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, 2022

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)

________________________________________________________________________________________________________ 

Montana		81-0331430
(State or other jurisdiction of incorporation or organization)		(IRS Employer Identification No.)
401 North 31st Street
Billings,	MT	59116-0918
(Address of principal executive offices)		(Zip Code)

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

_________________________________________________________________________________________________ 

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

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Class A common stock, no 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, 2022 – Class A common stock 104,447,711 

Quarterly Report on Form 10-Q

	FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES
	Index
	September 30, 2022
		Page Nos.
	Part I - Financial Information
Item 1.	Financial Statements (Unaudited)
	Consolidated Balance Sheets	3
	Consolidated Statements of Income	4
	Consolidated Statements of Comprehensive (Loss) Income	5
	Consolidated Statements of Changes in Stockholders’ Equity	6
	Consolidated Statements of Cash Flows	8
	Notes to Unaudited Consolidated Financial Statements	11
Item 2.	Management's Discussion and Analysis of Financial Condition and Results of Operations	51
Item 3.	Quantitative and Qualitative Disclosures about Market Risk	69
Item 4.	Controls and Procedures	69
	Part II - Other Information
Item 1.	Legal Proceedings	70
Item 1A.	Risk Factors	70
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	70
Item 3.	Defaults Upon Senior Securities	70
Item 4.	Mine Safety Disclosures	70
Item 5.	Other Information	70
Item 6.	Exhibits	71
Signatures		72

2

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(In millions, except share data)

(Unaudited)

	September 30, 2022		December 31, 2021
Assets
Cash and due from banks	$	390.4	$	168.6
Interest bearing deposits in banks	201.4		2,176.1
Federal funds sold	0.1		0.1
Total cash and cash equivalents	591.9		2,344.8
Investment securities:
Available-for-sale, at estimated fair value	6,783.4		4,820.5
Held-to-maturity, net of allowance for credit losses of $1.9 and $0 at September 30, 2022 and December 31, 2021 (estimated fair values of $3,063.5 and $1,667.5 at September 30, 2022 and December 31, 2021)	3,485.7		1,687.6
Total investment securities	10,269.1		6,508.1
Federal Home Loan Bank and Federal Reserve Bank stock, at cost	131.9		53.8
Loans held for sale	93.6		30.1
Loans held for investment, net of deferred fees and costs	17,603.5		9,331.7
Allowance for credit losses	213.0		122.3
Net loans held for investment	17,390.5		9,209.4
Goodwill	1,100.0		621.6
Company-owned life insurance	495.6		301.5
Premises and equipment, net of accumulated depreciation	445.4		299.6
Other intangibles, net of accumulated amortization	101.0		41.3
Accrued interest receivable	106.4		47.4
Mortgage servicing rights, net of accumulated amortization and impairment reserve	31.8		28.2
Other real estate owned	16.4		2.0
Deferred tax asset, net	223.8		—
Other assets	347.3		184.1
Total assets	$	31,344.7	$	19,671.9
Liabilities and Stockholders’ Equity
Deposits:
Non-interest bearing	$	8,163.3	$	5,568.3
Interest bearing	17,721.5		10,701.3
Total deposits	25,884.8		16,269.6
Securities sold under repurchase agreements	1,075.6		1,051.1
Accounts payable and accrued expenses	452.9		148.4
Accrued interest payable	7.4		3.7
Deferred tax liability, net	—		9.3
Long-term debt	120.7		112.4
Other borrowed funds	625.0		—
Allowance for credit losses on off-balance sheet credit exposures	9.7		3.8
Subordinated debentures held by subsidiary trusts	163.1		87.0
Total liabilities	28,339.2		17,685.3
Stockholders’ equity:
Preferred stock, no par value; 100,000 shares authorized; none issued and outstanding	—		—
Common stock, no par value; 150,000,000 and 100,000,000 shares authorized at September 30, 2022 and December 31, 2021; 104,450,804 shares and 62,200,456 shares issued and outstanding, respectively	2,477.4		945.0
Retained earnings	1,035.8		1,052.6
Accumulated other comprehensive loss, net	(507.7)		(11.0)
Total stockholders’ equity	3,005.5		1,986.6
Total liabilities and stockholders’ equity	$	31,344.7	$	19,671.9

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,
	2022		2021		2022		2021
Interest income:
Interest and fees on loans	$	218.3	$	111.9	$	561.7	$	325.1
Interest and dividends on investment securities:
Taxable	64.3		17.1		142.4		48.7
Exempt from federal taxes	1.4		1.4		4.1		4.2
Interest and dividends on FHLB and FRB stock	1.3		0.2		2.8		0.2
Interest on deposits in banks	1.4		0.7		6.5		1.7
Total interest income	286.7		131.3		717.5		379.9
Interest expense:
Interest on deposits	13.3		1.9		20.6		6.4
Interest on securities sold under repurchase agreements	0.8		0.1		1.4		0.3
Interest on other borrowed funds	2.4		—		2.4		—
Interest on long-term debt	1.5		1.5		4.6		4.5
Interest on subordinated debentures held by subsidiary trusts	1.9		0.7		4.3		2.1
Total interest expense	19.9		4.2		33.3		13.3
Net interest income	266.8		127.1		684.2		366.6
Provision for (reversal of) credit losses	8.4		—		68.0		(5.1)
Net interest income after provision for (reversal of) credit losses	258.4		127.1		616.2		371.7
Non-interest income:
Payment services revenues	20.4		12.2		54.7		33.8
Mortgage banking revenues	2.7		11.6		16.1		32.8
Wealth management revenues	8.5		6.5		25.9		19.1
Service charges on deposit accounts	5.7		4.4		19.7		12.1
Other service charges, commissions, and fees	4.7		1.4		12.6		5.1
Investment securities losses, net	(24.2)		0.3		(24.4)		0.2
Other income	5.1		3.1		17.0		9.8
Total non-interest income	22.9		39.5		121.6		112.9
Non-interest expense:
Salaries and wages	71.9		42.0		206.7		122.6
Employee benefits	19.6		12.9		60.2		43.7
Outsourced technology services	15.9		8.2		40.0		24.7
Occupancy, net	11.3		7.3		32.5		21.7
Furniture and equipment	5.8		4.5		17.0		13.0
OREO expense, net of income	—		—		0.1		(0.1)
Professional fees	5.1		2.7		14.5		9.3
FDIC insurance premiums	4.1		1.7		10.2		4.8
Other intangibles amortization	4.1		2.4		11.8		7.4
Other expenses	31.4		17.6		82.7		49.6
Acquisition related expenses	4.0		6.6		115.0		6.6
Total non-interest expense	173.2		105.9		590.7		303.3
Income before income tax	108.1		60.7		147.1		181.3
Provision for income tax	22.4		13.6		30.7		40.3
Net income	$	85.7	$	47.1	$	116.4	$	141.0
Earnings per common share (Basic)	$	0.80	$	0.76	$	1.13	$	2.29
Earnings per common share (Diluted)	$	0.80	$	0.76	$	1.13	$	2.28
Weighted average common shares outstanding (Basic)	106,525,974		61,673,656		102,879,422		61,641,342
Weighted average common shares outstanding (Diluted)	106,589,699		61,747,972		102,935,360		61,732,822

See accompanying notes to unaudited consolidated financial statements.

4

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME

(In millions)

(Unaudited)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Net income	$	85.7	$	47.1	$	116.4	$	141.0
Other comprehensive loss, before tax:
Investment securities available-for sale:
Change in net unrealized loss during period	(236.4)		(13.4)		(650.6)		(81.0)
Reclassification adjustment for net loss (gain) included in income	24.2		(0.3)		24.4		(0.2)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	—		—		0.2		—
Net change in unamortized (losses) gains on available-for-sale securities transferred into held-to-maturity	(1.7)		(2.5)		(25.6)		22.3
Change in unrealized (gain) loss on derivatives	(15.9)		3.2		(9.6)		2.3
Other comprehensive loss, before tax	(229.8)		(13.0)		(661.2)		(56.6)
Deferred tax benefit related to other comprehensive loss	51.9		3.2		164.5		14.3
Other comprehensive loss, net of tax	(177.9)		(9.8)		(496.7)		(42.3)
Comprehensive (loss) income, net of tax	$	(92.2)	$	37.3	$	(380.3)	$	98.7

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 income (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
	Common stock		Retained earnings		Accumulated other comprehensive income (loss)		Total stockholders’ equity
Balance at June 30, 2021	$	941.6	$	1,005.2	$	24.1	$	1,970.9
Net income	—		47.1		—		47.1
Other comprehensive loss, net of tax expense	—		—		(9.8)		(9.8)
Common stock transactions:
574 common shares purchased and retired	—		—		—		—
1,782 common shares issued	—		—		—		—
12,620 non-vested common shares issued	—		—		—		—
2,324 non-vested common shares forfeited or canceled	—		—		—		—
Stock-based compensation expense	2.0		—		—		2.0
Common stock cash dividends declared ($0.41 per share)	—		(25.4)		—		(25.4)
Balance at September 30, 2021	$	943.6	$	1,026.9	$	14.3	$	1,984.8

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 income (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
	Common stock		Retained earnings		Accumulated other comprehensive income (loss)		Total stockholders’ equity
Balance at December 31, 2020	$	941.1	$	962.1	$	56.6	$	1,959.8
Net income	—		141.0		—		141.0
Other comprehensive loss, net of tax expense	—		—		(42.3)		(42.3)
Common stock transactions:
128,038 common shares purchased and retired	(5.4)		—		—		(5.4)
19,081 common shares issued	—		—		—		—
241,307 non-vested common shares issued	—		—		—		—
39,993 non-vested common shares forfeited or canceled	—		—		—		—
42,987 stock options exercised, net of 6,177 shares tendered in payment of option price and income tax withholding amounts	0.4		—		—		0.4
Stock-based compensation expense	7.5		—		—		7.5
Common cash dividends declared ($1.23 per share)	—		(76.2)		—		(76.2)
Balance at September 30, 2021	$	943.6	$	1,026.9	$	14.3	$	1,984.8

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,
	2022		2021
Cash flows from operating activities:
Net income	$	116.4	$	141.0
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for (reversal of) credit losses	68.0		(5.1)
Net gain on disposal of premises and equipment	(2.3)		(1.9)
Depreciation and amortization	41.4		33.4
Net premium amortization on investment securities	16.7		29.0
Net loss on investment securities transactions	24.4		(0.2)
Realized and unrealized net gains on mortgage banking activities	(8.1)		(19.1)
Net gain on sale of OREO	(0.4)		(0.2)
Write-downs of OREO and other assets pending disposal	0.2		—
Net gain on extinguishment of debt	(1.4)		—
Mortgage servicing rights recovery	(3.4)		(5.9)
Deferred taxes	(4.8)		4.6
Net increase in cash surrender value of company-owned life insurance	(7.6)		(4.1)
Stock-based compensation expense	8.7		7.5
Originations of mortgage loans held for sale	(369.5)		(596.6)
Proceeds from sales of mortgage loans held for sale	387.2		645.1
Changes in operating assets and liabilities:
Increase in interest receivable	(25.9)		(1.8)
Increase in other assets	(14.9)		(21.8)
Increase in accrued interest payable	1.3		0.8
Increase in accounts payable and accrued expenses	212.6		0.7
Net cash provided by operating activities	438.6		205.4
Cash flows from investing activities:
Purchases of investment securities:
Held-to-maturity	(1,316.0)		(1,069.5)
Available-for-sale	(2,521.2)		(1,891.4)
Proceeds from sales, maturities, and pay-downs of investment securities:
Held-to-maturity	304.8		163.9
Available-for-sale	1,753.6		747.8
Purchases of Federal Home Loan Bank and Federal Reserve Bank stock	(115.8)		—
Proceeds from Federal Home Loan Bank and Federal Reserve Bank stock	53.3		—
Extensions of credit to clients, net of repayments	(465.6)		172.5
Recoveries of loans charged-off	10.8		7.2
Proceeds from sale of OREO	2.0		1.1
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	(27.2)		(5.5)
Net cash used in investing activities	$	(313.0)	$	(1,873.9)

8

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (continued) (In millions) (Unaudited)
	Nine Months Ended September 30,
	2022		2021
Cash flows from financing activities:
Net (decrease) increase in deposits	$	(2,072.8)	$	1,790.3
Net increase (decrease) in securities sold under repurchase agreements	51.6		(83.9)
Net increase in other borrowed funds	625.0		—
Repayments of long-term debt	(164.0)		—
Advances on long-term debt	14.4		—
Payment of stock issuance costs	(0.8)		—
Proceeds from issuance of common stock, net	0.1		0.4
Purchase and retirement of common stock	(198.9)		(5.4)
Dividends paid to common stockholders	(133.1)		(76.2)
Net cash (used in) provided by financing activities	(1,878.5)		1,625.2
Net decrease in cash and cash equivalents	(1,752.9)		(43.3)
Cash and cash equivalents at beginning of period	2,344.8		2,276.8
Cash and cash equivalents at end of period	$	591.9	$	2,233.5
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$	42.2	$	41.3
Cash paid during the period for interest expense	32.0		12.5
Supplemental disclosures of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	$	22.9	$	0.8
Transfer of held-to-maturity to available-for sale securities	10.9		—
Transfer of available-for sale to held-to-maturity securities	463.6		672.2
Transfer of held-for-sale to held for investment loans	19.8		—
Transfer of held for investment loans to held-for-sale	12.4		—
Transfer of loans to other real estate owned	0.4		0.7
Shares issued for acquisition	1,723.3		—
Capitalization of internally originated mortgage servicing rights	2.3		2.0

9

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (continued) (In millions) (Unaudited)
	Nine Months Ended September 30,
	2022		2021
Supplemental schedule of noncash investing activities from acquisition:
Investment securities	$	2,699.0	$	—
Securities purchased under agreement to resell	101.1		—
Loans held for sale	217.0		—
Loans held for investment, net	7,645.5		—
Premises and equipment	144.7		—
Goodwill	478.4		—
Other intangibles	72.9		—
Mortgage servicing rights	1.3		—
Company-owned life insurance	186.6		—
Deferred tax assets	63.6		—
Other real estate owned	15.8		—
Other assets	198.9		—
Total noncash assets acquired	11,824.8		—
Liabilities assumed:
Deposits	$	11,688.0	$	—
Securities sold under repurchase agreements	74.0		—
Accounts payable and accrued expenses	111.0		—
Long-term debt	159.3		—
Subordinated debentures held by subsidiary trusts	76.1		—
Total liabilities assumed	$	12,108.4	$	—

See accompanying notes to unaudited consolidated financial statements.

