.6)		1,224.9
Collateralized mortgage obligations	525.8		—		525.8		0.2		(76.7)		449.3
Corporate securities	80.1		(1.8)		78.3		—		(7.0)		71.3
Total	$	3,453.7	$	(1.9)	$	3,451.8	$	0.4	$	(400.0)	$	3,052.2
(1) Amortized cost presented above includes $20.2 million of unamortized losses and of $14.2 million unamortized gains 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, 2023 and December 31, 2022.

	Less than 12 Months				12 Months or More				Total
September 30, 2023	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	—	$	—	$	215.9	$	(34.2)	$	215.9	$	(34.2)
State, county, and municipal securities	1.0		—		199.7		(54.9)		200.7		(54.9)
Obligations of U.S. government agencies	—		—		161.5		(17.3)		161.5		(17.3)
U.S. agency commercial mortgage-backed securities	0.3		—		1,057.8		(125.1)		1,058.1		(125.1)
U.S. agency residential mortgage-backed securities	0.9		—		1,284.0		(189.3)		1,284.9		(189.3)
Collateralized mortgage obligations	—		—		1,143.7		(159.2)		1,143.7		(159.2)
Private mortgage-backed securities	—		—		207.3		(39.1)		207.3		(39.1)
Collateralized loan obligations	—		—		1,117.8		(8.9)		1,117.8		(8.9)
Corporate securities	—		—		226.6		(34.6)		226.6		(34.6)
Total	$	2.2	$	—	$	5,614.3	$	(662.6)	$	5,616.5	$	(662.6)

	Less than 12 Months				12 Months or More				Total
December 31, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	168.8	$	(4.7)	$	170.4	$	(29.8)	$	339.2	$	(34.5)
State, county, and municipal securities	104.9		(9.0)		146.1		(41.6)		251.0		(50.6)
Obligations of U.S. government agencies	152.2		(10.1)		46.1		(7.2)		198.3		(17.3)
U.S. agency commercial mortgage-backed securities	1,069.8		(59.9)		270.8		(57.0)		1,340.6		(116.9)
U.S. agency residential mortgage-backed securities	1,213.5		(112.3)		344.6		(55.4)		1,558.1		(167.7)
Collateralized mortgage obligations	1,016.4		(90.1)		333.0		(51.3)		1,349.4		(141.4)
Private mortgage-backed securities	133.1		(19.1)		94.9		(17.8)		228.0		(36.9)
Collateralized loan obligations	1,082.6		(33.1)		28.9		(0.5)		1,111.5		(33.6)
Corporate securities	130.6		(8.3)		110.8		(22.5)		241.4		(30.8)
Total	$	5,071.9	$	(346.6)	$	1,545.6	$	(283.1)	$	6,617.5	$	(629.7)

As of September 30, 2023 and December 31, 2022, there were no holdings of securities of any issuer, other than the U.S. government and its agencies, in an amount greater than 10% of stockholders’ equity.

The Company determines credit losses on both available-for-sale and held-to-maturity investment securities by a discounted cash flow approach using the 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. Credit losses on held-to-maturity investment securities are representative of current expected credit losses that management expects to be incurred over the life of the investment. The allowance for credit losses is established through a charge to provision for credit losses in current period earnings.

The available-for-sale 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 prepayment and 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, 2023 and December 31, 2022, the Company had 1,034 and 1,222 individual investment securities, respectively, that were in an unrealized loss position, which was related primarily to fluctuations in current interest rates. As of September 30, 2023, the Company had the intent and ability to hold these investment securities for a period of time sufficient to allow for an anticipated recovery. The Company does not intend to sell any of the available-for-sale securities in the above table, and the Company does not anticipate it will have to sell any securities before a recovery in cost.

The following table presents the activity in the allowance for credit losses related to available-for-sale investment securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Beginning balance	$	1.4	$	—	$	—	$	—
(Reduction of) provision for credit losses	(1.4)		—		—		—
Ending balance	$	—	$	—	$	—	$	—
The following table presents the activity in the allowance for credit losses related to held-to-maturity investment securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Beginning balance	$	0.7	$	1.6	$	1.9	$	—
Provision for (reduction of) credit losses	0.1		0.3		(1.1)		1.9
Ending balance	$	0.8	$	1.9	$	0.8	$	1.9

The Company had no allowance for credit losses for available-for-sale corporate investment securities as of September 30, 2023 and December 31, 2022, respectively. The Company had a $0.8 million and a $1.9 million allowance for credit losses for held-to-maturity corporate and state, county, and municipal investment securities as of September 30, 2023 and December 31, 2022, respectively.

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, 2023	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	398.4	$	—	$	—	$	—	$	—	$	—	$	398.4
State, county, and municipal securities	68.1		92.3		10.6		—		—		8.0		179.0
Obligations of U.S. government agencies	353.8		—		—		—		—		—		353.8
U.S. agency commercial mortgage-backed securities
FNMA/FHLMC	360.9		—		—		—		—		—		360.9
GNMA	154.3		—		—		—		—		—		154.3
U.S. agency residential mortgage-backed securities
FNMA/FHLMC	1,225.6		—		—		—		—		—		1,225.6
GNMA	44.2		—		—		—		—		—		44.2
Collateralized mortgage obligations
FNMA/FHLMC	342.0		—		—		—		—		—		342.0
GNMA	145.1		—		—		—		—		—		145.1
Corporate securities	—		—		—		47.0		5.0		5.0		57.0
Total	$	3,092.4	$	92.3	$	10.6	$	47.0	$	5.0	$	13.0	$	3,260.3

December 31, 2022	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	396.6	$	—	$	—	$	—	$	—	$	—	$	396.6
State, county, and municipal securities	68.3		92.8		11.5		—		—		8.6		181.2
Obligations of U.S. government agencies	351.7		—		—		—		—		—		351.7
U.S. agency commercial mortgage-backed securities
FNMA/FHLMC	364.9		—		—		—		—		—		364.9
GNMA	161.9		—		—		—		—		—		161.9
U.S. agency residential mortgage-backed securities
FNMA/FHLMC	1,342.9		—		—		—		—		—		1,342.9
GNMA	48.6		—		—		—		—		—		48.6
Collateralized mortgage obligations
FNMA/FHLMC	525.8		—		—		—		—		—		525.8
Corporate securities	—		—		—		65.1		10.0		5.0		80.1
Total	$	3,260.7	$	92.8	$	11.5	$	65.1	$	10.0	$	13.6	$	3,453.7

As of September 30, 2023 and December 31, 2022, the Company had $36.5 million and $38.9 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, 2023 and December 31, 2022, 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, 2023 and December 31, 2022, 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 months ended September 30, 2023. 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, as a result of the sale of $853.0 million in carrying value of investment securities. For the three and the nine month periods ended September 30, 2022, there were no material gross realized gains and $46.3 million of gross realized losses on the disposition of available-for-sale investment securities.

Maturities of securities do not reflect rate repricing opportunities present in adjustable-rate mortgage-backed securities. Maturities of mortgage-backed securities have been adjusted to reflect shorter maturities based upon estimated prepayments of principal. All other investment securities maturities are shown at contractual maturity dates.

	Available-for-Sale				Held-to-Maturity
September 30, 2023	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	1.6	$	1.5	$	308.7	$	304.5
After one year but within five years	1,036.0		941.3		346.4		320.2
After five years but within ten years	1,387.9		1,220.0		654.8		551.5
After ten years	3,864.7		3,464.9		1,950.4		1,619.9
Total	$	6,290.2	$	5,627.7	$	3,260.3	$	2,796.1

As of September 30, 2023, the Company held investment securities callable within one year having amortized costs and estimated fair values of $1,592.1 million and $1,514.4 million, respectively. These investment securities are primarily included in the “after ten years” category in the table above. As of September 30, 2023, the Company had no callable structured notes.

As of September 30, 2023 and December 31, 2022, the Company had amortized costs of $7,066.8 million and $4,998.9 million, respectively, for investment securities pledged to secure public deposits, securities sold under repurchase agreements, and as collateral for FHLB and the FRB term funding program line capacity that had estimated fair values of $6,169.7 million and $4,432.0 million, as of September 30, 2023 and December 31, 2022, 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, 2023 and December 31, 2022, the Company held $189.5 million and $198.6 million, respectively, in equity securities 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.

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Loans Held for Sale

9 Months Ended

Sep. 30, 2023

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, 2023		December 31, 2022
Loans held for sale:
Agricultural1	$	49.5	$	62.5
Construction, at lower of cost or market	6.4		10.5
Residential mortgage, at fair value	3.2		6.9
Total loans held for sale	$	59.1	$	79.9

1 As of September 30, 2023 the agricultural loans held were at lower of cost or market. At December 31, 2022, the Company held $57.0 million of agricultural loans at lower of cost or market and $5.5 million of agricultural loans on accrual status at fair value with an unpaid principal balance of $7.7 million, of which $5.6 million is 90 days or more past due.

The table below presents the non-residential mortgage loans held for sale activity for the 2023 period:

	Agricultural		Construction
Beginning balance	$	62.5	$	10.5
Loans held for investment transferred to loans held for sale	—		3.1
Repayments and discounted pay-offs	(15.2)		—
Loan disposals	—		(3.1)
Increase (decrease) in estimated fair value of the loans1	2.2		(4.1)
Ending balance	$	49.5	$	6.4

1 For the nine months ended September 30, 2023, the Company recorded a gain of $2.2 million and a loss of $4.1 million in other income within the consolidated statements of income related to fair value changes.

As of September 30, 2023, loans held for sale included nonaccrual loans of $31.6 million, of which $25.2 million were agricultural loans and $6.4 million was a construction loan. As of December 31, 2022, loans held for sale included nonaccrual loans of $39.8 million, of which $29.3 million were agricultural loans and $10.5 million was a construction loan.

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Loans Held for Investment

9 Months Ended

Sep. 30, 2023

Receivables [Abstract]

Loans

The following table presents loans by class of receivable and portfolio segment as of the dates indicated:

	September 30, 2023		December 31, 2022
Real estate:
Commercial	$	8,766.2	$	8,528.6
Construction	1,930.3		1,944.4
Residential	2,212.2		2,188.3
Agricultural	731.5		794.9
Total real estate	13,640.2		13,456.2
Consumer:
Indirect	751.7		829.7
Direct and advance lines	142.3		152.9
Credit card	71.6		75.9
Total consumer	965.6		1,058.5
Commercial	2,925.1		2,882.6
Agricultural	690.5		708.3
Other, including overdrafts	5.0		9.2
Loans held for investment	18,226.4		18,114.8
Deferred loan fees and costs	(13.1)		(15.6)
Loans held for investment, net of deferred fees and costs	18,213.3		18,099.2
Allowance for credit losses	(226.7)		(220.1)
Net loans held for investment	$	17,986.6	$	17,879.1

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, 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

Three Months Ended September 30, 2022	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	29.5	$	(5.5)	$	(0.1)	$	—	$	23.9
Owner occupied	26.6		(3.7)		—		1.8		24.7
Multi-family	33.4		(2.6)		(5.7)		—		25.1
Total commercial real estate	89.5		(11.8)		(5.8)		1.8		73.7
Construction:
Land acquisition & development	0.8		(0.2)		—		0.1		0.7
Residential construction	3.4		(0.3)		—		—		3.1
Commercial construction	14.9		16.4		(6.6)		—		24.7
Total construction	19.1		15.9		(6.6)		0.1		28.5
Residential real estate:
Residential 1-4 family	18.2		0.9		—		—		19.1
Home equity and HELOC	1.5		0.1		(0.1)		0.1		1.6
Total residential real estate	19.7		1.0		(0.1)		0.1		20.7
Agricultural real estate	5.4		0.4		—		—		5.8
Total real estate	133.7		5.5		(12.5)		2.0		128.7
Consumer:
Indirect	13.1		1.6		(1.2)		0.6		14.1
Direct and advance lines	5.0		1.3		(1.4)		0.4		5.3
Credit card	2.2		0.3		(0.3)		0.2		2.4
Total consumer	20.3		3.2		(2.9)		1.2		21.8
Commercial:
Commercial and floor plans	54.1		(2.2)		(0.5)		1.0		52.4
Commercial purpose secured by 1-4 family	5.5		0.4		—		—		5.9
Credit card	0.3		0.2		(0.3)		—		0.2
Total commercial	59.9		(1.6)		(0.8)		1.0		58.5
Agricultural:
Agricultural	6.5		(2.5)		—		—		4.0
Total agricultural	6.5		(2.5)		—		—		4.0
Total allowance for credit losses	$	220.4	$	4.6	$	(16.2)	$	4.2	$	213.0

Nine Months Ended September 30, 2022	Beginning Balance		ACL for PCD Loans		Provision for Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	17.3	$	17.2	$	(7.6)	$	(3.0)	$	—	$	23.9
Owner occupied	13.3		9.5		2.3		(2.2)		1.8		24.7
Multi-family	13.3		10.9		5.9		(5.7)		0.7		25.1
Total commercial real estate	43.9		37.6		0.6		(10.9)		2.5		73.7
Construction:
Land acquisition & development	0.5		3.4		(0.8)		(2.7)		0.3		0.7
Residential construction	2.4		—		0.7		—		—		3.1
Commercial construction	6.0		0.2		25.1		(6.6)		—		24.7
Total construction	8.9		3.6		25.0		(9.3)		0.3		28.5
Residential real estate:
Residential 1-4 family	13.4		0.1		5.4		(0.1)		0.3		19.1
Home equity and HELOC	1.2		—		0.1		(0.1)		0.4		1.6
Total residential real estate	14.6		0.1		5.5		(0.2)		0.7		20.7
Agricultural real estate	1.9		2.3		1.7		(0.2)		0.1		5.8
Total real estate	69.3		43.6		32.8		(20.6)		3.6		128.7
Consumer:
Indirect	14.3		—		0.9		(2.9)		1.8		14.1
Direct and advance lines	4.6		—		1.7		(2.8)		1.8		5.3
Credit card	2.2		—		1.6		(1.8)		0.4		2.4
Total consumer	21.1		—		4.2		(7.5)		4.0		21.8
Commercial:
Commercial and floor plans	27.1		11.2		18.1		(5.8)		1.8		52.4
Commercial purpose secured by 1-4 family	4.4		0.2		1.2		—		0.1		5.9
Credit card	0.1		—		0.6		(0.5)		—		0.2
Commercial	31.6		11.4		19.9		(6.3)		1.9		58.5
Agricultural:
Agricultural	0.3		4.5		3.3		(5.4)		1.3		4.0
Total agricultural	0.3		4.5		3.3		(5.4)		1.3		4.0
Total allowance for credit losses	$	122.3	$	59.5	$	60.2	$	(39.8)	$	10.8	$	213.0
(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 Financial Loans

A collateral-dependent financial 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, 2023	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	—	$	29.6	$	—	$	29.6
Construction	—		17.1		—		17.1
Residential	—		0.5		—		0.5
Agricultural	—		1.5		—		1.5
Total real estate	—		48.7		—		48.7
Commercial	4.4		1.6		0.9		6.9
Agricultural	0.7		—		—		0.7
Total collateral-dependent loans	$	5.1	$	50.3	$	0.9	$	56.3

	Collateral Type
As of December 31, 2022	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	1.7	$	15.8	$	—	$	17.5
Construction	—		3.2		—		3.2
Residential	—		0.5		—		0.5
Agricultural	0.2		5.8		—		6.0
Total real estate	1.9		25.3		—		27.2
Commercial	3.1		1.5		—		4.6
Agricultural	2.1		5.2		—		7.3
Total collateral-dependent loans	$	7.1	$	32.0	$	—	$	39.1

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, 2023	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate:
Commercial	$	1.2	$	0.4	$	—	$	1.6	$	8,733.6	$	31.0	$	8,766.2
Construction	6.5		7.5		0.5		14.5		1,898.4		17.4		1,930.3
Residential	2.4		1.8		1.0		5.2		2,197.5		9.5		2,212.2
Agricultural	0.4		1.5		—		1.9		724.2		5.4		731.5
Total real estate	10.5		11.2		1.5		23.2		13,553.7		63.3		13,640.2
Consumer:
Indirect	6.4		2.2		0.4		9.0		739.7		3.0		751.7
Direct	0.6		0.2		—		0.8		141.3		0.2		142.3
Credit card	0.6		0.4		0.5		1.5		70.1		—		71.6
Total consumer	7.6		2.8		0.9		11.3		951.1		3.2		965.6
Commercial	2.3		16.1		0.5		18.9		2,894.2		12.0		2,925.1
Agricultural	0.7		—		0.3		1.0		686.6		2.9		690.5
Other, including overdrafts	—		—		—		—		5.0		—		5.0
Loans held for investment	$	21.1	$	30.1	$	3.2	$	54.4	$	18,090.6	$	81.4	$	18,226.4

							Total Loans
	30 - 59		60 - 89		90 or more		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2022	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate:
Commercial	$	5.6	$	0.8	$	1.1	$	7.5	$	8,501.5	$	19.6	$	8,528.6
Construction	10.4		0.6		0.6		11.6		1,929.1		3.7		1,944.4
Residential	9.9		2.1		1.2		13.2		2,168.7		6.4		2,188.3
Agricultural	1.1		6.1		—		7.2		780.1		7.6		794.9
Total real estate	27.0		9.6		2.9		39.5		13,379.4		37.3		13,456.2
Consumer:
Indirect	9.3		2.4		0.6		12.3		814.7		2.7		829.7
Direct	0.8		0.3		0.1		1.2		151.4		0.3		152.9
Credit card	0.8		0.4		0.6		1.8		74.1		—		75.9
Total consumer	10.9		3.1		1.3		15.3		1,040.2		3.0		1,058.5
Commercial	7.1		1.7		2.1		10.9		2,861.5		10.2		2,882.6
Agricultural	0.8		2.2		0.1		3.1		696.5		8.7		708.3
Other, including overdrafts	—		—		—		—		9.2		—		9.2
Loans held for investment	$	45.8	$	16.6	$	6.4	$	68.8	$	17,986.8	$	59.2	$	18,114.8

(1) As of September 30, 2023 and December 31, 2022, 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, 2023 and 2022, respectively. There were $1.0 million and $1.9 million in reversals of accrued interest during the three and the nine months ended September 30, 2023, respectively, and no material reversals of accrued interest during the three and the nine months ended September 30, 2022.

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 borrowers payment relief. Effective January 1, 2023, the Company adopted ASU 2022-02, which eliminated accounting guidance for troubled debt restructurings while requiring disclosures of borrowers experiencing financial difficulty for modifications related to principal reductions, interest rate reductions, term extensions, and more than insignificant payment delay. See “Note 17 – Recent Authoritative Accounting Guidance” of these Notes to Unaudited Consolidated Financial Statements” for further discussion of the amendments in this update.

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, or a term extension or a combination thereof, among other things.

The following table presents the amortized cost basis of loans at September 30, 2023 that were both experiencing financial difficulty and modified during the three and the nine month periods ended September 30, 2023, by class and by type of modification. 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, 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, 2023, the Company excluded $1.7 million in accrued interest from the amortized cost of the identified loans.

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 nine months ended September 30, 2023, there were $0.1 million of loans classified as past due 30 days or more, with the remaining loans performing in accordance with the modified terms and are classified as current at September 30, 2023.

There were no commitments to lend additional funds to borrowers experiencing financial difficulty whose terms have been modified during the three and the nine month periods ended September 30, 2023 through either principal forgiveness, interest rate reduction, term extension, or other than insignificant payment delay.

The following table presents the financial effect of the loan modifications presented above to borrowers experiencing financial difficulty during the three and the nine month periods ended September 30, 2023:

				Term Extension and Interest Rate Reduction
Three Months Ended September 30, 2023	Principal Forgiveness		Weighted-Average Months of Term Extension	Weighted-Average Interest Rate Reduction		Weighted-Average Months of Term Extension
Real estate:
Commercial	$	—	4.6	0.25	%	6.0
Construction	—		9.0	—		—
Residential	—		144.4	—		—
Agricultural	—		4.0	—		—
Total real estate	—
Commercial	—		7.8	—		—
Agricultural	—		3.5	—		—
Loans held for investment (1)	$	—
Nine Months Ended September 30, 2023
Real estate:
Commercial	$	1.3	5.7	0.25	%	6.0
Construction	—		9.0	—		—
Residential	0.3		139.2	—		—
Agricultural	—		4.6	—		—
Total real estate	1.6
Commercial	—		8.8	—		—
Agricultural	—		9.2	—		—
Loans held for investment (1)	$	1.6

(1) Balances based on loan original contractual terms.

There were no payment defaults on these loans subsequent to their modifications during the three and the nine month periods ended September 30, 2023. 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 on the basis of 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.

Purchased Credit Deteriorated Loans (“PCD”)

The Company analyzes all acquired loans at the time of acquisition for more-than-insignificant deterioration in credit quality since their origination date. Such loans are classified as PCD, also referred to as PCD loans. Acquired loans classified as PCD are recorded at an initial amortized cost, which is comprised of the purchase price of the loans plus the initial allowance for credit losses for the loans, and any resulting discount or premium related to factors other than credit. The Company accounts for interest income on PCD loans using the interest method, whereby any purchase discounts or premiums are accreted or amortized into interest income as an adjustment of the loan’s yield.

The following table reconciles the par value, or initial amortized cost, of PCD loans acquired in the GWB acquisition as of February 1, 2022, or the date of the acquisition, with the purchase price (or initial fair value of the loans) as amended for measurement period adjustments:

Purchase price (initial fair value)	$	623.3
Allowance for credit losses (1)	298.2
Discount attributable to other factors (2)	57.7
Par value (unpaid principal balance)	$	979.2

(1) For acquired PCD loans, an allowance of $298.2 million was required with a corresponding increase to the amortized cost basis as of the acquisition date. For PCD loans where all or a portion of the loan balance had been previously written-off by GWB, or would be subject to write-off under the Company’s charge-off policy, a CECL allowance of $238.7 million, included as part of the grossed-up loan balance at acquisition was immediately written-off. The net impact to the allowance for PCD assets on the acquisition date was $59.5 million.

(2) Non-credit discount includes the difference between the amortized cost basis and the unpaid principal balance of $39.6 million established on PCD loans acquired from GWB and interest applied to principal of $18.1 million.

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 based on the aforementioned risk scale as of and for the periods ended:

	As of and for the nine months ended September 30, 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	$	845.8	$	2,240.2	$	1,649.9	$	1,245.7	$	732.7	$	1,741.5	$	42.8	$	21.6	$	8,520.2
Special mention	2.9		5.0		41.3		4.7		26.9		20.5		—		—		101.3
Substandard	28.0		26.0		19.6		9.6		30.4		28.4		1.0		—		143.0
Doubtful	—		0.3		1.4		—		—		—		—		—		1.7
Total	$	876.7	$	2,271.5	$	1,712.2	$	1,260.0	$	790.0	$	1,790.4	$	43.8	$	21.6	$	8,766.2
Current-period gross charge-offs	1.7		0.3		1.7		2.6		—		—		—		—		6.3
Construction real estate:
Pass	$	444.9	$	806.1	$	413.3	$	39.4	$	16.5	$	38.7	$	102.8	$	2.6	$	1,864.3
Special mention	4.1		11.4		6.5		—		—		0.2		—		0.8		23.0
Substandard	1.4		3.3		24.5		0.2		—		0.5		—		—		29.9
Doubtful	—		13.1		—		—		—		—		—		—		13.1
Total	$	450.4	$	833.9	$	444.3	$	39.6	$	16.5	$	39.4	$	102.8	$	3.4	$	1,930.3
Current-period gross charge-offs	—		—		0.1		—		—		—		—		9.6		9.7
Agricultural real estate:
Pass	$	60.5	$	133.1	$	158.8	$	95.9	$	59.4	$	130.1	$	27.8	$	0.1	$	665.7
Special mention	3.5		6.6		1.4		2.1		1.8		5.9		0.5		—		21.8
Substandard	8.1		19.8		4.8		2.2		0.5		8.6		—		—		44.0
Total	$	72.1	$	159.5	$	165.0	$	100.2	$	61.7	$	144.6	$	28.3	$	0.1	$	731.5
Current-period gross charge-offs	—		—		—		—		—		—		—		—		—
Commercial:
Pass	$	383.8	$	537.2	$	408.5	$	224.5	$	116.4	$	317.0	$	765.8	$	9.5	$	2,762.7
Special mention	2.3		4.9		6.7		4.7		2.5		1.4		14.8		0.1		37.4
Substandard	5.0		23.3		10.9		7.2		4.6		5.0		62.4		0.4		118.8
Doubtful	4.7		0.2		1.2		—		—		—		0.1		—		6.2
Total	$	395.8	$	565.6	$	427.3	$	236.4	$	123.5	$	323.4	$	843.1	$	10.0	$	2,925.1
Current-period gross charge-offs	—		0.3		0.3		0.4		0.1		0.1		0.9		0.1		2.2
Agricultural:
Pass	$	77.2	$	74.8	$	35.9	$	25.5	$	7.7	$	9.6	$	374.0	$	6.0	$	610.7
Special mention	0.9		1.1		0.8		0.2		0.2		0.2		9.7		—		13.1
Substandard	45.0		0.7		1.4		1.4		0.5		1.3		16.4		—		66.7
Total	$	123.1	$	76.6	$	38.1	$	27.1	$	8.4	$	11.1	$	400.1	$	6.0	$	690.5
Current-period gross charge-offs	—		—		—		—		—		—		—		—		—

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial real estate non-owner occupied:
Pass	$	1,162.6	$	861.3	$	661.1	$	467.6	$	241.5	$	890.4	$	29.2	$	4,313.7
Special mention	1.0		6.8		2.3		4.6		—		7.4		—		22.1
Substandard	0.1		13.9		10.8		18.2		19.6		9.8		—		72.4
Total	$	1,163.7	$	882.0	$	674.2	$	490.4	$	261.1	$	907.6	$	29.2	$	4,408.2
Commercial real estate owner occupied:
Pass	$	793.0	$	718.7	$	533.9	$	266.3	$	165.8	$	551.3	$	18.2	$	3,047.2
Special mention	10.9		14.2		12.3		6.1		5.6		5.5		1.1		55.7
Substandard	8.4		3.0		2.3		8.9		8.5		17.2		0.5		48.8
Doubtful	0.4		1.4		—		—		—		—		—		1.8
Total	$	812.7	$	737.3	$	548.5	$	281.3	$	179.9	$	574.0	$	19.8	$	3,153.5
Commercial multi-family:
Pass	$	369.2	$	204.9	$	189.0	$	52.1	$	35.0	$	113.7	$	1.0	$	964.9
Special mention	—		—		—		—		—		1.7		—		1.7
Substandard	—		—		—		—		—		0.3		—		0.3
Total	$	369.2	$	204.9	$	189.0	$	52.1	$	35.0	$	115.7	$	1.0	$	966.9
Land, acquisition and development:
Pass	$	152.5	$	114.4	$	29.5	$	17.0	$	10.9	$	28.4	$	22.2	$	374.9
Special mention	6.7		—		—		—		0.2		0.3		—		7.2
Substandard	—		0.3		0.2		—		—		0.4		—		0.9
Doubtful	—		3.2		—		—		—		—		—		3.2
Total	$	159.2	$	117.9	$	29.7	$	17.0	$	11.1	$	29.1	$	22.2	$	386.2
Residential construction:
Pass	$	118.4	$	119.9	$	0.4	$	0.3	$	0.4	$	5.8	$	270.1	$	515.3
Substandard	—		0.5		—		—		—		0.4		—		0.9
Total	$	118.4	$	120.4	$	0.4	$	0.3	$	0.4	$	6.2	$	270.1	$	516.2
Commercial construction:
Pass	$	442.7	$	374.8	$	89.7	$	45.9	$	0.4	$	—	$	10.6	$	964.1
Special mention	2.3		—		23.1		—		—		—		11.3		36.7
Substandard	16.8		24.4		—		—		—		—		—		41.2
Total	$	461.8	$	399.2	$	112.8	$	45.9	$	0.4	$	—	$	21.9	$	1,042.0
Agricultural real estate:
Pass	$	180.0	$	172.8	$	109.5	$	64.8	$	46.6	$	105.1	$	31.4	$	710.2
Special mention	22.4		0.7		1.2		2.6		10.0		3.2		11.0		51.1
Substandard	1.8		12.3		3.5		0.6		2.7		11.3		0.1		32.3
Doubtful	—		—		1.3		—		—		—		—		1.3
Total	$	204.2	$	185.8	$	115.5	$	68.0	$	59.3	$	119.6	$	42.5	$	794.9
Commercial and floor plans:
Pass	$	501.7	$	358.9	$	214.4	$	124.3	$	120.3	$	171.1	$	631.6	$	2,122.3
Special mention	15.9		6.8		1.3		4.4		0.9		4.9		18.5		52.7
Substandard	9.8		3.3		3.7		3.4		3.2		2.1		47.2		72.7
Doubtful	0.3		1.3		—		—		—		—		0.1		1.7
Total	$	527.7	$	370.3	$	219.4	$	132.1	$	124.4	$	178.1	$	697.4	$	2,249.4

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial purpose secured by 1-4 family:
Pass	$	191.7	$	134.5	$	69.8	$	30.4	$	29.9	$	39.5	$	28.9	$	524.7
Special mention	0.1		1.2		2.1		0.2		1.4		0.2		—		5.2
Substandard	0.2		0.3		0.1		0.3		0.9		1.2		—		3.0
Total	$	192.0	$	136.0	$	72.0	$	30.9	$	32.2	$	40.9	$	28.9	$	532.9
Agricultural:
Pass	$	127.2	$	59.7	$	31.8	$	10.6	$	8.6	$	3.1	$	375.1	$	616.1
Special mention	26.1		2.8		0.4		1.0		0.3		—		26.2		56.8
Substandard	22.8		4.6		2.8		0.6		1.2		0.2		0.8		33.0
Doubtful	—		0.5		—		—		—		—		—		0.5
Total	$	176.1	$	67.6	$	35.0	$	12.2	$	10.1	$	3.3	$	402.1	$	706.4

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, 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	$	38.6	$	317.5	$	513.2	$	512.8	$	92.3	$	227.2	$	475.6	$	24.5	$	2,201.7
Nonperforming	0.7		1.6		1.0		0.6		0.8		5.8		—		—		10.5
Total	$	39.3	$	319.1	$	514.2	$	513.4	$	93.1	$	233.0	$	475.6	$	24.5	$	2,212.2
Current-period gross charge-offs	0.3		—		0.1		0.1		—		0.1		—		—		0.6
Consumer indirect:
Performing	$	142.5	$	292.4	$	128.3	$	92.3	$	38.5	$	54.3	$	—	$	—	$	748.3
Nonperforming	0.4		1.2		0.7		0.4		0.2		0.5		—		—		3.4
Total	$	142.9	$	293.6	$	129.0	$	92.7	$	38.7	$	54.8	$	—	$	—	$	751.7
Current-period gross charge-offs	0.2		2.0		1.6		0.6		0.2		0.6		—		—		5.2
Consumer direct and advance lines:
Performing	$	35.3	$	36.8	$	21.1	$	10.8	$	4.4	$	7.0	$	26.5	$	0.2	$	142.1
Nonperforming	—		0.1		0.1		—		—		—		—		—		0.2
Total	$	35.3	$	36.9	$	21.2	$	10.8	$	4.4	$	7.0	$	26.5	$	0.2	$	142.3
Current-period gross charge-offs	0.1		0.3		0.2		0.3		0.1		2.1		0.1		—		3.2
Consumer credit card:
Performing	$	—	$	—	$	—	$	—	$	—	$	—	$	71.1	$	—	$	71.1
Nonperforming	—		—		—		—		—		—		0.5		—		0.5
Total	$	—	$	—	$	—	$	—	$	—	$	—	$	71.6	$	—	$	71.6
Current-period gross charge-offs	—		—		—		—		—		—		2.0		—		2.0

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Residential 1-4 family:
Performing	$	258.9	$	490.3	$	541.6	$	98.0	$	32.0	$	213.8	$	—	$	1,634.6
Nonperforming	—		0.2		0.1		0.5		0.3		3.7		—		4.8
Total	$	258.9	$	490.5	$	541.7	$	98.5	$	32.3	$	217.5	$	—	$	1,639.4
Consumer home equity and HELOC:
Performing	$	23.8	$	8.0	$	5.2	$	5.5	$	5.6	$	15.2	$	482.8	$	546.1
Nonperforming	0.6		0.3		0.2		0.2		0.1		1.2		0.2		2.8
Total	$	24.4	$	8.3	$	5.4	$	5.7	$	5.7	$	16.4	$	483.0	$	548.9
Consumer indirect:
Performing	$	380.3	$	176.4	$	130.0	$	59.7	$	33.6	$	46.3	$	—	$	826.3
Nonperforming	1.0		0.9		0.6		0.3		0.2		0.4		—		3.4
Total	$	381.3	$	177.3	$	130.6	$	60.0	$	33.8	$	46.7	$	—	$	829.7
Consumer direct and advance lines:
Performing	$	52.6	$	31.9	$	18.2	$	8.5	$	6.5	$	8.9	$	25.8	$	152.4
Nonperforming	0.1		0.1		0.1		—		—		0.1		0.1		0.5
Total	$	52.7	$	32.0	$	18.3	$	8.5	$	6.5	$	9.0	$	25.9	$	152.9

While the Company considers the performance of the loan portfolio on the allowance for credit losses, for certain credit card loan classes, the Company also evaluates credit quality based on the aging status of the loan, which was previously presented, and by payment activity of the credit card holder. The following table presents the recorded investment in credit card loans based on payment activity for the periods indicated:

As of December 31, 2022	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	75.4	$	100.0	$	1.9	$	177.3
Nonperforming	0.5		0.3		—		0.8
Total credit card	$	75.9	$	100.3	$	1.9	$	178.1

In the normal course of business, there were no material purchases of portfolio loans and no material sales of loans held for investment during the three and the nine months ended September 30, 2023 or 2022.