10

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., First Interstate Bank (“FIB”), and its other subsidiaries (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, 2022 and December 31, 2021, the results of operations, changes in stockholders’ equity, and cash flows for each of the three and the nine month periods ended September 30, 2022 and 2021, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2021 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, 2022 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, 2021, which includes a description of significant accounting policies. Operating results for the three and the nine months ended September 30, 2022 are not necessarily indicative of the results that may be expected for the year ending December 31, 2022.

(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. The acquisition of GWB 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 this 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. This determination is subject to refinement for up to one year after the closing date of the acquisition as additional information relative to the closing date fair values becomes available and such information is considered final, whichever is earlier.

The following table provides the provisional 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 as of September 30, 2022. We recorded the estimate of fair value based on initial valuations available 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 provisional goodwill of $478.4 million, which is not 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. Due to the recent closing of the transaction, all amounts reported are provisional pending the review of valuations obtained from third parties and other necessary information in support of related fair value accounting.

11

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 (“OREO”)	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	63.6
Other assets	198.9
Total assets acquired	13,353.3
Liabilities assumed:
Deposits	11,688.0
Securities sold under repurchase agreements	74.0
Accrued expenses and other liabilities	111.0
FHLB advances	122.9
Subordinated debt	36.4
Subordinated debentures held by subsidiary trusts	76.1
Total liabilities assumed	12,108.4
Net assets acquired	$	1,244.9
Consideration paid:
Class A common stock	1,723.3
Total consideration paid (1)	$	1,723.3
Goodwill	$	478.4

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

As of September 30, 2022, the Company recorded measurement period adjustments to the fair value marks. These adjustments included increases of $0.9 million in other assets and $0.9 million in accrued expenses and a decrease of $0.2 million in premises and equipment, which resulted in a net increase to goodwill of $0.2 million from the June 30, 2022 reported balances. The related impact to net income that would have been recognized in previous periods if the adjustments were recognized as of the acquisition date was not material to the consolidated financial statements.

The Company determined the fair value of loans, core deposit and customer relationship intangible assets, investment securities, premises and equipment, leases, mortgage servicing rights, deposits, FHLB advances, subordinated debt, and subordinated debentures held by subsidiary trusts with the assistance of third-party valuation specialists. The following is a description of the methods used to determine the fair values of significant assets and liabilities presented above.

Cash and cash equivalents

The carrying amount of these assets is a reasonable estimate of fair value based on the short-term nature of these assets.

12

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Investment Securities

Fair values for securities are based on quoted market prices, where available. If quoted market prices are not available, fair value estimates are based on observable inputs including quoted market prices for similar instruments, quoted market prices that are not in an active market or other inputs that are observable in the market. In the absence of observable inputs, fair value is estimated based on pricing models and/or discounted cash flow methodologies.

Loans held for sale

The loans held for sale portfolio was recorded at fair value based on quotes or bids from third party investors.

Loans held for investment

A valuation of the loans held for investment portfolio was performed by a third party as of the acquisition date in accordance with ASC 820 to assess the fair value of the loan portfolio, considering adjustments for interest rate risk, required equity return, servicing, credit, and liquidity risk. The loans held for investment portfolio was segmented into two groups including purchase credit deteriorated (PCD) loans and non-PCD loans. The non-PCD loans were pooled based on similar characteristics, such as loan type, fixed or adjustable interest rates, payment type, index rate and caps/floors, and non-accrual status. The PCD loans were valued at the loan level with similar characteristics noted above. The fair value was calculated using a discounted cash flow analysis. The discount rate utilized to analyze fair value considered the cost of funds rate, capital charge, servicing costs, and liquidity premium, mostly based on industry standards.

The Company is required to record PCD assets, defined as a more-than-insignificant deterioration in credit quality since origination or issuance, at the purchase price plus the allowance for credit losses expected at the time of acquisition. Under this method, there is no credit loss expense affecting net income on acquisition of PCD assets. Changes in estimates of expected credit losses after acquisition are recognized in subsequent periods as credit loss expense (or reversal of credit loss expense) arise. Any non-credit discount or premium resulting from acquiring a pool of purchased financial assets with credit deterioration is allocated to each individual asset. At the acquisition date, the initial allowance for credit losses determined on a collective basis is allocated to individual assets to appropriately allocate any non-credit discount or premium. The non-credit discount or premium, after the adjustment for the allowance for credit losses, is accreted to interest income using the interest method based on the effective interest rate determined after the adjustment for credit losses at the adoption date. Information regarding loans acquired at the acquisition date as amended for measurement period adjustments as of September 30, 2022 were as follows:

(In millions)
PCD loans:
Unpaid principal balance	$	979.2
Principal amounts previously written off by GWB	(238.7)
Interest applied to principal by GWB	(18.1)
Adjusted unpaid principal balance	722.4
Credit discount	(69.2)
Discount attributable to other factors	(29.9)
Fair value	623.3
Allowance for credit losses	59.5
Amortized cost basis	682.8
Non-PCD loans:
Unpaid principal balance	7,107.9
Credit discount (1)	(76.5)
Non-credit discount	(9.2)
Fair value	7,022.2
Amortized cost basis	$	7,705.0
(1) Represents the best estimate of the contractual cash flows not expected to be collected as of the acquisition date.

13

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Core deposit intangible

Core deposit intangible assets of $50.1 million on non-maturing deposits were determined by evaluating the underlying characteristics of the deposit relationships, including customer attrition, deposit interest rates and maintenance costs, and costs of alternative funding using the discounted cash flow approach. The core deposit intangibles represent the costs saved by the Company between maintaining the existing deposits and obtaining alternative funds over the life of the deposit base. These costs are amortized using an accelerated method over the estimated useful life of 10 years for the related deposits.

Premises and equipment

The fair values of premises are based on a market approach, using third-party appraisals and other analysis of value for land and premises.

Deposits

The fair values used for the demand and savings deposits equal the amounts payable on demand at the acquisition date. In determining the fair value of certificates of deposit, the cash flows of the contractual interest payments during the specific period of the certificates of deposit and scheduled principal payout were discounted to present value at market-based interest rates.

Customer relationship intangible

Customer relationship intangible assets of $22.8 million were determined using an excess earnings model associated with the expected fee income related to the underlying client relationships and is being amortized using the straight-line method over the estimated useful life of 12 years.

FHLB advances

The fair value of fixed rate Federal Home Loan Bank of Des Moines (“FHLB”) advances was determined using a discounted cash flow approach. The cash flows of the advances were projected based on scheduled payments of the fixed rate advances, which factored in prepayment fees. The cash flows were then discounted to present value using the FHLB rates as of February 1, 2022.

Subordinated debt and subordinated debentures held by subsidiary trusts

The fair value of subordinated debt and subordinated debentures held by subsidiary trusts was determined by using a discounted cash flow method using a market participant discount rate for similar instruments over the remaining terms.

Acquisition related expenses related to the GWB acquisition of $4.0 million and $115.0 million for the three and the nine month periods ended September 30, 2022, respectively, were included as a component of non-interest expense in the consolidated statements of income, of which none and approximately $26.8 million for the three and the nine month periods ended September 30, 2022, respectively, are acquisition related costs as defined by ASC 805. During the nine months ended September 30, 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, 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, First Interstate Bank, contemporaneously with the closing of the parent company merger. The core system conversion was completed on May 23, 2022.

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 presents certain unaudited pro forma financial information for illustrative purposes only, for the three and the nine month periods ended September 30, 2022 and 2021 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		2021		2022		2021
Total revenues	$	314.0	$	295.8	$	883.5	$	909.1
Net income	$	90.3	$	110.9	$	267.8	$	177.0
Earnings per common share (Basic)	$	0.85	$	1.02	$	2.60	$	1.63
Earnings per common share (Diluted)	$	0.85	$	1.02	$	2.60	$	1.63

(3)    Goodwill and Other Intangible Assets

Goodwill

Management analyzes its goodwill for impairment on an annual basis and between annual tests in certain circumstances, such as upon material adverse changes in legal, business, regulatory, and economic factors. An impairment loss is recorded to the extent that the carrying amount of goodwill exceeds its implied fair value. The Company performed an impairment assessment as of July 1, 2022 and 2021 and concluded that there was no impairment to goodwill.

The following table details changes in the recorded amount of goodwill as of the dates indicated:

	As of September 30,
	September 30, 2022		December 31, 2021
Net carrying value at beginning of the period	$	621.6	$	621.6
Provisional additions to goodwill from acquisition	478.4		—
Net carrying value at end of period	$	1,100.0	$	621.6

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, 2022 and December 31, 2021:

As of September 30, 2022	CDI		OCRI		Total
Gross other intangible assets, at beginning of the period	$	106.0	$	—	$	106.0
Provisional amounts established through acquisition	50.1		22.8		72.9
Reductions due to sale of health savings accounts	(1.4)		—		(1.4)
Accumulated amortization	(75.2)		(1.3)		(76.5)
Net other intangible assets, end of period	$	79.5	$	21.5	$	101.0
December 31, 2021
Gross other intangible assets, at beginning of the period	$	106.0	$	—	$	106.0
Accumulated amortization	(64.7)		—		(64.7)
Net other intangible assets, end of period	$	41.3	$	—	$	41.3

15

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The Company recorded $4.1 million and $2.4 million of other intangible asset amortization expense for the three months ended September 30, 2022 and 2021, respectively, and recorded $11.8 million and $7.4 million of other intangible asset amortization expense for the nine months ended September 30, 2022 and 2021, respectively

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:

Years Ending December 31,	CDI		OCRI		Total
2022 remaining	$	3.6	$	0.5	$	4.1
2023	13.7		1.9		15.6
2024	12.7		1.9		14.6
2025	11.8		1.9		13.7
2026	10.9		1.9		12.8
Thereafter	26.8		13.4		40.2
Total	$	79.5	$	21.5	$	101.0

(4)    Investment Securities

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

September 30, 2022	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	373.5	$	—	$	(36.7)	$	336.8
State, county, and municipal securities	317.8		—		(57.3)		260.5
Obligations of U.S. government agencies	216.3		—		(17.3)		199.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	4,852.2		0.2		(442.7)		4,409.7
Private mortgage-backed securities	270.3		—		(37.1)		233.2
Collateralized loan obligations	1,145.5		—		(40.4)		1,105.1
Corporate securities	272.6		—		(33.5)		239.1
Total	$	7,448.2	$	0.2	$	(665.0)	$	6,783.4

September 30, 2022	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	396.1	$	—	$	396.1	$	—	$	(10.6)	$	385.5
State, county, and municipal securities	184.0		(0.1)		183.9		0.2		(33.2)		150.9
Obligations of U.S. government agencies	350.8		—		350.8		—		(51.2)		299.6
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations (1)	2,476.6		—		2,476.6		—		(320.0)		2,156.6
Corporate securities	80.1		(1.8)		78.3		—		(7.4)		70.9
Total	$	3,487.6	$	(1.9)	$	3,485.7	$	0.2	$	(422.4)	$	3,063.5
(1) Amortized cost presented above include $20.8 million of unamortized losses and $15.2 million of unamortized gains in U.S. agency residential and commercial mortgage-backed securities and collateralized mortgage obligations related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity.

16

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

December 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	697.6	$	—	$	(12.9)	$	684.7
State, county, and municipal securities	434.7		2.1		(9.3)		427.5
Obligations of U.S. government agencies	356.0		0.1		(9.2)		346.9
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	2,027.3		14.1		(23.3)		2,018.1
Private mortgage-backed securities	174.4		0.1		(1.1)		173.4
Collateralized loan obligation	898.2		1.2		—		899.4
Corporate securities	271.1		3.0		(3.6)		270.5
Total	$	4,859.3	$	20.6	$	(59.4)	$	4,820.5

December 31, 2021	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
State, county, and municipal securities	$	67.6	$	—	$	67.6	$	2.0	$	(0.4)	$	69.2
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations(1)	1,609.0		—		1,609.0		13.2		(35.3)		1,586.9
Corporate securities	11.0		—		11.0		0.4		—		11.4
Total	$	1,687.6	$	—	$	1,687.6	$	15.6	$	(35.7)	$	1,667.5
(1) Amortized cost presented above include $20.1 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.

On February 1, 2022, in conjunction with the acquisition of GWB and under ASC 320, the Company transferred debt securities classified as held-to-maturity with an amortized cost of $10.7 million and an estimated fair value of $10.9 million to the available-for-sale category classification and transferred debt securities classified as available-for-sale with an amortized cost of $485.9 million and an estimated fair value of $463.6 million to the held-to-maturity classification to maintain the Company’s intended risk profile. The transfer of debt securities into the available-for-sale and held-to-maturity categories were recorded at fair value on the date of transfer. This discount, as well as the related unrealized loss in accumulated other comprehensive income, will be amortized into interest income as a yield adjustment over the remaining term of the securities. The amortization of the unrealized loss reported in accumulated other comprehensive (loss) income will offset the effect on interest income of the accretion of the discount. No gains or losses were recorded at the time of transfer.

The following tables show the gross unrealized losses and fair values of investment securities, aggregated by investment category, and the length of time individual investment securities have been in an unrealized loss position as of September 30, 2022 and December 31, 2021.