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Other Real Estate Owned

9 Months Ended

Sep. 30, 2023

Repossessed Assets [Abstract]

Other Real Estate Owned

Other real estate owned (“OREO”) is a category of real estate owned by the Company as a result of 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,
	2023		2022		2023		2022
Beginning balance	$	14.4	$	16.8	$	12.7	$	2.0
Acquired through acquisition	—		—		—		15.8
Additions	—		0.3		2.5		0.4
Valuation adjustments	(0.3)		(0.2)		(1.1)		(0.2)
Dispositions	(2.5)		(0.5)		(2.5)		(1.6)
Ending balance	$	11.6	$	16.4	$	11.6	$	16.4

The carrying value of foreclosed residential real estate properties included in OREO was not material as of September 30, 2023 and December 31, 2022. The Company had $0.4 million and no material 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, 2023 and December 31, 2022, respectively.

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Derivatives and Hedging Activities

9 Months Ended

Sep. 30, 2023

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 through the use of 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.

In the normal course of business, the Company enters into interest rate lock commitments to finance residential mortgage loans that are not designated as accounting hedges. These commitments, which contain fixed expiration dates, offer the borrower an interest rate guarantee, provided the loan meets underwriting guidelines, and closes within the timeframe established by the Company. Interest rate risk arises on these commitments and subsequently on closed loans if interest rates change between the time of the interest rate lock and the delivery of the loan to the investor. Loan commitments related to residential mortgage loans intended to be sold are considered derivatives and are recorded at fair value with changes in fair value recorded through earnings.

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 (loss).

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 for the most part 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. Interest rate swaps that were designated as cash flow hedges on the variable-rate borrowings (trust preferred securities) involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. During 2021 and the first quarter of 2022, such derivatives were used to hedge the variable cash flows associated with the existing trust preferred securities. The trades that the Company had in place on its trust preferred securities matured during the first and second quarters of 2022.

As part of the Company’s overall asset and liability management strategy, in August 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. Each of the collars designated as cash flow hedges synthetically fixes the interest income received by the Company when the collar index falls below a floor rate on a rate reset during the term of the collar and when the collar index exceeds the cap rate on a rate reset during the term of the collar without exchange of the underlying notional amount.

In October 2022, the Company 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. Each of these swaps designated as cash flow hedges synthetically fixes the interest income received by the Company without exchange of the underlying notional amount. Of the six trades with a total notional amount of $1.15 billion, four are effective with a total notional of $600.0 million. Of these effective trades, the two collars and one swap are related to variable-rate loans and the other swap is related to variable-rate securities.

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 (expense) 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 (expense) when interest payments are made on the Company’s variable-rate liabilities. During the next twelve months, the Company estimates that $15.0 million will be reclassified as an increase to interest expense.

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.

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, 2023				December 31, 2022
	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	$	192.9	$	7.1	$	191.9	$	8.1

Non-designated Hedge Derivatives

Derivatives 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 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 GWB 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 take into account 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, 2023					December 31, 2022
	Notional Amount		Consolidated Balance Sheet Location	Estimated Fair Value		Notional Amount		Consolidated Balance Sheet Location	Estimated Fair Value
Derivatives designated as accounting hedges:
Interest rate swap contracts	$	—		$	—	$	550.0		$	3.5
Derivatives not designated as accounting hedges:
Interest rate swap contracts	1,638.8			57.4		1,728.1			41.6
Forward loan sales contracts	8.0			—		12.6			0.1
Derivative assets	$	1,646.8	Other assets	$	57.4	$	2,290.7	Other assets	$	45.2
Derivatives designated as accounting hedges:
Interest rate collars	$	300.0		$	7.3	$	300.0		$	5.4
Interest rate swap contracts	850.0			18.6		300.0			0.3
Derivatives not designated as accounting hedges:
Interest rate swap contracts	1,638.8			184.1		1,728.1			153.9
Risk participation agreements	102.2			—		106.1			—
Interest rate lock commitments	7.0			—		14.8			—
Derivative liabilities	$	2,898.0	Accounts payable and accrued expenses	$	210.0	$	2,449.0	Accounts payable and accrued expenses	$	159.6

There was an unrealized fair value loss on cash flow hedging derivative instruments in accumulated other comprehensive income of $25.1 million and $31.2 million during the three and the nine months ended September 30, 2023. There were $5.6 million effects of derivative instruments in fair value or cash flow hedge accounting on accumulated other comprehensive loss during the three and the nine months ended September 30, 2022.

There were no material effects from the Company’s fair value or cash flow hedged derivative financial instruments on the consolidated statements of income during the three and the nine months ended September 30, 2023 or 2022.

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,
		2023		2022			2023		2022
	Location of Gain (Loss) Recognized in Income on Derivative	Amount of Gain (Loss) Recognized in Income on Derivative				Location of Loss Recognized in Income on Derivative	Amount of Loss Recognized in Income on Derivative
Interest rate lock commitments	Mortgage banking revenues	$	0.1	$	(0.2)	Mortgage banking revenues	$	(0.1)	$	(1.7)

The Company recorded swap fee revenues of $0.1 million and $2.5 million for the three months ended September 30, 2023 and September 30, 2022, and $0.7 million and $5.6 million for the nine months ended September 30, 2023 and September 30, 2022. The Company includes swap fee revenues in other service charges, commissions, and fees on the consolidated statements of income.

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, 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 contracts	$	57.4	$	—	$	57.4	$	—	$	38.6	$	18.8
Total derivatives	57.4		—		57.4		—		38.6		18.8
Total assets	$	57.4	$	—	$	57.4	$	—	$	38.6	$	18.8
(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	$	210.0	$	—	$	210.0	$	—	$	1.0	$	209.0
Total derivatives	210.0		—		210.0		—		1.0		209.0
Repurchase agreements	889.5		—		889.5		—		889.5		—
Total liabilities	$	1,099.5	$	—	$	1,099.5	$	—	$	890.5	$	209.0

	December 31, 2022
	Gross Assets Recognized		Gross Assets Offset in the Balance Sheet		Net Assets in the Balance Sheet		Financial Instruments		Cash Collateral Received		Net Amount
Interest rate swap contracts	$	45.1	$	—	$	45.1	$	—	$	45.1	$	—
Mortgage related derivatives	0.1		—		0.1		—		—		0.1
Total derivatives	45.2		—		45.2		—		45.1		0.1
Total assets	$	45.2	$	—	$	45.2	$	—	$	45.1	$	0.1
	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 contracts	$	159.6	$	—	$	159.6	$	—	$	—	$	159.6
Total derivatives	159.6		—		159.6		—		—		159.6
Repurchase agreements	1,052.9		—		1,052.9		—		1,052.9		—
Total liabilities	$	1,212.5	$	—	$	1,212.5	$	—	$	1,052.9	$	159.6

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 each of its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company's default on the indebtedness.

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, 2023 or December 31, 2022, it could have been required to settle its obligations under the agreements at the termination value.

As of September 30, 2023, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, was $0.9 million related to these agreements. As of September 30, 2023, the Company has minimum collateral posting thresholds with certain of its derivative counterparties and has $0.1 million posted excess collateral. If the Company had breached any of these provisions at September 30, 2023, it could have been required to settle its obligations under the agreements at their termination value.

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Other Borrowed Funds

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Long-Term Debt

At September 30, 2023, the Company had $2,067.0 million in outstanding FHLB borrowings, as compared to $2,327.0 million outstanding borrowings with the FHLB at December 31, 2022. At September 30, 2023, the Company has remaining available lines of credit with the FHLB of approximately $4,764.4 million, subject to collateral availability. The borrowings are collateralized by certain loans and securities with an advance equivalent collateral value of $6,831.4 million. As of September 30, 2023 and December 31, 2022, there were no long or short-term advances outstanding with the FHLB. As of September 30, 2023 and December 31, 2022, the Company had no other material outstanding borrowings classified as other borrowed funds.

The following table presents outstanding FHLB borrowings by maturity buckets for the dates indicated:

As of September 30, 2023	Average Rate		Outstanding Balance
Fixed rate borrowings with tenors of up to one week	5.52	%	$	106.0
Fixed rate borrowings with tenors of up to two weeks	5.51		100.0
Fixed rate borrowings with tenors of up to one month	5.50		925.0
Two-month fixed rate borrowings	5.56		500.0
Five-month fixed rate borrowings	5.56		436.0
			$	2,067.0
As of December 31, 2022	Rate		Outstanding Balance
Variable rate overnight borrowings	4.60	%	$	827.0
Fixed rate borrowings in tenors of up to one month	4.48		1,500.0
			$	2,327.0

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Capital Stock

9 Months Ended

Sep. 30, 2023

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. At the effective time of the conversion, each outstanding share of the 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. Accordingly, all references to Class A common stock in these financial statements and notes refer to the role of the Class A common stock in the GWB acquisition while all other references to the Company’s common capital stock have been retroactively changed to reference common stock.

The Company had 105,011,371 shares and 104,442,023 shares of common stock outstanding as of September 30, 2023 and December 31, 2022, respectively.

The Company completed the stock repurchase program adopted by the Company’s board of directors in 2022 and the Company’s board of directors has not authorized a stock repurchase program for 2023. There were 3,729,300 shares repurchased and retired under the stock repurchase program during the three months ended September 30, 2022 at a total cost of $133.1 million, including costs and commissions, at an average cost of $40.59 per share. There were 5.0 million shares repurchased and retired during the nine months ended September 30, 2022 at a total cost of $197.4 million, including costs and commissions, at an average cost of $39.48.

Other stock repurchases during the nine months ended September 30, 2023 and 2022, were redemptions of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants in the Company’s equity compensation plans.

During the nine months ended September 30, 2023, the Company issued 54,414 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.

On May 25, 2023, the Company filed a Registration Statement on Form S-8 to register an additional 2,000,000 shares of common stock to be issued pursuant to the Company's 2023 Equity and Incentive Plan.

On May 26, 2023, the Company filed a universal shelf registration statement on Form S-3, which was subsequently declared effective by the SEC. The shelf registration statement allows the Company to raise additional capital from time to time through offers and sales of registered securities consisting of debt securities, preferred stock, depositary shares, common stock, warrants, purchase contracts, and units or units consisting of any combination of the foregoing securities. The Company may sell these securities using the prospectus in the shelf registration statement, together with applicable prospectus supplements, from time to time, in one or more offerings.

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Earnings per Common Share

9 Months Ended

Sep. 30, 2023

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,
	2023		2022		2023		2022
Net income	$	72.7	$	85.7	$	196.0	$	116.4
Weighted average common shares outstanding for basic earnings per share computation	103,822,311		106,525,974		103,793,851		102,879,422
Dilutive effects of stock-based compensation	4,116		63,725		30,425		55,938
Weighted average common shares outstanding for diluted earnings per common share computation	103,826,427		106,589,699		103,824,276		102,935,360
Basic earnings per common share	$	0.70	$	0.80	$	1.89	$	1.13
Diluted earnings per common share	0.70		0.80		1.89		1.13
Anti-dilutive unvested time restricted stock	162,231		48,871		162,231		51,161

The Company had 967,996 and 481,567 shares of unvested restricted stock as of September 30, 2023 and 2022, respectively, that were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met.

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Regulatory Capital

9 Months Ended

Sep. 30, 2023

Banking and Thrift, Other Disclosure [Abstract]

Regulatory Capital

As of September 30, 2023 and December 31, 2022, 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, 2023 and December 31, 2022 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, 2023	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,957.6	13.19	%	$	1,794.5	8.00	%	$	2,355.3	10.50	%	$	2,243.1	10.00	%
FIB	2,782.1		12.43		1,790.8		8.00		2,350.5		10.50		2,238.6		10.00
Tier 1 risk-based capital:
Consolidated	2,471.6		11.02		1,345.9		6.00		1,906.6		8.50		1,794.5		8.00
FIB	2,553.7		11.41		1,343.1		6.00		1,902.8		8.50		1,790.8		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,471.6		11.02		1,009.4		4.50		1,570.2		7.00		1,458.0		6.50
FIB	2,553.7		11.41		1,007.3		4.50		1,567.0		7.00		1,455.1		6.50
Leverage capital ratio:
Consolidated	2,471.6		8.22		1,202.8		4.00		1,202.8		4.00		1,503.5		5.00
FIB	2,553.7		8.50		1,201.1		4.00		1,201.1		4.00		1,501.3		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, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,875.8	12.48	%	$	1,843.2	8.00	%	$	2,419.2	10.50	%	$	2,304.0	10.00	%
FIB	2,713.5		11.80		1,839.6		8.00		2,414.5		10.50		2,299.5		10.00
Tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,382.4		6.00		1,958.4		8.50		1,843.2		8.00
FIB	2,504.1		10.89		1,379.7		6.00		1,954.6		8.50		1,839.6		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,036.8		4.50		1,612.8		7.00		1,497.6		6.50
FIB	2,504.1		10.89		1,034.8		4.50		1,609.7		7.00		1,494.7		6.50
Leverage capital ratio:
Consolidated	2,408.8		7.75		1,242.9		4.00		1,242.9		4.00		1,553.6		5.00
FIB	2,504.1		8.07		1,241.1		4.00		1,241.1		4.00		1,551.4		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 reduction to retained earnings 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 ASC 326 on their regulatory capital computations. This interim rule is in addition to the three-year transition period already in place under the capital transition rule previously issued in February 2019. Banking organizations can elect to mitigate the estimated cumulative regulatory capital effects for an additional two years. This rule allows an institution to defer incorporating the impact of ASC 326 into its regulatory capital calculation, including ratios, over an extended period. Additionally, the interim rule extends the transition period whereby an institution can defer the impact from ASC 326 on the current period, determined based on the difference between the new ASC 326 allowance for credit losses and the allowance for loan losses under the incurred loss method from previous GAAP, for up to two years. The total impact related to ASC 326 would then be transitioned into regulatory capital and the associated ratios over a three-year transition period, beginning after the initial two-year deferral period, for a total transition period of five years. The Company elected to opt into the transition election and adopted transition relief over the permissible five-year period.

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Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

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, 2023, the Company had commitments under construction contracts of $7.0 million.

Residential mortgage loans sold to investors in the secondary market are sold with varying recourse provisions. Essentially all the loan sales agreements require the repurchase of a mortgage loan by the seller in situations such as breach of representation, warranty, or covenant; untimely document delivery; false or misleading statements; failure to obtain certain certificates or insurance; or unmarketability. Certain loan sales agreements contain repurchase requirements based on payment-related defects that are defined in terms of the number of days or months since the purchase, the sequence number of the payment, and/or the number of days of payment delinquency. Based on the specific terms stated in the agreements, the Company had $0.8 million of sold residential mortgage loans with recourse provisions still in effect as of September 30, 2023.

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Financial Instruments with Off-Balance Sheet Risk

9 Months Ended

Sep. 30, 2023

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,
	2023		2022		2023		2022
Beginning balance	$	20.8	$	6.2	$	16.2	$	3.8
Provision for credit loss expense	(2.0)		3.5		2.6		5.9
Ending balance	$	18.8	$	9.7	$	18.8	$	9.7

	September 30, 2023		December 31, 2022
Unused credit card lines	$	805.1	$	827.6
Commitments to extend credit	4,441.0		5,173.3
Standby letters of credit	94.7		93.8

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Other Comprehensive Income/Loss

9 Months Ended

Sep. 30, 2023

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,	2023		2022		2023		2022		2023		2022
Investment securities available-for sale:
Change in net unrealized losses during the period	$	(72.1)	$	(236.4)	$	(17.9)	$	(53.4)	$	(54.2)	$	(183.0)
Reclassification adjustment for net losses included in income	—		24.2		—		5.5		—		18.7
Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity	(0.3)		(1.7)		(0.1)		(0.4)		(0.2)		(1.3)
Change in net unrealized loss on derivatives	(11.0)		(15.9)		(2.7)		(3.6)		(8.3)		(12.3)
Total other comprehensive loss	$	(83.4)	$	(229.8)	$	(20.7)	$	(51.9)	$	(62.7)	$	(177.9)

	Pre-tax				Tax Expense (Benefit)				Net of Tax
Nine Months Ended September 30,	2023		2022		2023		2022		2023		2022
Investment securities available-for sale:
Change in net unrealized losses during period	$	(51.4)	$	(650.6)	$	(12.7)	$	(161.3)	$	(38.7)	$	(489.3)
Reclassification adjustment for net losses included in net income	23.5		24.4		5.8		5.5		17.7		18.9
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(7.2)		0.2		(1.8)		0.1		(5.4)		0.1
Net change in unamortized losses on available-for-sale securities transferred into held-to-maturity	(1.1)		(25.6)		(0.3)		(6.3)		(0.8)		(19.3)
Change in net unrealized loss on derivatives	(23.1)		(9.6)		(5.7)		(2.5)		(17.4)		(7.1)
Total other comprehensive loss	$	(59.3)	$	(661.2)	$	(14.7)	$	(164.5)	$	(44.6)	$	(496.7)

The components of accumulated other comprehensive loss, net of related tax effects, are as follows:

	September 30, 2023		December 31, 2022
Net unrealized loss on investment securities available-for-sale	$	(497.4)	$	(471.0)
Net unrealized loss on investment securities transferred to held-to-maturity	(5.4)		(4.5)
Net unrealized loss on derivatives	(18.9)		(1.6)
Net accumulated other comprehensive loss	$	(521.7)	$	(477.1)

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Fair Value Measurements

9 Months Ended

Sep. 30, 2023

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 during the three and the nine months ended September 30, 2023 and 2022.

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 during the three and the nine months ended September 30, 2023 and 2022.

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 change in the value of derivative assets attributable to basis risk, or the risk that offsetting investments in a hedging strategy will not experience price changes in entirely opposite directions, was not significant in the reported periods. The Company also compares the reasonableness of the pricing semi-annually 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 the 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 change in the value of derivative assets attributable to basis risk, or the risk that offsetting investments in a hedging strategy will not experience price changes in entirely opposite directions, was not significant in the reported periods. The Company also compares the reasonableness of the pricing semi-annually 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, 2023	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Investment debt securities available-for-sale:
U.S. Treasury notes	$	215.9	$	—	$	215.9	$	—
State, county, and municipal securities	202.6			—	202.6			—
Obligations of U.S. government agencies	162.0			—	162.0			—
U.S. agency commercial mortgage-backed securities	1,066.9			—	1,066.9			—
U.S. agency residential mortgage-backed securities	1,285.0			—	1,285.0			—
Collateralized mortgage obligations	1,143.7			—	1,143.7			—
Private mortgage-backed securities	207.3			—	207.3			—
Collateralized loan obligations	1,117.8			—	1,117.8			—
Corporate securities	226.5			—	226.5			—
Loans held for sale	3.2			—	3.2			—
Derivative assets:
Interest rate swap contracts	57.4			—	57.4			—
Derivative liabilities:
Interest rate collars	7.3			—	7.3			—
Interest rate swap contracts	202.7			—	202.7			—
Interest rate lock commitments	—			—	—			—
Deferred compensation plan assets	19.2			—	19.2			—
Deferred compensation plan liabilities	19.2			—	19.2			—

			Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Investment debt securities available-for-sale:
U.S. Treasury notes	$	642.7	$	—	$	642.7	$	—
State, county and municipal securities	263.7			—	263.7			—
Obligations of U.S. government agencies	198.9			—	198.9			—
U.S. agency commercial mortgage-backed securities	1,351.2			—	1,351.2			—
U.S. agency residential mortgage-backed securities	1,558.3			—	1,558.3			—
Collateralized mortgage obligations	1,350.2			—	1,350.2			—
Private mortgage-backed securities	228.0			—	228.0			—
Collateralized loan obligations	1,111.6			—	1,111.6			—
Corporate securities	241.5			—	241.5			—
Loans held for sale	12.4			—	6.9			5.5
Derivative assets:
Interest rate swap contracts	45.1			—	45.1			—
Forward loan sales contracts	0.1			—	0.1			—
Derivative liabilities
Interest rate collars	5.4			—	5.4			—
Interest rate swap contracts	154.2			—	154.2			—
Deferred compensation plan assets	18.7			—	18.7			—
Deferred compensation plan liabilities	18.7			—	18.7			—

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, 2023	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral-dependent loans	$	56.3	$	—	$	—	$	56.3
Loans held for sale	55.9			—		—	55.9
Other real estate owned	11.6			—		—	11.6
Long-lived assets to be disposed of by sale	4.5			—		—	4.5
				Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral-dependent loans	$	39.1	$	—	$	—	$	39.1
Loans held for sale	67.5			—		—	67.5
Other real estate owned	12.7			—		—	12.7
Long-lived assets to be disposed of by sale	5.5			—		—	5.5

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, 2023 and December 31, 2022, the Company had collateral-dependent loans with a carrying and fair value of $56.3 million and $39.1 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. The Company had $1.1 million and $0.2 million of write downs on OREO properties during the nine months ended September 30, 2023 and 2022, respectively.

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, 2023, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $9.1 million, reduced by write-downs of $4.6 million charged to other expense, and fair values aggregating $4.5 million. As of December 31, 2022, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $5.7 million, reduced by write-downs of $0.2 million charged to other expense, and fair values aggregating $5.5 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, 2023		December 31, 2022		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Collateral-dependent loans	$	56.3	$	39.1	Appraisal	Appraisal adjustment	0%	-	45%	(7%)
Loans held for sale	55.9		67.5		Fair value of collateral	Discount for type of property, age of appraisal, and current status	11%	-	23%	(17%)
Other real estate owned	11.6		12.7		Appraisal	Appraisal adjustment	15%	-	36%	(22%)
Long-lived assets to be disposed of by sale	4.5		5.5		Appraisal	Appraisal adjustment	0%	-	6%	(3%)

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, 2023	Carrying Amount		Estimated Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	$	593.1	$	593.1	$	593.1	$	—	$	—
Investment debt securities available-for-sale	5,627.7		5,627.7		—		5,627.7		—
Investment debt securities held-to-maturity	3,259.5		2,796.1		—		2,796.1		—
Accrued interest receivable	129.2		129.2		—		129.2		—
Mortgage servicing rights, net	29.1		35.6		—		35.6		—
Loans held for sale	59.1		59.1		—		3.2		55.9
Net loans held for investment	17,986.6		17,226.1		—		17,169.8		56.3
Derivative assets	57.4		57.4		—		57.4		—
Deferred compensation plan assets	19.2		19.2		—		19.2		—
Total financial assets	$	27,760.9	$	26,543.5	$	593.1	$	25,838.2	$	112.2
Financial liabilities:
Total deposits, excluding time deposits	$	20,516.8	$	20,516.8	$	20,516.8	$	—	$	—
Time deposits	3,162.7		3,126.2		—		3,126.2		—
Securities sold under repurchase agreements	889.5		889.5		—		889.5		—
Other borrowed funds	2,067.0		2,067.0		—		2,067.0		—
Accrued interest payable	63.7		63.7		—		63.7		—
Long-term debt	120.8		114.4		—		114.4		—
Subordinated debentures held by subsidiary trusts	163.1		152.5		—		152.5		—
Derivative liabilities	210.0		210.0		—		210.0		—
Deferred compensation plan liabilities	19.2		19.2		—		19.2		—
Total financial liabilities	$	27,212.8	$	27,159.3	$	20,516.8	$	6,642.5	$	—

					Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Carrying Amount		Estimated Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	$	870.5	$	870.5	$	870.5	$	—	$	—
Investment debt securities available-for-sale	6,946.1		6,946.1		—		6,946.1		—
Investment debt securities held-to-maturity	3,451.8		3,052.2		—		3,052.2		—
Accrued interest receivable	118.3		118.3		—		118.3		—
Mortgage servicing rights, net	31.1		37.4		—		37.4		—
Loans held for sale	79.9		79.9		—		6.9		73.0
Net loans held for investment	17,879.1		17,552.1		—		17,513.0		39.1
Derivative assets	45.2		45.2		—		45.2		—
Deferred compensation plan assets	18.7		18.7		—		18.7		—
Total financial assets	$	29,440.7	$	28,720.4	$	870.5	$	27,737.8	$	112.1
Financial liabilities:
Total deposits, excluding time deposits	$	23,145.2	$	23,145.2	$	23,145.2	$	—	$	—
Time deposits	1,928.4		1,876.1		—		1,876.1		—
Securities sold under repurchase agreements	1,052.9		1,052.9		—		1,052.9		—
Other borrowed funds	2,327.0		2,327.0		—		2,327.0		—
Accrued interest payable	14.5		14.5		—		14.5		—
Long-term debt	120.8		116.3		—		116.3		—
Subordinated debentures held by subsidiary trusts	163.1		155.8		—		155.8		—
Derivative liabilities	159.6		159.6		—		159.6		—
Deferred compensation plan liabilities	18.7		18.7		—		18.7		—
Total financial liabilities	$	28,930.2	$	28,866.1	$	23,145.2	$	5,720.9	$	—

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Recent Authoritative Accounting Guidance

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Recent Authoritative Accounting Guidance

Recent Authoritative Accounting GuidanceASU 2020-04, “Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Accounting.” In March 2020, the FASB issued ASU 2020-04, which provides temporary exceptions that are optional for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. For transactions that are modified because of reference rate reform and that meet certain scope guidance (i) modifications of loan agreements should be accounted for by prospectively adjusting the effective interest rate, with such modification considered to be "minor" so that any existing unamortized origination fees/costs will carry forward and continue to be amortized and (ii) modifications of lease agreements should be accounted for as a continuation of the existing agreement with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required for modifications will not be accounted for as separate contracts. ASU 2020-04 is effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within the Codification, the amendments in this ASU must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company adopted certain elections related to cash flow hedges which did not have a significant impact on the Company’s financial position or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2020-04 can generally be applied through December 31, 2024.

ASU 2021-01, “Reference Rate Reform (Topic 848)” In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform Topic 848, that clarifies certain exceptions that are optional in Topic 848 for contract modifications and hedge accounting and apply those exceptions to derivatives that are affected by the discounting transition. An entity may elect to apply the amendments in this ASU on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to the date of the issuance of a final ASU. If an entity elects to apply any of the amendments in this ASU for an eligible hedging relationship, any adjustments as a result of those elections must be reflected as of the date the entity applies the election. The amendments in this ASU do not apply to contract modifications made, new hedging relationships entered into, or existing hedging relationships evaluated for effectiveness in periods after December 31, 2022, except for hedging relationships existing as of December 31, 2022, that apply certain exceptions that are optional in which the accounting effects of the hedging activity are recorded through the end of the hedging relationship. 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 or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2021-01 can generally be applied through December 31, 2024.

ASU 2021-08, “Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers” In October 2021, the FASB issued ASU 2021-08, Business Combinations Topic 805, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, to address diversity in practice and inconsistency related to the accounting for revenue contracts with customers acquired in a business combination. The amendments require that an entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606 as if it had originated the contracts. The amendments also provide certain practical expedients for acquirers when recognizing and measuring acquired contract assets and contract liabilities from revenue contracts in a business combination and applies to contract assets and contract liabilities from other contracts to which the provisions of Topic 606 apply. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. Entities should apply the amendments prospectively to business combinations that occur after the effective date. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-01, “Derivatives and Hedging (Topic 815), Fair Value Hedging—Portfolio Layer Method” In March 2022, the FASB issued ASU 2022-01, Derivatives and Hedging Topic 815, Fair Value Hedging—Portfolio Layer Method that clarifies the accounting for and promotes consistency in the reporting of hedge basis adjustments applicable to both a single hedged layer and multiple hedged layers. The amendments allow nonprepayable financial assets also to be included in a closed portfolio hedged using the portfolio layer method. That expanded scope permits an entity to apply the same portfolio hedging method to both prepayable and nonprepayable financial assets, thereby allowing consistent accounting for similar hedges. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings and Vintage Disclosures” In March 2022, the FASB issued ASU 2022-02, Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings (TDRs) and Vintage Disclosures that eliminate the accounting guidance for TDRs by creditors in Subtopic 310-40, Receivables—Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Rather than applying the recognition and measurement guidance for TDRs, an entity must apply the loan refinancing and restructuring guidance to determine whether a modification results in a new loan or a continuation of an existing loan. The amendment also requires an entity disclose current-period gross writeoffs by year of origination for financing receivables and net investments in leases within the scope of Subtopic 326. The amendments are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 on a prospective basis, and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity. Prior to the adoption of ASU 2022-02, a TDR occurred when a loan to a borrower experiencing financial difficulty was restructured with a concession provided that a creditor would not otherwise consider. For the Company’s accounting policy related to TDRs granted prior to the adoption of ASU 2022-02, see “Note 1 – Summary of Significant Accounting Policies” in Part IV, Item 15 “Notes to Consolidated Financial Statements” within our Annual Report on Form 10-K for the year ended December 31, 2022. See “Note 6 – Loans Held For Investment” of these Notes to the Unaudited Consolidated Financial Statements” for further details of the amendments in this update.

ASU 2022-06, “Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848” In December 2022, the FASB issued ASU 2022-06, Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848 that extends the period of time preparers can utilize the reference rate reform relief guidance provided by ASU 2020-04 and ASU 2021-01, which are discussed above. ASU 2022-06, which was effective upon issuance, defers the sunset date of this prior guidance from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief guidance in Topic 848. The adoption of ASU 2022-06 did not have a significant impact on the Company’s financial position, results of operations, or liquidity.