	Less than 12 Months				12 Months or More				Total
September 30, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	168.2	$	(5.1)	$	168.6	$	(31.6)	$	336.8	$	(36.7)
State, county, and municipal securities	110.6		(14.4)		136.4		(42.9)		247.0		(57.3)
Obligations of U.S. government agencies	152.4		(10.9)		45.9		(6.4)		198.3		(17.3)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	3,697.1		(308.8)		699.8		(133.9)		4,396.9		(442.7)
Private mortgage-backed securities	206.1		(32.3)		27.0		(4.8)		233.1		(37.1)
Collateralized loan obligations	1,076.1		(39.8)		29.0		(0.6)		1,105.1		(40.4)
Corporate securities	144.0		(10.4)		95.0		(23.1)		239.0		(33.5)
Total	$	5,554.5	$	(421.7)	$	1,201.7	$	(243.3)	$	6,756.2	$	(665.0)

17

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, 2021	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	684.7	$	(12.9)	$	—	$	—	$	684.7	$	(12.9)
State, county, and municipal securities	278.7		(9.1)		5.0		(0.2)		283.7		(9.3)
Obligations of U.S. government agencies	297.0		(8.9)		16.4		(0.3)		313.4		(9.2)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	1,262.8		(23.0)		26.4		(0.3)		1,289.2		(23.3)
Private mortgage-backed securities	127.2		(1.1)		—		—		127.2		(1.1)
Corporate securities	109.9		(3.3)		20.9		(0.3)		130.8		(3.6)
Total	$	2,760.3	$	(58.3)	$	68.7	$	(1.1)	$	2,829.0	$	(59.4)

As of September 30, 2022 and December 31, 2021, 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 acquired $2,356.9 million of available-for-sale securities and $342.1 million of held-to-maturity securities in connection with the acquisition of GWB. Such securities were evaluated and it was determined that there were no investment securities that met the definition of a PCD asset and none were classified as PCD upon acquisition.

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 may 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 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. The Company had no allowance for credit losses for available-for-sale investment securities as of September 30, 2022 and December 31, 2021.

As of September 30, 2022 and December 31, 2021, the Company had 1,239 and 285 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, 2022, 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 held-to-maturity securities classified as corporate and state, county, and municipal securities:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Beginning balance	$	1.6	$	—	$	—	$	—
Provision for credit loss expense	0.3		—		1.9		—
Ending balance of allowance for credit losses	$	1.9	$	—	$	1.9	$	—

There was no allowance for credit losses on held-to-maturity securities at December 31, 2021.

18

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

On a quarterly basis, the Company refreshes the credit quality 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, 2022	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	396.1	$	—	$	—	$	—	$	—	$	—	$	396.1
State, county, and municipal securities	69.4		93.8		12.0		—		—		8.8		184.0
Obligations of U.S. government agencies	350.8		—		—		—		—		—		350.8
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
FNMA/FHLMC	2,261.3		—		—		—		—		—		2,261.3
GNMA	215.3		—		—		—		—		—		215.3
Corporate securities	—		—		—		65.1		10.0		5.0		80.1
Total	$	3,292.9	$	93.8	$	12.0	$	65.1	$	10.0	$	13.8	$	3,487.6

December 31, 2021	AAA		AA		A		BBB		Not Rated		Total
State, county, and municipal securities	$	17.2	$	31.6	$	14.7	$	—	$	4.1	$	67.6
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
FNMA/FHLMC	1,439.1		—		—		—		—		1,439.1
GNMA	169.9		—		—		—		—		169.9
Corporate securities	—		—		4.0		7.0		—		11.0
Total	$	1,626.2	$	31.6	$	18.7	$	7.0	$	4.1	$	1,687.6

As of September 30, 2022 and December 31, 2021, the Company had $34.3 million and $16.6 million, respectively, of accrued interest receivable on the consolidated balance sheet. The Company does not consider accrued interest receivable in the carrying amount of financial assets held at the amortized cost basis or in the allowance for credit losses calculation.

As of September 30, 2022 and December 31, 2021, 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, 2022 and December 31, 2021, there were no collateral dependent available-for-sale or held-to-maturity securities.

There were no material gross realized gains and $46.3 million in gross realized losses on the disposition of available-for-sale investment securities, primarily related to the $500.0 million in US treasury notes, during the three months ended September 30, 2022. The gross realized losses were offset by $22.1 million in deferred gains realized related to the termination of the fair value derivative for a net realized loss of $24.2 million. For the nine months ended September 30, 2022, there were no material gross realized gains and $46.4 million in gross realized losses. For the three and the nine month periods ended September 30, 2021, there were no material gross realized gains and no material gross realized losses.

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.

19

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	Available-for-Sale				Held-to-Maturity
September 30, 2022	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	57.1	$	56.4	$	5.1	$	5.0
After one year but within five years	1,049.0		998.0		546.0		524.2
After five years but within ten years	1,918.3		1,710.2		797.1		695.2
After ten years	4,423.8		4,018.8		2,139.4		1,839.1
Total	$	7,448.2	$	6,783.4	$	3,487.6	$	3,063.5

As of September 30, 2022, the Company held investment securities callable within one year having amortized costs and estimated fair values of $777.7 million and $706.2 million, respectively. These investment securities are primarily included in the “after five years but within ten years” category in the table above. As of September 30, 2022, the Company had no callable structured notes.

As of September 30, 2022 and December 31, 2021, the Company has amortized costs of $4,836.7 million and $2,617.8 million, respectively, for investment securities pledged to secure public deposits and securities sold under repurchase agreements and had approximate fair values of $4,265.1 million and $2,610.8 million, as of September 30, 2022 and December 31, 2021, 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, 2022 and December 31, 2021, the Company held $131.9 million and $53.8 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 segment for the dates indicated:

	September 30, 2022		December 31, 2021
Loans Held for Sale:
Agricultural	$	63.0	$	—
Commercial construction	12.4		—
Residential real estate	18.2		30.1
Total loans held for sale	$	93.6	$	30.1

Residential real estate loans that the Company originated with the intent to sell are recorded at fair value. Conforming agency mortgage production is sold on a servicing retained basis. Certain loans, such as government guaranteed mortgage loans, are sold on a servicing released basis. The fair value of loans held for sale are primarily determined based on quoted prices for similar loans in active markets or outstanding commitments from third-party investors. Net unrealized losses, if any, are recorded as a valuation allowance and charged to non-interest income in the consolidated statements from operations. Net gains and losses on loan sales are recorded as a component of non-interest income.

As of September 30, 2022, loans held for sale included nonaccrual loans of $43.1 million, of which $30.7 million were agricultural loans and $12.4 million was a commercial construction loan. There were no loans held for sale that were considered a troubled debt restructuring as of September 30, 2022.

On February 1, 2022, in conjunction with the acquisition of GWB, agricultural loans with a carrying value of $155.8 million and commercial loans with a carrying value of $24.0 million were reclassified as loans held for sale from loans held for investment due to management’s intent and decision to sell the loans.

20

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Subsequent to the acquisition date, agricultural loans with a carrying value of $19.8 million were reclassified from loans held for sale to loans held for investment due to management’s change in intent and decision not to sell the loans. On the date of transfer, the amortized cost exceeded the fair value of the loans due to credit deterioration. The Company recorded a charge-off of $5.1 million to the allowance for credit losses, which established a new aggregate cost basis for the loans of $14.7 million on the date of transfer. In addition to the reclassification of agricultural loans, subsequent to the acquisition date, the Company increased the fair value mark on loans held for sale of $35.1 million, transferred a $12.4 million legacy commercial construction loan from loans held for investment to loans held for sale, sold $23.4 million of commercial loans, and recorded $108.7 million of net repayments and discounted pay-offs.

(6)    Loans Held for Investment

The following table presents loans by segment as of the dates indicated:

	September 30, 2022		December 31, 2021
Real estate loans:
Commercial	$	8,026.9	$	3,971.5
Construction loans:
Land acquisition & development	393.2		247.8
Residential	501.4		262.0
Commercial	1,128.4		498.0
Total construction loans	2,023.0		1,007.8
Residential	2,127.7		1,538.2
Agricultural	800.9		213.9
Total real estate loans	12,978.5		6,731.4
Consumer loans:
Indirect	780.8		737.6
Direct and advance lines	155.0		129.2
Credit card	74.2		64.9
Total consumer loans	1,010.0		931.7
Commercial	2,966.1		1,475.5
Agricultural	658.2		203.9
Other, including overdrafts	3.8		1.5
Loans held for investment	17,616.6		9,344.0
Deferred loan fees and costs	(13.1)		(12.3)
Loans held for investment, net of deferred fees and costs	17,603.5		9,331.7
Allowance for credit losses	(213.0)		(122.3)
Net loans held for investment	$	17,390.5	$	9,209.4

21

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Allowance for Credit Losses

The following tables represent, by loan portfolio segment, the activity in the allowance for credit losses for loans held for investment:

Three Months Ended September 30, 2022	Beginning Balance		Provisional ACL Recorded for PCD loans		Provision for (reversal of) Credit Losses		Loans Charged-Off		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
(1) Amounts presented exclude the allowance for credit losses related to unfunded commitments. These amounts are included in Note “Financial Instruments with Off-Balance Sheet Risk” and the allowance for credit losses related to investment securities which are included in Note “Investment Securities” included in this report.

22

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		Provisional ACL Recorded for PCD loans		Provision for (reversal of) Credit Losses (2)		Loans Charged-Off		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
Total 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 are exclusive of the allowance for credit losses related to unfunded commitments which are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.
(2) Amounts include $68.3 million related to the acquired GWB non-PCD loans.

23

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Three Months Ended September 30, 2021	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	22.9	$	1.1	$	—	$	—	$	24.0
Owner occupied	16.6		(0.6)		—		—		16.0
Multi-family	11.6		0.2		—		—		11.8
Total commercial real estate	51.1		0.7		—		—		51.8
Construction:
Land acquisition & development	1.0		(0.2)		—		0.1		0.9
Residential construction	1.5		0.3		—		—		1.8
Commercial construction	8.0		(1.3)		—		—		6.7
Total construction	10.5		(1.2)		—		0.1		9.4
Residential real estate:
Residential 1-4 family	13.4		(0.2)		—		—		13.2
Home equity and HELOC	1.4		(0.1)		—		0.1		1.4
Total residential real estate	14.8		(0.3)		—		0.1		14.6
Agricultural real estate	3.0		0.1		—		—		3.1
Total real estate	79.4		(0.7)		—		0.2		78.9
Consumer:
Indirect	15.8		(0.1)		(0.8)		0.5		15.4
Direct and advance lines	4.6		0.5		(0.8)		0.4		4.7
Credit card	1.6		0.4		(0.4)		0.2		1.8
Total consumer	22.0		0.8		(2.0)		1.1		21.9
Commercial:
Commercial and floor plans	29.0		0.3		(0.1)		0.2		29.4
Commercial purpose secured by 1-4 family	4.4		(0.2)		—		—		4.2
Credit card	0.3		—		—		—		0.3
Total commercial	33.7		0.1		(0.1)		0.2		33.9
Agricultural:
Agricultural	0.4		—		—		—		0.4
Total agricultural	0.4		—		—		—		0.4
Total allowance for credit losses	$	135.5	$	0.2	$	(2.1)	$	1.5	$	135.1
(1) Amounts presented exclude the allowance for credit losses related to unfunded commitments. These amounts are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.

24

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, 2021	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	25.5	$	(1.6)	$	—	$	0.1	$	24.0
Owner occupied	18.3		—		(2.3)		—		16.0
Multi-family	11.0		0.8		—		—		11.8
Total commercial real estate	54.8		(0.8)		(2.3)		0.1		51.8
Construction:
Land acquisition & development	1.3		(0.8)		(0.1)		0.5		0.9
Residential construction	1.6		0.3		(0.1)		—		1.8
Commercial construction	7.3		(0.6)		(0.1)		0.1		6.7
Total construction	10.2		(1.1)		(0.3)		0.6		9.4
Residential real estate:
Residential 1-4 family	11.4		1.8		—		—		13.2
Home equity and HELOC	1.4		(0.2)		(0.1)		0.3		1.4
Total residential real estate	12.8		1.6		(0.1)		0.3		14.6
Agricultural real estate	2.7		0.4		—		—		3.1
Total real estate	80.5		0.1		(2.7)		1.0		78.9
Consumer:
Indirect	16.7		(0.3)		(2.9)		1.9		15.4
Direct and advance lines	4.6		1.2		(2.0)		0.9		4.7
Credit card	2.6		—		(1.4)		0.6		1.8
Total consumer	23.9		0.9		(6.3)		3.4		21.9
Commercial:
Commercial and floor plans	34.2		(4.9)		(2.2)		2.3		29.4
Commercial purpose secured by 1-4 family	4.7		(0.8)		(0.1)		0.4		4.2
Credit card	0.3		0.2		(0.3)		0.1		0.3
Total commercial	39.2		(5.5)		(2.6)		2.8		33.9
Agricultural:
Agricultural	0.7		(0.1)		(0.2)		—		0.4
Total agricultural	0.7		(0.1)		(0.2)		—		0.4
Total allowance for credit losses	$	144.3	$	(4.6)	$	(11.8)	$	7.2	$	135.1
(1) Amounts presented are exclusive of the allowance for credit losses related to unfunded commitments which are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.

Collateral-Dependent Financial Loans

A collateral-dependent financial loan relies solely on the operation or sale of the collateral for repayment. In evaluating the overall risk associated with a loan, the Company considers (1) character, overall financial condition and resources, and payment record of the borrower; (2) the prospects for support from any financially responsible guarantors; and (3) the nature and degree of protection provided by the cash flow and value of any underlying collateral. The loan may become collateral-dependent when 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.