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. Early adoption is permitted for all entities in any interim period. If an entity adopts the amendments in an interim period, it shall adopt them as of the beginning of the fiscal year that includes that interim period. The amendments must be applied on either a modified retrospective or a retrospective basis (except for certain LIHTC investments not accounted for using the proportional amortization method). 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.

ASU 2023-05, “Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement” In August 2023, the FASB issued ASU 2023-05, Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement that requires certain joint ventures to apply a new basis of accounting upon formation by recognizing and initially measuring most of their assets and liabilities at fair value. The objectives of the amendments are to provide decision-useful information to investors and other allocators of capital in a joint venture's financial statements and also to reduce diversity in practice. These amendments are effective prospectively for all joint venture formations with a formation date on or after January 1, 2025. The Company does not anticipate the adoption of ASU 2023-05 will have a significant impact on the Company’s financial position, results of operations, or liquidity.

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Subsequent Events

9 Months Ended

Sep. 30, 2023

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 24, 2023, the Company declared a quarterly dividend to common shareholders of $0.47 per share, to be paid on November 16, 2023 to shareholders of record as of November 6, 2023.

No other undisclosed events requiring recognition or disclosure were identified.

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Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2023

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 during the three and the nine months ended September 30, 2023 and 2022.

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 during the three and the nine months ended September 30, 2023 and 2022.

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 change in the value of derivative assets attributable to basis risk, or the risk that offsetting investments in a hedging strategy will not experience price changes in entirely opposite directions, was not significant in the reported periods. The Company also compares the reasonableness of the pricing semi-annually 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 the 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 change in the value of derivative assets attributable to basis risk, or the risk that offsetting investments in a hedging strategy will not experience price changes in entirely opposite directions, was not significant in the reported periods. The Company also compares the reasonableness of the pricing semi-annually 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.

Recent Authoritative Accounting Guidance

Recent Authoritative Accounting GuidanceASU 2020-04, “Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Accounting.” In March 2020, the FASB issued ASU 2020-04, which provides temporary exceptions that are optional for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. For transactions that are modified because of reference rate reform and that meet certain scope guidance (i) modifications of loan agreements should be accounted for by prospectively adjusting the effective interest rate, with such modification considered to be "minor" so that any existing unamortized origination fees/costs will carry forward and continue to be amortized and (ii) modifications of lease agreements should be accounted for as a continuation of the existing agreement with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required for modifications will not be accounted for as separate contracts. ASU 2020-04 is effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within the Codification, the amendments in this ASU must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company adopted certain elections related to cash flow hedges which did not have a significant impact on the Company’s financial position or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2020-04 can generally be applied through December 31, 2024.

ASU 2021-01, “Reference Rate Reform (Topic 848)” In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform Topic 848, that clarifies certain exceptions that are optional in Topic 848 for contract modifications and hedge accounting and apply those exceptions to derivatives that are affected by the discounting transition. An entity may elect to apply the amendments in this ASU on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to the date of the issuance of a final ASU. If an entity elects to apply any of the amendments in this ASU for an eligible hedging relationship, any adjustments as a result of those elections must be reflected as of the date the entity applies the election. The amendments in this ASU do not apply to contract modifications made, new hedging relationships entered into, or existing hedging relationships evaluated for effectiveness in periods after December 31, 2022, except for hedging relationships existing as of December 31, 2022, that apply certain exceptions that are optional in which the accounting effects of the hedging activity are recorded through the end of the hedging relationship. 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 or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2021-01 can generally be applied through December 31, 2024.

ASU 2021-08, “Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers” In October 2021, the FASB issued ASU 2021-08, Business Combinations Topic 805, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, to address diversity in practice and inconsistency related to the accounting for revenue contracts with customers acquired in a business combination. The amendments require that an entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606 as if it had originated the contracts. The amendments also provide certain practical expedients for acquirers when recognizing and measuring acquired contract assets and contract liabilities from revenue contracts in a business combination and applies to contract assets and contract liabilities from other contracts to which the provisions of Topic 606 apply. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. Entities should apply the amendments prospectively to business combinations that occur after the effective date. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-01, “Derivatives and Hedging (Topic 815), Fair Value Hedging—Portfolio Layer Method” In March 2022, the FASB issued ASU 2022-01, Derivatives and Hedging Topic 815, Fair Value Hedging—Portfolio Layer Method that clarifies the accounting for and promotes consistency in the reporting of hedge basis adjustments applicable to both a single hedged layer and multiple hedged layers. The amendments allow nonprepayable financial assets also to be included in a closed portfolio hedged using the portfolio layer method. That expanded scope permits an entity to apply the same portfolio hedging method to both prepayable and nonprepayable financial assets, thereby allowing consistent accounting for similar hedges. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings and Vintage Disclosures” In March 2022, the FASB issued ASU 2022-02, Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings (TDRs) and Vintage Disclosures that eliminate the accounting guidance for TDRs by creditors in Subtopic 310-40, Receivables—Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Rather than applying the recognition and measurement guidance for TDRs, an entity must apply the loan refinancing and restructuring guidance to determine whether a modification results in a new loan or a continuation of an existing loan. The amendment also requires an entity disclose current-period gross writeoffs by year of origination for financing receivables and net investments in leases within the scope of Subtopic 326. The amendments are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 on a prospective basis, and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity. Prior to the adoption of ASU 2022-02, a TDR occurred when a loan to a borrower experiencing financial difficulty was restructured with a concession provided that a creditor would not otherwise consider. For the Company’s accounting policy related to TDRs granted prior to the adoption of ASU 2022-02, see “Note 1 – Summary of Significant Accounting Policies” in Part IV, Item 15 “Notes to Consolidated Financial Statements” within our Annual Report on Form 10-K for the year ended December 31, 2022. See “Note 6 – Loans Held For Investment” of these Notes to the Unaudited Consolidated Financial Statements” for further details of the amendments in this update.

ASU 2022-06, “Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848” In December 2022, the FASB issued ASU 2022-06, Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848 that extends the period of time preparers can utilize the reference rate reform relief guidance provided by ASU 2020-04 and ASU 2021-01, which are discussed above. ASU 2022-06, which was effective upon issuance, defers the sunset date of this prior guidance from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief guidance in Topic 848. The adoption of ASU 2022-06 did not have a significant impact on the Company’s financial position, results of operations, or liquidity.

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. Early adoption is permitted for all entities in any interim period. If an entity adopts the amendments in an interim period, it shall adopt them as of the beginning of the fiscal year that includes that interim period. The amendments must be applied on either a modified retrospective or a retrospective basis (except for certain LIHTC investments not accounted for using the proportional amortization method). 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.

ASU 2023-05, “Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement” In August 2023, the FASB issued ASU 2023-05, Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement that requires certain joint ventures to apply a new basis of accounting upon formation by recognizing and initially measuring most of their assets and liabilities at fair value. The objectives of the amendments are to provide decision-useful information to investors and other allocators of capital in a joint venture's financial statements and also to reduce diversity in practice. These amendments are effective prospectively for all joint venture formations with a formation date on or after January 1, 2025. The Company does not anticipate the adoption of ASU 2023-05 will have a significant impact on the Company’s financial position, results of operations, or liquidity.

Financing Receivable, Allowance for Credit Losses, Policy for Uncollectible Amounts

The allowance for credit losses is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected over the life of the loans. Loans are charged off against the allowance when management confirms that a loan balance is uncollectible. The Company applies recoveries when received and has elected not to forecast recoveries for purposes of calculating the allowance for credit losses.

Management estimates the allowance balance using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. Adjustments to historical loss information are made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix and trends, asset quality, or term. Other loan-specific risk characteristics may include changes in environmental and economic conditions, such as changes in unemployment rates, property values, or other relevant factors.

The allowance for credit losses is measured on a collective basis when similar risk characteristics exist.

Annualized loss rates are recalculated quarterly, with subsequent recoveries captured in the quarter a loan was charged off and are averaged across a look back period from 2009 to the current period. Expected future principal and interest cash flows are calculated using contractual repayment terms while considering prepayment, utilization, interest rate, and probability of default assumptions. Macroeconomic models calculate segment-specific multipliers using third party forecast data. The multipliers adjust the annual loss rates to the level expected under the economic conditions over the 2-year forecast period, followed by a 1-year straight-line reversion to the unadjusted historical average loss rates. The unadjusted loss rates then apply for the remaining life of the loan. Estimated losses are totaled and aggregated to the portfolio segment level.

The Company segments the loan portfolio into pools based on the following risk characteristics: financial asset type, collateral type, loan structure, credit characteristics, outstanding loan balances, contractual terms and prepayment assumptions, utilization assumptions, industry of borrower and concentrations, and historical or expected credit loss.

Off-Balance-Sheet Credit Exposure, Policy

Allowance for Credit Losses on Off-Balance Sheet Credit Exposures. The Company estimates expected credit losses over the contractual period in which the Company is exposed to credit risk via a contractual obligation to extend credit unless that obligation is unconditionally cancellable by the Company. Management considers our unused credit card lines and federal fund lines, extended to others, to be unconditionally cancellable.

The allowance for credit losses on off-balance sheet credit exposures is adjusted as a provision for credit loss expense. The estimate considers the likelihood that funding will occur and an estimate of expected credit losses on commitments expected to be funded over the estimated life.

The Company has identified commitments to extend credit and standby letters of credit determined not to be unconditionally cancellable as categories with off-balance sheet credit exposures and uses the commitment balance, expected loss rate, expected cash flows, and utilization rate as primary assumptions to develop the allowance for credit losses on those exposures. The utilization rate represents management’s best estimate of the probability that the unfunded portion of the commitment will be funded given existing economic conditions.

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Accounting Changes and Error Corrections (Policies)

9 Months Ended

Sep. 30, 2023

Accounting Changes and Error Corrections [Abstract]

Recent Authoritative Accounting Guidance

Recent Authoritative Accounting GuidanceASU 2020-04, “Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Accounting.” In March 2020, the FASB issued ASU 2020-04, which provides temporary exceptions that are optional for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. For transactions that are modified because of reference rate reform and that meet certain scope guidance (i) modifications of loan agreements should be accounted for by prospectively adjusting the effective interest rate, with such modification considered to be "minor" so that any existing unamortized origination fees/costs will carry forward and continue to be amortized and (ii) modifications of lease agreements should be accounted for as a continuation of the existing agreement with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required for modifications will not be accounted for as separate contracts. ASU 2020-04 is effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within the Codification, the amendments in this ASU must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company adopted certain elections related to cash flow hedges which did not have a significant impact on the Company’s financial position or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2020-04 can generally be applied through December 31, 2024.

ASU 2021-01, “Reference Rate Reform (Topic 848)” In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform Topic 848, that clarifies certain exceptions that are optional in Topic 848 for contract modifications and hedge accounting and apply those exceptions to derivatives that are affected by the discounting transition. An entity may elect to apply the amendments in this ASU on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or on a prospective basis to new modifications from any date within an interim period that includes or is subsequent to the date of the issuance of a final ASU. If an entity elects to apply any of the amendments in this ASU for an eligible hedging relationship, any adjustments as a result of those elections must be reflected as of the date the entity applies the election. The amendments in this ASU do not apply to contract modifications made, new hedging relationships entered into, or existing hedging relationships evaluated for effectiveness in periods after December 31, 2022, except for hedging relationships existing as of December 31, 2022, that apply certain exceptions that are optional in which the accounting effects of the hedging activity are recorded through the end of the hedging relationship. 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 or results of operations. Based upon the amendments provided in ASU 2022-06 discussed below, ASU 2021-01 can generally be applied through December 31, 2024.

ASU 2021-08, “Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers” In October 2021, the FASB issued ASU 2021-08, Business Combinations Topic 805, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, to address diversity in practice and inconsistency related to the accounting for revenue contracts with customers acquired in a business combination. The amendments require that an entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606 as if it had originated the contracts. The amendments also provide certain practical expedients for acquirers when recognizing and measuring acquired contract assets and contract liabilities from revenue contracts in a business combination and applies to contract assets and contract liabilities from other contracts to which the provisions of Topic 606 apply. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. Entities should apply the amendments prospectively to business combinations that occur after the effective date. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-01, “Derivatives and Hedging (Topic 815), Fair Value Hedging—Portfolio Layer Method” In March 2022, the FASB issued ASU 2022-01, Derivatives and Hedging Topic 815, Fair Value Hedging—Portfolio Layer Method that clarifies the accounting for and promotes consistency in the reporting of hedge basis adjustments applicable to both a single hedged layer and multiple hedged layers. The amendments allow nonprepayable financial assets also to be included in a closed portfolio hedged using the portfolio layer method. That expanded scope permits an entity to apply the same portfolio hedging method to both prepayable and nonprepayable financial assets, thereby allowing consistent accounting for similar hedges. The amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity.

ASU 2022-02, “Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings and Vintage Disclosures” In March 2022, the FASB issued ASU 2022-02, Financial Instruments—Credit Losses (Topic 326), Troubled Debt Restructurings (TDRs) and Vintage Disclosures that eliminate the accounting guidance for TDRs by creditors in Subtopic 310-40, Receivables—Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Rather than applying the recognition and measurement guidance for TDRs, an entity must apply the loan refinancing and restructuring guidance to determine whether a modification results in a new loan or a continuation of an existing loan. The amendment also requires an entity disclose current-period gross writeoffs by year of origination for financing receivables and net investments in leases within the scope of Subtopic 326. The amendments are effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The amendments in this ASU became effective for the Company on January 1, 2023 on a prospective basis, and did not have a significant impact on the Company’s consolidated financial statements, results of operations, or liquidity. Prior to the adoption of ASU 2022-02, a TDR occurred when a loan to a borrower experiencing financial difficulty was restructured with a concession provided that a creditor would not otherwise consider. For the Company’s accounting policy related to TDRs granted prior to the adoption of ASU 2022-02, see “Note 1 – Summary of Significant Accounting Policies” in Part IV, Item 15 “Notes to Consolidated Financial Statements” within our Annual Report on Form 10-K for the year ended December 31, 2022. See “Note 6 – Loans Held For Investment” of these Notes to the Unaudited Consolidated Financial Statements” for further details of the amendments in this update.

ASU 2022-06, “Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848” In December 2022, the FASB issued ASU 2022-06, Reference Rate Reform (Topic 848), Deferral of the Sunset Date of Topic 848 that extends the period of time preparers can utilize the reference rate reform relief guidance provided by ASU 2020-04 and ASU 2021-01, which are discussed above. ASU 2022-06, which was effective upon issuance, defers the sunset date of this prior guidance from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief guidance in Topic 848. The adoption of ASU 2022-06 did not have a significant impact on the Company’s financial position, results of operations, or liquidity.

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. Early adoption is permitted for all entities in any interim period. If an entity adopts the amendments in an interim period, it shall adopt them as of the beginning of the fiscal year that includes that interim period. The amendments must be applied on either a modified retrospective or a retrospective basis (except for certain LIHTC investments not accounted for using the proportional amortization method). 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.

ASU 2023-05, “Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement” In August 2023, the FASB issued ASU 2023-05, Business Combinations—Joint Venture Formations (Subtopic 805-60), Recognition and Initial Measurement that requires certain joint ventures to apply a new basis of accounting upon formation by recognizing and initially measuring most of their assets and liabilities at fair value. The objectives of the amendments are to provide decision-useful information to investors and other allocators of capital in a joint venture's financial statements and also to reduce diversity in practice. These amendments are effective prospectively for all joint venture formations with a formation date on or after January 1, 2025. The Company does not anticipate the adoption of ASU 2023-05 will have a significant impact on the Company’s financial position, results of operations, or liquidity.

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Acquisitions (Tables)

9 Months Ended

Sep. 30, 2023

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

As of February 1, 2022
Assets acquired:
Cash and cash equivalents	$	2,006.9
Investment securities	2,699.0
Securities purchased under agreement to resell	101.1
Loans held for sale	217.0
Loans held for investment	7,705.0
Allowance for credit losses	(59.5)
Premises and equipment, including right of use lease assets	144.7
Other real estate owned	15.8
Company-owned life insurance	186.6
Core deposit intangibles	50.1
Customer relationship intangible	22.8
Mortgage servicing rights	1.3
Deferred tax assets, net	60.2
Other assets	200.8
Total assets acquired	13,351.8
Liabilities assumed:
Deposits	11,688.0
Securities sold under repurchase agreements	74.0
Accrued expenses and other liabilities	110.4
FHLB advances	122.9
Subordinated debt	36.4
Subordinated debentures held by subsidiary trusts	76.1
Total liabilities assumed	12,107.8
Net assets acquired	$	1,244.0
Consideration paid:
Class A common stock	1,723.3
Total consideration paid (1)	$	1,723.3
Goodwill	$	479.3

(1) Includes $13 thousand of cash paid in lieu of fractional shares.

Schedule of Pro Forma Financial Information

The following table presents certain unaudited pro forma financial information for illustrative purposes only, for the three and the nine month periods ended September 30, 2022 as if GWB had been acquired on January 1, 2021. This unaudited pro forma information combines the historical results of GWB with the Company’s consolidated historical results and includes certain adjustments reflecting the estimated impact of certain fair value adjustments for the respective periods. The pro forma information is not indicative of what would have occurred had the acquisition occurred at the beginning of the year prior to the acquisition. The unaudited pro forma information does not consider any changes to the provision for credit losses resulting from recording loan assets at fair value, cost savings, or business synergies. As a result, actual amounts would have differed from the unaudited pro forma information presented, and the differences could be significant.

	Three Months Ended September 30,		Nine Months Ended September 30,
	2022		2022
Total revenues	$	314.0	$	883.5
Net income	$	90.3	$	267.8
Earnings per common share (Basic)	$	0.85	$	2.60
Earnings per common share (Diluted)	$	0.85	$	2.60

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Goodwill and Core Deposit Intangibles (Tables)

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangibles

Other intangible assets are comprised of core deposit intangibles (“CDI”) and other customer relationship intangibles (“OCRI”) and amounted to the following at September 30, 2023 and December 31, 2022:

September 30, 2023	CDI		OCRI		Total
Gross other intangible assets, at January 1, 2023	$	154.7	$	22.8	$	177.5
Accumulated amortization	(89.1)		(3.2)		(92.3)
Net other intangible assets, at September 30, 2023	$	65.6	$	19.6	$	85.2
December 31, 2022
Gross other intangible assets, at January 1, 2022	$	106.0	$	—	$	106.0
Amounts established through acquisition	50.1		22.8		72.9
Reductions due to sale of health savings accounts	(1.4)		—		(1.4)
Accumulated amortization	(78.8)		(1.7)		(80.5)
Net other intangible assets, at December 31, 2022	$	75.9	$	21.1	$	97.0

Schedule of Future Amortization Expense

The following table provides the estimated aggregate future amortization expense of other intangible assets at September 30, 2023:

Years Ending December 31,	CDI		OCRI		Total
2023 remaining	$	3.4	$	0.4	$	3.8
2024	12.7		1.9		14.6
2025	11.8		1.9		13.7
2026	10.9		1.9		12.8
2027	8.2		1.9		10.1
Thereafter	18.6		11.6		30.2
Total	$	65.6	$	19.6	$	85.2

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Investment Securities (Tables)

9 Months Ended

Sep. 30, 2023

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, 2023	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	250.1	$	—	$	250.1	$	—	$	(34.2)	$	215.9
State, county, and municipal securities	257.5		—		257.5		—		(54.9)		202.6
Obligations of U.S. government agencies	179.3		—		179.3		—		(17.3)		162.0
U.S. agency commercial mortgage-backed securities	1,191.9		—		1,191.9		0.1		(125.1)		1,066.9
U.S. agency residential mortgage-backed securities	1,474.3		—		1,474.3		—		(189.3)		1,285.0
Collateralized mortgage obligations	1,302.9		—		1,302.9		—		(159.2)		1,143.7
Private mortgage-backed securities	246.4		—		246.4		—		(39.1)		207.3
Collateralized loan obligations	1,126.7		—		1,126.7		—		(8.9)		1,117.8
Corporate securities	261.1		—		261.1		—		(34.6)		226.5
Total	$	6,290.2	$	—	$	6,290.2	$	0.1	$	(662.6)	$	5,627.7

September 30, 2023	Amortized Cost1		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	398.4	$	—	$	398.4	$	—	$	(6.8)	$	391.6
State, county, and municipal securities	179.0		—		179.0		—		(34.9)		144.1
Obligations of U.S. government agencies	353.8		—		353.8		—		(59.5)		294.3
U.S. agency commercial mortgage-backed securities	515.2		—		515.2		—		(71.9)		443.3
U.S. agency residential mortgage-backed securities	1,269.8		—		1,269.8		—		(197.2)		1,072.6
Collateralized mortgage obligations	487.1		—		487.1		—		(86.2)		400.9
Corporate securities	57.0		(0.8)		56.2		—		(6.9)		49.3
Total	$	3,260.3	$	(0.8)	$	3,259.5	$	—	$	(463.4)	$	2,796.1
(1) Amortized cost presented above includes $11.4 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 $18.6 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, 2022	Amortized Cost		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	675.1	$	—	$	675.1	$	2.1	$	(34.5)	$	642.7
State, county, and municipal securities	314.3		—		314.3		—		(50.6)		263.7
Obligations of U.S. government agencies	216.2		—		216.2		—		(17.3)		198.9
U.S. agency commercial mortgage-backed securities	1,468.0		—		1,468.0		0.2		(117.0)		1,351.2
U.S. agency residential mortgage-backed securities	1,726.0		—		1,726.0		—		(167.7)		1,558.3
Collateralized mortgage obligations	1,491.5		—		1,491.5		—		(141.3)		1,350.2
Private mortgage-backed securities	264.9		—		264.9		—		(36.9)		228.0
Collateralized loan obligations	1,145.2		—		1,145.2		—		(33.6)		1,111.6
Corporate securities	272.3		—		272.3		—		(30.8)		241.5
Total	$	7,573.5	$	—	$	7,573.5	$	2.3	$	(629.7)	$	6,946.1

December 31, 2022	Amortized Cost1		Allowance for Credit Losses		Net Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	396.6	$	—	$	396.6	$	—	$	(10.2)	$	386.4
State, county, and municipal securities	181.2		(0.1)		181.1		0.2		(31.6)		149.7
Obligations of U.S. government agencies	351.7		—		351.7		—		(49.6)		302.1
U.S. agency commercial mortgage-backed securities	526.8		—		526.8		—		(58.3)		468.5
U.S. agency residential mortgage-backed securities	1,391.5		—		1,391.5		—		(166.6)		1,224.9
Collateralized mortgage obligations	525.8		—		525.8		0.2		(76.7)		449.3
Corporate securities	80.1		(1.8)		78.3		—		(7.0)		71.3
Total	$	3,453.7	$	(1.9)	$	3,451.8	$	0.4	$	(400.0)	$	3,052.2
(1) Amortized cost presented above includes $20.2 million of unamortized losses and of $14.2 million unamortized gains 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, 2023 and December 31, 2022.

	Less than 12 Months				12 Months or More				Total
September 30, 2023	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	—	$	—	$	215.9	$	(34.2)	$	215.9	$	(34.2)
State, county, and municipal securities	1.0		—		199.7		(54.9)		200.7		(54.9)
Obligations of U.S. government agencies	—		—		161.5		(17.3)		161.5		(17.3)
U.S. agency commercial mortgage-backed securities	0.3		—		1,057.8		(125.1)		1,058.1		(125.1)
U.S. agency residential mortgage-backed securities	0.9		—		1,284.0		(189.3)		1,284.9		(189.3)
Collateralized mortgage obligations	—		—		1,143.7		(159.2)		1,143.7		(159.2)
Private mortgage-backed securities	—		—		207.3		(39.1)		207.3		(39.1)
Collateralized loan obligations	—		—		1,117.8		(8.9)		1,117.8		(8.9)
Corporate securities	—		—		226.6		(34.6)		226.6		(34.6)
Total	$	2.2	$	—	$	5,614.3	$	(662.6)	$	5,616.5	$	(662.6)

	Less than 12 Months				12 Months or More				Total
December 31, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	168.8	$	(4.7)	$	170.4	$	(29.8)	$	339.2	$	(34.5)
State, county, and municipal securities	104.9		(9.0)		146.1		(41.6)		251.0		(50.6)
Obligations of U.S. government agencies	152.2		(10.1)		46.1		(7.2)		198.3		(17.3)
U.S. agency commercial mortgage-backed securities	1,069.8		(59.9)		270.8		(57.0)		1,340.6		(116.9)
U.S. agency residential mortgage-backed securities	1,213.5		(112.3)		344.6		(55.4)		1,558.1		(167.7)
Collateralized mortgage obligations	1,016.4		(90.1)		333.0		(51.3)		1,349.4		(141.4)
Private mortgage-backed securities	133.1		(19.1)		94.9		(17.8)		228.0		(36.9)
Collateralized loan obligations	1,082.6		(33.1)		28.9		(0.5)		1,111.5		(33.6)
Corporate securities	130.6		(8.3)		110.8		(22.5)		241.4		(30.8)
Total	$	5,071.9	$	(346.6)	$	1,545.6	$	(283.1)	$	6,617.5	$	(629.7)

Debt Securities, Held-to-maturity, Allowance for Credit Loss

The following table presents the activity in the allowance for credit losses related to available-for-sale investment securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Beginning balance	$	1.4	$	—	$	—	$	—
(Reduction of) provision for credit losses	(1.4)		—		—		—
Ending balance	$	—	$	—	$	—	$	—
The following table presents the activity in the allowance for credit losses related to held-to-maturity investment securities:
	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Beginning balance	$	0.7	$	1.6	$	1.9	$	—
Provision for (reduction of) credit losses	0.1		0.3		(1.1)		1.9
Ending balance	$	0.8	$	1.9	$	0.8	$	1.9

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, 2023	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	398.4	$	—	$	—	$	—	$	—	$	—	$	398.4
State, county, and municipal securities	68.1		92.3		10.6		—		—		8.0		179.0
Obligations of U.S. government agencies	353.8		—		—		—		—		—		353.8
U.S. agency commercial mortgage-backed securities
FNMA/FHLMC	360.9		—		—		—		—		—		360.9
GNMA	154.3		—		—		—		—		—		154.3
U.S. agency residential mortgage-backed securities
FNMA/FHLMC	1,225.6		—		—		—		—		—		1,225.6
GNMA	44.2		—		—		—		—		—		44.2
Collateralized mortgage obligations
FNMA/FHLMC	342.0		—		—		—		—		—		342.0
GNMA	145.1		—		—		—		—		—		145.1
Corporate securities	—		—		—		47.0		5.0		5.0		57.0
Total	$	3,092.4	$	92.3	$	10.6	$	47.0	$	5.0	$	13.0	$	3,260.3

December 31, 2022	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	396.6	$	—	$	—	$	—	$	—	$	—	$	396.6
State, county, and municipal securities	68.3		92.8		11.5		—		—		8.6		181.2
Obligations of U.S. government agencies	351.7		—		—		—		—		—		351.7
U.S. agency commercial mortgage-backed securities
FNMA/FHLMC	364.9		—		—		—		—		—		364.9
GNMA	161.9		—		—		—		—		—		161.9
U.S. agency residential mortgage-backed securities
FNMA/FHLMC	1,342.9		—		—		—		—		—		1,342.9
GNMA	48.6		—		—		—		—		—		48.6
Collateralized mortgage obligations
FNMA/FHLMC	525.8		—		—		—		—		—		525.8
Corporate securities	—		—		—		65.1		10.0		5.0		80.1
Total	$	3,260.7	$	92.8	$	11.5	$	65.1	$	10.0	$	13.6	$	3,453.7

Maturities of Investment Securities

Maturities of mortgage-backed securities have been adjusted to reflect shorter maturities based upon estimated prepayments of principal. All other investment securities maturities are shown at contractual maturity dates.

	Available-for-Sale				Held-to-Maturity
September 30, 2023	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	1.6	$	1.5	$	308.7	$	304.5
After one year but within five years	1,036.0		941.3		346.4		320.2
After five years but within ten years	1,387.9		1,220.0		654.8		551.5
After ten years	3,864.7		3,464.9		1,950.4		1,619.9
Total	$	6,290.2	$	5,627.7	$	3,260.3	$	2,796.1

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Loans Held for Sale (Tables)

9 Months Ended

Sep. 30, 2023

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, 2023		December 31, 2022
Loans held for sale:
Agricultural1	$	49.5	$	62.5
Construction, at lower of cost or market	6.4		10.5
Residential mortgage, at fair value	3.2		6.9
Total loans held for sale	$	59.1	$	79.9

1 As of September 30, 2023 the agricultural loans held were at lower of cost or market. At December 31, 2022, the Company held $57.0 million of agricultural loans at lower of cost or market and $5.5 million of agricultural loans on accrual status at fair value with an unpaid principal balance of $7.7 million, of which $5.6 million is 90 days or more past due.

Non-Residential Loans Held for Sale

The table below presents the non-residential mortgage loans held for sale activity for the 2023 period:

	Agricultural		Construction
Beginning balance	$	62.5	$	10.5
Loans held for investment transferred to loans held for sale	—		3.1
Repayments and discounted pay-offs	(15.2)		—
Loan disposals	—		(3.1)
Increase (decrease) in estimated fair value of the loans1	2.2		(4.1)
Ending balance	$	49.5	$	6.4

1 For the nine months ended September 30, 2023, the Company recorded a gain of $2.2 million and a loss of $4.1 million in other income within the consolidated statements of income related to fair value changes.