25

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NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The following tables present the amortized cost basis of collateral-dependent loans by class of loans as of the dates indicated:

	Collateral Type
As of September 30, 2022	Business Assets		Real Property		Other		Total
Real estate	$	2.2	$	39.1	$	—	$	41.3
Commercial	1.4		4.9		—		6.3
Agricultural	0.3		9.7		—		10.0
Total collateral-dependent	$	3.9	$	53.7	$	—	$	57.6

	Collateral Type
As of December 31, 2021	Business Assets		Real Property		Other		Total
Real estate	$	1.2	$	7.0	$	—	$	8.2
Commercial	1.8		1.0		—		2.8
Agricultural	—		0.7		—		0.7
Total collateral-dependent	$	3.0	$	8.7	$	—	$	11.7

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 greater than 90 days past due continue to accrue interest. The following tables present the contractual aging of the Company’s recorded amortized cost basis in loans by portfolio as of the dates indicated.

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of September 30, 2022	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate
Commercial	$	9.7	$	2.7	$	1.4	$	13.8	$	7,986.6	$	26.5	$	8,026.9
Construction:
Land acquisition & development	0.6		0.4		0.2		1.2		388.1		3.9		393.2
Residential	3.9		—		0.4		4.3		497.1		—		501.4
Commercial	6.8		—		—		6.8		1,121.6		—		1,128.4
Total construction loans	11.3		0.4		0.6		12.3		2,006.8		3.9		2,023.0
Residential	1.1		3.4		1.2		5.7		2,115.6		6.4		2,127.7
Agricultural	1.3		—		0.7		2.0		783.3		15.6		800.9
Total real estate loans	23.4		6.5		3.9		33.8		12,892.3		52.4		12,978.5
Consumer:
Indirect consumer	6.0		1.3		0.2		7.5		771.3		2.0		780.8
Other consumer	0.7		0.2		0.1		1.0		153.9		0.1		155.0
Credit card	0.6		0.4		0.5		1.5		72.7		—		74.2
Total consumer loans	7.3		1.9		0.8		10.0		997.9		2.1		1,010.0
Commercial	9.5		1.7		1.8		13.0		2,941.4		11.7		2,966.1
Agricultural	2.1		0.1		0.1		2.3		642.7		13.2		658.2
Other, including overdrafts	—		—		—		—		3.8		—		3.8
Loans held for investment	$	42.3	$	10.2	$	6.6	$	59.1	$	17,478.1	$	79.4	$	17,616.6

26

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NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2021	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate
Commercial	$	1.1	$	1.0	$	0.6	$	2.7	$	3,960.8	$	8.0	$	3,971.5
Construction:
Land acquisition & development	0.2		—		—		0.2		246.9		0.7		247.8
Residential	4.2		—		—		4.2		257.8		—		262.0
Commercial	—		—		—		—		498.0		—		498.0
Total construction loans	4.4		—		—		4.4		1,002.7		0.7		1,007.8
Residential	3.0		0.8		0.1		3.9		1,531.4		2.9		1,538.2
Agricultural	1.9		0.2		—		2.1		206.9		4.9		213.9
Total real estate loans	10.4		2.0		0.7		13.1		6,701.8		16.5		6,731.4
Consumer:
Indirect consumer	5.1		1.4		0.4		6.9		729.0		1.7		737.6
Other consumer	0.5		0.2		0.1		0.8		128.3		0.1		129.2
Credit card	0.6		0.2		0.5		1.3		63.6		—		64.9
Total consumer loans	6.2		1.8		1.0		9.0		920.9		1.8		931.7
Commercial	4.9		0.7		1.1		6.7		1,463.8		5.0		1,475.5
Agricultural	0.7		—		—		0.7		201.6		1.6		203.9
Other, including overdrafts	—		—		—		—		1.5		—		1.5
Loans held for investment	$	22.2	$	4.5	$	2.8	$	29.5	$	9,289.6	$	24.9	$	9,344.0

(1) As of September 30, 2022 and December 31, 2021, 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, 2022 and 2021, respectively. There were $0.6 million and no reversals of accrued interest at September 30, 2022 and September 30, 2021. respectively.

Troubled Debt Restructurings

Modifications of performing 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 and typically include adjustments such as changes to interest rates, the implementation of interest only periods of less than twelve months, the deferment of short-term payments, and extension of amortization periods. A loan modification is considered a troubled debt restructuring if the borrower is experiencing financial difficulties and the Company, for economic or legal reasons, grants a concession to the borrower that it would not under other circumstances. Certain troubled loans are on non-accrual status at the time of debt restructuring. These restructured loans may be returned to accrual status if the borrower has exhibited sustained repayment performance in compliance with the restructuring agreement for a period of at least six months and the Company is reasonably assured of the borrower’s future performance. If the troubled debt restructuring meets these performance criteria, and the interest rate granted at the modification date is equal to or greater than the rate that the Company might grant for a new loan at the same time at comparable risk, then the loan will be reclassified to performing status and the accrual of interest will resume. Loans that return to performing status will continue to be evaluated individually for credit deterioration in the ordinary course of business.

The Company renegotiated loans in troubled debt restructurings in the amount of $68.1 million as of September 30, 2022, of which $8.4 million were included in non-accrual loans and $59.7 million were on accrual status. As of September 30, 2022, the Company allocated $0.4 million of its allowance for credit losses to these loans. The Company had no material commitments to lend additional funds to borrowers whose existing loans had been renegotiated or classified as non-accrual.

The Company renegotiated loans in troubled debt restructurings in the amount of $6.2 million as of December 31, 2021, of which $3.9 million were included in non-accrual loans and $2.3 million were on accrual status. As of December 31, 2021, the Company allocated $0.1 million of its allowance for credit losses to these loans. The Company had no material commitments to lend additional funds to borrowers whose existing loans had been renegotiated or classified as non-accrual.

27

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The Company had $48.1 million and $71.7 million of new troubled debt restructurings during the three and the nine months ended September 30, 2022, respectively.

	Number of Notes	Type of Concession								Principal Balance at Restructure
Three Months Ended September 30, 2022		Interest only period		Extension of term or amortization schedule		Interest rate adjustment		Other (1)
Commercial real estate	1	$	—	$	—	$	—	$	46.1	$	46.1
Agricultural real estate	1	—		0.1		—		—		0.1
Commercial	1	—		1.9		—		—		1.9
Total loans restructured during period	3	$	—	$	2.0	$	—	$	46.1	$	48.1
(1) Other includes concessions that reduce or defer payments for a specified period of time and/or concessions that do not fit into other designated categories.
	Number of Notes	Type of Concession								Principal Balance at Restructure
Nine Months Ended September 30, 2022		Interest only period		Extension of term or amortization schedule		Interest rate adjustment		Other (1)
Commercial real estate	4	$	3.2	$	4.2	$	—	$	46.3	$	53.7
Residential real estate	2	—		0.6		—		—		0.6
Agriculture real estate	2	—		9.0		—		—		9.0
Commercial	3	—		1.9		—		0.6		2.5
Agriculture	1	—		—		—		5.9		5.9
Total loans restructured during period	12	$	3.2	$	15.7	$	—	$	52.8	$	71.7
(1) Other includes concessions that reduce or defer payments for a specified period of time and/or concessions that do not fit into other designated categories.

For troubled debt restructurings that were on non-accrual status or otherwise deemed collateral-dependent before a modification, the Company may record an allowance for credit losses depending on the circumstances. In periods after modification, the Company continues to evaluate all troubled debt restructurings for possible credit deterioration and, where deterioration is observed, recognizes credit loss through the allowance. Additionally, the Company continues to work these loans through the credit cycle through charge-off, pay-off, or foreclosure. Financial effects of modifications of troubled debt restructurings may include principal loan forgiveness or other charge-offs directly related to the restructuring. The Company had $5.7 million in charge-offs directly related to modifying an acquired PCD loan, for which a troubled debt restructuring was initiated during the three and the nine months ended September 30, 2022. The Company had no charge-offs directly related to troubled debt restructurings during the three and the nine months ended September 30, 2021.

The Company had no material troubled debt restructurings resulting in payment default during the previous 12 months ended September 30, 2022. The Company considers a payment default to occur on troubled debt restructurings when the loan is 90 days or more past due or the loan is placed on non-accrual status after the modification.

The Company modified the terms of certain other loans with a total recorded investment of $191.4 million as of September 30, 2022, where the loan did not meet the definition of a troubled debt restructuring and the borrowers had not been experiencing financial difficulties or there were delays in a payment considered to be insignificant. The Company determines whether a borrower is experiencing financial difficulty by evaluating the probability that the borrower will be in payment default on any of its debt in the foreseeable future without the modification as required under the Company’s internal underwriting policy.

28

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

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 the date of the acquisition with the purchase price (or initial fair value of the loans) as amended for measurement period adjustments as of September 30, 2022:

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 GWB PCD loans acquired 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 managed 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.

29

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 loan losses of the following segments based on the aforementioned risk scale for the periods indicated:

	September 30, 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	$	784.9	$	784.8	$	666.7	$	463.9	$	279.4	$	913.3	$	27.5	$	3,920.5
Special mention	6.0		4.4		0.4		4.7		8.3		19.8		—		43.6
Substandard	3.5		33.2		10.7		18.9		20.1		9.5		—		95.9
Doubtful	—		—		—		—		1.8		—		—		1.8
Total	$	794.4	$	822.4	$	677.8	$	487.5	$	309.6	$	942.6	$	27.5	$	4,061.8
Commercial real estate owner occupied:
Pass	$	621.4	$	757.4	$	552.2	$	282.9	$	177.4	$	589.9	$	16.3	$	2,997.5
Special mention	5.2		8.8		1.5		11.1		2.8		9.8		0.3		39.5
Substandard	12.1		3.0		2.3		4.6		2.8		17.8		0.4		43.0
Doubtful	0.4		1.5		—		—		7.9		2.0		—		11.8
Total	$	639.1	$	770.7	$	556.0	$	298.6	$	190.9	$	619.5	$	17.0	$	3,091.8
Commercial multi-family:
Pass	$	267.4	$	209.6	$	188.8	$	52.5	$	35.7	$	115.7	$	1.5	$	871.2
Special mention	—		—		—		—		—		1.8		—		1.8
Substandard	—		—		—		—		—		0.3		—		0.3
Total	$	267.4	$	209.6	$	188.8	$	52.5	$	35.7	$	117.8	$	1.5	$	873.3
Land, acquisition and development:
Pass	$	122.7	$	141.0	$	31.7	$	25.6	$	12.4	$	30.1	$	17.7	$	381.2
Special mention	6.7		—		—		—		0.2		0.3		—		7.2
Substandard	—		0.8		0.2		—		—		0.6		—		1.6
Doubtful	—		3.2		—		—		—		—		—		3.2
Total	$	129.4	$	145.0	$	31.9	$	25.6	$	12.6	$	31.0	$	17.7	$	393.2
Residential construction:
Pass	$	104.2	$	133.9	$	0.4	$	9.2	$	0.4	$	5.5	$	247.0	$	500.6
Substandard	—		0.4		—		—		—		0.4		—		0.8
Total	$	104.2	$	134.3	$	0.4	$	9.2	$	0.4	$	5.9	$	247.0	$	501.4
Commercial construction:
Pass	$	358.1	$	469.0	$	180.9	$	76.2	$	0.5	$	—	$	15.6	$	1,100.3
Special mention	2.1		—		23.1		—		—		—		—		25.2
Substandard	2.9		—		—		—		—		—		—		2.9
Total	$	363.1	$	469.0	$	204.0	$	76.2	$	0.5	$	—	$	15.6	$	1,128.4
Agricultural real estate:
Pass	$	162.5	$	175.6	$	119.5	$	67.3	$	48.0	$	111.9	$	28.7	$	713.5
Special mention	2.0		2.8		2.3		2.3		9.6		3.3		11.2		33.5
Substandard	1.1		13.9		3.6		3.4		3.2		14.2		11.4		50.8
Doubtful	—		—		3.1		—		—		—		—		3.1
Total	$	165.6	$	192.3	$	128.5	$	73.0	$	60.8	$	129.4	$	51.3	$	800.9
Commercial and floor plans:
Pass	$	415.9	$	406.3	$	233.4	$	138.5	$	130.3	$	178.9	$	707.5	$	2,210.8
Special mention	10.1		9.6		2.1		3.9		1.4		5.2		64.5		96.8
Substandard	8.0		1.2		3.4		2.7		3.5		2.4		6.6		27.8
Doubtful	0.3		4.7		—		—		—		—		—		5.0
Total	$	434.3	$	421.8	$	238.9	$	145.1	$	135.2	$	186.5	$	778.6	$	2,340.4

30

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	September 30, 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	$	155.8	$	140.4	$	71.6	$	31.4	$	31.0	$	43.2	$	29.9	$	503.3
Special mention	0.2		1.1		2.3		0.2		1.5		0.3		—		5.6
Substandard	0.2		0.3		0.1		0.3		0.9		1.2		0.1		3.1
Total	$	156.2	$	141.8	$	74.0	$	31.9	$	33.4	$	44.7	$	30.0	$	512.0
Agricultural:
Pass	$	107.6	$	70.9	$	35.0	$	12.8	$	9.9	$	1.5	$	356.3	$	594.0
Special mention	1.5		3.4		0.6		1.2		0.7		—		12.1		19.5
Substandard	23.1		6.5		5.0		0.9		4.2		1.1		1.4		42.2
Doubtful	—		0.6		—		—		—		—		—		0.6
Total	$	132.2	$	81.4	$	40.6	$	14.9	$	14.8	$	2.6	$	369.8	$	656.3

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial real estate non-owner occupied:
Pass	$	507.9	$	452.2	$	237.9	$	150.4	$	76.3	$	409.0	$	15.3	$	1,849.0
Special mention	0.2		3.1		2.1		—		—		3.6		—		9.0
Substandard	3.9		15.3		2.3		0.7		1.0		12.4		—		35.6
Total	$	512.0	$	470.6	$	242.3	$	151.1	$	77.3	$	425.0	$	15.3	$	1,893.6
Commercial real estate owner occupied:
Pass	$	452.7	$	314.9	$	235.0	$	151.0	$	94.5	$	322.5	$	14.2	$	1,584.8
Special mention	1.3		3.2		1.5		7.4		3.5		13.8		—		30.7
Substandard	3.8		4.3		4.7		5.4		2.7		20.3		—		41.2
Total	$	457.8	$	322.4	$	241.2	$	163.8	$	100.7	$	356.6	$	14.2	$	1,656.7
Commercial multi-family:
Pass	$	129.1	$	118.6	$	43.9	$	15.4	$	36.0	$	76.7	$	1.5	$	421.2
Total	$	129.1	$	118.6	$	43.9	$	15.4	$	36.0	$	76.7	$	1.5	$	421.2
Land, acquisition and development:
Pass	$	113.0	$	41.5	$	34.2	$	14.8	$	19.8	$	20.8	$	1.2	$	245.3
Special mention	—		0.1		—		—		0.1		0.3		—		0.5
Substandard	0.8		0.2		—		0.6		0.3		0.1		—		2.0
Total	$	113.8	$	41.8	$	34.2	$	15.4	$	20.2	$	21.2	$	1.2	$	247.8
Residential construction:
Pass	$	112.4	$	7.0	$	13.7	$	0.9	$	—	$	—	$	127.2	$	261.2
Substandard	—		0.4		—		—		0.4		—		—		0.8
Total	$	112.4	$	7.4	$	13.7	$	0.9	$	0.4	$	—	$	127.2	$	262.0
Commercial construction:
Pass	$	209.7	$	141.4	$	118.8	$	27.6	$	—	$	0.5	$	—	$	498.0
Total	$	209.7	$	141.4	$	118.8	$	27.6	$	—	$	0.5	$	—	$	498.0

31

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Agricultural real estate:
Pass	$	58.3	$	36.9	$	35.1	$	22.6	$	11.8	$	28.1	$	4.9	$	197.7
Special mention	0.1		1.3		1.2		0.1		0.1		0.9		0.9		4.6
Substandard	4.0		0.4		1.0		0.6		1.3		4.3		—		11.6
Total	$	62.4	$	38.6	$	37.3	$	23.3	$	13.2	$	33.3	$	5.8	$	213.9
Commercial and floor plans:
Pass	$	394.2	$	165.7	$	94.5	$	73.5	$	47.1	$	91.3	$	224.7	$	1,091.0
Special mention	0.8		11.4		0.8		0.8		3.0		2.3		7.0		26.1
Substandard	1.3		2.8		1.6		2.6		0.6		4.1		2.6		15.6
Total	$	396.3	$	179.9	$	96.9	$	76.9	$	50.7	$	97.7	$	234.3	$	1,132.7
Commercial purpose secured by 1-4 family:
Pass	$	94.9	$	55.0	$	27.8	$	23.1	$	15.3	$	32.2	$	14.4	$	262.7
Special mention	—		0.2		0.2		0.5		0.1		0.6		—		1.6
Substandard	1.3		1.2		0.6		0.6		0.2		1.3		0.1		5.3
Total	$	96.2	$	56.4	$	28.6	$	24.2	$	15.6	$	34.1	$	14.5	$	269.6
Agricultural:
Pass	$	35.1	$	16.2	$	9.0	$	5.4	$	2.1	$	1.6	$	108.9	$	178.3
Special mention	0.2		4.1		0.1		0.4		0.6		0.3		7.0		12.7
Substandard	4.9		0.7		0.6		2.5		—		0.1		2.6		11.4
Total	$	40.2	$	21.0	$	9.7	$	8.3	$	2.7	$	2.0	$	118.5	$	202.4

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, and loans modified under troubled debt restructurings are considered nonperforming for purposes of credit quality evaluation. The following tables present the recorded investment of our other loan portfolios based on the credit risk profile of loans that are performing and loans that are nonperforming as of the periods indicated:

	September 30, 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	$	195.3	$	466.3	$	550.2	$	102.3	$	32.6	$	230.2	$	—	$	1,576.9
Nonperforming	—		0.2		0.4		0.5		0.4		3.4		—		4.9
Total	$	195.3	$	466.5	$	550.6	$	102.8	$	33.0	$	233.6	$	—	$	1,581.8
Consumer home equity and HELOC:
Performing	$	14.9	$	8.7	$	5.4	$	4.4	$	5.7	$	17.6	$	486.5	$	543.2
Nonperforming	0.5		0.3		0.1		0.1		0.1		1.2		0.4		2.7
Total	$	15.4	$	9.0	$	5.5	$	4.5	$	5.8	$	18.8	$	486.9	$	545.9
Consumer indirect:
Performing	$	279.0	$	194.9	$	144.5	$	69.0	$	39.5	$	51.7	$	—	$	778.6
Nonperforming	0.2		0.6		0.4		0.3		0.2		0.5		—		2.2
Total	$	279.2	$	195.5	$	144.9	$	69.3	$	39.7	$	52.2	$	—	$	780.8
Consumer direct and advance line:
Performing	$	45.0	$	36.2	$	20.9	$	10.5	$	7.9	$	9.7	$	24.6	$	154.8
Nonperforming	—		0.1		—		—		—		0.1		—		0.2
Total	$	45.0	$	36.3	$	20.9	$	10.5	$	7.9	$	9.8	$	24.6	$	155.0

32

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Residential 1-4 family:
Performing	$	360.9	$	477.0	$	74.7	$	27.5	$	25.7	$	176.5	$	—	$	1,142.3
Nonperforming	—		0.3		—		—		0.2		0.8		—		1.3
Total	$	360.9	$	477.3	$	74.7	$	27.5	$	25.9	$	177.3	$	—	$	1,143.6
Consumer home equity and HELOC:
Performing	$	11.1	$	7.0	$	3.7	$	4.8	$	3.6	$	12.0	$	350.7	$	392.9
Nonperforming	0.3		—		0.3		—		0.6		0.5		—		1.7
Total	$	11.4	$	7.0	$	4.0	$	4.8	$	4.2	$	12.5	$	350.7	$	394.6
Consumer indirect:
Performing	$	272.6	$	208.6	$	108.3	$	64.0	$	37.0	$	45.0	$	—	$	735.5
Nonperforming	0.5		0.5		0.4		0.2		0.1		0.4		—		2.1
Total	$	273.1	$	209.1	$	108.7	$	64.2	$	37.1	$	45.4	$	—	$	737.6
Consumer direct and advance line:
Performing	$	42.5	$	27.9	$	15.0	$	13.3	$	5.8	$	7.6	$	16.9	$	129.0
Nonperforming	0.1		—		—		0.1		—		—		—		0.2
Total	$	42.6	$	27.9	$	15.0	$	13.4	$	5.8	$	7.6	$	16.9	$	129.2

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 September 30, 2022	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	73.8	$	113.3	$	1.9	$	189.0
Nonperforming	0.4		0.4		—		0.8
Total credit card	$	74.2	$	113.7	$	1.9	$	189.8

As of December 31, 2021	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	64.4	$	73.1	$	1.5	$	139.0
Nonperforming	0.5		0.1		—		0.6
Total credit card	$	64.9	$	73.2	$	1.5	$	139.6

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, 2022 or 2021.

(7)    Other Real Estate Owned

Other real estate owned 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 other real estate owned is reflected in the following table:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Beginning balance	$	16.8	$	2.0	$	2.0	$	2.5
Acquired through acquisition	—		—		15.8		—
Additions	0.3		0.4		0.4		0.7
Valuation adjustments	(0.2)		—		(0.2)		—
Dispositions	(0.5)		(0.1)		(1.6)		(0.9)
Ending balance	$	16.4	$	2.3	$	16.4	$	2.3

33

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The carrying value of foreclosed residential real estate properties included in other real estate owned was not material as of September 30, 2022 and December 31, 2021. The Company had 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, 2022 and December 31, 2021.

(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 marked to market through earnings. In addition to the effects of the change in market interest rate, the fair value measurement of the derivative also contemplates the expected cash flows to be received from the counterparty from the future sale of the loan.

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 marked to market through earnings and are not designated as accounting hedges during the interest rate lock commitment period and through the duration of the forward loan sales contracts. Exclusive of the fair value component associated with the projected cash flows from the loan delivery to the investor, the changes in fair value related to movements in market rates of the interest rate lock commitments and the forward loan sales contracts generally move in opposite directions, and the net impact of changes in these valuations on net income during the loan commitment period is generally inconsequential. When the loan is funded to the borrower, the interest rate lock commitment derivative expires, and the Company records a loan held for sale. The forward loan sales contract acts as a hedge against the variability in cash to be received from the loan sale. The changes in measurement of the estimated fair values of the interest rate lock commitments and forward loan sales contracts are included in mortgage banking revenues in the accompanying consolidated statements of income.

The Company also enters into certain interest rate swap contracts that are not designated as hedging instruments. These derivative contracts relate to transactions in which the Company enters into an interest rate swap with a client while at the same time entering into an offsetting interest rate swap with a third-party financial institution. Because the Company acts as an intermediary for the client, changes in the fair value of the underlying derivative contracts for the most part offset each other and do not significantly impact the Company’s results of operations.

34

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Cash Flow Hedges of Interest Rate Risk

The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, 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 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 variable-rate borrowings (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. 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.

For derivatives 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 (loss) income and subsequently reclassified into interest expense in the same period(s) during which the hedged transaction affects earnings. Amounts reported in accumulated other comprehensive (loss) income related to derivatives will be reclassified as interest expense when interest payments are made on the Company’s variable-rate liabilities. During the next twelve months, the Company estimates that no material amounts 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 2021, the Company entered into two forward starting, fixed interest rate fair value hedges associated with U.S. Treasury securities. During the second quarter of 2022, the Company terminated the $500.0 million, two-year forward starting, three-year pay-fixed interest rate swap, resulting in a $23.3 million gain. The gain associated with the $500.0 million interest rate swap was to be accreted into income through May 2026. However, the U.S. Treasury securities associated with the swap were sold during the third quarter of 2022. As such, the gain was accreted through August 2022 and then in September 2022 the remaining gain was recognized as income. 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 balance sheet related to cumulative basis adjustment for fair value hedges for the periods indicated:

	September 30, 2022				December 31, 2021
	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	$	—	$	—	$	695.6	$	(4.4)

35

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Non-designated Hedge Derivatives

Derivatives not designated as 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 enters into these credit risk participation agreements in instances in which the Company is 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 balance sheet.

	September 30, 2022					December 31, 2021
	Notional Amount		Balance Sheet Location	Estimated Fair Value		Notional Amount		Balance Sheet Location	Estimated Fair Value
Derivatives designated as hedges:
Interest rate swap contracts	—			—		700.0			4.1
Derivatives not designated as hedges:
Interest rate swap contracts	1,743.3			42.1		913.9			22.2
Interest rate lock commitments	—			—		77.3			1.8
Forward loan sales contracts	32.3			0.6		—			—
Derivative assets in the balance sheet	$	1,775.6	Other Assets	$	42.7	$	1,691.2	Other Assets	$	28.1
Derivatives designated as hedges:
Interest rate collars	$	300.0		$	5.6	$	—		$	—
Interest rate swap contracts	—			—		87.6			0.1
Derivatives not designated as hedges:
Interest rate swap contracts	1,743.3			163.7		913.9			18.1
Risk participation agreements	107.2			0.1		—			—
Interest rate lock commitments	25.9			0.5		—			—
Forward loan sales contracts	—			—		102.4			—
Derivative liabilities in the balance sheet	$	2,176.4	Accrued Expenses	$	169.9	$	1,103.9	Accrued Expenses	$	18.2

There was a $5.6 million unrealized fair value loss on derivative instruments in accumulated other comprehensive loss during the three and the nine months ended September 30, 2022. There were no material effects of derivative instruments in fair value or cash flow hedge accounting on accumulated other comprehensive (loss) income during the three and the nine months ended 2021.

36

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 effects from the Company’s fair value or cash flow hedged derivative financial instruments on the income statement during the three and the nine months ended September 30, 2022 or 2021.

The table below presents the effect of the Company’s derivative financial instruments that are not designated as hedging instruments on the income statement for the periods indicated:

	Three Months Ended September 30,					Nine Months Ended September 30,
		2022		2021			2022		2021
	Location of (Loss) Gain Recognized in Income on Derivative	Amount of (Loss) Gain Recognized in Income on Derivative				Location of (Loss) Gain Recognized in Income on Derivative	Amount of (Loss) Gain Recognized in Income on Derivative
Interest rate lock commitments	Mortgage banking revenues	$	(0.2)	$	1.3	Mortgage banking revenues	$	(1.7)	$	1.7

The Company recorded swap fee revenues of $2.5 million and $0.4 million for the three months ended September 30, 2022 and September 30, 2021, respectively, and $5.6 million and $1.6 million for the nine months ended September 30, 2022 and September 30, 2021, respectively. The Company includes swap fee revenues in other service charges, commissions, and fees.