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Loans Held for Investment (Tables)

9 Months Ended

Sep. 30, 2023

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, 2023		December 31, 2022
Real estate:
Commercial	$	8,766.2	$	8,528.6
Construction	1,930.3		1,944.4
Residential	2,212.2		2,188.3
Agricultural	731.5		794.9
Total real estate	13,640.2		13,456.2
Consumer:
Indirect	751.7		829.7
Direct and advance lines	142.3		152.9
Credit card	71.6		75.9
Total consumer	965.6		1,058.5
Commercial	2,925.1		2,882.6
Agricultural	690.5		708.3
Other, including overdrafts	5.0		9.2
Loans held for investment	18,226.4		18,114.8
Deferred loan fees and costs	(13.1)		(15.6)
Loans held for investment, net of deferred fees and costs	18,213.3		18,099.2
Allowance for credit losses	(226.7)		(220.1)
Net loans held for investment	$	17,986.6	$	17,879.1

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, 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

Three Months Ended September 30, 2022	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	29.5	$	(5.5)	$	(0.1)	$	—	$	23.9
Owner occupied	26.6		(3.7)		—		1.8		24.7
Multi-family	33.4		(2.6)		(5.7)		—		25.1
Total commercial real estate	89.5		(11.8)		(5.8)		1.8		73.7
Construction:
Land acquisition & development	0.8		(0.2)		—		0.1		0.7
Residential construction	3.4		(0.3)		—		—		3.1
Commercial construction	14.9		16.4		(6.6)		—		24.7
Total construction	19.1		15.9		(6.6)		0.1		28.5
Residential real estate:
Residential 1-4 family	18.2		0.9		—		—		19.1
Home equity and HELOC	1.5		0.1		(0.1)		0.1		1.6
Total residential real estate	19.7		1.0		(0.1)		0.1		20.7
Agricultural real estate	5.4		0.4		—		—		5.8
Total real estate	133.7		5.5		(12.5)		2.0		128.7
Consumer:
Indirect	13.1		1.6		(1.2)		0.6		14.1
Direct and advance lines	5.0		1.3		(1.4)		0.4		5.3
Credit card	2.2		0.3		(0.3)		0.2		2.4
Total consumer	20.3		3.2		(2.9)		1.2		21.8
Commercial:
Commercial and floor plans	54.1		(2.2)		(0.5)		1.0		52.4
Commercial purpose secured by 1-4 family	5.5		0.4		—		—		5.9
Credit card	0.3		0.2		(0.3)		—		0.2
Total commercial	59.9		(1.6)		(0.8)		1.0		58.5
Agricultural:
Agricultural	6.5		(2.5)		—		—		4.0
Total agricultural	6.5		(2.5)		—		—		4.0
Total allowance for credit losses	$	220.4	$	4.6	$	(16.2)	$	4.2	$	213.0

Nine Months Ended September 30, 2022	Beginning Balance		ACL for PCD Loans		Provision for Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	17.3	$	17.2	$	(7.6)	$	(3.0)	$	—	$	23.9
Owner occupied	13.3		9.5		2.3		(2.2)		1.8		24.7
Multi-family	13.3		10.9		5.9		(5.7)		0.7		25.1
Total commercial real estate	43.9		37.6		0.6		(10.9)		2.5		73.7
Construction:
Land acquisition & development	0.5		3.4		(0.8)		(2.7)		0.3		0.7
Residential construction	2.4		—		0.7		—		—		3.1
Commercial construction	6.0		0.2		25.1		(6.6)		—		24.7
Total construction	8.9		3.6		25.0		(9.3)		0.3		28.5
Residential real estate:
Residential 1-4 family	13.4		0.1		5.4		(0.1)		0.3		19.1
Home equity and HELOC	1.2		—		0.1		(0.1)		0.4		1.6
Total residential real estate	14.6		0.1		5.5		(0.2)		0.7		20.7
Agricultural real estate	1.9		2.3		1.7		(0.2)		0.1		5.8
Total real estate	69.3		43.6		32.8		(20.6)		3.6		128.7
Consumer:
Indirect	14.3		—		0.9		(2.9)		1.8		14.1
Direct and advance lines	4.6		—		1.7		(2.8)		1.8		5.3
Credit card	2.2		—		1.6		(1.8)		0.4		2.4
Total consumer	21.1		—		4.2		(7.5)		4.0		21.8
Commercial:
Commercial and floor plans	27.1		11.2		18.1		(5.8)		1.8		52.4
Commercial purpose secured by 1-4 family	4.4		0.2		1.2		—		0.1		5.9
Credit card	0.1		—		0.6		(0.5)		—		0.2
Commercial	31.6		11.4		19.9		(6.3)		1.9		58.5
Agricultural:
Agricultural	0.3		4.5		3.3		(5.4)		1.3		4.0
Total agricultural	0.3		4.5		3.3		(5.4)		1.3		4.0
Total allowance for credit losses	$	122.3	$	59.5	$	60.2	$	(39.8)	$	10.8	$	213.0
(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, 2023	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	—	$	29.6	$	—	$	29.6
Construction	—		17.1		—		17.1
Residential	—		0.5		—		0.5
Agricultural	—		1.5		—		1.5
Total real estate	—		48.7		—		48.7
Commercial	4.4		1.6		0.9		6.9
Agricultural	0.7		—		—		0.7
Total collateral-dependent loans	$	5.1	$	50.3	$	0.9	$	56.3

	Collateral Type
As of December 31, 2022	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	1.7	$	15.8	$	—	$	17.5
Construction	—		3.2		—		3.2
Residential	—		0.5		—		0.5
Agricultural	0.2		5.8		—		6.0
Total real estate	1.9		25.3		—		27.2
Commercial	3.1		1.5		—		4.6
Agricultural	2.1		5.2		—		7.3
Total collateral-dependent loans	$	7.1	$	32.0	$	—	$	39.1

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, 2023	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate:
Commercial	$	1.2	$	0.4	$	—	$	1.6	$	8,733.6	$	31.0	$	8,766.2
Construction	6.5		7.5		0.5		14.5		1,898.4		17.4		1,930.3
Residential	2.4		1.8		1.0		5.2		2,197.5		9.5		2,212.2
Agricultural	0.4		1.5		—		1.9		724.2		5.4		731.5
Total real estate	10.5		11.2		1.5		23.2		13,553.7		63.3		13,640.2
Consumer:
Indirect	6.4		2.2		0.4		9.0		739.7		3.0		751.7
Direct	0.6		0.2		—		0.8		141.3		0.2		142.3
Credit card	0.6		0.4		0.5		1.5		70.1		—		71.6
Total consumer	7.6		2.8		0.9		11.3		951.1		3.2		965.6
Commercial	2.3		16.1		0.5		18.9		2,894.2		12.0		2,925.1
Agricultural	0.7		—		0.3		1.0		686.6		2.9		690.5
Other, including overdrafts	—		—		—		—		5.0		—		5.0
Loans held for investment	$	21.1	$	30.1	$	3.2	$	54.4	$	18,090.6	$	81.4	$	18,226.4

							Total Loans
	30 - 59		60 - 89		90 or more		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2022	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate:
Commercial	$	5.6	$	0.8	$	1.1	$	7.5	$	8,501.5	$	19.6	$	8,528.6
Construction	10.4		0.6		0.6		11.6		1,929.1		3.7		1,944.4
Residential	9.9		2.1		1.2		13.2		2,168.7		6.4		2,188.3
Agricultural	1.1		6.1		—		7.2		780.1		7.6		794.9
Total real estate	27.0		9.6		2.9		39.5		13,379.4		37.3		13,456.2
Consumer:
Indirect	9.3		2.4		0.6		12.3		814.7		2.7		829.7
Direct	0.8		0.3		0.1		1.2		151.4		0.3		152.9
Credit card	0.8		0.4		0.6		1.8		74.1		—		75.9
Total consumer	10.9		3.1		1.3		15.3		1,040.2		3.0		1,058.5
Commercial	7.1		1.7		2.1		10.9		2,861.5		10.2		2,882.6
Agricultural	0.8		2.2		0.1		3.1		696.5		8.7		708.3
Other, including overdrafts	—		—		—		—		9.2		—		9.2
Loans held for investment	$	45.8	$	16.6	$	6.4	$	68.8	$	17,986.8	$	59.2	$	18,114.8

(1) As of September 30, 2023 and December 31, 2022, 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, 2023 and 2022, respectively. There were $1.0 million and $1.9 million in reversals of accrued interest during the three and the nine months ended September 30, 2023, respectively, and no material reversals of accrued interest during the three and the nine months ended September 30, 2022.

Financing Receivable, Excluding Accrued Interest, Modified Period

The following table presents the amortized cost basis of loans at September 30, 2023 that were both experiencing financial difficulty and modified during the three and the nine month periods ended September 30, 2023, by class and by type of modification. 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, 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, 2023, the Company excluded $1.7 million in accrued interest from the amortized cost of the identified loans.

Schedule of Acquired Loans with Credit Impairment

The following table reconciles the par value, or initial amortized cost, of PCD loans acquired in the GWB acquisition as of February 1, 2022, or the date of the acquisition, with the purchase price (or initial fair value of the loans) as amended for measurement period adjustments:

Purchase price (initial fair value)	$	623.3
Allowance for credit losses (1)	298.2
Discount attributable to other factors (2)	57.7
Par value (unpaid principal balance)	$	979.2

(1) For acquired PCD loans, an allowance of $298.2 million was required with a corresponding increase to the amortized cost basis as of the acquisition date. For PCD loans where all or a portion of the loan balance had been previously written-off by GWB, or would be subject to write-off under the Company’s charge-off policy, a CECL allowance of $238.7 million, included as part of the grossed-up loan balance at acquisition was immediately written-off. The net impact to the allowance for PCD assets on the acquisition date was $59.5 million.

(2) Non-credit discount includes the difference between the amortized cost basis and the unpaid principal balance of $39.6 million established on PCD loans acquired from GWB and interest applied to principal of $18.1 million.

Schedule of Recorded Investment in Criticized Loans by Class and Credit Quality Indicator

The Company evaluates the credit quality and loan performance for the allowance for credit losses of the following class of receivables based on the aforementioned risk scale as of and for the periods ended:

	As of and for the nine months ended September 30, 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	$	845.8	$	2,240.2	$	1,649.9	$	1,245.7	$	732.7	$	1,741.5	$	42.8	$	21.6	$	8,520.2
Special mention	2.9		5.0		41.3		4.7		26.9		20.5		—		—		101.3
Substandard	28.0		26.0		19.6		9.6		30.4		28.4		1.0		—		143.0
Doubtful	—		0.3		1.4		—		—		—		—		—		1.7
Total	$	876.7	$	2,271.5	$	1,712.2	$	1,260.0	$	790.0	$	1,790.4	$	43.8	$	21.6	$	8,766.2
Current-period gross charge-offs	1.7		0.3		1.7		2.6		—		—		—		—		6.3
Construction real estate:
Pass	$	444.9	$	806.1	$	413.3	$	39.4	$	16.5	$	38.7	$	102.8	$	2.6	$	1,864.3
Special mention	4.1		11.4		6.5		—		—		0.2		—		0.8		23.0
Substandard	1.4		3.3		24.5		0.2		—		0.5		—		—		29.9
Doubtful	—		13.1		—		—		—		—		—		—		13.1
Total	$	450.4	$	833.9	$	444.3	$	39.6	$	16.5	$	39.4	$	102.8	$	3.4	$	1,930.3
Current-period gross charge-offs	—		—		0.1		—		—		—		—		9.6		9.7
Agricultural real estate:
Pass	$	60.5	$	133.1	$	158.8	$	95.9	$	59.4	$	130.1	$	27.8	$	0.1	$	665.7
Special mention	3.5		6.6		1.4		2.1		1.8		5.9		0.5		—		21.8
Substandard	8.1		19.8		4.8		2.2		0.5		8.6		—		—		44.0
Total	$	72.1	$	159.5	$	165.0	$	100.2	$	61.7	$	144.6	$	28.3	$	0.1	$	731.5
Current-period gross charge-offs	—		—		—		—		—		—		—		—		—
Commercial:
Pass	$	383.8	$	537.2	$	408.5	$	224.5	$	116.4	$	317.0	$	765.8	$	9.5	$	2,762.7
Special mention	2.3		4.9		6.7		4.7		2.5		1.4		14.8		0.1		37.4
Substandard	5.0		23.3		10.9		7.2		4.6		5.0		62.4		0.4		118.8
Doubtful	4.7		0.2		1.2		—		—		—		0.1		—		6.2
Total	$	395.8	$	565.6	$	427.3	$	236.4	$	123.5	$	323.4	$	843.1	$	10.0	$	2,925.1
Current-period gross charge-offs	—		0.3		0.3		0.4		0.1		0.1		0.9		0.1		2.2
Agricultural:
Pass	$	77.2	$	74.8	$	35.9	$	25.5	$	7.7	$	9.6	$	374.0	$	6.0	$	610.7
Special mention	0.9		1.1		0.8		0.2		0.2		0.2		9.7		—		13.1
Substandard	45.0		0.7		1.4		1.4		0.5		1.3		16.4		—		66.7
Total	$	123.1	$	76.6	$	38.1	$	27.1	$	8.4	$	11.1	$	400.1	$	6.0	$	690.5
Current-period gross charge-offs	—		—		—		—		—		—		—		—		—

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial real estate non-owner occupied:
Pass	$	1,162.6	$	861.3	$	661.1	$	467.6	$	241.5	$	890.4	$	29.2	$	4,313.7
Special mention	1.0		6.8		2.3		4.6		—		7.4		—		22.1
Substandard	0.1		13.9		10.8		18.2		19.6		9.8		—		72.4
Total	$	1,163.7	$	882.0	$	674.2	$	490.4	$	261.1	$	907.6	$	29.2	$	4,408.2
Commercial real estate owner occupied:
Pass	$	793.0	$	718.7	$	533.9	$	266.3	$	165.8	$	551.3	$	18.2	$	3,047.2
Special mention	10.9		14.2		12.3		6.1		5.6		5.5		1.1		55.7
Substandard	8.4		3.0		2.3		8.9		8.5		17.2		0.5		48.8
Doubtful	0.4		1.4		—		—		—		—		—		1.8
Total	$	812.7	$	737.3	$	548.5	$	281.3	$	179.9	$	574.0	$	19.8	$	3,153.5
Commercial multi-family:
Pass	$	369.2	$	204.9	$	189.0	$	52.1	$	35.0	$	113.7	$	1.0	$	964.9
Special mention	—		—		—		—		—		1.7		—		1.7
Substandard	—		—		—		—		—		0.3		—		0.3
Total	$	369.2	$	204.9	$	189.0	$	52.1	$	35.0	$	115.7	$	1.0	$	966.9
Land, acquisition and development:
Pass	$	152.5	$	114.4	$	29.5	$	17.0	$	10.9	$	28.4	$	22.2	$	374.9
Special mention	6.7		—		—		—		0.2		0.3		—		7.2
Substandard	—		0.3		0.2		—		—		0.4		—		0.9
Doubtful	—		3.2		—		—		—		—		—		3.2
Total	$	159.2	$	117.9	$	29.7	$	17.0	$	11.1	$	29.1	$	22.2	$	386.2
Residential construction:
Pass	$	118.4	$	119.9	$	0.4	$	0.3	$	0.4	$	5.8	$	270.1	$	515.3
Substandard	—		0.5		—		—		—		0.4		—		0.9
Total	$	118.4	$	120.4	$	0.4	$	0.3	$	0.4	$	6.2	$	270.1	$	516.2
Commercial construction:
Pass	$	442.7	$	374.8	$	89.7	$	45.9	$	0.4	$	—	$	10.6	$	964.1
Special mention	2.3		—		23.1		—		—		—		11.3		36.7
Substandard	16.8		24.4		—		—		—		—		—		41.2
Total	$	461.8	$	399.2	$	112.8	$	45.9	$	0.4	$	—	$	21.9	$	1,042.0
Agricultural real estate:
Pass	$	180.0	$	172.8	$	109.5	$	64.8	$	46.6	$	105.1	$	31.4	$	710.2
Special mention	22.4		0.7		1.2		2.6		10.0		3.2		11.0		51.1
Substandard	1.8		12.3		3.5		0.6		2.7		11.3		0.1		32.3
Doubtful	—		—		1.3		—		—		—		—		1.3
Total	$	204.2	$	185.8	$	115.5	$	68.0	$	59.3	$	119.6	$	42.5	$	794.9
Commercial and floor plans:
Pass	$	501.7	$	358.9	$	214.4	$	124.3	$	120.3	$	171.1	$	631.6	$	2,122.3
Special mention	15.9		6.8		1.3		4.4		0.9		4.9		18.5		52.7
Substandard	9.8		3.3		3.7		3.4		3.2		2.1		47.2		72.7
Doubtful	0.3		1.3		—		—		—		—		0.1		1.7
Total	$	527.7	$	370.3	$	219.4	$	132.1	$	124.4	$	178.1	$	697.4	$	2,249.4

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial purpose secured by 1-4 family:
Pass	$	191.7	$	134.5	$	69.8	$	30.4	$	29.9	$	39.5	$	28.9	$	524.7
Special mention	0.1		1.2		2.1		0.2		1.4		0.2		—		5.2
Substandard	0.2		0.3		0.1		0.3		0.9		1.2		—		3.0
Total	$	192.0	$	136.0	$	72.0	$	30.9	$	32.2	$	40.9	$	28.9	$	532.9
Agricultural:
Pass	$	127.2	$	59.7	$	31.8	$	10.6	$	8.6	$	3.1	$	375.1	$	616.1
Special mention	26.1		2.8		0.4		1.0		0.3		—		26.2		56.8
Substandard	22.8		4.6		2.8		0.6		1.2		0.2		0.8		33.0
Doubtful	—		0.5		—		—		—		—		—		0.5
Total	$	176.1	$	67.6	$	35.0	$	12.2	$	10.1	$	3.3	$	402.1	$	706.4

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, 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	$	38.6	$	317.5	$	513.2	$	512.8	$	92.3	$	227.2	$	475.6	$	24.5	$	2,201.7
Nonperforming	0.7		1.6		1.0		0.6		0.8		5.8		—		—		10.5
Total	$	39.3	$	319.1	$	514.2	$	513.4	$	93.1	$	233.0	$	475.6	$	24.5	$	2,212.2
Current-period gross charge-offs	0.3		—		0.1		0.1		—		0.1		—		—		0.6
Consumer indirect:
Performing	$	142.5	$	292.4	$	128.3	$	92.3	$	38.5	$	54.3	$	—	$	—	$	748.3
Nonperforming	0.4		1.2		0.7		0.4		0.2		0.5		—		—		3.4
Total	$	142.9	$	293.6	$	129.0	$	92.7	$	38.7	$	54.8	$	—	$	—	$	751.7
Current-period gross charge-offs	0.2		2.0		1.6		0.6		0.2		0.6		—		—		5.2
Consumer direct and advance lines:
Performing	$	35.3	$	36.8	$	21.1	$	10.8	$	4.4	$	7.0	$	26.5	$	0.2	$	142.1
Nonperforming	—		0.1		0.1		—		—		—		—		—		0.2
Total	$	35.3	$	36.9	$	21.2	$	10.8	$	4.4	$	7.0	$	26.5	$	0.2	$	142.3
Current-period gross charge-offs	0.1		0.3		0.2		0.3		0.1		2.1		0.1		—		3.2
Consumer credit card:
Performing	$	—	$	—	$	—	$	—	$	—	$	—	$	71.1	$	—	$	71.1
Nonperforming	—		—		—		—		—		—		0.5		—		0.5
Total	$	—	$	—	$	—	$	—	$	—	$	—	$	71.6	$	—	$	71.6
Current-period gross charge-offs	—		—		—		—		—		—		2.0		—		2.0

	December 31, 2022
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2022		2021		2020		2019		2018		Prior		Revolving Loans Amortized Cost Basis		Total
Residential 1-4 family:
Performing	$	258.9	$	490.3	$	541.6	$	98.0	$	32.0	$	213.8	$	—	$	1,634.6
Nonperforming	—		0.2		0.1		0.5		0.3		3.7		—		4.8
Total	$	258.9	$	490.5	$	541.7	$	98.5	$	32.3	$	217.5	$	—	$	1,639.4
Consumer home equity and HELOC:
Performing	$	23.8	$	8.0	$	5.2	$	5.5	$	5.6	$	15.2	$	482.8	$	546.1
Nonperforming	0.6		0.3		0.2		0.2		0.1		1.2		0.2		2.8
Total	$	24.4	$	8.3	$	5.4	$	5.7	$	5.7	$	16.4	$	483.0	$	548.9
Consumer indirect:
Performing	$	380.3	$	176.4	$	130.0	$	59.7	$	33.6	$	46.3	$	—	$	826.3
Nonperforming	1.0		0.9		0.6		0.3		0.2		0.4		—		3.4
Total	$	381.3	$	177.3	$	130.6	$	60.0	$	33.8	$	46.7	$	—	$	829.7
Consumer direct and advance lines:
Performing	$	52.6	$	31.9	$	18.2	$	8.5	$	6.5	$	8.9	$	25.8	$	152.4
Nonperforming	0.1		0.1		0.1		—		—		0.1		0.1		0.5
Total	$	52.7	$	32.0	$	18.3	$	8.5	$	6.5	$	9.0	$	25.9	$	152.9

The following table presents the recorded investment in credit card loans based on payment activity for the periods indicated:

As of December 31, 2022	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	75.4	$	100.0	$	1.9	$	177.3
Nonperforming	0.5		0.3		—		0.8
Total credit card	$	75.9	$	100.3	$	1.9	$	178.1

Financial Receivable, Excluding Accrued Interest, Modified Period, Financial Difficulty

The following table presents the financial effect of the loan modifications presented above to borrowers experiencing financial difficulty during the three and the nine month periods ended September 30, 2023:

				Term Extension and Interest Rate Reduction
Three Months Ended September 30, 2023	Principal Forgiveness		Weighted-Average Months of Term Extension	Weighted-Average Interest Rate Reduction		Weighted-Average Months of Term Extension
Real estate:
Commercial	$	—	4.6	0.25	%	6.0
Construction	—		9.0	—		—
Residential	—		144.4	—		—
Agricultural	—		4.0	—		—
Total real estate	—
Commercial	—		7.8	—		—
Agricultural	—		3.5	—		—
Loans held for investment (1)	$	—
Nine Months Ended September 30, 2023
Real estate:
Commercial	$	1.3	5.7	0.25	%	6.0
Construction	—		9.0	—		—
Residential	0.3		139.2	—		—
Agricultural	—		4.6	—		—
Total real estate	1.6
Commercial	—		8.8	—		—
Agricultural	—		9.2	—		—
Loans held for investment (1)	$	1.6

(1) Balances based on loan original contractual terms.

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Other Real Estate Owned (Tables)

9 Months Ended

Sep. 30, 2023

Repossessed Assets [Abstract]

Other Real Estate Owned Roll Forward

Other real estate owned (“OREO”) is a category of real estate owned by the Company as a result of 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,
	2023		2022		2023		2022
Beginning balance	$	14.4	$	16.8	$	12.7	$	2.0
Acquired through acquisition	—		—		—		15.8
Additions	—		0.3		2.5		0.4
Valuation adjustments	(0.3)		(0.2)		(1.1)		(0.2)
Dispositions	(2.5)		(0.5)		(2.5)		(1.6)
Ending balance	$	11.6	$	16.4	$	11.6	$	16.4

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Derivatives and Hedging Activities (Tables)

9 Months Ended

Sep. 30, 2023

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, 2023				December 31, 2022
	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	$	192.9	$	7.1	$	191.9	$	8.1

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 take into account 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, 2023					December 31, 2022
	Notional Amount		Consolidated Balance Sheet Location	Estimated Fair Value		Notional Amount		Consolidated Balance Sheet Location	Estimated Fair Value
Derivatives designated as accounting hedges:
Interest rate swap contracts	$	—		$	—	$	550.0		$	3.5
Derivatives not designated as accounting hedges:
Interest rate swap contracts	1,638.8			57.4		1,728.1			41.6
Forward loan sales contracts	8.0			—		12.6			0.1
Derivative assets	$	1,646.8	Other assets	$	57.4	$	2,290.7	Other assets	$	45.2
Derivatives designated as accounting hedges:
Interest rate collars	$	300.0		$	7.3	$	300.0		$	5.4
Interest rate swap contracts	850.0			18.6		300.0			0.3
Derivatives not designated as accounting hedges:
Interest rate swap contracts	1,638.8			184.1		1,728.1			153.9
Risk participation agreements	102.2			—		106.1			—
Interest rate lock commitments	7.0			—		14.8			—
Derivative liabilities	$	2,898.0	Accounts payable and accrued expenses	$	210.0	$	2,449.0	Accounts payable and accrued expenses	$	159.6

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,
		2023		2022			2023		2022
	Location of Gain (Loss) Recognized in Income on Derivative	Amount of Gain (Loss) Recognized in Income on Derivative				Location of Loss Recognized in Income on Derivative	Amount of Loss Recognized in Income on Derivative
Interest rate lock commitments	Mortgage banking revenues	$	0.1	$	(0.2)	Mortgage banking revenues	$	(0.1)	$	(1.7)

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, 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 contracts	$	57.4	$	—	$	57.4	$	—	$	38.6	$	18.8
Total derivatives	57.4		—		57.4		—		38.6		18.8
Total assets	$	57.4	$	—	$	57.4	$	—	$	38.6	$	18.8
(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	$	210.0	$	—	$	210.0	$	—	$	1.0	$	209.0
Total derivatives	210.0		—		210.0		—		1.0		209.0
Repurchase agreements	889.5		—		889.5		—		889.5		—
Total liabilities	$	1,099.5	$	—	$	1,099.5	$	—	$	890.5	$	209.0

	December 31, 2022
	Gross Assets Recognized		Gross Assets Offset in the Balance Sheet		Net Assets in the Balance Sheet		Financial Instruments		Cash Collateral Received		Net Amount
Interest rate swap contracts	$	45.1	$	—	$	45.1	$	—	$	45.1	$	—
Mortgage related derivatives	0.1		—		0.1		—		—		0.1
Total derivatives	45.2		—		45.2		—		45.1		0.1
Total assets	$	45.2	$	—	$	45.2	$	—	$	45.1	$	0.1
	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 contracts	$	159.6	$	—	$	159.6	$	—	$	—	$	159.6
Total derivatives	159.6		—		159.6		—		—		159.6
Repurchase agreements	1,052.9		—		1,052.9		—		1,052.9		—
Total liabilities	$	1,212.5	$	—	$	1,212.5	$	—	$	1,052.9	$	159.6

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Debt (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Schedule of Debt

The following table presents outstanding FHLB borrowings by maturity buckets for the dates indicated:

As of September 30, 2023	Average Rate		Outstanding Balance
Fixed rate borrowings with tenors of up to one week	5.52	%	$	106.0
Fixed rate borrowings with tenors of up to two weeks	5.51		100.0
Fixed rate borrowings with tenors of up to one month	5.50		925.0
Two-month fixed rate borrowings	5.56		500.0
Five-month fixed rate borrowings	5.56		436.0
			$	2,067.0
As of December 31, 2022	Rate		Outstanding Balance
Variable rate overnight borrowings	4.60	%	$	827.0
Fixed rate borrowings in tenors of up to one month	4.48		1,500.0
			$	2,327.0

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Earnings per Common Share (Tables)

9 Months Ended

Sep. 30, 2023

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,
	2023		2022		2023		2022
Net income	$	72.7	$	85.7	$	196.0	$	116.4
Weighted average common shares outstanding for basic earnings per share computation	103,822,311		106,525,974		103,793,851		102,879,422
Dilutive effects of stock-based compensation	4,116		63,725		30,425		55,938
Weighted average common shares outstanding for diluted earnings per common share computation	103,826,427		106,589,699		103,824,276		102,935,360
Basic earnings per common share	$	0.70	$	0.80	$	1.89	$	1.13
Diluted earnings per common share	0.70		0.80		1.89		1.13
Anti-dilutive unvested time restricted stock	162,231		48,871		162,231		51,161

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Regulatory Capital (Tables)

9 Months Ended

Sep. 30, 2023

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, 2023 and December 31, 2022 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, 2023	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,957.6	13.19	%	$	1,794.5	8.00	%	$	2,355.3	10.50	%	$	2,243.1	10.00	%
FIB	2,782.1		12.43		1,790.8		8.00		2,350.5		10.50		2,238.6		10.00
Tier 1 risk-based capital:
Consolidated	2,471.6		11.02		1,345.9		6.00		1,906.6		8.50		1,794.5		8.00
FIB	2,553.7		11.41		1,343.1		6.00		1,902.8		8.50		1,790.8		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,471.6		11.02		1,009.4		4.50		1,570.2		7.00		1,458.0		6.50
FIB	2,553.7		11.41		1,007.3		4.50		1,567.0		7.00		1,455.1		6.50
Leverage capital ratio:
Consolidated	2,471.6		8.22		1,202.8		4.00		1,202.8		4.00		1,503.5		5.00
FIB	2,553.7		8.50		1,201.1		4.00		1,201.1		4.00		1,501.3		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, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,875.8	12.48	%	$	1,843.2	8.00	%	$	2,419.2	10.50	%	$	2,304.0	10.00	%
FIB	2,713.5		11.80		1,839.6		8.00		2,414.5		10.50		2,299.5		10.00
Tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,382.4		6.00		1,958.4		8.50		1,843.2		8.00
FIB	2,504.1		10.89		1,379.7		6.00		1,954.6		8.50		1,839.6		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,408.8		10.45		1,036.8		4.50		1,612.8		7.00		1,497.6		6.50
FIB	2,504.1		10.89		1,034.8		4.50		1,609.7		7.00		1,494.7		6.50
Leverage capital ratio:
Consolidated	2,408.8		7.75		1,242.9		4.00		1,242.9		4.00		1,553.6		5.00
FIB	2,504.1		8.07		1,241.1		4.00		1,241.1		4.00		1,551.4		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.