The tables below present the gross presentation, the effects of offsetting, and a net presentation of the Company’s derivatives as of the periods indicated:

	September 30, 2022
	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	$	42.1	$	—	$	42.1	$	—	$	42.1	$	—
Mortgage related derivatives	0.6		—		0.6		—		—		0.6
Total derivatives	42.7		—		42.7		—		42.1		0.6
Total assets	$	42.7	$	—	$	42.7	$	—	$	42.1	$	0.6
(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	$	169.3	$	—	$	169.3	$	—	$	5.6	$	163.7
Risk participation agreements	0.1		—		0.1		—		—		0.1
Mortgage related derivatives	0.5		—		0.5		—		—		0.5
Total derivatives	169.9		—		169.9		—		5.6		164.3
Repurchase agreements	1,075.6		—		1,075.6		—		1,075.6		—
Total liabilities	$	1,245.5	$	—	$	1,245.5	$	—	$	1,081.2	$	164.3

37

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	December 31, 2021
	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	$	26.3	$	—	$	26.3	$	—	$	8.0	$	18.3
Mortgage related derivatives	1.8		—		1.8		—		—		1.8
Total derivatives	28.1		—		28.1		—		8.0		20.1
Total assets	$	28.1	$	—	$	28.1	$	—	$	8.0	$	20.1
	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	$	18.2	$	—	$	18.2	$	—	$	—	$	18.2
Total derivatives	18.2		—		18.2		—		—		18.2
Repurchase agreements	1,051.1		—		1,051.1		—		1,051.1		—
Total liabilities	$	1,069.3	$	—	$	1,069.3	$	—	$	1,051.1	$	18.2

Credit-risk-related Contingent Feature

The Company has agreements with each of its derivative counterparties that contain a provision where if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations.

The Company has agreements with certain of its derivative counterparties that contain a provision where if the Company fails to maintain its status as a well / adequately capitalized institution, then in certain instances the Company could be required to post additional capital and in certain instances the counterparty would have the right to terminate the derivative positions and the Company would be required to settle its obligations under the agreements.

As of September 30, 2022, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, was $5.6 million related to these agreements. As of September 30, 2022, the Company has minimum collateral posting thresholds with certain of its derivative counterparties and has not posted excess collateral. If the Company had breached any of these provisions at September 30, 2022, it could have been required to settle its obligations under the agreements at their termination value of $5.6 million.

(9)    Capital Stock

On February 1, 2022, the Company issued 46,879,601 shares of its Class A common stock with an aggregate value of approximately $1.7 billion as consideration for the acquisition of Great Western. During the nine months ended September 30, 2022 and 2021, the Company also issued 33,769 shares and 19,081 shares, respectively, of its Class A common stock to directors for their annual service on the Company's board of directors. The aggregate value of the shares issued to directors is included in employee benefits in the consolidated statement of income and in stock-based compensation expense in the consolidated statements of changes in stockholders' equity.

On March 25, 2022, all outstanding shares of the Company’s Class B common stock automatically converted into shares of the Company’s Class A common stock on a one-for-one basis, pursuant to the terms of the Company’s Third Amended and Restated Articles of Incorporation, as amended (the “Charter”). No additional shares of Class B common stock are permitted to be issued. The conversion occurred automatically pursuant to the Company’s Charter because the number of the Company’s outstanding shares of Class B common stock represented on March 25, 2022, the record date for determining the shareholders of the Company entitled to notice of, and to vote at, the Company’s 2022 Annual Meeting of Shareholders, was less than twenty percent (20%) of the aggregate number of all of the outstanding shares of Class A common stock and Class B common stock of the Company. The former holders of Class B common stock now hold Class A common stock with the same voting powers, preferences, rights and qualifications, limitations and restrictions as the other holders of Class A common stock. All shares of the Company’s outstanding capital stock are now composed solely of shares of Class A common stock and are entitled to one vote per share. The Company’s Class A common stock will continue to trade on the NASDAQ Stock Market under the ticker symbol “FIBK”.

38

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

On May 25, 2022, the Company’s board of directors adopted a new stock repurchase program to replace the program that had been in place since 2019 and had 1,889,158 shares of Class A common stock remaining to be purchased thereunder. Under the new stock repurchase program, the Company may repurchase up to 5.0 million of its outstanding shares of Class A common stock. There were 3,279,300 shares repurchased and retired under the new 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. The shares of common stock repurchased during the period completes the 5.0 million shares authorized to be repurchased. The 5.0 million shares repurchased during the nine months ended September 30, 2022 were purchased at a total cost of $197.4 million, including costs and commissions, at an average per share cost of $39.48.

All other stock repurchases during the nine months ended September 30, 2022 and 2021, 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.

The Company had 104,450,804 shares of Class A common stock outstanding as of September 30, 2022. The Company had 41,699,409 shares of Class A common stock and 20,501,047 shares of Class B common stock outstanding as of December 31, 2021.

(10)    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,
	2022		2021		2022		2021
Net income	$	85.7	$	47.1	$	116.4	$	141.0
Weighted average common shares outstanding for basic earnings per share computation	106,525,974		61,673,656		102,879,422		61,641,342
Dilutive effects of stock-based compensation	63,725		74,316		55,938		91,480
Weighted average common shares outstanding for diluted earnings per common share computation	106,589,699		61,747,972		102,935,360		61,732,822
Basic earnings per common share	$	0.80	$	0.76	$	1.13	$	2.29
Diluted earnings per common share	$	0.80	$	0.76	$	1.13	$	2.28
Anti-dilutive unvested time restricted stock	48,871		89,142		51,161		88,677

The Company had 481,567 and 355,981 shares of unvested restricted stock as of September 30, 2022 and 2021, respectively, that were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met.

39

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(11)    Regulatory Capital

As of September 30, 2022 and December 31, 2021, 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, 2022 and December 31, 2021 are presented in the following tables: 

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(1)
September 30, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,820.2	12.50	%	$	1,804.7	8.00	%	$	2,368.7	10.50	%	$	2,255.9	10.00	%
FIB	2,704.8		12.01		1,801.1		8.00		2,363.9		10.50		2,251.4		10.00
Tier 1 risk-based capital:
Consolidated	2,366.8		10.49		1,353.5		6.00		1,917.5		8.50		1,804.7		8.00
FIB	2,508.9		11.14		1,350.8		6.00		1,913.7		8.50		1,801.1		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,366.8		10.49		1,015.1		4.50		1,579.1		7.00		1,466.3		6.50
FIB	2,508.9		11.14		1,013.1		4.50		1,576.0		7.00		1,463.4		6.50
Leverage capital ratio:
Consolidated	2,366.8		7.67		1,234.4		4.00		1,234.4		4.00		1,543.0		5.00
FIB	2,508.9		8.14		1,232.2		4.00		1,232.2		4.00		1,540.2		5.00

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(1)
December 31, 2021	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,659.3	14.11	%	$	940.9	8.00	%	$	1,235.0	10.50	%	$	1,176.2	10.00	%
FIB	1,472.5		12.56		938.0		8.00		1,231.1		10.50		1,172.5		10.00
Tier 1 risk-based capital:
Consolidated	1,469.0		12.49		705.7		6.00		999.7		8.50		940.9		8.00
FIB	1,382.2		11.79		703.5		6.00		996.6		8.50		938.0		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,384.8		11.77		529.3		4.50		823.3		7.00		764.5		6.50
FIB	1,382.2		11.79		527.6		4.50		820.8		7.00		762.1		6.50
Leverage capital ratio:
Consolidated	1,469.0		7.68		765.5		4.00		765.5		4.00		956.9		5.00
FIB	1,382.2		7.24		764.1		4.00		764.1		4.00		955.1		5.00

(1) 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.

40

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 the Current Expected Credit Loss accounting standard (“CECL”), or ASC 326, 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 transitioning 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.

(12)    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, 2022, the Company had commitments under construction contracts of $1.6 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 $1.0 million of sold residential mortgage loans with recourse provisions still in effect as of September 30, 2022.

(13)    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.    

41

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,
	2022		2021		2022		2021
Beginning balance	$	6.2	$	3.4	$	3.8	$	3.7
Provision for (reversal of) credit loss expense	3.5		(0.2)		5.9		(0.5)
Ending balance of allowance for off-balance sheet credit losses	$	9.7	$	3.2	$	9.7	$	3.2

	September 30, 2022		December 31, 2021
Unused credit card lines	$	814.9	$	681.6
Commitments to extend credit	5,011.0		2,539.8
Standby letter of credit	92.4		57.5

(14)    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,	2022		2021		2022		2021		2022		2021
Investment securities available-for sale:
Change in net unrealized loss during period	$	(236.4)	$	(13.4)	$	(53.4)	$	(3.3)	$	(183.0)	$	(10.1)
Reclassification adjustment for net loss (gain) included in net income	24.2		(0.3)		5.5		(0.1)		18.7		(0.2)
Net change in unamortized (gains) losses on available-for-sale securities transferred into held-to-maturity	(1.7)		(2.5)		(0.4)		(0.6)		(1.3)		(1.9)
Change in net unrealized gain (loss) on derivatives	(15.9)		3.2		(3.6)		0.8		(12.3)		2.4
Total other comprehensive loss	$	(229.8)	$	(13.0)	$	(51.9)	$	(3.2)	$	(177.9)	$	(9.8)

	Pre-tax				Tax Expense (Benefit)				Net of Tax
Nine Months Ended September 30,	2022		2021		2022		2021		2022		2021
Investment securities available-for sale:
Change in net unrealized loss during period	$	(650.6)	$	(81.0)	$	(161.3)	$	(20.5)	$	(489.3)	$	(60.5)
Reclassification adjustment for net loss (gain) included in net income	24.4		(0.2)		5.5		(0.1)		18.9		(0.1)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0.2		—		0.1		—		0.1		—
Net change in unamortized (gains) losses on available-for-sale securities transferred into held-to-maturity	(25.6)		22.3		(6.3)		5.7		(19.3)		16.6
Change in net unrealized gain (loss) on derivatives	(9.6)		2.3		(2.5)		0.6		(7.1)		1.7
Total other comprehensive loss	$	(661.2)	$	(56.6)	$	(164.5)	$	(14.3)	$	(496.7)	$	(42.3)

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

	September 30, 2022		December 31, 2021
Net unrealized loss on investment securities available-for-sale	$	(499.1)	$	(29.0)
Net unrealized (loss) gain on investment securities transferred to held-to-maturity	(4.4)		15.0
Net unrealized gain on derivatives	(4.2)		3.0
Net accumulated other comprehensive loss	$	(507.7)	$	(11.0)

(15)    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.

42

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, 2022 and 2021.

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 transfers between fair value hierarchy levels during the three and the nine months ended September 30, 2022 and 2021.

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 other things. 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 three-month LIBOR forward curve to estimate variable rate cash inflows and the Secured Overnight Financing Rate 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..

43

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 as well as ours. 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, 2022	Balance		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	$	336.8	$	336.8	$	—	$	—
State, county, and municipal securities	260.5			—	260.5			—
Obligations of U.S. government agencies	199.0			—	199.0			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	4,409.7			—	4,409.7			—
Private mortgage-backed securities	233.2			—	233.2			—
Collateralized loan obligations	1,105.1			—	1,105.1			—
Corporate securities	239.1			—	239.1			—
Loans held for sale	93.6			—	93.6			—
Derivative assets:
Interest rate swap contracts	42.1			—	42.1			—
Forward loan sale contracts	0.6			—	0.6			—
Derivative liabilities:
Interest rate collars	5.6			—	5.6			—
Interest rate swap contracts	163.7			—	163.7			—
Risk participation agreements	0.1			—	0.1			—
Interest rate lock commitments	0.5			—	0.5			—
Deferred compensation plan assets	19.0			—	19.0			—
Deferred compensation plan liabilities	19.0			—	19.0			—

44

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, 2021	Balance		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	$	684.7	$	684.7	$	—	$	—
State, county and municipal securities	427.5			—	427.5			—
Obligations of U.S. government agencies	346.9			—	346.9			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	2,018.1			—	2,018.1			—
Private mortgage-backed securities	173.4			—	173.4			—
Collateralized loan obligations	899.4			—	899.4			—
Corporate securities	270.5			—	270.5			—
Loans held for sale	30.1			—	30.1			—
Derivative assets:
Interest rate swap contracts	26.3			—	26.3			—
Interest rate lock commitments	1.8			—	1.8			—
Derivative liabilities
Interest rate swap contracts	18.2			—	18.2			—
Deferred compensation plan assets	21.4			—	21.4			—
Deferred compensation plan liabilities	21.4			—	21.4			—

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, 2022	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral dependent loans	$	57.6	$	—	$	—	$	57.6
Other real estate owned	16.4			—		—	16.4
Long-lived assets to be disposed of by sale	6.7			—		—	6.7
				Fair Value Measurements at Reporting Date Using
As of December 31, 2021	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral dependent loans	$	11.7	$	—	$	—	$	11.7
Other real estate owned	2.0			—		—	2.0
Long-lived assets to be disposed of by sale	1.3			—		—	1.3

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, 2022 and December 31, 2021, the Company had collateral-dependent loans with a carrying and fair value of $57.6 million and $11.7 million, respectively.

45

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

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 no material write downs on OREO properties during the nine months ended September 30, 2022 and 2021, 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, 2022, the Company had long-lived assets to be disposed of by sale with carrying and fair values aggregating $6.7 million, with no write-downs charged to other expense. As of December 31, 2021, the Company had long-lived assets to be disposed of by sale with carrying and fair values aggregating $1.3 million, with no write-downs charged to other expense.         

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, 2022		December 31, 2021		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Collateral dependent loans	$	57.6	$	11.7	Appraisal	Appraisal adjustment	1%	-	18%	(7%)
Other real estate owned	16.4		2.0		Appraisal	Appraisal adjustment	0%	-	0%	0%
Long-lived assets to be disposed of by sale	6.7		1.3		Appraisal	Appraisal adjustment	0%	-	0%	0%

The Company is required to disclose the fair value of financial instruments for which it is practical to estimate fair value. The methodologies for estimating the fair value of financial instruments that are measured at fair value on a recurring or non-recurring basis are discussed above. The methodologies for estimating the fair value of other financial instruments are discussed below. For financial instruments bearing a variable interest rate where no credit risk exists, it is presumed that recorded book values are reasonable estimates of fair value.        

Financial Assets. Carrying values of cash, cash equivalents, and accrued interest receivable approximate fair values due to the liquid and/or short-term nature of these instruments. Fair values for investment securities held-to-maturity are obtained from an independent pricing service, which considers observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the investment’s terms and conditions, among other things. Fair values of fixed rate loans and variable rate loans that reprice on an infrequent basis are estimated by discounting future cash flows using current interest rates at which similar loans with similar terms would be made to borrowers of similar credit quality using an exit price notion. Carrying values of variable rate loans that reprice frequently, and with no change in credit risk, approximate the fair values of these instruments.