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Comprehensive Text Block List (Tables)

9 Months Ended

Sep. 30, 2023

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,
	2023		2022		2023		2022
Beginning balance	$	20.8	$	6.2	$	16.2	$	3.8
Provision for credit loss expense	(2.0)		3.5		2.6		5.9
Ending balance	$	18.8	$	9.7	$	18.8	$	9.7

	September 30, 2023		December 31, 2022
Unused credit card lines	$	805.1	$	827.6
Commitments to extend credit	4,441.0		5,173.3
Standby letters of credit	94.7		93.8

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Other Comprehensive Income/Loss (Tables)

9 Months Ended

Sep. 30, 2023

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,	2023		2022		2023		2022		2023		2022
Investment securities available-for sale:
Change in net unrealized losses during the period	$	(72.1)	$	(236.4)	$	(17.9)	$	(53.4)	$	(54.2)	$	(183.0)
Reclassification adjustment for net losses included in income	—		24.2		—		5.5		—		18.7
Net change in unamortized losses on available-for-sale investment securities transferred into held-to-maturity	(0.3)		(1.7)		(0.1)		(0.4)		(0.2)		(1.3)
Change in net unrealized loss on derivatives	(11.0)		(15.9)		(2.7)		(3.6)		(8.3)		(12.3)
Total other comprehensive loss	$	(83.4)	$	(229.8)	$	(20.7)	$	(51.9)	$	(62.7)	$	(177.9)

	Pre-tax				Tax Expense (Benefit)				Net of Tax
Nine Months Ended September 30,	2023		2022		2023		2022		2023		2022
Investment securities available-for sale:
Change in net unrealized losses during period	$	(51.4)	$	(650.6)	$	(12.7)	$	(161.3)	$	(38.7)	$	(489.3)
Reclassification adjustment for net losses included in net income	23.5		24.4		5.8		5.5		17.7		18.9
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(7.2)		0.2		(1.8)		0.1		(5.4)		0.1
Net change in unamortized losses on available-for-sale securities transferred into held-to-maturity	(1.1)		(25.6)		(0.3)		(6.3)		(0.8)		(19.3)
Change in net unrealized loss on derivatives	(23.1)		(9.6)		(5.7)		(2.5)		(17.4)		(7.1)
Total other comprehensive loss	$	(59.3)	$	(661.2)	$	(14.7)	$	(164.5)	$	(44.6)	$	(496.7)

Schedule of Accumulated Other Comprehensive Income (Loss)

The components of accumulated other comprehensive loss, net of related tax effects, are as follows:

	September 30, 2023		December 31, 2022
Net unrealized loss on investment securities available-for-sale	$	(497.4)	$	(471.0)
Net unrealized loss on investment securities transferred to held-to-maturity	(5.4)		(4.5)
Net unrealized loss on derivatives	(18.9)		(1.6)
Net accumulated other comprehensive loss	$	(521.7)	$	(477.1)

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Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

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, 2023	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Investment debt securities available-for-sale:
U.S. Treasury notes	$	215.9	$	—	$	215.9	$	—
State, county, and municipal securities	202.6			—	202.6			—
Obligations of U.S. government agencies	162.0			—	162.0			—
U.S. agency commercial mortgage-backed securities	1,066.9			—	1,066.9			—
U.S. agency residential mortgage-backed securities	1,285.0			—	1,285.0			—
Collateralized mortgage obligations	1,143.7			—	1,143.7			—
Private mortgage-backed securities	207.3			—	207.3			—
Collateralized loan obligations	1,117.8			—	1,117.8			—
Corporate securities	226.5			—	226.5			—
Loans held for sale	3.2			—	3.2			—
Derivative assets:
Interest rate swap contracts	57.4			—	57.4			—
Derivative liabilities:
Interest rate collars	7.3			—	7.3			—
Interest rate swap contracts	202.7			—	202.7			—
Interest rate lock commitments	—			—	—			—
Deferred compensation plan assets	19.2			—	19.2			—
Deferred compensation plan liabilities	19.2			—	19.2			—

			Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Investment debt securities available-for-sale:
U.S. Treasury notes	$	642.7	$	—	$	642.7	$	—
State, county and municipal securities	263.7			—	263.7			—
Obligations of U.S. government agencies	198.9			—	198.9			—
U.S. agency commercial mortgage-backed securities	1,351.2			—	1,351.2			—
U.S. agency residential mortgage-backed securities	1,558.3			—	1,558.3			—
Collateralized mortgage obligations	1,350.2			—	1,350.2			—
Private mortgage-backed securities	228.0			—	228.0			—
Collateralized loan obligations	1,111.6			—	1,111.6			—
Corporate securities	241.5			—	241.5			—
Loans held for sale	12.4			—	6.9			5.5
Derivative assets:
Interest rate swap contracts	45.1			—	45.1			—
Forward loan sales contracts	0.1			—	0.1			—
Derivative liabilities
Interest rate collars	5.4			—	5.4			—
Interest rate swap contracts	154.2			—	154.2			—
Deferred compensation plan assets	18.7			—	18.7			—
Deferred compensation plan liabilities	18.7			—	18.7			—

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, 2023	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral-dependent loans	$	56.3	$	—	$	—	$	56.3
Loans held for sale	55.9			—		—	55.9
Other real estate owned	11.6			—		—	11.6
Long-lived assets to be disposed of by sale	4.5			—		—	4.5
				Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral-dependent loans	$	39.1	$	—	$	—	$	39.1
Loans held for sale	67.5			—		—	67.5
Other real estate owned	12.7			—		—	12.7
Long-lived assets to be disposed of by sale	5.5			—		—	5.5

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, 2023		December 31, 2022		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Collateral-dependent loans	$	56.3	$	39.1	Appraisal	Appraisal adjustment	0%	-	45%	(7%)
Loans held for sale	55.9		67.5		Fair value of collateral	Discount for type of property, age of appraisal, and current status	11%	-	23%	(17%)
Other real estate owned	11.6		12.7		Appraisal	Appraisal adjustment	15%	-	36%	(22%)
Long-lived assets to be disposed of by sale	4.5		5.5		Appraisal	Appraisal adjustment	0%	-	6%	(3%)

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, 2023	Carrying Amount		Estimated Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	$	593.1	$	593.1	$	593.1	$	—	$	—
Investment debt securities available-for-sale	5,627.7		5,627.7		—		5,627.7		—
Investment debt securities held-to-maturity	3,259.5		2,796.1		—		2,796.1		—
Accrued interest receivable	129.2		129.2		—		129.2		—
Mortgage servicing rights, net	29.1		35.6		—		35.6		—
Loans held for sale	59.1		59.1		—		3.2		55.9
Net loans held for investment	17,986.6		17,226.1		—		17,169.8		56.3
Derivative assets	57.4		57.4		—		57.4		—
Deferred compensation plan assets	19.2		19.2		—		19.2		—
Total financial assets	$	27,760.9	$	26,543.5	$	593.1	$	25,838.2	$	112.2
Financial liabilities:
Total deposits, excluding time deposits	$	20,516.8	$	20,516.8	$	20,516.8	$	—	$	—
Time deposits	3,162.7		3,126.2		—		3,126.2		—
Securities sold under repurchase agreements	889.5		889.5		—		889.5		—
Other borrowed funds	2,067.0		2,067.0		—		2,067.0		—
Accrued interest payable	63.7		63.7		—		63.7		—
Long-term debt	120.8		114.4		—		114.4		—
Subordinated debentures held by subsidiary trusts	163.1		152.5		—		152.5		—
Derivative liabilities	210.0		210.0		—		210.0		—
Deferred compensation plan liabilities	19.2		19.2		—		19.2		—
Total financial liabilities	$	27,212.8	$	27,159.3	$	20,516.8	$	6,642.5	$	—

					Fair Value Measurements at Reporting Date Using
As of December 31, 2022	Carrying Amount		Estimated Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	$	870.5	$	870.5	$	870.5	$	—	$	—
Investment debt securities available-for-sale	6,946.1		6,946.1		—		6,946.1		—
Investment debt securities held-to-maturity	3,451.8		3,052.2		—		3,052.2		—
Accrued interest receivable	118.3		118.3		—		118.3		—
Mortgage servicing rights, net	31.1		37.4		—		37.4		—
Loans held for sale	79.9		79.9		—		6.9		73.0
Net loans held for investment	17,879.1		17,552.1		—		17,513.0		39.1
Derivative assets	45.2		45.2		—		45.2		—
Deferred compensation plan assets	18.7		18.7		—		18.7		—
Total financial assets	$	29,440.7	$	28,720.4	$	870.5	$	27,737.8	$	112.1
Financial liabilities:
Total deposits, excluding time deposits	$	23,145.2	$	23,145.2	$	23,145.2	$	—	$	—
Time deposits	1,928.4		1,876.1		—		1,876.1		—
Securities sold under repurchase agreements	1,052.9		1,052.9		—		1,052.9		—
Other borrowed funds	2,327.0		2,327.0		—		2,327.0		—
Accrued interest payable	14.5		14.5		—		14.5		—
Long-term debt	120.8		116.3		—		116.3		—
Subordinated debentures held by subsidiary trusts	163.1		155.8		—		155.8		—
Derivative liabilities	159.6		159.6		—		159.6		—
Deferred compensation plan liabilities	18.7		18.7		—		18.7		—
Total financial liabilities	$	28,930.2	$	28,866.1	$	23,145.2	$	5,720.9	$	—

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Acquisitions - Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
	Feb. 01, 2022 USD ($) office $ / shares shares	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 1,100.9		$ 1,100.9		$ 1,100.9
Acquisition related expenses		$ 0.0	$ 4.0	$ 0.0	$ 115.0
Business Acquisition, Goodwill, Expected Tax Deductible Amount	$ 31.7
Core Deposits
Business Acquisition [Line Items]
Estimated useful lives of related deposits				10 years
Great Western Bank
Business Acquisition [Line Items]
Number of banking offices acquired | office	174
Total consideration exchanged	$ 1,723.3
Goodwill	479.3
Core deposit intangibles	50.1
Customer relationship intangible	22.8
Great Western Bank | First Interstate Foundation
Business Acquisition [Line Items]
Acquisition related costs	21.5
Great Western Bank | Scott Family
Business Acquisition [Line Items]
Acquisition related costs	$ 8.2
Great Western Bank | Class A Common Stock
Business Acquisition [Line Items]
Number of shares issued in connection with Cascade merger (in shares) | shares	46.9
Price per share of First Interstate Class A common stock (in dollars per share) | $ / shares	$ 36.76

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Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Feb. 01, 2022	Sep. 30, 2023	Dec. 31, 2022
Liabilities assumed:
Goodwill		$ 1,100,900	$ 1,100,900
Great Western Bank
Assets acquired:
Cash and cash equivalents	$ 2,006,900
Investment securities	2,699,000
Securities purchased under agreement to resell	101,100
Loans held for sale	217,000
Loans held for investment	7,705,000
Allowance for credit losses	(59,500)
Premises and equipment, including right of use lease assets	144,700
Other real estate owned	15,800
Company-owned life insurance	186,600
Core deposit intangibles	50,100
Customer relationship intangible	22,800
Mortgage servicing rights	1,300
Deferred tax assets, net	60,200
Other assets	200,800
Total assets acquired	13,351,800
Liabilities assumed:
Deposits	11,688,000
Securities sold under repurchase agreements	74,000
Accrued expenses and other liabilities	110,400
FHLB advances	122,900
Subordinated debt	36,400
Subordinated debentures held by subsidiary trusts	76,100
Total liabilities assumed	12,107,800
Net assets acquired	1,244,000
Class A common stock	1,723,300
Total consideration paid (1)	1,723,300
Goodwill	479,300
Cash paid in lieu of fractional shares	$ 13

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Acquisitions - Schedule of Acquired loans with Credit Impairment (Details) $ in Millions	Feb. 01, 2022 USD ($)
Business Acquisition [Line Items]
Purchase price (initial fair value)	$ 623.3
Allowance for credit losses	$ 298.2

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Acquisitions - Schedule of Acquired Loans not Deemed to Have Credit Impairment (Details) $ in Millions	Feb. 01, 2022 USD ($)
Business Acquisition [Line Items]
Purchase price (initial fair value)	$ 623.3
Allowance for credit losses	$ 298.2

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Acquisitions - Summary of Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 0.85	$ 2.60
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 0.85	$ 2.60
Great Western Bank
Business Acquisition [Line Items]
Total revenues	$ 314.0	$ 883.5
Net income	$ 90.3	$ 267.8

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Goodwill and Core Deposit Intangibles - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	Jul. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of goodwill	$ 0
Goodwill [Line Items]
Amortization of intangible assets		$ 3,900,000	$ 4,100,000	$ 11,800,000	$ 11,800,000
Core Deposits
Goodwill [Line Items]
Weighted average useful lives of related deposits				10 years
OCRI
Goodwill [Line Items]
Weighted average useful lives of related deposits				12 years

XML

Goodwill and Core Deposit Intangibles - Goodwill Carrying Value (Details) $ in Millions	Sep. 30, 2023 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

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Goodwill and Core Deposit Intangibles - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2023	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
2024		$ 14.6
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	$ 177.5		$ 106.0
Finite-Lived Intangible Assets Acquired	72.9
Finite-Lived Intangible Assets, Period Increase (Decrease)	(1.4)
Finite-Lived Intangible Assets, Accumulated Amortization	(80.5)	(92.3)
75900000	97.0	85.2
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2024		12.7
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	154.7		106.0
Finite-Lived Intangible Assets Acquired	50.1
Finite-Lived Intangible Assets, Period Increase (Decrease)	(1.4)
Finite-Lived Intangible Assets, Accumulated Amortization	(78.8)	(89.1)
75900000	75.9	65.6
OCRI
Finite-Lived Intangible Assets [Line Items]
2024		1.9
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	22.8		$ 0.0
Finite-Lived Intangible Assets Acquired	22.8
Finite-Lived Intangible Assets, Period Increase (Decrease)	0.0
Finite-Lived Intangible Assets, Accumulated Amortization	(1.7)	(3.2)
75900000	$ 21.1	$ 19.6

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Goodwill and Core Deposit Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
2023 remaining	$ 3.8
2024	14.6
2025	13.7
2026	12.8
2027	10.1
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	30.2
Total	85.2	$ 97.0
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2023 remaining	3.4
2024	12.7
2025	11.8
2026	10.9
2027	8.2
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	18.6
Total	65.6	75.9
OCRI
Finite-Lived Intangible Assets [Line Items]
2023 remaining	0.4
2024	1.9
2025	1.9
2026	1.9
2027	1.9
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	11.6
Total	$ 19.6	$ 21.1

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Investment Securities - Amortized Cost and Approximate Fair Values of Investment Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Available-for-Sale:
Gross Unrealized Gains	$ 0.1		$ 2.3
Gross Unrealized Losses	(662.6)		(629.7)
Held-to-Maturity:
Investment securities classified as held to maturity	3,260.3		3,453.7
Allowance for Credit Losses	(0.8)	$ (0.7)	(1.9)	$ (1.9)	$ (1.6)	$ 0.0
Net Amortized Cost	3,259.5		3,451.8
Gross Unrealized Gains	0.0		0.4
Gross Unrealized Losses	(463.4)		(400.0)
Investment debt securities held-to-maturity	2,796.1		3,052.2
Estimated Fair Value	5,627.7		6,946.1
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	6,290.2		7,573.5
Allowance for Credit Losses	0.0	$ (1.4)	0.0	$ 0.0	$ 0.0	$ 0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	6,290.2		7,573.5
U.S. Treasury notes
Available-for-Sale:
Gross Unrealized Gains	0.0		2.1
Gross Unrealized Losses	(34.2)		(34.5)
Held-to-Maturity:
Investment securities classified as held to maturity	398.4		396.6
Allowance for Credit Losses	0.0		0.0
Net Amortized Cost	398.4		396.6
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(6.8)		(10.2)
Investment debt securities held-to-maturity	391.6		386.4
Estimated Fair Value	215.9		642.7
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	250.1		675.1
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	250.1		675.1
State, county, and municipal securities
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(54.9)		(50.6)
Held-to-Maturity:
Investment securities classified as held to maturity	179.0		181.2
Allowance for Credit Losses	0.0		(0.1)
Net Amortized Cost	179.0		181.1
Gross Unrealized Gains	0.0		0.2
Gross Unrealized Losses	(34.9)		(31.6)
Investment debt securities held-to-maturity	144.1		149.7
Estimated Fair Value	202.6		263.7
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	257.5		314.3
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	257.5		314.3
Obligations of U.S. government agencies
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(17.3)		(17.3)
Held-to-Maturity:
Investment securities classified as held to maturity	353.8		351.7
Allowance for Credit Losses	0.0		0.0
Net Amortized Cost	353.8		351.7
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(59.5)		(49.6)
Investment debt securities held-to-maturity	294.3		302.1
Estimated Fair Value	162.0		198.9
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	179.3		216.2
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	179.3		216.2
Corporate Debt Securities
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(34.6)		(30.8)
Held-to-Maturity:
Investment securities classified as held to maturity	57.0		80.1
Allowance for Credit Losses	(0.8)		(1.8)
Net Amortized Cost	56.2		78.3
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(6.9)		(7.0)
Investment debt securities held-to-maturity	49.3		71.3
Estimated Fair Value	226.5		241.5
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	261.1		272.3
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	261.1		272.3
Collateralized Mortgage Obligations
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(159.2)		(141.3)
Held-to-Maturity:
Investment securities classified as held to maturity	487.1		525.8
Allowance for Credit Losses	0.0		0.0
Net Amortized Cost	487.1		525.8
Gross Unrealized Gains	0.0		0.2
Gross Unrealized Losses	(86.2)		(76.7)
Investment debt securities held-to-maturity	400.9		449.3
Estimated Fair Value	1,143.7		1,350.2
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,302.9		1,491.5
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,302.9		1,491.5
Commercial Mortgage-Backed Securities
Available-for-Sale:
Gross Unrealized Gains	0.1		0.2
Gross Unrealized Losses	(125.1)		(117.0)
Held-to-Maturity:
Investment securities classified as held to maturity	515.2		526.8
Allowance for Credit Losses	0.0		0.0
Net Amortized Cost	515.2		526.8
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(71.9)		(58.3)
Investment debt securities held-to-maturity	443.3		468.5
Estimated Fair Value	1,066.9		1,351.2
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,191.9		1,468.0
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,191.9		1,468.0
Residential Mortgage Backed Securities
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(189.3)		(167.7)
Held-to-Maturity:
Investment securities classified as held to maturity	1,269.8		1,391.5
Allowance for Credit Losses	0.0		0.0
Net Amortized Cost	1,269.8		1,391.5
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(197.2)		(166.6)
Investment debt securities held-to-maturity	1,072.6		1,224.9
Estimated Fair Value	1,285.0		1,558.3
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,474.3		1,726.0
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,474.3		1,726.0
Private mortgage-backed securities
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(39.1)		(36.9)
Held-to-Maturity:
Estimated Fair Value	207.3		228.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	246.4		264.9
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	246.4		264.9
Collateralized Loan Obligations
Available-for-Sale:
Gross Unrealized Gains	0.0		0.0
Gross Unrealized Losses	(8.9)		(33.6)
Held-to-Maturity:
Estimated Fair Value	1,117.8		1,111.6
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,126.7		1,145.2
Allowance for Credit Losses	0.0		0.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	$ 1,126.7		$ 1,145.2

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Investment Securities - Gross Unrealized Losses and Fair Values of Investment Securities (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Available-for-Sale:
Fair Value, Less than 12 Months	$ 2.2	$ 5,071.9
Gross Unrealized Losses, Less than 12 Months	0.0	(346.6)
Fair Value, 12 Months or Longer	5,614.3	1,545.6
Gross Unrealized Losses, 12 Months or Longer	(662.6)	(283.1)
Fair Value, Total	5,616.5	6,617.5
Gross Unrealized Losses, Total	(662.6)	(629.7)
Allowance for Credit Losses	0.0	0.0	$ (1.4)	$ 0.0	$ 0.0	$ 0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	6,290.2	7,573.5
Gross Unrealized Gains	0.1	2.3
Gross Unrealized Losses	(662.6)	(629.7)
Estimated Fair Value	5,627.7	6,946.1
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	6,290.2	7,573.5
Investment securities classified as held to maturity	3,260.3	3,453.7
Allowance for Credit Losses	(0.8)	(1.9)	$ (0.7)	$ (1.9)	$ (1.6)	$ 0.0
Net Amortized Cost	3,259.5	3,451.8
Gross Unrealized Gains	0.0	0.4
Gross Unrealized Losses	(463.4)	(400.0)
Investment debt securities held-to-maturity	2,796.1	3,052.2
US Treasury Notes 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	215.9
Gross Unrealized Losses, 12 Months or Longer	(34.2)
Fair Value, Total	215.9
Gross Unrealized Losses, Total	(34.2)
U.S. Treasury notes
Available-for-Sale:
Fair Value, Less than 12 Months		168.8
Gross Unrealized Losses, Less than 12 Months		(4.7)
Fair Value, 12 Months or Longer		170.4
Gross Unrealized Losses, 12 Months or Longer		(29.8)
Fair Value, Total		339.2
Gross Unrealized Losses, Total		(34.5)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	250.1	675.1
Gross Unrealized Gains	0.0	2.1
Gross Unrealized Losses	(34.2)	(34.5)
Estimated Fair Value	215.9	642.7
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	250.1	675.1
Investment securities classified as held to maturity	398.4	396.6
Allowance for Credit Losses	0.0	0.0
Net Amortized Cost	398.4	396.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(6.8)	(10.2)
Investment debt securities held-to-maturity	391.6	386.4
State, county, and municipal securities
Available-for-Sale:
Fair Value, Less than 12 Months	1.0	104.9
Gross Unrealized Losses, Less than 12 Months	0.0	(9.0)
Fair Value, 12 Months or Longer	199.7	146.1
Gross Unrealized Losses, 12 Months or Longer	(54.9)	(41.6)
Fair Value, Total	200.7	251.0
Gross Unrealized Losses, Total	(54.9)	(50.6)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	257.5	314.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(54.9)	(50.6)
Estimated Fair Value	202.6	263.7
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	257.5	314.3
Investment securities classified as held to maturity	179.0	181.2
Allowance for Credit Losses	0.0	(0.1)
Net Amortized Cost	179.0	181.1
Gross Unrealized Gains	0.0	0.2
Gross Unrealized Losses	(34.9)	(31.6)
Investment debt securities held-to-maturity	144.1	149.7
Obligations of U.S. government agencies
Available-for-Sale:
Fair Value, Less than 12 Months	0.0	152.2
Gross Unrealized Losses, Less than 12 Months	0.0	(10.1)
Fair Value, 12 Months or Longer	161.5	46.1
Gross Unrealized Losses, 12 Months or Longer	(17.3)	(7.2)
Fair Value, Total	161.5	198.3
Gross Unrealized Losses, Total	(17.3)	(17.3)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	179.3	216.2
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(17.3)	(17.3)
Estimated Fair Value	162.0	198.9
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	179.3	216.2
Investment securities classified as held to maturity	353.8	351.7
Allowance for Credit Losses	0.0	0.0
Net Amortized Cost	353.8	351.7
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(59.5)	(49.6)
Investment debt securities held-to-maturity	294.3	302.1
Private mortgage-backed securities
Available-for-Sale:
Fair Value, Less than 12 Months	0.0	133.1
Gross Unrealized Losses, Less than 12 Months	0.0	(19.1)
Fair Value, 12 Months or Longer	207.3	94.9
Gross Unrealized Losses, 12 Months or Longer	(39.1)	(17.8)
Fair Value, Total	207.3	228.0
Gross Unrealized Losses, Total	(39.1)	(36.9)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	246.4	264.9
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(39.1)	(36.9)
Estimated Fair Value	207.3	228.0
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	246.4	264.9
Collateralized Loan Obligations
Available-for-Sale:
Fair Value, Less than 12 Months	0.0	1,082.6
Gross Unrealized Losses, Less than 12 Months	0.0	(33.1)
Fair Value, 12 Months or Longer	1,117.8	28.9
Gross Unrealized Losses, 12 Months or Longer	(8.9)	(0.5)
Fair Value, Total	1,117.8	1,111.5
Gross Unrealized Losses, Total	(8.9)	(33.6)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,126.7	1,145.2
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(8.9)	(33.6)
Estimated Fair Value	1,117.8	1,111.6
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,126.7	1,145.2
Corporate Debt Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0.0	130.6
Gross Unrealized Losses, Less than 12 Months	0.0	(8.3)
Fair Value, 12 Months or Longer	226.6	110.8
Gross Unrealized Losses, 12 Months or Longer	(34.6)	(22.5)
Fair Value, Total	226.6	241.4
Gross Unrealized Losses, Total	(34.6)	(30.8)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	261.1	272.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(34.6)	(30.8)
Estimated Fair Value	226.5	241.5
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	261.1	272.3
Investment securities classified as held to maturity	57.0	80.1
Allowance for Credit Losses	(0.8)	(1.8)
Net Amortized Cost	56.2	78.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(6.9)	(7.0)
Investment debt securities held-to-maturity	49.3	71.3
Commercial Mortgage-Backed Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0.3	1,069.8
Gross Unrealized Losses, Less than 12 Months	0.0	(59.9)
Fair Value, 12 Months or Longer	1,057.8	270.8
Gross Unrealized Losses, 12 Months or Longer	(125.1)	(57.0)
Fair Value, Total	1,058.1	1,340.6
Gross Unrealized Losses, Total	(125.1)	(116.9)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,191.9	1,468.0
Gross Unrealized Gains	0.1	0.2
Gross Unrealized Losses	(125.1)	(117.0)
Estimated Fair Value	1,066.9	1,351.2
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,191.9	1,468.0
Investment securities classified as held to maturity	515.2	526.8
Allowance for Credit Losses	0.0	0.0
Net Amortized Cost	515.2	526.8
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(71.9)	(58.3)
Investment debt securities held-to-maturity	443.3	468.5
Residential Mortgage Backed Securities
Available-for-Sale:
Fair Value, Less than 12 Months	0.9	1,213.5
Gross Unrealized Losses, Less than 12 Months	0.0	(112.3)
Fair Value, 12 Months or Longer	1,284.0	344.6
Gross Unrealized Losses, 12 Months or Longer	(189.3)	(55.4)
Fair Value, Total	1,284.9	1,558.1
Gross Unrealized Losses, Total	(189.3)	(167.7)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,474.3	1,726.0
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(189.3)	(167.7)
Estimated Fair Value	1,285.0	1,558.3
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,474.3	1,726.0
Investment securities classified as held to maturity	1,269.8	1,391.5
Allowance for Credit Losses	0.0	0.0
Net Amortized Cost	1,269.8	1,391.5
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(197.2)	(166.6)
Investment debt securities held-to-maturity	1,072.6	1,224.9
Collateralized Mortgage Obligations
Available-for-Sale:
Fair Value, Less than 12 Months	0.0	1,016.4
Gross Unrealized Losses, Less than 12 Months	0.0	(90.1)
Fair Value, 12 Months or Longer	1,143.7	333.0
Gross Unrealized Losses, 12 Months or Longer	(159.2)	(51.3)
Fair Value, Total	1,143.7	1,349.4
Gross Unrealized Losses, Total	(159.2)	(141.4)
Allowance for Credit Losses	0.0	0.0
Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss	1,302.9	1,491.5
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	(159.2)	(141.3)
Estimated Fair Value	1,143.7	1,350.2
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,302.9	1,491.5
Investment securities classified as held to maturity	487.1	525.8
Allowance for Credit Losses	0.0	0.0
Net Amortized Cost	487.1	525.8
Gross Unrealized Gains	0.0	0.2
Gross Unrealized Losses	(86.2)	(76.7)
Investment debt securities held-to-maturity	400.9	449.3
US agency, residential and commercial MBS and CMOs
Available-for-Sale:
Debt Securities, Held-To-Maturity, Transfer, Unamortized Gain	11.4	14.2
State, county & municipal, obligations of US govt agencies and CLOs
Available-for-Sale:
Debt Securities, Held-To-Maturity, Transfer, Unamortized Loss	$ 18.6	$ 20.2

XML

Investment Securities - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) Investments	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Investments	Sep. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($) Investments	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 0.8	$ 1.9	$ 0.8	$ 1.9	$ 0.7	$ 1.9	$ 1.6	$ 0.0
Interest Receivable	129.2		129.2			118.3
Debt Securities, Available-for-sale, Realized Gain	0.0	0.0		0.0
Debt Securities, Available-for-sale, Realized Loss	0.0	$ (46.3)	(23.5)	$ (46.3)
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	7,066.8		7,066.8			4,998.9
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	$ 6,169.7		$ 6,169.7			$ 4,432.0
Investment securities in an unrealized loss position (securities) | Investments	1,034		1,034			1,222
Debt Securities, Current	$ 853.0		$ 853.0
Callable Within One Year
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost of investment securities callable after one year but within five years	1,592.1		1,592.1
Fair value of investment securities callable after one year but within five years	1,514.4		1,514.4
Callable structured notes amortized costs	$ 0.0		$ 0.0

XML

Investment Securities - Available-for-Sale Allowance for Credit loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 1.4	$ 0.0	$ 0.0	$ 0.0
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	$ (1.4)	$ 0.0	$ 0.0	$ 0.0

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Investment Securities - Held-To-Maturity Allowance For Credit Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 0.8	$ 1.9	$ 0.8	$ 1.9	$ 0.7	$ 1.9	$ 1.6	$ 0.0
Debt Securities, Held-to-Maturity, Credit Loss Expense (Reversal)	$ 0.1	$ 0.3	$ (1.1)	$ 1.9

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Investment Securities - Credit Quality Indicators (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	$ 3,260.3	$ 3,453.7
AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	3,092.4	3,260.7
AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	92.3	92.8
A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	10.6	11.5
BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	47.0	65.1
Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	13.0	13.6
BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5.0	10.0
U.S. Treasury notes
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	398.4	396.6
U.S. Treasury notes | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	398.4	396.6
U.S. Treasury notes | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
U.S. Treasury notes | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
U.S. Treasury notes | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	0.0
State, county, and municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	179.0	181.2
State, county, and municipal securities | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	68.1	68.3
State, county, and municipal securities | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	92.3	92.8
State, county, and municipal securities | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	10.6	11.5
State, county, and municipal securities | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
State, county, and municipal securities | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	8.0	8.6
State, county, and municipal securities | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
Obligations of U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	353.8	351.7
Obligations of U.S. government agencies | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	353.8	351.7
Obligations of U.S. government agencies | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	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	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	0.0
Corporate securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	57.0	80.1
Corporate securities | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
Corporate securities | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
Corporate securities | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
Corporate securities | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	47.0	65.1
Corporate securities | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5.0	5.0
Corporate securities | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5.0	10.0
Commercial Mortgage-Backed Securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	515.2	526.8
Commercial Mortgage-Backed Securities | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	360.9	364.9
Commercial Mortgage-Backed Securities | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	360.9	364.9
Commercial Mortgage-Backed Securities | FNMA/FHLMC | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	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	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	0.0
Commercial Mortgage-Backed Securities | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	154.3	161.9
Commercial Mortgage-Backed Securities | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	154.3	161.9
Commercial Mortgage-Backed Securities | GNMA | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	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	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	0.0
Residential Mortgage Backed Securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	1,269.8	1,391.5
Residential Mortgage Backed Securities | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	1,225.6	1,342.9
Residential Mortgage Backed Securities | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	1,225.6	1,342.9
Residential Mortgage Backed Securities | FNMA/FHLMC | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	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	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	0.0
Residential Mortgage Backed Securities | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	44.2	48.6
Residential Mortgage Backed Securities | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	44.2	48.6
Residential Mortgage Backed Securities | GNMA | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	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	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	0.0
Collateralized Mortgage Obligations
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	487.1	525.8
Collateralized Mortgage Obligations | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	342.0	525.8
Collateralized Mortgage Obligations | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	342.0	525.8
Collateralized Mortgage Obligations | FNMA/FHLMC | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	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	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	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	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	$ 0.0
Collateralized Mortgage Obligations | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	145.1
Collateralized Mortgage Obligations | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	145.1
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

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Investment Securities - Maturities of Investment Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Available-for-Sale, Amortized Cost
Available-for-Sale Amortized Cost, Within One Year	$ 1.6
Available-for-Sale Amortized Cost, After One Year but Within Five Years	1,036.0
Available-for-Sale Amortized Cost, After Five Years but Within Ten Years	1,387.9
Available-for-Sale Amortized Cost, After Ten Years	3,864.7
Amortized Cost	6,290.2	$ 7,573.5
Available-for-Sale, Estimated Fair Value
Available-for-Sale Estimated Fair Value, Within One Year	1.5
Available-for-Sale Estimated Fair Value, After One Year but Within Five Years	941.3
Available-for-Sale Estimated Fair Value, After Five Years but Within Ten Years	1,220.0
Available-for-Sale Estimated Fair Value, After Ten Years	3,464.9
Estimated Fair Value	5,627.7	6,946.1
Held-to-Maturity, Amortized Cost
Held-to-Maturity Amortized Cost, Within One Year	308.7
Held-to-Maturity Amortized Cost, After One Year but Within Five Years	346.4
Held-to-Maturity Amortized Cost, After Five Years but Within Ten Years	654.8
Held-to-Maturity Amortized Cost, After Ten Years	1,950.4
Amortized Cost1	3,260.3	3,453.7
Held-to-Maturity, Estimated Fair Value
Held-to-Maturity Estimated Fair Value, Within One Year	304.5
Held-to-Maturity Estimated Fair Value, After One Year but Within Five Years	320.2
Held-to-Maturity Estimated Fair Value, After Five Years but Within Ten Years	551.5
Held-to-Maturity Estimated Fair Value, After Ten Years	1,619.9
Investment debt securities held-to-maturity	2,796.1	3,052.2
Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	7,066.8	4,998.9
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	$ 6,169.7	$ 4,432.0

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Loans Held for Sale - By Segment (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Loans held for sale	$ 59.1		$ 79.9
Transfer of loans to held-for-sale	3.1	$ 12.4
Transfer of loans from held-for-sale to held for investment	0.0	$ 19.8
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	59.1		79.9
Commercial construction
Debt Securities, Available-for-sale [Line Items]
Loans held for sale	6.4		10.5
Transfer of loans to held-for-sale	3.1
Increase (Decrease) in Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value under Fair Value Option	(4.1)
Proceeds from Collection of Loans Held-for-sale	0.0
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	6.4		10.5
Agricultural
Debt Securities, Available-for-sale [Line Items]
Loans held for sale	49.5		62.5
Transfer of loans to held-for-sale	0.0
Increase (Decrease) in Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value under Fair Value Option	2.2
Proceeds from Collection of Loans Held-for-sale	(15.2)
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	49.5		62.5
Loans held for sale			5.5
Unpaid Principle Balance of Loans Held for Sale			7.7
Real Estate Sector
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	$ 3.2		6.9
Equal to or Greater than 90 Days Past Due | Agricultural
Debt Securities, Available-for-sale [Line Items]
Unpaid Principle Balance of Loans Held for Sale			5.6
Lower of Cost or Market | Agricultural
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance			$ 57.0

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Non-Residential Loans Held for Sale (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	$ 59.1		$ 79.9
Transfer of loans to held-for-sale	3.1	$ 12.4
Loans held for sale	59.1		79.9
Agricultural
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	49.5		62.5
Proceeds from Collection of Loans Held-for-sale	(15.2)
Transfer of loans to held-for-sale	0.0
Increase (Decrease) in Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value under Fair Value Option	2.2
Loans held for sale	49.5		62.5
Proceeds from Sale of Loans Held-for-sale	0.0
Commercial construction
Debt Securities, Available-for-sale [Line Items]
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	6.4		10.5
Proceeds from Collection of Loans Held-for-sale	0.0
Transfer of loans to held-for-sale	3.1
Increase (Decrease) in Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value under Fair Value Option	(4.1)
Loans held for sale	6.4		$ 10.5
Proceeds from Sale of Loans Held-for-sale	$ (3.1)

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Loans Held for Sale - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Nonaccrual loans	$ 31.6		$ 39.8
Transfer of loans from held-for-sale to held for investment	0.0	$ 19.8
Loans held for sale	59.1		79.9
Transfer of loans to held-for-sale	3.1	$ 12.4
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	59.1		79.9
Agricultural
Debt Securities, Available-for-sale [Line Items]
Nonaccrual loans	25.2		29.3
Loans held for sale	49.5		62.5
Transfer of loans to held-for-sale	0.0
Proceeds from Collection of Loans Held-for-sale	15.2
Increase (Decrease) in Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value under Fair Value Option	2.2
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	49.5		62.5
Commercial construction
Debt Securities, Available-for-sale [Line Items]
Nonaccrual loans	6.4		10.5
Loans held for sale	6.4		10.5
Transfer of loans to held-for-sale	3.1
Proceeds from Collection of Loans Held-for-sale	0.0
Increase (Decrease) in Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value under Fair Value Option	(4.1)
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance	$ 6.4		$ 10.5

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Loans Held for Investment - Schedule of Loans by Segment (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Deferred loan fees and costs	$ (13.1)		$ (15.6)
Loans held for investment, net of deferred fees and costs	18,213.3		18,099.2
Allowance for credit losses	(226.7)	$ (224.6)	(220.1)	$ (213.0)	$ (220.4)	$ (122.3)
Net loans held for investment	17,986.6		17,879.1
Nonaccrual loans	31.6		39.8
Commercial real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(73.7)	(89.5)	(43.9)
Financing Receivable, Loan in Process	1.6		7.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	8,766.2		8,528.6
Nonaccrual loans	31.0		19.6
Commercial real estate | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.2		5.6
Commercial real estate | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		0.8
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		1.1
Commercial real estate | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	8,733.6		8,501.5
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(3.1)	(3.4)	(2.4)
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(24.7)	(14.9)	(6.0)
Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	14.5		11.6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,930.3		1,944.4
Nonaccrual loans	17.4		3.7
Total construction loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.5		10.4
Total construction loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	7.5		0.6
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	0.5		0.6
Total construction loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1,898.4		1,929.1
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(20.7)	(19.7)	(14.6)
Financing Receivable, Loan in Process	5.2		13.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,212.2		2,188.3
Nonaccrual loans	9.5		6.4
Residential | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.4		9.9
Residential | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.8		2.1
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	1.0		1.2
Residential | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,197.5		2,168.7
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(5.8)	(5.4)	(1.9)
Financing Receivable, Loan in Process	1.9		7.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	731.5		794.9
Nonaccrual loans	5.4		7.6
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		1.1
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.5		6.1
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		0.0
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	724.2		780.1
Total real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(162.2)	(158.7)	(138.7)	(128.7)	(133.7)	(69.3)
Financing Receivable, Loan in Process	23.2		39.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,640.2		13,456.2
Nonaccrual loans	63.3		37.3
Total real estate | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	10.5		27.0
Total real estate | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	11.2		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	1.5		2.9
Total real estate | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	13,553.7		13,379.4
Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(14.1)	(13.1)	(14.3)
Financing Receivable, Loan in Process	9.0		12.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	751.7		829.7
Nonaccrual loans	3.0		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		9.3
Indirect consumer | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.2		2.4
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	0.4		0.6
Indirect consumer | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	739.7		814.7
Direct and advance lines
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(5.3)	(5.0)	(4.6)
Financing Receivable, Loan in Process	0.8		1.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	142.3		152.9
Nonaccrual loans	0.2		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	0.6		0.8
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	0.2		0.3
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		0.1
Direct and advance lines | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	141.3		151.4
Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses				(2.4)	(2.2)	(2.2)
Financing Receivable, Loan in Process	1.5		1.8
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	71.6		75.9
Nonaccrual loans	0.0		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	0.6		0.8
Credit card | 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
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	0.5		0.6
Credit card | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	70.1		74.1
Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(12.9)	(13.7)	(23.3)	(21.8)	(20.3)	(21.1)
Financing Receivable, Loan in Process	11.3		15.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	965.6		1,058.5
Nonaccrual loans	3.2		3.0
Total consumer loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	7.6		10.9
Total consumer loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.8		3.1
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	0.9		1.3
Total consumer loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	951.1		1,040.2
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(48.4)	(49.5)	(54.9)	(58.5)	(59.9)	(31.6)
Financing Receivable, Loan in Process	18.9		10.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,925.1		2,882.6
Nonaccrual loans	12.0		10.2
Commercial | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.3		7.1
Commercial | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	16.1		1.7
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	0.5		2.1
Commercial | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,894.2		2,861.5
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(3.2)	$ (2.7)	(3.2)	$ (4.0)	$ (6.5)	$ (0.3)
Financing Receivable, Loan in Process	1.0		3.1
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	690.5		708.3
Nonaccrual loans	2.9		8.7
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.7		0.8
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.0		2.2
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	0.3		0.1
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	686.6		696.5
Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.0		0.0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	5.0		9.2
Nonaccrual loans	0.0		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		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		0.0
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		0.0
Other, including overdrafts | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	5.0		9.2
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	54.4		68.8
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	18,226.4		18,114.8
Nonaccrual loans	81.4		59.2
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	21.1		45.8
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	30.1		16.6
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	3.2		6.4
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	$ 18,090.6		$ 17,986.8

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Loans Held for Investment - Schedule of Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 224.6	$ 220.4	$ 220.1	$ 122.3
(Reduction of) provision for credit losses	(0.1)	8.4	26.8	68.0
Loans Charged-Off(2)	(6.2)	(16.2)	(29.2)	(39.8)
Recoveries Collected	5.1	4.2	10.5	10.8
Ending balance	226.7	213.0	226.7	213.0
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	3.2	4.6	25.3	60.2
Provisional ACL Recorded for PCD loans				59.5
Non-owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		29.5		17.3
(Reduction of) provision for credit losses		(5.5)		(7.6)
Loans Charged-Off(2)		(0.1)		(3.0)
Recoveries Collected		0.0		0.0
Ending balance		23.9		23.9
Provisional ACL Recorded for PCD loans				17.2
Owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		26.6		13.3
(Reduction of) provision for credit losses		(3.7)		2.3
Loans Charged-Off(2)		0.0		(2.2)
Recoveries Collected		1.8		1.8
Ending balance		24.7		24.7
Provisional ACL Recorded for PCD loans				9.5
Multi-family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		33.4		13.3
(Reduction of) provision for credit losses		(2.6)		5.9
Loans Charged-Off(2)		(5.7)		(5.7)
Recoveries Collected		0.0		0.7
Ending balance		25.1		25.1
Provisional ACL Recorded for PCD loans				10.9
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		89.5		43.9
(Reduction of) provision for credit losses		(11.8)		0.6
Loans Charged-Off(2)		(5.8)	(6.3)	(10.9)
Recoveries Collected		1.8		2.5
Ending balance		73.7		73.7
Provisional ACL Recorded for PCD loans				37.6
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2.7	6.5	3.2	0.3
(Reduction of) provision for credit losses	0.5	(2.5)	(0.4)	3.3
Loans Charged-Off(2)	0.0	0.0	0.0	(5.4)
Recoveries Collected	0.0	0.0	0.4	1.3
Ending balance	3.2	4.0	3.2	4.0
Provisional ACL Recorded for PCD loans				4.5
Commercial and floor plans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		54.1		27.1
(Reduction of) provision for credit losses		(2.2)		18.1
Loans Charged-Off(2)		(0.5)		(5.8)
Recoveries Collected		1.0		1.8
Ending balance		52.4		52.4
Provisional ACL Recorded for PCD loans				11.2
Commercial purpose secured by 1-4 family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5.5		4.4
(Reduction of) provision for credit losses		0.4		1.2
Loans Charged-Off(2)		0.0		0.0
Recoveries Collected		0.0		0.1
Ending balance		5.9		5.9
Provisional ACL Recorded for PCD loans				0.2
Residential construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3.4		2.4
(Reduction of) provision for credit losses		(0.3)		0.7
Loans Charged-Off(2)		0.0		0.0
Recoveries Collected		0.0		0.0
Ending balance		3.1		3.1
Provisional ACL Recorded for PCD loans				0.0
Commercial construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		14.9		6.0
(Reduction of) provision for credit losses		16.4		25.1
Loans Charged-Off(2)		(6.6)		(6.6)
Recoveries Collected		0.0		0.0
Ending balance		24.7		24.7
Provisional ACL Recorded for PCD loans				0.2
Total construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19.1		8.9
(Reduction of) provision for credit losses		15.9		25.0
Loans Charged-Off(2)		(6.6)		(9.3)
Recoveries Collected		0.1		0.3
Ending balance		28.5		28.5
Provisional ACL Recorded for PCD loans				3.6
Residential 1-4 family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		18.2		13.4
(Reduction of) provision for credit losses		0.9		5.4
Loans Charged-Off(2)		0.0		(0.1)
Recoveries Collected		0.0		0.3
Ending balance		19.1		19.1
Provisional ACL Recorded for PCD loans				0.1
Home equity and HELOC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1.5		1.2
(Reduction of) provision for credit losses		0.1		0.1
Loans Charged-Off(2)		(0.1)		(0.1)
Recoveries Collected		0.1		0.4
Ending balance		1.6		1.6
Provisional ACL Recorded for PCD loans				0.0
Residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19.7		14.6
(Reduction of) provision for credit losses		1.0		5.5
Loans Charged-Off(2)		(0.1)	(0.6)	(0.2)
Recoveries Collected		0.1		0.7
Ending balance		20.7		20.7
Provisional ACL Recorded for PCD loans				0.1
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5.4		1.9
(Reduction of) provision for credit losses		0.4		1.7
Loans Charged-Off(2)		0.0	0.0	(0.2)
Recoveries Collected		0.0		0.1
Ending balance		5.8		5.8
Provisional ACL Recorded for PCD loans				2.3
Total real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	158.7	133.7	138.7	69.3
(Reduction of) provision for credit losses	1.8	5.5	35.6	32.8
Loans Charged-Off(2)	(1.8)	(12.5)	(16.6)	(20.6)
Recoveries Collected	3.5	2.0	4.5	3.6
Ending balance	162.2	128.7	162.2	128.7
Provisional ACL Recorded for PCD loans				43.6
Indirect consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		13.1		14.3
(Reduction of) provision for credit losses		1.6		0.9
Loans Charged-Off(2)		(1.2)	(5.2)	(2.9)
Recoveries Collected		0.6		1.8
Ending balance		14.1		14.1
Provisional ACL Recorded for PCD loans				0.0
Direct and advance lines
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5.0		4.6
(Reduction of) provision for credit losses		1.3		1.7
Loans Charged-Off(2)		(1.4)	(3.2)	(2.8)
Recoveries Collected		0.4		1.8
Ending balance		5.3		5.3
Provisional ACL Recorded for PCD loans				0.0
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		2.2		2.2
(Reduction of) provision for credit losses		0.3		1.6
Loans Charged-Off(2)		(0.3)	(2.0)	(1.8)
Recoveries Collected		0.2		0.4
Ending balance		2.4		2.4
Provisional ACL Recorded for PCD loans				0.0
Total consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	13.7	20.3	23.3	21.1
(Reduction of) provision for credit losses	1.8	3.2	(3.7)	4.2
Loans Charged-Off(2)	(3.7)	(2.9)	(10.4)	(7.5)
Recoveries Collected	1.1	1.2	3.7	4.0
Ending balance	12.9	21.8	12.9	21.8
Provisional ACL Recorded for PCD loans				0.0
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		0.3		0.1
(Reduction of) provision for credit losses		0.2		0.6
Loans Charged-Off(2)		(0.3)		(0.5)
Recoveries Collected		0.0		0.0
Ending balance		0.2		0.2
Provisional ACL Recorded for PCD loans				0.0
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	49.5	59.9	54.9	31.6
(Reduction of) provision for credit losses	(0.9)	(1.6)	(6.2)	19.9
Loans Charged-Off(2)	(0.7)	(0.8)	(2.2)	(6.3)
Recoveries Collected	0.5	1.0	1.9	1.9
Ending balance	$ 48.4	58.5	$ 48.4	58.5
Provisional ACL Recorded for PCD loans				11.4
Land Acquisition And Development Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		0.8		0.5
(Reduction of) provision for credit losses		(0.2)		(0.8)
Loans Charged-Off(2)		0.0		(2.7)
Recoveries Collected		0.1		0.3
Ending balance		$ 0.7		0.7
Provisional ACL Recorded for PCD loans				$ 3.4

XML

Loans Held for Investment - Schedule of Allowance for Credit Losses for Loans Held for Investment (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) Investments	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Investments	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) Investments
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 224.6	$ 220.4	$ 220.1	$ 122.3
Provision charged to operating expense	(0.1)	8.4	26.8	68.0
Loans Charged-Off(2)	(6.2)	(16.2)	(29.2)	(39.8)
Ending balance	226.7	213.0	226.7	213.0
Provisional ACL Recorded for PCD loans				59.5
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	3.2	4.6	25.3	60.2
Financing Receivable, Allowance for Credit Loss, Recovery	5.1	4.2	10.5	10.8
Interest Receivable	129.2		129.2		$ 118.3
Debt Securities, Available-for-sale, Realized Loss	$ 0.0	(46.3)	$ (23.5)	(46.3)
Investment securities in an unrealized loss position (securities) | Investments	1,034		1,034		1,222
Debt Securities, Available-for-sale, Realized Gain	$ 0.0	0.0		0.0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	7,066.8		$ 7,066.8		$ 4,998.9
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	6,169.7		6,169.7		4,432.0
Callable Within One Year
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Amortized cost of investment securities callable after one year but within five years	1,592.1		1,592.1
Fair value of investment securities callable after one year but within five years	1,514.4		1,514.4
Callable structured notes amortized costs	0.0		0.0
Debt Securities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Interest Receivable	36.5		36.5		$ 38.9
Commercial Real Estate Non Owner Occupied Loans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		29.5		17.3
Provision charged to operating expense		(5.5)		(7.6)
Loans Charged-Off(2)		(0.1)		(3.0)
Ending balance		23.9		23.9
Provisional ACL Recorded for PCD loans				17.2
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.0
Agricultural Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2.7	6.5	3.2	0.3
Provision charged to operating expense	0.5	(2.5)	(0.4)	3.3
Loans Charged-Off(2)	0.0	0.0	0.0	(5.4)
Ending balance	3.2	4.0	3.2	4.0
Provisional ACL Recorded for PCD loans				4.5
Financing Receivable, Allowance for Credit Loss, Recovery	0.0	0.0	0.4	1.3
Commercial and Floor Plans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		54.1		27.1
Provision charged to operating expense		(2.2)		18.1
Loans Charged-Off(2)		(0.5)		(5.8)
Ending balance		52.4		52.4
Provisional ACL Recorded for PCD loans				11.2
Financing Receivable, Allowance for Credit Loss, Recovery		1.0		1.8
Commercial Real Estate Owner Occupied [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		26.6		13.3
Provision charged to operating expense		(3.7)		2.3
Loans Charged-Off(2)		0.0		(2.2)
Ending balance		24.7		24.7
Provisional ACL Recorded for PCD loans				9.5
Financing Receivable, Allowance for Credit Loss, Recovery		1.8		1.8
Commercial Real Estate Multi-family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		33.4		13.3
Provision charged to operating expense		(2.6)		5.9
Loans Charged-Off(2)		(5.7)		(5.7)
Ending balance		25.1		25.1
Provisional ACL Recorded for PCD loans				10.9
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.7
Commercial real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		89.5		43.9
Provision charged to operating expense		(11.8)		0.6
Loans Charged-Off(2)		(5.8)	(6.3)	(10.9)
Ending balance		73.7		73.7
Provisional ACL Recorded for PCD loans				37.6
Financing Receivable, Allowance for Credit Loss, Recovery		1.8		2.5
Land Acquisition And Development Construction Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		0.8		0.5
Provision charged to operating expense		(0.2)		(0.8)
Loans Charged-Off(2)		0.0		(2.7)
Ending balance		0.7		0.7
Provisional ACL Recorded for PCD loans				3.4
Financing Receivable, Allowance for Credit Loss, Recovery		0.1		0.3
Residential construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3.4		2.4
Provision charged to operating expense		(0.3)		0.7
Loans Charged-Off(2)		0.0		0.0
Ending balance		3.1		3.1
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.0
Commercial construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		14.9		6.0
Provision charged to operating expense		16.4		25.1
Loans Charged-Off(2)		(6.6)		(6.6)
Ending balance		24.7		24.7
Provisional ACL Recorded for PCD loans				0.2
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.0
Construction Loans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19.1		8.9
Provision charged to operating expense		15.9		25.0
Loans Charged-Off(2)		(6.6)		(9.3)
Ending balance		28.5		28.5
Provisional ACL Recorded for PCD loans				3.6
Financing Receivable, Allowance for Credit Loss, Recovery		0.1		0.3
Residential Real Estate 1-4 Family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		18.2		13.4
Provision charged to operating expense		0.9		5.4
Loans Charged-Off(2)		0.0		(0.1)
Ending balance		19.1		19.1
Provisional ACL Recorded for PCD loans				0.1
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.3
Home Equity Line of Credit [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1.5		1.2
Provision charged to operating expense		0.1		0.1
Loans Charged-Off(2)		(0.1)		(0.1)
Ending balance		1.6		1.6
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery		0.1		0.4
Residential Real Estate [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19.7		14.6
Provision charged to operating expense		1.0		5.5
Loans Charged-Off(2)		(0.1)	(0.6)	(0.2)
Ending balance		20.7		20.7
Provisional ACL Recorded for PCD loans				0.1
Financing Receivable, Allowance for Credit Loss, Recovery		0.1		0.7
Agricultural Real Estate Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5.4		1.9
Provision charged to operating expense		0.4		1.7
Loans Charged-Off(2)		0.0	0.0	(0.2)
Ending balance		5.8		5.8
Provisional ACL Recorded for PCD loans				2.3
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.1
Real Estate Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	158.7	133.7	138.7	69.3
Provision charged to operating expense	1.8	5.5	35.6	32.8
Loans Charged-Off(2)	(1.8)	(12.5)	(16.6)	(20.6)
Ending balance	162.2	128.7	162.2	128.7
Provisional ACL Recorded for PCD loans				43.6
Financing Receivable, Allowance for Credit Loss, Recovery	3.5	2.0	4.5	3.6
Consumer Indirect Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		13.1		14.3
Provision charged to operating expense		1.6		0.9
Loans Charged-Off(2)		(1.2)	(5.2)	(2.9)
Ending balance		14.1		14.1
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery		0.6		1.8
Direct consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5.0		4.6
Provision charged to operating expense		1.3		1.7
Loans Charged-Off(2)		(1.4)	(3.2)	(2.8)
Ending balance		5.3		5.3
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery		0.4		1.8
Credit Card Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		2.2		2.2
Provision charged to operating expense		0.3		1.6
Loans Charged-Off(2)		(0.3)	(2.0)	(1.8)
Ending balance		2.4		2.4
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery		0.2		0.4
Consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	13.7	20.3	23.3	21.1
Provision charged to operating expense	1.8	3.2	(3.7)	4.2
Loans Charged-Off(2)	(3.7)	(2.9)	(10.4)	(7.5)
Ending balance	12.9	21.8	12.9	21.8
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery	1.1	1.2	3.7	4.0
Commercial Purpose secured by 1-4 Family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5.5		4.4
Provision charged to operating expense		0.4		1.2
Loans Charged-Off(2)		0.0		0.0
Ending balance		5.9		5.9
Provisional ACL Recorded for PCD loans				0.2
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.1
Commercial Borrower [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		0.3		0.1
Provision charged to operating expense		0.2		0.6
Loans Charged-Off(2)		(0.3)		(0.5)
Ending balance		0.2		0.2
Provisional ACL Recorded for PCD loans				0.0
Financing Receivable, Allowance for Credit Loss, Recovery		0.0		0.0
Commercial Portfolio Segment [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	49.5	59.9	54.9	31.6
Provision charged to operating expense	(0.9)	(1.6)	(6.2)	19.9
Loans Charged-Off(2)	(0.7)	(0.8)	(2.2)	(6.3)
Ending balance	48.4	58.5	48.4	58.5
Provisional ACL Recorded for PCD loans				11.4
Financing Receivable, Allowance for Credit Loss, Recovery	$ 0.5	$ 1.0	$ 1.9	$ 1.9