Financial Liabilities. The fair values of demand deposits, savings accounts, securities sold under repurchase agreements, and accrued interest payable are the amounts that are payable on demand at the reporting date. The fair values of fixed-maturity certificates of deposit are estimated using external market rates that are currently offered for deposits that have similar remaining maturities. The fair values of derivative liabilities are obtained from an independent pricing service, which considers observable data that may include the three-month LIBOR forward curve, the federal funds effective swap rate and cash flows, among other things. The carrying values of the interest-bearing demand notes to the United States Treasury are deemed an approximation of fair values due to the frequent repayment and repricing at market rates. The fixed and floating rate subordinated debentures, floating rate subordinated term loan, notes payable to the FHLB, 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.    

46

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

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, 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	$	591.9	$	591.9	$	591.9	$	—	$	—
Investment debt securities available-for-sale	6,783.4		6,783.4		336.8		6,446.6		—
Investment debt securities held-to-maturity	3,485.7		3,063.5		385.5		2,678.0		—
Accrued interest receivable	106.4		106.4		—		106.4		—
Mortgage servicing rights, net	31.8		36.6		—		36.6		—
Loans held for sale	93.6		93.6		—		93.6		—
Net loans held for investment	17,390.5		17,293.6		—		17,236.0		57.6
Derivative assets	42.7		42.7		—		42.7		—
Deferred compensation plan assets	19.0		19.0		—		19.0		—
Total financial assets	$	28,545.0	$	28,030.7	$	1,314.2	$	26,658.9	$	57.6
Financial liabilities:
Total deposits, excluding time deposits	$	24,255.6	$	24,255.6	$	24,255.6	$	—	$	—
Time deposits	1,629.2		1,587.2		—		1,587.2		—
Securities sold under repurchase agreements	1,075.6		1,075.6		—		1,075.6		—
Other borrowed funds	625.0		625.0		—		625.0		—
Accrued interest payable	7.4		7.4		—		7.4		—
Long-term debt	120.7		116.7		—		116.7		—
Subordinated debentures held by subsidiary trusts	163.1		157.1		—		157.1		—
Derivative liabilities	169.9		169.9		—		169.9		—
Deferred compensation plan liabilities	19.0		19.0		—		19.0		—
Total financial liabilities	$	28,065.5	$	28,013.5	$	24,255.6	$	3,757.9	$	—

47

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, 2021	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	$	2,344.8	$	2,344.8	$	2,344.8	$	—	$	—
Investment debt securities available-for-sale	4,820.5		4,820.5		684.7		4,135.8		—
Investment debt securities held-to-maturity	1,687.6		1,667.5		—		1,667.5		—
Accrued interest receivable	47.4		47.4		—		47.4		—
Mortgage servicing rights, net	28.2		28.2		—		28.2		—
Loans held for sale	30.1		30.1		—		30.1		—
Net loans held for investment	9,209.4		9,254.3		—		9,242.6		11.7
Derivative assets	28.1		28.1		—		28.1		—
Deferred compensation plan assets	21.4		21.4		—		21.4		—
Total financial assets	$	18,217.5	$	18,242.3	$	3,029.5	$	15,201.1	$	11.7
Financial liabilities:
Total deposits, excluding time deposits	$	15,303.1	$	15,303.1	$	15,303.1	$	—	$	—
Time deposits	966.5		963.1		—		963.1		—
Securities sold under repurchase agreements	1,051.1		1,051.1		—		1,051.1		—
Accrued interest payable	3.7		3.7		—		3.7		—
Long-term debt	112.4		120.7		—		120.7		—
Subordinated debentures held by subsidiary trusts	87.0		85.5		—		85.5		—
Derivative liabilities	18.2		18.2		—		18.2		—
Deferred compensation plan liabilities	21.4		21.4		—		21.4		—
Total financial liabilities	$	17,563.4	$	17,566.8	$	15,303.1	$	2,263.7	$	—

(16)    Other Borrowed Funds            

At September 30, 2022, the Company had $625.0 million in outstanding Federal Home Loan Bank (“FHLB”) borrowings consisting of $550.0 million in 3.29% variable rate overnight borrowings and $75.0 million in 3.20% fixed rate one-month borrowings, as compared to no outstanding borrowings from the FHLB at December 31, 2021. The Company has a remaining borrowing capacity at FHLB of $3,962.4 million. The borrowings are collateralized by certain loans with an advance equivalent collateral value of $4,588.0 million.

48

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(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. The Company is currently evaluating the impact of the adoption of other expedients in the standard and does not anticipate it will have a significant impact on the Company’s financial position or results of operations.

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 (including periods after December 31, 2022). 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.

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. Early adoption is permitted, including in any interim period, for public business entities for periods for which financial statements have not yet been issued, and for all other entities for periods for which financial statements have not yet been made available for issuance. 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.

49

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

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. Entities should apply the amendments prospectively to business combinations that occur after the effective date. Early adoption in an interim period is permitted for public business entities, with the effect of adopting the amendments related to basis adjustments reflected as of the beginning of the fiscal year of adoption. 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.

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. Entities should apply the amendments prospectively except for the transition method related to the recognition and measurement of TDRs, an entity has the option to apply a modified retrospective transition method, resulting in a cumulative-effect adjustment to retained earnings in the period of adoption. Early adoption of the amendments are permitted, including adoption in an interim period. If an entity elects to early adopt the amendments in an interim period, the guidance should be applied as of the beginning of the fiscal year that includes the interim period. An entity may elect to early adopt the amendments about TDRs and related disclosure enhancements separately from the amendments related to vintage disclosures. 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.

(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, 2022, the Company declared a quarterly dividend to common shareholders of $0.47 per share, to be paid on November 18, 2022 to shareholders of record as of November 8, 2022.

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, 2021, 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, 2021, 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.

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 308 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.

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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 deposits 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) core deposit 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

During the past few years, we have increased our community banking footprint across the Rocky Mountain and Pacific Northwest regions and have expanded into the Midwest and Southwest regions, in large part due to our acquisition activity. We continue to evaluate bank acquisitions and other strategic opportunities on an on-going basis.

On September 15, 2021, the Company entered into a definitive agreement to acquire all 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. The acquisition of GWB 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 and core systems converted in May 2022, at which point GWB’s operations were integrated with the Company’s operations. The accompanying consolidated statements of income for the nine months ended September 30, 2022, include the results of operations of the acquired entity from the February 1, 2022 acquisition date.

On March 25, 2022, all outstanding shares of the Company’s Class B common stock automatically converted into shares of the Company’s Class A common stock on a one-for-one basis, pursuant to the terms of the Company’s Third Amended and Restated Articles of Incorporation, as amended (the “Charter”). No additional shares of Class B common stock are permitted to be issued. The former holders of Class B common stock now hold Class A common stock with the same voting powers, preferences, rights and qualifications, limitations and restrictions as the other holders of Class A common stock. All shares of the Company’s outstanding capital stock are now composed solely of shares of Class A common stock and are entitled to one vote per share. The Company’s Class A common stock will continue to trade on the NASDAQ Stock Market under the ticker symbol “FIBK”

U.S. inflation data hit a multi-decade high in June 2022, climbing to 9.1%, as reported by the Bureau of Labor Statistics, and then decreased slightly to 8.2% in September 2022. The effect of inflation on the Company differs significantly from the effect on other industries. While our operating expenses are affected by general inflation, the asset and liability structure of the Company is largely of monetary items. Monetary items, such as cash, investments, loans, deposits and other borrowings, are those 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, on businesses and consumers and their ability or willingness to invest, save or spend, and perhaps on their ability to repay loans.

The Federal Reserve has stated its objective of returning inflation to 2% and has been aggressively acting to achieve this goal. The Federal Reserve increased short-term interest rates 25 basis points on March 16, 2022, 50 basis points on May 4, 2022, 75 basis points on June 15, 2022, 75 basis points on July 27, 2022, 75 basis points on September 21, 2022, and another 75 basis points on November 2, 2022. The Federal Reserve has also signaled an expectation on ongoing increases in the short-term interest rates at each of its remaining meetings in 2022, with a target rate of 4.40% by December 31, 2022. Prior to this, short-term interest rates had remained steady since March 2020. With these recent interest rate increases, the short end (up to two years) of the yield curve has steepened. While net interest margins remain below historical levels, net interest income continues to rise as a result of higher yields and a more favorable asset mix. However, increases in interest rates may have negative impacts on the Company’s clients and their ability to repay loans.

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Gross domestic product declined for the first and second quarters of 2022 with the recent advance estimate released for the third quarter of 2022 suggesting a 2.6% increase for the quarter ending September 30, 2022. It is unclear whether the economic performance of the U.S. economy suffered a minor slip in 2022 from its regular pattern of growth or whether the negative growth is the beginning of a more sustained economic slowdown, downturn, or recession; any one of these could impact the Company whether it impacts the level of deposits by our clients, whether by causing higher volume of withdrawals or lower volume of deposits, and thus impacting one of our primary lending sources. The credit quality of the Company’s loans may also be impacted as clients weather adverse economic conditions which could result in an increase in credit losses or other related expenses.

Management continues to monitor the impact of COVID-19 on the Company’s financial results. Over the past year, the COVID-19 pandemic has affected our operations to a limited degree, although it has had varying degrees of disruptions and restrictions on our borrowers and to our borrowers’ operations, staffing, and demand for certain products and services.

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 the line items included in our balance sheet and statements of income, as well as 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 nationally.

As discussed in our Annual Report on Form 10-K for the year ended December 31, 2021, 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, 2021.

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, 2021, 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, 2021, during the quarterly period covered by this quarterly report.

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.

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Results of Operations

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

Net income increased $38.6 million, or 82.0%, to $85.7 million, or $0.80 per share during the three months ended September 30, 2022, as compared to net income of $47.1 million, or $0.76 per share for the same period in 2021. The increase during the quarter ended September 30, 2022 was primarily attributable to the acquisition of Great Western, partially offset by the loss on the sale of securities. Net income decreased $24.6 million, or 17.4%, to $116.4 million, or $1.13 per share during the nine months ended September 30, 2022, as compared to net income of $141.0 million, or $2.29 per share for the same period in 2021. The decrease was primarily attributable to the loss on sale of securities, along with the acquisition costs and the purchase accounting provision expense for the nine months ended September 30, 2022 associated with the acquisition of Great Western.

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.

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.

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Average Balance Sheets, Yields and Rates	Three Months Ended
(Dollars in millions)	September 30, 2022						September 30, 2021
	Average Balance		Interest		Average Rate		Average Balance		Interest		Average Rate
Interest earning assets:
Loans (1) (2)	$	17,543.8	$	220.2	4.98	%	$	9,805.2	$	112.2	4.54	%
Investment securities (2)	10,819.6		65.9		2.42		5,875.0		18.8		1.27
Investment in FHLB and FRB stock	121.7		1.3		4.24		53.4		0.2		1.49
Interest bearing deposits in banks	244.4		1.4		2.27		1,712.2		0.7		0.16
Federal funds sold	1.7		—		—		0.1		—		—
Total interest earning assets	$	28,731.2	$	288.8	3.99	%	$	17,445.9	$	131.9	3.00	%
Non-earning assets	2,922.5						1,635.3
Total assets	$	31,653.7					$	19,081.2
Interest-bearing liabilities:
Demand deposits	$	7,824.3	$	5.1	0.26	%	$	4,474.0	$	0.4	0.04	%
Savings deposits	8,689.0		7.0		0.32		4,842.9		0.4		0.03
Time deposits	1,502.3		1.2		0.32		996.9		1.1		0.44
Repurchase agreements	1,107.7		0.8		0.29		993.5		0.1		0.04
Other borrowed funds	370.9		2.4		2.57		—		—		—
Long-term debt	120.4		1.5		4.94		112.4		1.5		5.29
Subordinated debentures held by subsidiary trusts	163.1		1.9		4.62		87.0		0.7		3.19
Total interest-bearing liabilities	$	19,777.7	$	19.9	0.40	%	$	11,506.7	$	4.2	0.14	%
Non-interest-bearing deposits	8,212.6						5,416.5
Other non-interest-bearing liabilities	423.7						172.7
Stockholders’ equity	3,239.7						1,985.3
Total liabilities and stockholders’ equity	$	31,653.7					$	19,081.2
Net FTE interest income			$	268.9					$	127.7
Less FTE adjustments (2)			(2.1)						(0.6)
Net interest income from consolidated statements of income			$	266.8					$	127.1
Interest rate spread					3.59	%					2.86	%
Net FTE interest margin (3)					3.71						2.90
Cost of funds, including non-interest-bearing demand deposits (4)					0.28						0.10
(1) Average loan balances include loans held for sale and non-accrual loans. Interest income on loans includes amortization of deferred loan fees, net of deferred loan costs of $0.7 million and $13.6 million at September 30, 2022 and September 30, 2021, respectively.
(2) Interest income and average rates for tax exempt loans and securities are presented on a fully taxable equivalent, or FTE, basis utilizing the 21% federal income tax rate.
(3) Net FTE interest margin during the period equals (i) the difference between annualized interest income on interest earning assets and the annualized interest expense on interest bearing liabilities, divided by (ii) average interest earning assets for the period.
(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 included interest accretion related to the fair valuation of acquired loans of $17.7 million during the three months ended September 30, 2022, compared to interest accretion of $2.3 million during the three months ended September 30, 2021.