XML

Loans Held for Investment - Schedule of Contractual Aging of Loans by Portfolio (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	$ 31,600,000		$ 31,600,000		$ 39,800,000
Financing Receivable, Nonaccrual, Interest Income			0
Impaired Financing Receivable, Interest Income, Accrual Method	0	$ 0	0	$ 0
Less loans charged-off	6,200,000	16,200,000	29,200,000	39,800,000
Accrued interest reversal	(1,000,000)	0	1,900,000
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,600,000		1,600,000		7,500,000
Nonaccrual loans	31,000,000.0		31,000,000.0		19,600,000
Less loans charged-off		5,800,000	6,300,000	10,900,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	21,600,000		21,600,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	876,700,000		876,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,271,500,000		2,271,500,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,712,200,000		1,712,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,260,000,000		1,260,000,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	790,000,000.0		790,000,000.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,790,400,000		1,790,400,000
Financing Receivable, Excluding Accrued Interest, Revolving	43,800,000		43,800,000
Total	8,766,200,000		8,766,200,000
Commercial real estate | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	21,600,000		21,600,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	845,800,000		845,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,240,200,000		2,240,200,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,649,900,000		1,649,900,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,245,700,000		1,245,700,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	732,700,000		732,700,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,741,500,000		1,741,500,000
Financing Receivable, Excluding Accrued Interest, Revolving	42,800,000		42,800,000
Total	8,520,200,000		8,520,200,000
Commercial real estate | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	2,900,000		2,900,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	5,000,000.0		5,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	41,300,000		41,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	4,700,000		4,700,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	26,900,000		26,900,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	20,500,000		20,500,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0
Total	101,300,000		101,300,000
Commercial real estate | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	28,000,000.0		28,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	26,000,000.0		26,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	19,600,000		19,600,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	9,600,000		9,600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	30,400,000		30,400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	28,400,000		28,400,000
Financing Receivable, Excluding Accrued Interest, Revolving	1,000,000.0		1,000,000.0
Total	143,000,000.0		143,000,000.0
Commercial real estate | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	300,000		300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,400,000		1,400,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Revolving	0		0
Total	1,700,000		1,700,000
Residential construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					118,400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					120,400,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					6,200,000
Financing Receivable, Excluding Accrued Interest, Revolving					270,100,000
Total					516,200,000
Residential construction | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					118,400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					119,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					5,800,000
Financing Receivable, Excluding Accrued Interest, Revolving					270,100,000
Total					515,300,000
Residential construction | Substandard
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					500,000
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					400,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					900,000
Commercial construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		6,600,000		6,600,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					461,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					399,200,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					112,800,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					45,900,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Revolving					21,900,000
Total					1,042,000,000
Commercial construction | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					442,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					374,800,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					89,700,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					45,900,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0
Financing Receivable, Excluding Accrued Interest, Revolving					10,600,000
Total					964,100,000
Commercial construction | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					2,300,000
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					23,100,000
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					11,300,000
Total					36,700,000
Commercial construction | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					16,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					24,400,000
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
Total					41,200,000
Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	14,500,000		14,500,000		11,600,000
Nonaccrual loans	17,400,000		17,400,000		3,700,000
Less loans charged-off			9,700,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	3,400,000		3,400,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	450,400,000		450,400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	833,900,000		833,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	444,300,000		444,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39,600,000		39,600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16,500,000		16,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	39,400,000		39,400,000
Financing Receivable, Excluding Accrued Interest, Revolving	102,800,000		102,800,000
Total	1,930,300,000		1,930,300,000
Total construction loans | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	2,600,000		2,600,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	444,900,000		444,900,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	806,100,000		806,100,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	413,300,000		413,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39,400,000		39,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16,500,000		16,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	38,700,000		38,700,000
Financing Receivable, Excluding Accrued Interest, Revolving	102,800,000		102,800,000
Total	1,864,300,000		1,864,300,000
Total construction loans | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	800,000		800,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	4,100,000		4,100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	11,400,000		11,400,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6,500,000		6,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	200,000		200,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0
Total	23,000,000.0		23,000,000.0
Total construction loans | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1,400,000		1,400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,300,000		3,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	24,500,000		24,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	200,000		200,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	500,000		500,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0
Total	29,900,000		29,900,000
Total construction loans | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	13,100,000		13,100,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Revolving	0		0
Total	13,100,000		13,100,000
Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	5,200,000		5,200,000		13,200,000
Nonaccrual loans	9,500,000		9,500,000		6,400,000
Less loans charged-off		100,000	600,000	200,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	24,500,000		24,500,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	39,300,000		39,300,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	319,100,000		319,100,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	514,200,000		514,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	513,400,000		513,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	93,100,000		93,100,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	233,000,000.0		233,000,000.0
Financing Receivable, Excluding Accrued Interest, Revolving	475,600,000		475,600,000
Total	2,212,200,000		2,212,200,000
Residential | Performing
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	24,500,000		24,500,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	38,600,000		38,600,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	317,500,000		317,500,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	513,200,000		513,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	512,800,000		512,800,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	92,300,000		92,300,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	227,200,000		227,200,000
Financing Receivable, Excluding Accrued Interest, Revolving	475,600,000		475,600,000
Total	2,201,700,000		2,201,700,000
Residential | Nonperforming
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	700,000		700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,600,000		1,600,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,000,000.0		1,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	600,000		600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	800,000		800,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5,800,000		5,800,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0
Total	10,500,000		10,500,000
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,900,000		1,900,000		7,200,000
Nonaccrual loans	5,400,000		5,400,000		7,600,000
Less loans charged-off		0	0	200,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	100,000		100,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	72,100,000		72,100,000		204,200,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	159,500,000		159,500,000		185,800,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	165,000,000.0		165,000,000.0		115,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	100,200,000		100,200,000		68,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	61,700,000		61,700,000		59,300,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	144,600,000		144,600,000		119,600,000
Financing Receivable, Excluding Accrued Interest, Revolving	28,300,000		28,300,000		42,500,000
Total	731,500,000		731,500,000		794,900,000
Agricultural | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	100,000		100,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	60,500,000		60,500,000		180,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	133,100,000		133,100,000		172,800,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	158,800,000		158,800,000		109,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	95,900,000		95,900,000		64,800,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	59,400,000		59,400,000		46,600,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	130,100,000		130,100,000		105,100,000
Financing Receivable, Excluding Accrued Interest, Revolving	27,800,000		27,800,000		31,400,000
Total	665,700,000		665,700,000		710,200,000
Agricultural | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3,500,000		3,500,000		22,400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6,600,000		6,600,000		700,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,400,000		1,400,000		1,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	2,100,000		2,100,000		2,600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1,800,000		1,800,000		10,000,000.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5,900,000		5,900,000		3,200,000
Financing Receivable, Excluding Accrued Interest, Revolving	500,000		500,000		11,000,000.0
Total	21,800,000		21,800,000		51,100,000
Agricultural | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	8,100,000		8,100,000		1,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	19,800,000		19,800,000		12,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	4,800,000		4,800,000		3,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	2,200,000		2,200,000		600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	500,000		500,000		2,700,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	8,600,000		8,600,000		11,300,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		100,000
Total	44,000,000.0		44,000,000.0		32,300,000
Agricultural | 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					1,300,000
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
Total					1,300,000
Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	23,200,000		23,200,000		39,500,000
Nonaccrual loans	63,300,000		63,300,000		37,300,000
Less loans charged-off	1,800,000	12,500,000	16,600,000	20,600,000
Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9,000,000.0		9,000,000.0		12,300,000
Nonaccrual loans	3,000,000.0		3,000,000.0		2,700,000
Less loans charged-off		1,200,000	5,200,000	2,900,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	142,900,000		142,900,000		381,300,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	293,600,000		293,600,000		177,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	129,000,000.0		129,000,000.0		130,600,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	92,700,000		92,700,000		60,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	38,700,000		38,700,000		33,800,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	54,800,000		54,800,000		46,700,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Total	751,700,000		751,700,000		829,700,000
Indirect consumer | Performing
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	142,500,000		142,500,000		380,300,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	292,400,000		292,400,000		176,400,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	128,300,000		128,300,000		130,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	92,300,000		92,300,000		59,700,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	38,500,000		38,500,000		33,600,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	54,300,000		54,300,000		46,300,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Total	748,300,000		748,300,000		826,300,000
Indirect consumer | Nonperforming
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	400,000		400,000		1,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,200,000		1,200,000		900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	700,000		700,000		600,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	400,000		400,000		300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	200,000		200,000		200,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	500,000		500,000		400,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		0
Total	3,400,000		3,400,000		3,400,000
Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	800,000		800,000		1,200,000
Nonaccrual loans	200,000		200,000		300,000
Less loans charged-off		1,400,000	3,200,000	2,800,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	200,000		200,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	35,300,000		35,300,000		52,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	36,900,000		36,900,000		32,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21,200,000		21,200,000		18,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	10,800,000		10,800,000		8,500,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	4,400,000		4,400,000		6,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7,000,000.0		7,000,000.0		9,000,000.0
Financing Receivable, Excluding Accrued Interest, Revolving	26,500,000		26,500,000		25,900,000
Total	142,300,000		142,300,000		152,900,000
Direct and advance lines | Performing
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	200,000		200,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	35,300,000		35,300,000		52,600,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	36,800,000		36,800,000		31,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21,100,000		21,100,000		18,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	10,800,000		10,800,000		8,500,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	4,400,000		4,400,000		6,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7,000,000.0		7,000,000.0		8,900,000
Financing Receivable, Excluding Accrued Interest, Revolving	26,500,000		26,500,000		25,800,000
Total	142,100,000		142,100,000		152,400,000
Direct and advance lines | Nonperforming
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	100,000		100,000		100,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	100,000		100,000		100,000
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		100,000
Financing Receivable, Excluding Accrued Interest, Revolving	0		0		100,000
Total	200,000		200,000		500,000
Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,500,000		1,500,000		1,800,000
Nonaccrual loans	0		0		0
Less loans charged-off		300,000	2,000,000.0	1,800,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		178,100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Revolving	71,600,000		71,600,000
Total	71,600,000		71,600,000
Credit card | Performing
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		177,300,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Revolving	71,100,000		71,100,000
Total	71,100,000		71,100,000
Credit card | Nonperforming
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0		0		800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Revolving	500,000		500,000
Total	500,000		500,000
Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11,300,000		11,300,000		15,300,000
Nonaccrual loans	3,200,000		3,200,000		3,000,000.0
Less loans charged-off	3,700,000	2,900,000	10,400,000	7,500,000
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	18,900,000		18,900,000		10,900,000
Nonaccrual loans	12,000,000.0		12,000,000.0		10,200,000
Less loans charged-off	700,000	800,000	2,200,000	6,300,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	10,000,000.0		10,000,000.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	395,800,000		395,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	565,600,000		565,600,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	427,300,000		427,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	236,400,000		236,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	123,500,000		123,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	323,400,000		323,400,000
Financing Receivable, Excluding Accrued Interest, Revolving	843,100,000		843,100,000
Total	2,925,100,000		2,925,100,000
Commercial | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9,500,000		9,500,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	383,800,000		383,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	537,200,000		537,200,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	408,500,000		408,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	224,500,000		224,500,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	116,400,000		116,400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	317,000,000.0		317,000,000.0
Financing Receivable, Excluding Accrued Interest, Revolving	765,800,000		765,800,000
Total	2,762,700,000		2,762,700,000
Commercial | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	100,000		100,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	2,300,000		2,300,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,900,000		4,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6,700,000		6,700,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	4,700,000		4,700,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	2,500,000		2,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,400,000		1,400,000
Financing Receivable, Excluding Accrued Interest, Revolving	14,800,000		14,800,000
Total	37,400,000		37,400,000
Commercial | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	400,000		400,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	5,000,000.0		5,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	23,300,000		23,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	10,900,000		10,900,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	7,200,000		7,200,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	4,600,000		4,600,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5,000,000.0		5,000,000.0
Financing Receivable, Excluding Accrued Interest, Revolving	62,400,000		62,400,000
Total	118,800,000		118,800,000
Commercial | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	4,700,000		4,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	200,000		200,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,200,000		1,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Excluding Accrued Interest, Revolving	100,000		100,000
Total	6,200,000		6,200,000
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,000,000.0		1,000,000.0		3,100,000
Nonaccrual loans	2,900,000		2,900,000		8,700,000
Less loans charged-off	0	0	0	5,400,000
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6,000,000.0		6,000,000.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	123,100,000		123,100,000		176,100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	76,600,000		76,600,000		67,600,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	38,100,000		38,100,000		35,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	27,100,000		27,100,000		12,200,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	8,400,000		8,400,000		10,100,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	11,100,000		11,100,000		3,300,000
Financing Receivable, Excluding Accrued Interest, Revolving	400,100,000		400,100,000		402,100,000
Total	690,500,000		690,500,000		706,400,000
Agricultural | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6,000,000.0		6,000,000.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	77,200,000		77,200,000		127,200,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	74,800,000		74,800,000		59,700,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	35,900,000		35,900,000		31,800,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	25,500,000		25,500,000		10,600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7,700,000		7,700,000		8,600,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	9,600,000		9,600,000		3,100,000
Financing Receivable, Excluding Accrued Interest, Revolving	374,000,000.0		374,000,000.0		375,100,000
Total	610,700,000		610,700,000		616,100,000
Agricultural | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	900,000		900,000		26,100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,100,000		1,100,000		2,800,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	800,000		800,000		400,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	200,000		200,000		1,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	200,000		200,000		300,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	200,000		200,000		0
Financing Receivable, Excluding Accrued Interest, Revolving	9,700,000		9,700,000		26,200,000
Total	13,100,000		13,100,000		56,800,000
Agricultural | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0		0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	45,000,000.0		45,000,000.0		22,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	700,000		700,000		4,600,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,400,000		1,400,000		2,800,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,400,000		1,400,000		600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	500,000		500,000		1,200,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,300,000		1,300,000		200,000
Financing Receivable, Excluding Accrued Interest, Revolving	16,400,000		16,400,000		800,000
Total	66,700,000		66,700,000		33,000,000.0
Agricultural | 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					500,000
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
Total					500,000
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
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	54,400,000		54,400,000		68,800,000
Nonaccrual loans	81,400,000		81,400,000		59,200,000
Non-owner occupied
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		100,000		3,000,000.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1,163,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					882,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					674,200,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					490,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					261,100,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					907,600,000
Financing Receivable, Excluding Accrued Interest, Revolving					29,200,000
Total					4,408,200,000
Non-owner occupied | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1,162,600,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					861,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					661,100,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					467,600,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					241,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					890,400,000
Financing Receivable, Excluding Accrued Interest, Revolving					29,200,000
Total					4,313,700,000
Non-owner occupied | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					6,800,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					2,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					4,600,000
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					7,400,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					22,100,000
Non-owner occupied | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					13,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					10,800,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					18,200,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					19,600,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					9,800,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					72,400,000
Owner occupied
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		0		2,200,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					812,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					737,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					548,500,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					281,300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					179,900,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					574,000,000.0
Financing Receivable, Excluding Accrued Interest, Revolving					19,800,000
Total					3,153,500,000
Owner occupied | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					793,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					718,700,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					533,900,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					266,300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					165,800,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					551,300,000
Financing Receivable, Excluding Accrued Interest, Revolving					18,200,000
Total					3,047,200,000
Owner occupied | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					10,900,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					14,200,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					12,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					6,100,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					5,600,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					5,500,000
Financing Receivable, Excluding Accrued Interest, Revolving					1,100,000
Total					55,700,000
Owner occupied | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					8,400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					3,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					2,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					8,900,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					8,500,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					17,200,000
Financing Receivable, Excluding Accrued Interest, Revolving					500,000
Total					48,800,000
Owner occupied | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					400,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					1,400,000
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
Total					1,800,000
Multi-family
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		5,700,000		5,700,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					369,200,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					204,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					189,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					52,100,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					35,000,000.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					115,700,000
Financing Receivable, Excluding Accrued Interest, Revolving					1,000,000.0
Total					966,900,000
Multi-family | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					369,200,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					204,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					189,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					52,100,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					35,000,000.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					113,700,000
Financing Receivable, Excluding Accrued Interest, Revolving					1,000,000.0
Total					964,900,000
Multi-family | 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
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					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					1,700,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					1,700,000
Multi-family | Substandard
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					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					300,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					300,000
Commercial and floor plans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		500,000		5,800,000
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					527,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					370,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					219,400,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					132,100,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					124,400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					178,100,000
Financing Receivable, Excluding Accrued Interest, Revolving					697,400,000
Total					2,249,400,000
Commercial and floor plans | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					501,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					358,900,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					214,400,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					124,300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					120,300,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					171,100,000
Financing Receivable, Excluding Accrued Interest, Revolving					631,600,000
Total					2,122,300,000
Commercial and floor plans | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					15,900,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					6,800,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					1,300,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					4,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					900,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					4,900,000
Financing Receivable, Excluding Accrued Interest, Revolving					18,500,000
Total					52,700,000
Commercial and floor plans | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					9,800,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					3,300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					3,700,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					3,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					3,200,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					2,100,000
Financing Receivable, Excluding Accrued Interest, Revolving					47,200,000
Total					72,700,000
Commercial and floor plans | Doubtful
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					300,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					1,300,000
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					100,000
Total					1,700,000
Commercial purpose secured by 1-4 family
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off		$ 0		$ 0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					192,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					136,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					72,000,000.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					30,900,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					32,200,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					40,900,000
Financing Receivable, Excluding Accrued Interest, Revolving					28,900,000
Total					532,900,000
Commercial purpose secured by 1-4 family | Pass
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					191,700,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					134,500,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					69,800,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					30,400,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					29,900,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					39,500,000
Financing Receivable, Excluding Accrued Interest, Revolving					28,900,000
Total					524,700,000
Commercial purpose secured by 1-4 family | Other Assets Especially Mentioned
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					100,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					1,200,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					2,100,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					200,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					1,400,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					200,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					5,200,000
Commercial purpose secured by 1-4 family | Substandard
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					200,000
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					300,000
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					100,000
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					300,000
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					900,000
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					1,200,000
Financing Receivable, Excluding Accrued Interest, Revolving					0
Total					3,000,000.0
30 to 59 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,200,000		1,200,000		5,600,000
30 to 59 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6,500,000		6,500,000		10,400,000
30 to 59 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,400,000		2,400,000		9,900,000
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	400,000		400,000		1,100,000
30 to 59 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	10,500,000		10,500,000		27,000,000.0
30 to 59 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6,400,000		6,400,000		9,300,000
30 to 59 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	600,000		600,000		800,000
30 to 59 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	600,000		600,000		800,000
30 to 59 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	7,600,000		7,600,000		10,900,000
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,300,000		2,300,000		7,100,000
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	700,000		700,000		800,000
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	21,100,000		21,100,000		45,800,000
60 to 89 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	400,000		400,000		800,000
60 to 89 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	7,500,000		7,500,000		600,000
60 to 89 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,800,000		1,800,000		2,100,000
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,500,000		1,500,000		6,100,000
60 to 89 Days Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11,200,000		11,200,000		9,600,000
60 to 89 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,200,000		2,200,000		2,400,000
60 to 89 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	200,000		200,000		300,000
60 to 89 Days Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	400,000		400,000		400,000
60 to 89 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,800,000		2,800,000		3,100,000
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	16,100,000		16,100,000		1,700,000
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		2,200,000
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	30,100,000		30,100,000		16,600,000
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		1,100,000
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	500,000		500,000		600,000
Equal to or Greater than 90 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,000,000.0		1,000,000.0		1,200,000
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	1,500,000		1,500,000		2,900,000
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	400,000		400,000		600,000
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		100,000
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	500,000		500,000		600,000
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	900,000		900,000		1,300,000
Equal to or Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	500,000		500,000		2,100,000
Equal to or Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	300,000		300,000		100,000
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	3,200,000		3,200,000		6,400,000
Financial Asset, Not Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	8,733,600,000		8,733,600,000		8,501,500,000
Financial Asset, Not Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,898,400,000		1,898,400,000		1,929,100,000
Financial Asset, Not Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,197,500,000		2,197,500,000		2,168,700,000
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	724,200,000		724,200,000		780,100,000
Financial Asset, Not Past Due | Total real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13,553,700,000		13,553,700,000		13,379,400,000
Financial Asset, Not Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	739,700,000		739,700,000		814,700,000
Financial Asset, Not Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	141,300,000		141,300,000		151,400,000
Financial Asset, Not Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	70,100,000		70,100,000		74,100,000
Financial Asset, Not Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	951,100,000		951,100,000		1,040,200,000
Financial Asset, Not Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,894,200,000		2,894,200,000		2,861,500,000
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	686,600,000		686,600,000		696,500,000
Financial Asset, Not Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	5,000,000.0		5,000,000.0		9,200,000
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	$ 18,090,600,000		18,090,600,000		$ 17,986,800,000
Year One, Originated, Current Fiscal Year | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			1,700,000
Year One, Originated, Current Fiscal Year | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Year One, Originated, Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			300,000
Year One, Originated, Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Year One, Originated, Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			200,000
Year One, Originated, Current Fiscal Year | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Year One, Originated, Current Fiscal Year | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Year One, Originated, Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Year One, Originated, Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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			300,000
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
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			2,000,000.0
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			300,000
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
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			300,000
Year Two, Originated, Fiscal Year Before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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			1,700,000
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			100,000
Year Three, Originated, Two Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Year Three, Originated, Two Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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			1,600,000
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			200,000
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
Year Three, Originated, Two Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			300,000
Year Three, Originated, Two Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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			2,600,000
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
Year Four, Originated, Three Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Year Four, Originated, Three Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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			600,000
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			300,000
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
Year Four, Originated, Three Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			400,000
Year Four, Originated, Three Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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
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
Year Five, Originated, Four Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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
Year Five, Originated, Four Years before Current Fiscal Year | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			200,000
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			100,000
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
Year Five, Originated, Four Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Year Five, Originated, Four Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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
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
Originated, More than Five Years before Current Fiscal Year | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Originated, More than Five Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			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			600,000
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			2,100,000
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
Originated, More than Five Years before Current Fiscal Year | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Originated, More than Five Years before Current Fiscal Year | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Revolving | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			2,000,000.0
Revolving | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			900,000
Revolving | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			9,600,000
Revolving, Converted to Term | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			0
Revolving, Converted to Term | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			100,000
Revolving, Converted to Term | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Less loans charged-off			$ 0

XML

Loans Held for Investment - Schedule of Recorded Investment in Criticized Loans by Class and Credit Quality Indicator (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Commitments to purchase or sell	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Proceeds from sale of loans held-for-investment	0.0	0.0	0.0	0.0
Less loans charged-off	(6.2)	(16.2)	(29.2)	(39.8)
Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					$ 4,408.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1,163.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					882.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					674.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					490.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					261.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					907.6
Financing Receivable, Excluding Accrued Interest, Revolving					29.2
Less loans charged-off		(0.1)		(3.0)
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	8,766.2		8,766.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	876.7		876.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,271.5		2,271.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,712.2		1,712.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,260.0		1,260.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	790.0		790.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,790.4		1,790.4
Financing Receivable, Excluding Accrued Interest, Revolving	43.8		43.8
Less loans charged-off		(5.8)	(6.3)	(10.9)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	21.6		21.6
Commercial | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(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			(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			(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			(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			0.0
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					516.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					118.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					120.4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					6.2
Financing Receivable, Excluding Accrued Interest, Revolving					270.1
Less loans charged-off		0.0		0.0
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1,042.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					461.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					399.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					112.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					45.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					21.9
Less loans charged-off		(6.6)		(6.6)
Total construction
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off		(6.6)		(9.3)
Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,212.2		2,212.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	39.3		39.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	319.1		319.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	514.2		514.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	513.4		513.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	93.1		93.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	233.0		233.0
Financing Receivable, Excluding Accrued Interest, Revolving	475.6		475.6
Less loans charged-off		(0.1)	(0.6)	(0.2)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	24.5		24.5
Residential | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(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			0.0
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)
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)
Residential | Year Five, Originated, Four Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0.0
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)
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	1,930.3		1,930.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	450.4		450.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	833.9		833.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	444.3		444.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39.6		39.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16.5		16.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	39.4		39.4
Financing Receivable, Excluding Accrued Interest, Revolving	102.8		102.8
Less loans charged-off			(9.7)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	3.4		3.4
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			(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			0.0
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			(9.6)
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	731.5		731.5		794.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	72.1		72.1		204.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	159.5		159.5		185.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	165.0		165.0		115.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	100.2		100.2		68.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	61.7		61.7		59.3
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	144.6		144.6		119.6
Financing Receivable, Excluding Accrued Interest, Revolving	28.3		28.3		42.5
Less loans charged-off		0.0	0.0	(0.2)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1
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	(1.8)	(12.5)	(16.6)	(20.6)
Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	751.7		751.7		829.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	142.9		142.9		381.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	293.6		293.6		177.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	129.0		129.0		130.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	92.7		92.7		60.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	38.7		38.7		33.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	54.8		54.8		46.7
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Less loans charged-off		(1.2)	(5.2)	(2.9)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		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)
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			(2.0)
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			(1.6)
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			(0.6)
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			(0.2)
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			(0.6)
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	142.3		142.3		152.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	35.3		35.3		52.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	36.9		36.9		32.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21.2		21.2		18.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	10.8		10.8		8.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	4.4		4.4		6.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.0		7.0		9.0
Financing Receivable, Excluding Accrued Interest, Revolving	26.5		26.5		25.9
Less loans charged-off		(1.4)	(3.2)	(2.8)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.2		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)
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			(0.3)
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			(0.2)
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			(0.3)
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)
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			(2.1)
Direct consumer | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(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	71.6		71.6
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		178.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	71.6		71.6
Less loans charged-off		(0.3)	(2.0)	(1.8)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		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			(2.0)
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	(3.7)	(2.9)	(10.4)	(7.5)
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,925.1		2,925.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	395.8		395.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	565.6		565.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	427.3		427.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	236.4		236.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	123.5		123.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	323.4		323.4
Financing Receivable, Excluding Accrued Interest, Revolving	843.1		843.1
Less loans charged-off	(0.7)	(0.8)	(2.2)	(6.3)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	10.0		10.0
Commercial | Year One, Originated, Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			0.0
Commercial | Year Two, Originated, Fiscal Year Before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(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			(0.3)
Commercial | Year Four, Originated, Three Years before Current Fiscal Year
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.4)
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)
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)
Commercial | Revolving
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.9)
Commercial | Revolving, Converted to Term
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off			(0.1)
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	690.5		690.5		706.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	123.1		123.1		176.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	76.6		76.6		67.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	38.1		38.1		35.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	27.1		27.1		12.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	8.4		8.4		10.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	11.1		11.1		3.3
Financing Receivable, Excluding Accrued Interest, Revolving	400.1		400.1		402.1
Less loans charged-off	0.0	0.0	0.0	(5.4)
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.0		6.0
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
Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					3,153.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					812.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					737.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					548.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					281.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					179.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					574.0
Financing Receivable, Excluding Accrued Interest, Revolving					19.8
Less loans charged-off		0.0		(2.2)
Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					966.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					369.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					204.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					189.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					52.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					35.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					115.7
Financing Receivable, Excluding Accrued Interest, Revolving					1.0
Less loans charged-off		(5.7)		(5.7)
Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					2,249.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					527.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					370.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					219.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					132.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					124.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					178.1
Financing Receivable, Excluding Accrued Interest, Revolving					697.4
Less loans charged-off		(0.5)		(5.8)
Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					532.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					192.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					136.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					72.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					30.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					32.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					40.9
Financing Receivable, Excluding Accrued Interest, Revolving					28.9
Less loans charged-off		0.0		0.0
Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Less loans charged-off		(0.3)		(0.5)
Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1,639.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					258.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					490.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					541.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					98.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					32.3
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					217.5
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Less loans charged-off		0.0		(0.1)
Consumer Home Equity and HELOC
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					548.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					24.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					8.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					5.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					5.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					5.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					16.4
Financing Receivable, Excluding Accrued Interest, Revolving					483.0
Land Acquisition And Development Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					386.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					159.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					117.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					29.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					17.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					11.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					29.1
Financing Receivable, Excluding Accrued Interest, Revolving					22.2
Less loans charged-off		$ 0.0		$ (2.7)
Pass | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					4,313.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1,162.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					861.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					661.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					467.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					241.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					890.4
Financing Receivable, Excluding Accrued Interest, Revolving					29.2
Pass | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	8,520.2		8,520.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	845.8		845.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,240.2		2,240.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1,649.9		1,649.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1,245.7		1,245.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	732.7		732.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1,741.5		1,741.5
Financing Receivable, Excluding Accrued Interest, Revolving	42.8		42.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	21.6		21.6
Pass | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					515.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					118.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					119.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					5.8
Financing Receivable, Excluding Accrued Interest, Revolving					270.1
Pass | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					964.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					442.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					374.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					89.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					45.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					10.6
Pass | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	1,864.3		1,864.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	444.9		444.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	806.1		806.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	413.3		413.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	39.4		39.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	16.5		16.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	38.7		38.7
Financing Receivable, Excluding Accrued Interest, Revolving	102.8		102.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	2.6		2.6
Pass | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	665.7		665.7		710.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	60.5		60.5		180.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	133.1		133.1		172.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	158.8		158.8		109.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	95.9		95.9		64.8
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	59.4		59.4		46.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	130.1		130.1		105.1
Financing Receivable, Excluding Accrued Interest, Revolving	27.8		27.8		31.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1
Pass | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,762.7		2,762.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	383.8		383.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	537.2		537.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	408.5		408.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	224.5		224.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	116.4		116.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	317.0		317.0
Financing Receivable, Excluding Accrued Interest, Revolving	765.8		765.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	9.5		9.5
Pass | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	610.7		610.7		616.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	77.2		77.2		127.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	74.8		74.8		59.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	35.9		35.9		31.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	25.5		25.5		10.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	7.7		7.7		8.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	9.6		9.6		3.1
Financing Receivable, Excluding Accrued Interest, Revolving	374.0		374.0		375.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	6.0		6.0
Pass | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					3,047.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					793.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					718.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					533.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					266.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					165.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					551.3
Financing Receivable, Excluding Accrued Interest, Revolving					18.2
Pass | Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					964.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					369.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					204.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					189.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					52.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					35.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					113.7
Financing Receivable, Excluding Accrued Interest, Revolving					1.0
Pass | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					2,122.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					501.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					358.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					214.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					124.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					120.3
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					171.1
Financing Receivable, Excluding Accrued Interest, Revolving					631.6
Pass | Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					524.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					191.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					134.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					69.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					30.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					29.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					39.5
Financing Receivable, Excluding Accrued Interest, Revolving					28.9
Pass | Land Acquisition And Development Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					374.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					152.5
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					114.4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					29.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					17.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					10.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					28.4
Financing Receivable, Excluding Accrued Interest, Revolving					22.2
Other Assets Especially Mentioned | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					22.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					6.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					2.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					4.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					7.4
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	101.3		101.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	2.9		2.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	5.0		5.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	41.3		41.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	4.7		4.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	26.9		26.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	20.5		20.5
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					36.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					2.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					23.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					11.3
Other Assets Especially Mentioned | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	23.0		23.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	4.1		4.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	11.4		11.4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6.5		6.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.2		0.2
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.8		0.8
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	21.8		21.8		51.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	3.5		3.5		22.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	6.6		6.6		0.7
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1.4		1.4		1.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	2.1		2.1		2.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	1.8		1.8		10.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.9		5.9		3.2
Financing Receivable, Excluding Accrued Interest, Revolving	0.5		0.5		11.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	37.4		37.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	2.3		2.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.9		4.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	6.7		6.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	4.7		4.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	2.5		2.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1.4		1.4
Financing Receivable, Excluding Accrued Interest, Revolving	14.8		14.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.1		0.1
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	13.1		13.1		56.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.9		0.9		26.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.1		1.1		2.8
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.8		0.8		0.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.2		0.2		1.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.2		0.2		0.3
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.2		0.2		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	9.7		9.7		26.2
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Other Assets Especially Mentioned | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					55.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					10.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					14.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					12.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					6.1
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					5.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					5.5
Financing Receivable, Excluding Accrued Interest, Revolving					1.1
Other Assets Especially Mentioned | Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					1.7
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Other Assets Especially Mentioned | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					52.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					15.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					6.8
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					4.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					4.9
Financing Receivable, Excluding Accrued Interest, Revolving					18.5
Other Assets Especially Mentioned | Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					5.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					1.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					2.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					1.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Other Assets Especially Mentioned | Land Acquisition And Development Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					7.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					6.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Substandard | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					72.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.1
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					13.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					10.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					18.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					19.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					9.8
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	143.0		143.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	28.0		28.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	26.0		26.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	19.6		19.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	9.6		9.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	30.4		30.4
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	28.4		28.4
Financing Receivable, Excluding Accrued Interest, Revolving	1.0		1.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Substandard | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					0.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					41.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					16.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					24.4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Substandard | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	29.9		29.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	1.4		1.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	3.3		3.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	24.5		24.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.2		0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.5		0.5
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	44.0		44.0		32.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	8.1		8.1		1.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	19.8		19.8		12.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	4.8		4.8		3.5
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	2.2		2.2		0.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.5		0.5		2.7
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	8.6		8.6		11.3
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	118.8		118.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	5.0		5.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	23.3		23.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	10.9		10.9
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	7.2		7.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	4.6		4.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.0		5.0
Financing Receivable, Excluding Accrued Interest, Revolving	62.4		62.4
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.4		0.4
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	66.7		66.7		33.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	45.0		45.0		22.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.7		0.7		4.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1.4		1.4		2.8
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	1.4		1.4		0.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.5		0.5		1.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	1.3		1.3		0.2
Financing Receivable, Excluding Accrued Interest, Revolving	16.4		16.4		0.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Substandard | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					48.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					8.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					3.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					2.3
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					8.9
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					8.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					17.2
Financing Receivable, Excluding Accrued Interest, Revolving					0.5
Substandard | Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					0.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Substandard | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					72.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					9.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					3.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					3.7
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					3.4
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					3.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					2.1
Financing Receivable, Excluding Accrued Interest, Revolving					47.2
Substandard | Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					3.0
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.9
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					1.2
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Substandard | Land Acquisition And Development Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					0.9
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	1.7		1.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.3		0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1.4		1.4
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Doubtful | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	13.1		13.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	13.1		13.1
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Doubtful | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.0
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					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	6.2		6.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	4.7		4.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.2		0.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1.2		1.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	0.1		0.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Doubtful | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					0.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Doubtful | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.4
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					1.4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Doubtful | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					1.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.1
Doubtful | Land Acquisition And Development Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					3.2
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					3.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Performing | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	2,201.7		2,201.7
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	38.6		38.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	317.5		317.5
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	513.2		513.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	512.8		512.8
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	92.3		92.3
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	227.2		227.2
Financing Receivable, Excluding Accrued Interest, Revolving	475.6		475.6
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	24.5		24.5
Performing | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	748.3		748.3		826.3
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	142.5		142.5		380.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	292.4		292.4		176.4
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	128.3		128.3		130.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	92.3		92.3		59.7
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	38.5		38.5		33.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	54.3		54.3		46.3
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Performing | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	142.1		142.1		152.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	35.3		35.3		52.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	36.8		36.8		31.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	21.1		21.1		18.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	10.8		10.8		8.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	4.4		4.4		6.5
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	7.0		7.0		8.9
Financing Receivable, Excluding Accrued Interest, Revolving	26.5		26.5		25.8
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.2		0.2
Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	71.1		71.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		177.3
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	71.1		71.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Performing | Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					1,634.6
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					258.9
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					490.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					541.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					98.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					32.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					213.8
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Performing | Consumer Home Equity and HELOC
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					546.1
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					23.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					8.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					5.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					5.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					5.6
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					15.2
Financing Receivable, Excluding Accrued Interest, Revolving					482.8
Nonperforming | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	10.5		10.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.7		0.7
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.6		1.6
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	1.0		1.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.6		0.6
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.8		0.8
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	5.8		5.8
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Nonperforming | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	3.4		3.4		3.4
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.4		0.4		1.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.2		1.2		0.9
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.7		0.7		0.6
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.4		0.4		0.3
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.2		0.2		0.2
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.5		0.5		0.4
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Nonperforming | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	0.2		0.2		0.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		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		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0		0.1
Financing Receivable, Excluding Accrued Interest, Revolving	0.0		0.0		0.1
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	0.0		0.0
Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total	0.5		0.5
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year	0.0		0.0		0.8
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year	0.0		0.0
Financing Receivable, Excluding Accrued Interest, Revolving	0.5		0.5
Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan	$ 0.0		$ 0.0
Nonperforming | Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					4.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.1
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.5
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					3.7
Financing Receivable, Excluding Accrued Interest, Revolving					0.0
Nonperforming | Consumer Home Equity and HELOC
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Total					2.8
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.6
Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year					0.3
Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year					0.2
Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year					0.1
Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year					1.2
Financing Receivable, Excluding Accrued Interest, Revolving					0.2
Agriculture Portfolio Segment [Member] | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1.9
Agriculture Portfolio Segment [Member] | Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					1.9
Agriculture Portfolio Segment [Member] | Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.0
Commercial | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					100.3
Commercial | Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					100.0
Commercial | Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					0.3
Total consumer loans | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					75.9
Total consumer loans | Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					75.4
Total consumer loans | Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year					$ 0.5

XML

Loans Held for Investment - Schedule of PCD Loans (Details) $ in Millions	Feb. 01, 2022 USD ($)
Receivables [Abstract]
Purchase price (initial fair value)	$ 623.3
Allowance for credit losses	(298.2)
Non-credit discount at acquisition	57.7
Par value (unpaid principal balance)	979.2
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses, Decreases	238.7
Business Combination, Impact On Purchased Credit Deteriorated Loans	59.5
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Difference Between Amortized Cost Basis And Unpaid Principal Balance	39.6
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Interest Applied To Principal	$ 18.1

XML

Loans Held for Investment - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	$ 0.1	$ (8.4)	$ (26.8)	$ (68.0)
Accounts Receivable, Allowance for Credit Loss	226.7	213.0	226.7	213.0	$ 224.6	$ 220.1	$ 220.4	$ 122.3
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	3.2	4.6	25.3	60.2
Impaired Financing Receivable, Interest Income, Accrual Method	0.0	0.0	0.0	0.0
Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	(1.8)	(5.5)	(35.6)	(32.8)
Accounts Receivable, Allowance for Credit Loss	162.2	128.7	162.2	128.7	158.7	138.7	133.7	69.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	13,640.2		13,640.2			13,456.2
Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	0.9	1.6	6.2	(19.9)
Accounts Receivable, Allowance for Credit Loss	48.4	58.5	48.4	58.5	49.5	54.9	59.9	31.6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,925.1		2,925.1			2,882.6
Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	(0.5)	2.5	0.4	(3.3)
Accounts Receivable, Allowance for Credit Loss	3.2	4.0	3.2	4.0	$ 2.7	3.2	6.5	0.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	690.5		690.5			708.3
Owner occupied
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		3.7		(2.3)
Accounts Receivable, Allowance for Credit Loss		24.7		24.7			26.6	13.3
Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		11.8		(0.6)
Accounts Receivable, Allowance for Credit Loss		73.7		73.7			89.5	43.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	8,766.2		8,766.2			8,528.6
Residential construction
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		0.3		(0.7)
Accounts Receivable, Allowance for Credit Loss		3.1		3.1			3.4	2.4
Commercial construction
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		(16.4)		(25.1)
Accounts Receivable, Allowance for Credit Loss		24.7		24.7			14.9	6.0
Total construction
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		(15.9)		(25.0)
Accounts Receivable, Allowance for Credit Loss		28.5		28.5			19.1	8.9
Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		(0.9)		(5.4)
Accounts Receivable, Allowance for Credit Loss		19.1		19.1			18.2	13.4
Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		(1.0)		(5.5)
Accounts Receivable, Allowance for Credit Loss		20.7		20.7			19.7	14.6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,212.2		2,212.2			2,188.3
Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense		(0.4)		(1.7)
Accounts Receivable, Allowance for Credit Loss		$ 5.8		$ 5.8			$ 5.4	$ 1.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	731.5		731.5			794.9
Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,930.3		1,930.3			1,944.4
Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	56.3		56.3			39.1
Collateral [Member] | Total real estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	48.7		48.7			27.2
Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	6.9		6.9			4.6
Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.7		0.7			7.3
Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	29.6		29.6			17.5
Collateral [Member] | Residential
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.5		0.5			0.5
Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1.5		1.5			6.0
Collateral [Member] | Total construction loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	17.1		17.1			3.2
Business Assets [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	5.1		5.1			7.1
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		0.0			1.9
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	4.4		4.4			3.1
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	0.7		0.7			2.1
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		0.0			1.7
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		0.0			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		0.0			0.2
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		0.0			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	50.3		50.3			32.0
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	48.7		48.7			25.3
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	1.6		1.6			1.5
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	0.0		0.0			5.2
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	29.6		29.6			15.8
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	0.5		0.5			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	1.5		1.5			5.8
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	17.1		17.1			3.2
Other Property [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.9		0.9			0.0
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		0.0			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	0.9		0.9			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		0.0			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	0.0		0.0			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		0.0			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		0.0			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		$ 0.0			$ 0.0

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Loans Held for Investment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Receivables [Abstract]
Commitments to purchase or sell	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Proceeds from sale of loans held-for-investment	0.0	$ 0.0	0.0	$ 0.0
Interest Receivable	$ 129.2		$ 129.2		$ 118.3

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Loans Held for Investment - Schedule of Modifications to Borrowers (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Modifications to Borrowers [Line Items]
Interest Receivable	$ 129.2	$ 129.2	$ 118.3
Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	1.7
Financing Receivable, Excluding Accrued Interest, Modified Period	33.2	91.2
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 32.6	$ 88.9
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.18%	0.50%
Interest Receivable	$ 1.7	$ 1.7
Financing Receivable, Loan in Process	0.1	0.1
Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	1.6
Agricultural
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	1.9	1.9	7.2
Agricultural | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	0.0
Financing Receivable, Excluding Accrued Interest, Modified Period	6.1	6.4
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 6.1	$ 6.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.83%	0.87%
Agricultural | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 0.0
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	4 years	4 years 7 months 6 days
Agricultural
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 1.0	$ 1.0	3.1
Agricultural | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	0.0
Financing Receivable, Excluding Accrued Interest, Modified Period	0.5	36.4
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 0.5	$ 36.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.07%	5.27%
Agricultural | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 0.0
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	3 years 6 months	9 years 2 months 12 days
Other, including overdrafts
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 0.0	$ 0.0	0.0
Commercial
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	1.6	1.6	7.5
Commercial | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	1.6
Financing Receivable, Excluding Accrued Interest, Modified Period	11.5	25.2
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 10.9	$ 23.0
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.13%	0.29%
Commercial | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 1.3
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	4 years 7 months 6 days	5 years 8 months 12 days
Total construction loans
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 14.5	$ 14.5	11.6
Total construction loans | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	0.0
Financing Receivable, Excluding Accrued Interest, Modified Period	13.1	13.2
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 13.1	$ 13.2
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.68%	0.68%
Total construction loans | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 0.0
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	9 years	9 years
Residential
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 5.2	$ 5.2	13.2
Residential | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	0.1
Financing Receivable, Excluding Accrued Interest, Modified Period	0.4	0.6
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 0.4	$ 0.5
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.02%	0.03%
Residential | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 0.3
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	144 years 4 months 24 days	139 years 2 months 12 days
Total real estate
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 23.2	$ 23.2	39.5
Total real estate | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	1.7
Financing Receivable, Excluding Accrued Interest, Modified Period	31.1	45.4
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 30.5	$ 43.1
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.23%	0.33%
Total real estate | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 1.6
Commercial
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	18.9	18.9	10.9
Commercial | Borrowers in Financial Distress
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	0.0	0.0
Financing Receivable, Excluding Accrued Interest, Modified Period	1.6	9.4
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension	$ 1.6	$ 9.4
Financing Receivable, Modification to Total Financing Receivables, Excluding Accrued Interest, Percent	0.05%	0.32%
Commercial | Borrowers in Financial Difficulty
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Excluding Accrued Interest, Modified Period, Principal Forgiveness	$ 0.0	$ 0.0
Financing Receivable, Excluding Accrued Interest, Modified Period, Term Extension, Weighted-Average Months	7 years 9 months 18 days	8 years 9 months 18 days
Indirect consumer
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 9.0	$ 9.0	12.3
Direct and advance lines
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	0.8	0.8	1.2
Credit Card Receivable [Member]
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	1.5	1.5	1.8
Total consumer loans
Financing Receivable, Modifications to Borrowers [Line Items]
Financing Receivable, Loan in Process	$ 11.3	$ 11.3	$ 15.3

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Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Repossessed Assets [Abstract]
Balance at beginning of year	$ 14.4	$ 16.8	$ 12.7	$ 2.0
OREO acquired through acquisitions	0.0	0.0	0.0	15.8
Additions	0.0	0.3	2.5	0.4
Write-down of OREO	(0.3)	(0.2)	(1.1)	(0.2)
Dispositions	(2.5)	(0.5)	(2.5)	(1.6)
Balance at end of year	$ 11.6	$ 16.4	$ 11.6	$ 16.4

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Other Real Estate Owned - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Balance at beginning of year
Carrying values of foreclosed residential real estate properties	$ 0.0
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 0.4	$ 0.0

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Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	$ 1,646.8	$ 2,290.7
Derivative Asset, Estimated Fair Value	57.4	45.2
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	2,898.0	2,449.0
Derivative Liabilities, Estimated Fair Value	210.0	159.6
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	1,638.8	1,728.1
Derivative Asset, Estimated Fair Value	57.4	41.6
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	1,638.8	1,728.1
Derivative Liabilities, Estimated Fair Value	184.1	153.9
Not Designated as Hedging Instrument | Interest rate lock commitments
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	7.0	14.8
Derivative Liabilities, Estimated Fair Value	0.0	0.0
Not Designated as Hedging Instrument | Forward loan sales contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	8.0	12.6
Designated as Hedging Instrument [Member] | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	0.0	550.0
Derivative Asset, Estimated Fair Value	0.0	3.5
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	850.0	300.0
Derivative Liabilities, Estimated Fair Value	$ 18.6	$ 0.3

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Derivatives and Hedging Activities - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financial Assets
Gross Amounts Recognized	$ 57.4		$ 57.4		$ 45.2
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	57.4		57.4		45.2
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	38.6		38.6		45.1
Net Amount	18.8		18.8		0.1
Financial Liabilities
Gross Amounts Recognized	210.0		210.0		159.6
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	210.0		210.0		159.6
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	1.0		1.0		0.0
Net Amount	209.0		209.0		159.6
Repurchase agreements
Gross Amounts Recognized	889.5		889.5		1,052.9
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	889.5		889.5		1,052.9
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	889.5		889.5		1,052.9
Net Amount	0.0		0.0		0.0
Total assets and liabilities
Gross Amounts Recognized	1,099.5		1,099.5		1,212.5
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	1,099.5		1,099.5		1,212.5
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	890.5		890.5		1,052.9
Net Amount	209.0		209.0		159.6
Derivative Liability, Notional Amount	2,898.0		2,898.0		2,449.0
Not Designated as Hedging Instrument
Total assets and liabilities
Amount of net gains recognized in mortgage banking revenues	0.1	$ (0.2)	(0.1)	$ (1.7)
Interest Rate Swap
Financial Assets
Gross Amounts Recognized	57.4		57.4		45.1
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	57.4		57.4		45.1
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	38.6		38.6		45.1
Net Amount	18.8		18.8		0.0
Financial Liabilities
Gross Amounts Recognized	210.0		210.0		159.6
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	210.0		210.0		159.6
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	1.0		1.0		0.0
Net Amount	209.0		209.0		159.6
Interest Rate Swap | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	1,638.8		1,638.8		1,728.1
Mortgage Related Derivatives
Financial Assets
Gross Amounts Recognized					0.1
Gross Amounts Offset in the Balance Sheet					0.0
Net Amounts in the Balance Sheet					0.1
Financial Instruments					0.0
Fair Value of Financial Collateral in the Balance Sheet					0.0
Net Amount					0.1
Risk Participation Agreements | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	102.2		102.2		106.1
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	$ 7.0		$ 7.0		$ 14.8

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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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Derivative [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 15.0		$ 15.0
Derivative Instruments and Hedges, Assets	192.9		192.9		$ 191.9
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	7.1		7.1		8.1
Financial Instruments	0.0		0.0		0.0
Derivative Asset, Notional Amount	1,646.8		1,646.8		2,290.7
Derivative Asset, Estimated Fair Value	57.4		57.4		45.2
Derivative Liability, Notional Amount	2,898.0		2,898.0		2,449.0
Derivative Liabilities, Estimated Fair Value	210.0		210.0		159.6
Collateral Pledged
Derivative [Line Items]
Derivative, Fair Value, Net	0.9		0.9
Financial Instruments	0.1		0.1
Not Designated as Hedging Instrument
Derivative [Line Items]
Amount of net fee income recognized in other non-interest income	0.1	$ 2.5	0.7	$ 5.6
Amount of net gains recognized in mortgage banking revenues	0.1	(0.2)	(0.1)	(1.7)
Interest Rate Swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	850.0		850.0
Financial Instruments	0.0		0.0		0.0
Interest Rate Swap | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	0.0		0.0		550.0
Derivative Asset, Estimated Fair Value	0.0		0.0		3.5
Derivative Liability, Notional Amount	850.0		850.0		300.0
Derivative Liabilities, Estimated Fair Value	18.6		18.6		0.3
Interest Rate Swap | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	1,638.8		1,638.8		1,728.1
Derivative Asset, Estimated Fair Value	57.4		57.4		41.6
Derivative Liability, Notional Amount	1,638.8		1,638.8		1,728.1
Derivative Liabilities, Estimated Fair Value	184.1		184.1		153.9
Risk Participation Agreements | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Notional Amount	102.2		102.2		106.1
Derivative Liabilities, Estimated Fair Value	0.0		0.0		0.0
Forward Contracts | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Fair Value, Net	0.0		0.0		0.1
Derivative Asset, Notional Amount	8.0		8.0		12.6
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Notional Amount	7.0		7.0		14.8
Derivative Liabilities, Estimated Fair Value	0.0		0.0		0.0
Interest Rate Collars
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	300.0		300.0
Interest Rate Collars | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	300.0		300.0		300.0
Derivative Liabilities, Estimated Fair Value	7.3		7.3		$ 5.4
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	$ (25.1)	$ (5.6)	$ (31.2)	$ (5.6)

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Derivative Instruments and Hedging Activities - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	$ 192.9		$ 192.9		$ 191.9
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	7.1		7.1		$ 8.1
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	15.0		15.0
Derivative Instruments and Hedges, Noncurrent	600.0		600.0
Interest Income
Derivative [Line Items]
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	0.0	$ 0.0	0.0	$ 0.0
Interest Rate Swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	850.0		850.0
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	(25.1)	(5.6)	(31.2)	(5.6)
Interest Rate Collars
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	300.0		300.0
Interest Rate Swap and Interest Rate Collar
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	$ 1,150.0		$ 1,150.0
three-year forward starting, four-year pay fixed interest rate swap [Member]
Derivative [Line Items]
Derivative Instruments and Hedges, Assets		200.0		200.0
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)		$ 8.5		$ 8.5

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Other Borrowed Funds - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Advance from Federal Home Loan Bank	$ 2,067.0	$ 2,327.0
Notes Payable to FHLB | Subsidiaries | Federal Home Loan Bank Advances
Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds	4,764.4
Federal Home Loan Bank, Advances, General Debt Obligations, Maximum Amount Available	$ 6,831.4

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Debt (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Advance from Federal Home Loan Bank	$ 2,067.0	$ 2,327.0
Average fixed rate borrowings in tenors up to one-week
Fixed-to-floating rate (percent)	5.52%
Advance from Federal Home Loan Bank	$ 106.0
5.30% average fixed rate borrowings in tenors up to two-weeks
Fixed-to-floating rate (percent)	5.51%
Advance from Federal Home Loan Bank	$ 100.0
5.01% fixed rate borrowings in tenors up to one-month
Fixed-to-floating rate (percent)	5.50%	4.48%
Advance from Federal Home Loan Bank	$ 925.0	$ 1,500.0
5.11% average fixed rate borrowings in tenors of 2-month
Fixed-to-floating rate (percent)	5.56%
Advance from Federal Home Loan Bank	$ 500.0
5.56% average fixed rate borrowings in tenors of 5-months
Fixed-to-floating rate (percent)	5.56%
Advance from Federal Home Loan Bank	$ 436.0
Variable rate overnight borrowings
Fixed-to-floating rate (percent)		4.60%
Advance from Federal Home Loan Bank		$ 827.0

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Capital Stock (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Feb. 01, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	May 25, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Shares outstanding (in shares)		105,011,371		105,011,371			104,442,023
Common shares issued (in shares)					46,913,370
Stock repurchased and retired (in shares)		494	3,280,042	55,922	5,039,784
Stock Repurchased and Retired During Period, Value		$ 0.0	$ 133.0	$ 1.9	$ 198.9
Common Stock, Shares, Issued		105,011,371		105,011,371			104,442,023
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized						2,000,000
Accelerated Share Repurchases, Adjustment to Recorded Amount					$ 133.1
Shares repurchased, average cost per share (in dollars per share)					$ 40.59
Great Western Bank
Class of Stock [Line Items]
Total consideration exchanged	$ 1,723.3
Class A Common Stock
Class of Stock [Line Items]
Shares outstanding (in shares)							104,442,023
Stock repurchased and retired (in shares)					3,729,300
Common Stock, Shares, Issued							104,442,023
Class A Common Stock | Great Western Bank
Class of Stock [Line Items]
Number of shares issued as consideration (in shares)	46,900,000
Director [Member]
Class of Stock [Line Items]
Common shares issued (in shares)				54,414
Director [Member] | Class A Common Stock
Class of Stock [Line Items]
Dividend, Share-based Payment Arrangement, Paid-in-Kind				$ 1.2

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Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 72.7	$ 85.7	$ 196.0	$ 116.4
Weighted average common shares outstanding for basic earnings per share computation (in shares)	103,822,311	106,525,974	103,793,851	102,879,422
Dilutive effects of stock-based compensation (in shares)	4,116	63,725	30,425	55,938
Weighted average common shares outstanding for diluted earnings per common share computation (in shares)	103,826,427	106,589,699	103,824,276	102,935,360
Basic earnings per common share (in dollars per share)	$ 0.70	$ 0.80	$ 1.89	$ 1.13
Diluted earnings per common share (in dollars per share)	$ 0.70	$ 0.80	$ 1.89	$ 1.13
Restricted Stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)	162,231	48,871	162,231	51,161
Unvested restricted stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)			967,996	481,567

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Regulatory Capital (Details) $ in Millions	Jan. 01, 2020 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained Earnings (Accumulated Deficit)		$ 1,122.3	$ 1,072.7
Total risk-based capital:
Actual, Amount		$ 2,957.6	$ 2,875.8
Actual, Ratio		0.1319	0.1248
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,794.5	$ 1,843.2
Minimum Required for Capital Adequacy Purposes, Ratio		0.0800	0.0800
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 2,355.3	$ 2,419.2
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		10.50%	10.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 2,243.1	$ 2,304.0
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		$ 1,009.4	$ 1,036.8
Tier 1 risk-based capital:
Actual, Amount		$ 2,471.6	$ 2,408.8
Actual, Ratio		0.1102	0.1045
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,345.9	$ 1,382.4
Minimum Required for Capital Adequacy Purposes, Ratio		0.0600	0.0600
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,906.6	$ 1,958.4
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		8.50%	8.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,794.5	$ 1,843.2
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		0.1102	0.1045
Banking Regulation, Common Equity Tier One Risk-Based Capital, Well Capitalized, Minimum		$ 1,458.0	$ 1,497.6
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		2,471.6	2,408.8
Common equity tier 1 risk-based capital:
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,570.2	$ 1,612.8
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		7.00%	7.00%
Leverage capital ratio:
Actual, Amount		$ 2,471.6	$ 2,408.8
Actual, Ratio		0.0822	0.0775
Banking Regulation, Tier One Leverage Capital, Capital Adequacy, Minimum		$ 1,202.8	$ 1,242.9
Capital Adequacy Purposes and Conservation Buffer, Ratio		0.0400	0.0400
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,503.5	$ 1,553.6
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		$ 2,782.1	$ 2,713.5
Actual, Ratio		0.1243	0.1180
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,790.8	$ 1,839.6
Minimum Required for Capital Adequacy Purposes, Ratio		0.0800	0.0800
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 2,350.5	$ 2,414.5
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		10.50%	10.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 2,238.6	$ 2,299.5
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		$ 1,007.3	$ 1,034.8
Tier 1 risk-based capital:
Actual, Amount		$ 2,553.7	$ 2,504.1
Actual, Ratio		0.1141	0.1089
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,343.1	$ 1,379.7
Minimum Required for Capital Adequacy Purposes, Ratio		0.0600	0.0600
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,902.8	$ 1,954.6
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		8.50%	8.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,790.8	$ 1,839.6
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		0.1141	0.1089
Banking Regulation, Common Equity Tier One Risk-Based Capital, Well Capitalized, Minimum		$ 1,455.1	$ 1,494.7
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		2,553.7	2,504.1
Common equity tier 1 risk-based capital:
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,567.0	$ 1,609.7
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		7.00%	7.00%
Leverage capital ratio:
Actual, Amount		$ 2,553.7	$ 2,504.1
Actual, Ratio		0.0850	0.0807
Banking Regulation, Tier One Leverage Capital, Capital Adequacy, Minimum		$ 1,201.1	$ 1,241.1
Capital Adequacy Purposes and Conservation Buffer, Ratio		0.0400	0.0400
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,501.3	$ 1,551.4
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Ratio		0.0500	0.0500

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Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Shares outstanding (in shares)	105,011,371	104,442,023
Class A Common Stock
Loss Contingencies [Line Items]
Shares outstanding (in shares)		104,442,023
Mortgage Loans Held For Sale [Member]
Loss Contingencies [Line Items]
Mortgage loans with recourse provision in effect	$ 0.8
Construction Contracts
Loss Contingencies [Line Items]
Commitments under construction contracts	$ 7.0

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Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Entity Information [Line Items]
Off-Balance Sheet, Credit Loss, Liability	$ 18.8	$ 9.7	$ 18.8	$ 9.7	$ 20.8	$ 16.2	$ 6.2	$ 3.8
Provision for credit loss expense	(3.2)	(4.6)	(25.3)	(60.2)
Credit Extension Commitments	4,441.0		4,441.0			5,173.3
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	805.1		805.1			827.6
Standby Letter of Credit
Entity Information [Line Items]
Credit Extension Commitments	94.7		94.7			$ 93.8
Cumulative effect, period of adoption, adjusted balance
Entity Information [Line Items]
Provision for credit loss expense	$ (2.0)	$ 3.5	$ 2.6	$ 5.9

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Other Comprehensive Income/Loss - Schedule of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investment securities available-for sale:
Change in net unrealized gain during period, pre-tax	$ (72.1)	$ (236.4)	$ (51.4)	$ (650.6)
Change in net unrealized gain during period, tax expense (benefit)	(17.9)	(53.4)	(12.7)	(161.3)
Change in net unrealized gain during period, net of tax	(54.2)	(183.0)	(38.7)	(489.3)
Reclassification adjustment for net gains included in income, pre-tax	0.0	24.2	23.5	24.4
Reclassification adjustment for net gains included in income, tax expense (benefit)	0.0	5.5	5.8	5.5
Reclassification adjustment for net gains included in income, net of tax	0.0	18.7	17.7	18.9
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale, net of tax			7.2	(0.2)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale, tax			1.8	(0.1)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale, pre-tax			5.4	(0.1)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, pre-tax	(0.3)	(1.7)	(1.1)	(25.6)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	(0.1)	(0.4)	(0.3)	(6.3)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, net of tax	(0.2)	(1.3)	(0.8)	(19.3)
Unrealized loss on derivatives, pre-tax	(11.0)	(15.9)	(23.1)	(9.6)
Unrealized loss on derivatives, tax expense (benefit)	(2.7)	(3.6)	(5.7)	(2.5)
Unrealized loss on derivatives, net of tax	(8.3)	(12.3)	(17.4)	(7.1)
Other comprehensive loss, before tax	(83.4)	(229.8)	(59.3)	(661.2)
Other Comprehensive Income (Loss), tax expense (benefit)	(20.7)	(51.9)	(14.7)	(164.5)
Other Comprehensive Income (Loss), Net of Tax	$ (62.7)	$ (177.9)	$ (44.6)	$ (496.7)

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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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ 3,085.5	$ 3,005.5	$ 3,085.5	$ 3,005.5	$ 3,073.8	$ 3,121.1	$ 3,271.9	$ 1,986.6
Net unrealized gain (loss) on derivatives	(8.3)	(12.3)	(17.4)	(7.1)
Change in net unrealized gain during period, pre-tax	(72.1)	(236.4)	(51.4)	(650.6)
Change in net unrealized gain during period, tax expense (benefit)	(17.9)	(53.4)	(12.7)	(161.3)
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(54.2)	(183.0)	(38.7)	(489.3)
Reclassification adjustment for net losses included in income	0.0	24.2	23.5	24.4
Reclassification adjustment for net gains included in income, tax expense (benefit)	0.0	5.5	5.8	5.5
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.0	18.7	17.7	18.9
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax	(0.3)	(1.7)	(1.1)	(25.6)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	(0.1)	(0.4)	(0.3)	(6.3)
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), after Tax	(0.2)	(1.3)	(0.8)	(19.3)
Unrealized loss on derivatives, pre-tax	(11.0)	(15.9)	(23.1)	(9.6)
Unrealized loss on derivatives, tax expense (benefit)	(2.7)	(3.6)	(5.7)	(2.5)
Other comprehensive loss, before tax	(83.4)	(229.8)	(59.3)	(661.2)
Other Comprehensive Income (Loss), tax expense (benefit)	(20.7)	(51.9)	(14.7)	(164.5)
Other Comprehensive Income (Loss), Net of Tax	(62.7)	(177.9)	(44.6)	(496.7)
Net unrealized loss on investment securities available-for-sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	(497.4)		(497.4)		(471.0)
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax			(5.4)		(4.5)
Net unrealized loss on derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on derivatives			(18.9)		(1.6)
Net accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ (521.7)	$ (507.7)	$ (521.7)	$ (507.7)	$ (477.1)	$ (459.0)	$ (329.8)	$ (11.0)

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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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Derivative assets	57.4		57.4		$ 45.2
Derivative liabilities	210.0		210.0		159.6
Write downs	(0.3)	$ (0.2)	(1.1)	$ (0.2)
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		0.0		0.0
Deferred compensation plan assets	0.0		0.0		0.0
Deferred compensation plan liabilities	0.0		0.0		0.0
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	3.2		3.2		6.9
Deferred compensation plan assets	19.2		19.2		18.7
Deferred compensation plan liabilities	19.2		19.2		18.7
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		0.0		5.5
Deferred compensation plan assets	0.0		0.0		0.0
Deferred compensation plan liabilities	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	215.9		215.9		642.7
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	202.6		202.6		263.7
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	162.0		162.0		198.9
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	207.3		207.3		228.0
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	226.5		226.5		241.5
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]
Investment debt securities available-for-sale	0.0		0.0		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		0.0		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		0.0		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	56.3		56.3		39.1
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	1,117.8		1,117.8		1,111.6
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	1,066.9		1,066.9		1,351.2
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	1,285.0		1,285.0		1,558.3
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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	0.0		0.0		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]
Investment debt securities available-for-sale	1,143.7		1,143.7		1,350.2
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]
Investment debt securities available-for-sale	0.0		0.0		0.0
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	5,627.7		5,627.7		6,946.1
Derivative assets	57.4		57.4		45.2
Derivative liabilities	210.0		210.0		159.6
Deferred compensation plan assets	19.2		19.2		18.7
Deferred compensation plan liabilities	19.2		19.2		18.7
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	3.2		3.2		12.4
Deferred compensation plan assets	19.2		19.2		18.7
Deferred compensation plan liabilities	19.2		19.2		18.7
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	0.0		0.0		0.0
Derivative assets	0.0		0.0		0.0
Derivative liabilities	0.0		0.0		0.0
Deferred compensation plan assets	0.0		0.0		0.0
Deferred compensation plan liabilities	0.0		0.0		0.0
Estimated Fair Value | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	5,627.7		5,627.7		6,946.1
Derivative assets	57.4		57.4		45.2
Derivative liabilities	210.0		210.0		159.6
Deferred compensation plan assets	19.2		19.2		18.7
Deferred compensation plan liabilities	19.2		19.2		18.7
Estimated Fair Value | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	0.0		0.0		0.0
Derivative assets	0.0		0.0		0.0
Derivative liabilities	0.0		0.0		0.0
Deferred compensation plan assets	0.0		0.0		0.0
Deferred compensation plan liabilities	0.0		0.0		0.0
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]
Investment debt securities available-for-sale	215.9		215.9		642.7
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]
Investment debt securities available-for-sale	202.6		202.6		263.7
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]
Investment debt securities available-for-sale	162.0		162.0		198.9
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]
Investment debt securities available-for-sale	207.3		207.3		228.0
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]
Investment debt securities available-for-sale	226.5		226.5		241.5
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	56.3		56.3		39.1
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]
Investment debt securities available-for-sale	1,117.8		1,117.8		1,111.6
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]
Investment debt securities available-for-sale	1,066.9		1,066.9		1,351.2
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]
Investment debt securities available-for-sale	1,285.0		1,285.0		1,558.3
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]
Investment debt securities available-for-sale	1,143.7		1,143.7		1,350.2
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	5,627.7		5,627.7		6,946.1
Derivative assets	57.4		57.4		45.2
Derivative liabilities	210.0		210.0		159.6
Deferred compensation plan assets	19.2		19.2		18.7
Deferred compensation plan liabilities	19.2		19.2		18.7
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	56.3		56.3		39.1
Long-lived assets to be disposed of by sale	4.5		$ 4.5		$ 5.5
Long-Lived Assets Held-for-sale, Description			9.1 million		5.7 million
Change During Period | 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	4.6		$ 4.6		$ 0.2
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	57.4		57.4		45.1
Derivative liabilities	210.0		210.0		159.6
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		0.0		0.0
Derivative liabilities	0.0		0.0		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	57.4		57.4		45.1
Derivative liabilities	202.7		202.7		154.2
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		0.0		0.0
Derivative liabilities	0.0		0.0		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	57.4		57.4		45.1
Derivative liabilities	202.7		202.7		154.2
Interest Rate Lock Commitments | 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		0.0
Interest Rate Lock Commitments | 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	0.0		0.0
Interest Rate Lock Commitments | 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		0.0
Interest Rate Lock Commitments | 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	0.0		0.0
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					0.0
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
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					0.0
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
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		0.0		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	7.3		7.3		5.4
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		0.0		0.0
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	7.3		7.3		5.4
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		0.0		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		0.0		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	4.5		4.5		5.5
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	$ 4.5		$ 4.5		$ 5.5

XML

Fair Value Measurements - Fair Value Inputs, Quantitative Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Real Estate Acquired Through Foreclosure	$ 11.6	$ 16.4	$ 11.6	$ 16.4	$ 14.4	$ 12.7	$ 16.8	$ 2.0
Material write downs	0.3	$ 0.2	1.1	$ 0.2
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	56.3		56.3			39.1
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	56.3		56.3			39.1
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		0.0			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		0.0			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	$ 56.3		$ 56.3			39.1
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	0.45		0.45
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	(0.07)		(0.07)
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	$ 11.6		$ 11.6			12.7
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		0.0			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		0.0			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	$ 11.6		$ 11.6			12.7
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	0.15		0.15
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	0.36		0.36
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	(0.22)		(0.22)
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	$ 55.9		$ 55.9			67.5
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		0.0			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		0.0			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	$ 55.9		$ 55.9
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	0.11		0.11
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	0.23		0.23
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	(0.17)		(0.17)
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	$ 4.5		$ 4.5			5.5
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		0.0			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		0.0			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	$ 4.5		$ 4.5			$ 5.5
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	0.06		0.06
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	(0.03)		(0.03)

XML

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments by Level of Valuation Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Financial assets:
Investment debt securities held-to-maturity	$ 2,796.1	$ 3,052.2
Derivative assets	57.4	45.2
Financial liabilities:
Derivative liabilities	210.0	159.6
Estimated Fair Value
Financial assets:
Cash and cash equivalents	593.1	870.5
Investment debt securities available-for-sale	5,627.7	6,946.1
Investment debt securities held-to-maturity	2,796.1	3,052.2
Accrued interest receivable	129.2	118.3
Mortgage servicing rights, net	35.6	37.4
Loans held for sale	59.1	79.9
Net loans held for investment	17,226.1	17,552.1
Derivative assets	57.4	45.2
Deferred compensation plan assets	19.2	18.7
Total financial assets	26,543.5	28,720.4
Financial liabilities:
Total deposits, excluding time deposits	20,516.8	23,145.2
Time deposits	3,126.2	1,876.1
Securities sold under repurchase agreements	889.5	1,052.9
Other Borrowings	2,067.0	2,327.0
Accrued interest payable	63.7	14.5
Long-term debt	114.4	116.3
Subordinated debentures held by subsidiary trusts	152.5	155.8
Derivative liabilities	210.0	159.6
Deferred compensation plan liabilities	19.2	18.7
Total financial liabilities	27,159.3	28,866.1
Carrying Amount
Financial assets:
Cash and cash equivalents	593.1	870.5
Investment debt securities available-for-sale	5,627.7	6,946.1
Investment debt securities held-to-maturity	3,259.5	3,451.8
Accrued interest receivable	129.2	118.3
Mortgage servicing rights, net	29.1	31.1
Loans held for sale	59.1	79.9
Net loans held for investment	17,986.6	17,879.1
Derivative assets	57.4	45.2
Deferred compensation plan assets	19.2	18.7
Total financial assets	27,760.9	29,440.7
Financial liabilities:
Total deposits, excluding time deposits	20,516.8	23,145.2
Time deposits	3,162.7	1,928.4
Securities sold under repurchase agreements	889.5	1,052.9
Other Borrowings	2,067.0	2,327.0
Accrued interest payable	63.7	14.5
Long-term debt	120.8	120.8
Subordinated debentures held by subsidiary trusts	163.1	163.1
Derivative liabilities	210.0	159.6
Deferred compensation plan liabilities	19.2	18.7
Total financial liabilities	27,212.8	28,930.2
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	593.1	870.5
Investment debt securities available-for-sale	0.0	0.0
Investment debt securities held-to-maturity	0.0	0.0
Accrued interest receivable	0.0	0.0
Mortgage servicing rights, net	0.0	0.0
Loans held for sale	0.0	0.0
Net loans held for investment	0.0	0.0
Derivative assets	0.0	0.0
Deferred compensation plan assets	0.0	0.0
Total financial assets	593.1	870.5
Financial liabilities:
Total deposits, excluding time deposits	20,516.8	23,145.2
Time deposits	0.0	0.0
Securities sold under repurchase agreements	0.0	0.0
Other Borrowings	0.0	0.0
Accrued interest payable	0.0	0.0
Long-term debt	0.0	0.0
Subordinated debentures held by subsidiary trusts	0.0	0.0
Derivative liabilities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Total financial liabilities	20,516.8	23,145.2
Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0.0	0.0
Investment debt securities available-for-sale	5,627.7	6,946.1
Investment debt securities held-to-maturity	2,796.1	3,052.2
Accrued interest receivable	129.2	118.3
Mortgage servicing rights, net	35.6	37.4
Loans held for sale	3.2	6.9
Net loans held for investment	17,169.8	17,513.0
Derivative assets	57.4	45.2
Deferred compensation plan assets	19.2	18.7
Total financial assets	25,838.2	27,737.8
Financial liabilities:
Total deposits, excluding time deposits	0.0	0.0
Time deposits	3,126.2	1,876.1
Securities sold under repurchase agreements	889.5	1,052.9
Other Borrowings	2,067.0	2,327.0
Accrued interest payable	63.7	14.5
Long-term debt	114.4	116.3
Subordinated debentures held by subsidiary trusts	152.5	155.8
Derivative liabilities	210.0	159.6
Deferred compensation plan liabilities	19.2	18.7
Total financial liabilities	6,642.5	5,720.9
Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0.0	0.0
Investment debt securities available-for-sale	0.0	0.0
Investment debt securities held-to-maturity	0.0	0.0
Accrued interest receivable	0.0	0.0
Mortgage servicing rights, net	0.0	0.0
Loans held for sale	55.9	73.0
Net loans held for investment	56.3	39.1
Derivative assets	0.0	0.0
Deferred compensation plan assets	0.0	0.0
Total financial assets	112.2	112.1
Financial liabilities:
Total deposits, excluding time deposits	0.0	0.0
Time deposits	0.0	0.0
Securities sold under repurchase agreements	0.0	0.0
Other Borrowings	0.0	0.0
Accrued interest payable	0.0	0.0
Long-term debt	0.0	0.0
Subordinated debentures held by subsidiary trusts	0.0	0.0
Derivative liabilities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Total financial liabilities	$ 0.0	$ 0.0

XML

Subsequent Events (Details)	Oct. 24, 2023 $ / shares
Class A Common Stock | Subsequent Event
Subsequent Event [Line Items]
Dividend amount per share (in dollars)	$ 0.47