Net interest income increased $139.7 million, or 109.9%, to $266.8 million during the three months ended September 30, 2022, as compared to $127.1 million for the same period in 2021. The increase is a result of the growth in average earning assets, primarily related to the GWB acquisition, a favorable shift in the mix of earning assets, and higher yields on earning assets, which was partially offset by a decrease of $13.9 million in PPP loan income and higher interest expense. The Company earned a total of $0.3 million of interest income, including loan fees, on PPP loans during the three months ended September 30, 2022 as compared to $14.2 million of interest income, including loan fees, on PPP loans for the same period in 2021.

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Average Balance Sheets, Yields and Rates	Nine Months Ended
(Dollars in millions)	September 30, 2022						September 30, 2021
	Average Balance		Interest		Average Rate		Average Balance		Interest		Average Rate
Interest earning assets:
Loans (1) (2)	$	16,425.3	$	566.7	4.61	%	$	9,882.3	$	325.9	4.41	%
Investment securities (2)	9,835.0		147.3		2.00		5,147.5		53.8		1.40
Investment in FHLB and FRB stock	103.2		2.8		3.63		53.4		0.2		0.50
Interest bearing deposits in banks	1,841.5		6.5		0.47		1,824.9		1.7		0.12
Federal funds sold	0.6		—		—		0.1		—		—
Total interest earning assets	$	28,205.6	$	723.3	3.43	%	$	16,908.2	$	381.6	3.02	%
Non-earning assets	2,726.5						1,633.1
Total assets	$	30,932.1					$	18,541.3
Interest bearing liabilities:
Demand deposits	$	7,596.0	$	7.8	0.14	%	$	4,349.1	$	1.4	0.04	%
Savings deposits	8,829.1		9.7		0.15		4,710.1		1.1		0.03
Time deposits	1,485.4		3.1		0.28		1,020.3		3.9		0.51
Repurchase agreements	1,122.4		1.4		0.17		1,020.8		0.3		0.04
Other borrowed funds	125.0		2.4		2.57		—		—		—
Long-term debt	122.7		4.6		5.01		112.4		4.5		5.35
Subordinated debentures held by subsidiary trusts	154.4		4.3		3.72		87.0		2.1		3.23
Total interest-bearing liabilities	$	19,435.0	$	33.3	0.23	%	$	11,299.7	$	13.3	0.16	%
Non-interest-bearing deposits	7,925.0						5,096.5
Other non-interest-bearing liabilities	335.7						179.6
Stockholders’ equity	3,236.4						1,965.5
Total liabilities and stockholders’ equity	$	30,932.1					$	18,541.3
Net FTE interest income			$	690.0					$	368.3
Less FTE adjustments (2)			(5.8)						(1.7)
Net interest income from consolidated statements of income			$	684.2					$	366.6
Interest rate spread					3.20	%					2.86	%
Net FTE interest margin (3)					3.27						2.91
Cost of funds, including non-interest-bearing demand deposits (4)					0.16						0.11
(1) Average loan balances include mortgage loans held for sale and non-accrual loans. Interest income on loans includes amortization of deferred loan fees, net of deferred loan costs of $6.3 million at September 30, 2022 and $30.7 million at September 30, 2021.
(2) Interest income and average rates for tax exempt loans and securities are presented on a fully taxable equivalent, or FTE, basis utilizing the 21% federal income tax rate.
(3) Net FTE interest margin during the period equals (i) the difference between annualized interest income on interest earning assets and the annualized interest expense on interest bearing liabilities, divided by (ii) average interest earning assets for the period.
(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 included interest accretion related to the fair valuation of acquired loans of $34.4 million during the nine months ended September 30, 2022, compared to interest accretion of $7.2 million for the same period in 2021.

Our net FTE interest margin ratio increased 81 basis points to 3.71% for the three months ended September 30, 2022, as compared to 2.90% for the same period in 2021. Similarly, our net FTE interest margin ratio increased 36 basis points to 3.27% for the nine months ended September 30, 2022, as compared to 2.91% for the same period in 2021. The increases in net FTE interest margin ratio during the three months ended September 30, 2022, as compared to the same period in 2021, and during the nine months ended September 30, 2022, as compared to the same period in 2021, were primarily the result of increased yields on earning assets, due to a shift in the mix of earning assets toward investment securities and loans, and higher yields on loans, investment securities and cash.

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Exclusive of the impact of interest accretion on acquired loans and PPP loan income, our net FTE interest margin ratio was 3.47% during the three months ended September 30, 2022, as compared to 2.60% for the same period in 2021, or an 87-basis point increase, and 3.06% during the nine months ended September 30, 2022, as compared to 2.69% in the same period in 2021, or a 37-basis point increase. These increases were primarily the result of increased yields on earning assets and a shift in the mix of earning assets toward loans and investment securities and away from cash.

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, 2022 and 2021. 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, 2022 compared with Three Months Ended September 30, 2021						Nine Months Ended September 30, 2022 compared with Nine Months Ended September 30, 2021
	Volume		Rate		Net		Volume		Rate		Net
Interest earning assets:
Loans (1)	$	88.6	$	19.4	$	108.0	$	215.8	$	25.0	$	240.8
Investment securities (1)	15.8		31.3		47.1		49.0		44.5		93.5
Investment in FHLB and FRB stock	0.3		0.8		1.1		0.2		2.4		2.6
Interest bearing deposits in banks	(0.6)		1.3		0.7		—		4.8		4.8
Total change	104.1		52.8		156.9		265.0		76.7		341.7
Interest bearing liabilities:
Demand deposits	0.3		4.4		4.7		1.0		5.4		6.4
Savings deposits	0.3		6.3		6.6		0.9		7.7		8.6
Time deposits	0.6		(0.5)		0.1		1.8		(2.6)		(0.8)
Repurchase agreements	—		0.7		0.7		—		1.1		1.1
Other borrowed funds	—		2.4		2.4		—		2.4		2.4
Long-term debt	0.1		(0.1)		—		0.4		(0.3)		0.1
Subordinated debentures held by subsidiary trusts	0.6		0.6		1.2		1.6		0.6		2.2
Total change	1.9		13.8		15.7		5.7		14.3		20.0
Increase (decrease) in FTE net interest income (1)	$	102.2	$	39.0	$	141.2	$	259.3	$	62.4	$	321.7

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

Provision for (Reversal of) Credit Losses

The Company had an $8.4 million provision for credit losses during the three months ended September 30, 2022, as compared to no provision for or reversal of credit losses during same period in 2021. The provision incorporated the impact of net charge-offs of $12.0 million, or an annualized 0.27% of average loans outstanding, for the third quarter of 2022, compared to $0.6 million, or an annualized 0.02% of average loans outstanding during same period in 2021. The Company had a $68.0 million provision for credit losses during the nine months ended September 30, 2022, as compared to a $5.1 million reversal of credit losses during same period in 2021. The provision during the nine months ended September 30, 2022 includes $68.3 million related to the acquired non-PCD loans, $5.9 million related to the unfunded commitments, $1.9 million related to the held-to-maturity securities, and a net provision reversal of $8.1 million as a result of sustained improvement in loan quality trends in certain loan categories, offset by a negative trend in the economic outlook. The nine months ended September 30, 2022 provision considered the impact of net charge-offs of $29.0 million, or an annualized 0.24% of average loans outstanding, compared to $4.6 million, or an annualized 0.06% of average loans outstanding during same period in 2021. Charge-offs incurred during the first nine months of 2022 were primarily related to the restructuring of loans acquired in the GWB transaction.

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.             

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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 dates indicated:

Non-interest income	Three Months Ended September 30,				$ Change		% Change		Nine Months Ended September 30,				$ Change		% Change
(Dollars in millions)	2022		2021						2022		2021
Payment services revenues	$	20.4	$	12.2	$	8.2	67.2	%	$	54.7	$	33.8	$	20.9	61.8	%
Mortgage banking revenues	2.7		11.6		(8.9)		(76.7)		16.1		32.8		(16.7)		(50.9)
Wealth management revenues	8.5		6.5		2.0		30.8		25.9		19.1		6.8		35.6
Service charges on deposit accounts	5.7		4.4		1.3		29.5		19.7		12.1		7.6		62.8
Other service charges, commissions and fees	4.7		1.4		3.3		235.7		12.6		5.1		7.5		147.1
Investment securities gains (losses), net	(24.2)		0.3		(24.5)		NM		(24.4)		0.2		(24.6)		NM
Other income	5.1		3.1		2.0		64.5		17.0		9.8		7.2		73.5
Total non-interest income	$	22.9	$	39.5	$	(16.6)	(42.0)	%	$	121.6	$	112.9	$	8.7	7.7	%

Total non-interest income decreased $16.6 million, or 42.0%, to $22.9 million for the three months ended September 30, 2022, as compared to $39.5 million for the same period in 2021 and increased $8.7 million, or 7.7%, to $121.6 million for the nine months ended September 30, 2022, as compared to $112.9 million for the same period in 2021. Significant components of theses fluctuations 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 increased $8.2 million, or 67.2%, to $20.4 million during the three months ended September 30, 2022, as compared to $12.2 million earned during the same period in 2021. For the nine months ended September 30, 2022, payment services revenues increased $20.9 million, or 61.8%, to $54.7 million, as compared to $33.8 million during the same period in 2021. The increase in payment services revenues is mainly the result of increased volume associated with the acquisition of GWB and overall higher business credit card volume during the three and the nine months ended September 30, 2022.

Mortgage banking revenues include gains on residential real estate loans sold, 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 $8.9 million, or 76.7%, to $2.7 million during the three months ended September 30, 2022, as compared to $11.6 million during the same period in 2021. For the nine months ended September 30, 2022, mortgage banking revenues decreased $16.7 million, or 50.9%, to $16.1 million as compared to $32.8 million during the same period in 2021. Included in the nine months ending September 30, 2022 was a $3.4 million recovery of mortgage servicing rights impairment compared to a $5.9 million recovery of impairment during the same period in 2021. Excluding the impairment recovery in both periods, mortgage banking revenues decreased $14.1 million during the nine months ended September 30, 2022, compared to the nine months ended September 30, 2021. The decrease in mortgage banking revenues was driven by a decline in both home loan production volume and tighter gain-on-sale spreads, largely as a result of higher interest rates during the nine months ended September 30, 2022.

Wealth management revenues are principally comprised of fees earned for management of trust assets and investment services. Wealth management revenues increased $2.0 million, or 30.8%, to $8.5 million during the three months ended September 30, 2022, as compared to $6.5 million during the same period in 2021. For the nine months ended September 30, 2022, wealth management revenues increased $6.8 million, or 35.6%, to $25.9 million as compared to $19.1 million during the same period in 2021. The increases are primarily due to increased volume associated with the acquisition of GWB, which were partially offset by the decline in market values impacting assets under management. The Company had $7.3 billion of assets under management at September 30, 2022 compared to $5.7 billion at September 30, 2021.

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Service charge fees are primarily driven by service and overdraft charges on deposit accounts. Service charges increased $1.3 million, or 29.5%, to $5.7 million during the three months ended September 30, 2022, as compared to $4.4 million during the same period in 2021. For the nine months ended September 30, 2022, service charges on deposit accounts increased $7.6 million, or 62.8%, to $19.7 million as compared to $12.1 million during the same period in 2021, primarily due to increased volume as a result of the acquisition of GWB, partially offset by the Company’s decision to discontinue assessing non-sufficient fund charges and reducing overdraft fees.

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 increased $3.3 million, or 235.7%, to $4.7 million during the three months ended September 30, 2022, as compared to $1.4 million during the same period in 2021. For the nine months ended September 30, 2022, other service charges, commissions and fees increased $7.5 million, or 147.1%, to $12.6 million as compared to $5.1 million during the same period in 2021. The increases were primarily due to increased volume as a result of the acquisition of GWB and increased swap fee revenues earned on derivative interest rate swap contracts offered to clients during the three and the nine months ended September 30, 2022.

Investment securities gains (losses), net includes realized gains and losses associated with the sales of investment securities. Investment securities gain (losses), net decreased $24.5 million to a loss of $24.2 million during the three months ended September 30, 2022 as compared to a gain of $0.3 million during the same period in 2021. For the nine months ended September 30, 2022, investment securities gains (losses), net decreased $24.6 million to a loss of $24.4 million as compared to a gain of $0.2 million during the same period in 2021. The decrease was due to a loss of $46.3 million incurred on the sale of $500 million in U.S. treasury notes previously swapped. The loss was offset by the recognition of a deferred swap termination gain of $22.1 million.

Other income primarily includes company-owned life insurance revenues, check printing income, agency stock dividends, and gains on sales of miscellaneous assets. Other income increased $2.0 million, or 64.5%, to $5.1 million during the three months ended September 30, 2022, as compared to $3.1 million during the same period in 2021 primarily due to an increase in the cash surrender value of life insurance. For the nine months ended September 30, 2022, other income increased $7.2 million or 73.5%, to $17.0 million as compared to $9.8 million during the same period in 2021. The increases were primarily due to an increase in the cash surrender value of life insurance, gains on the sale of premises and equipment, a $1.7 million recovery in the credit valuation discount on derivatives acquired in the GWB acquisition, and a $1.4 million gain on the disposition of the GWB acquired subordinated debt.

Non-interest Expense

Non-interest expense increased $67.3 million, or 63.6%, to $173.2 million during the three months ended September 30, 2022 as compared to $105.9 million during the same period in 2021 and increased $287.4 million, or 94.8%, to $590.7 million during the nine months ended September 30, 2022 as compared to $303.3 million during the same period in 2021. For the nine months ended September 30, 2022, the increase was mainly a result of $115.0 million of acquisition expenses related to the GWB acquisition, increased expenses related to the now combined operations, post-GWB acquisition, and higher incentive and donation expenses as a result of Company performance. 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 “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Recent Developments” included herein and “Note 2 – Acquisitions” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report.

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

Non-interest expense	Three Months Ended September 30,				$ Change		% Change		Nine Months Ended September 30,				$ Change		% Change
(Dollars in millions)	2022		2021						2022		2021
Salaries and wages	$	71.9	$	42.0	$	29.9	71.2	%	$	206.7	$	122.6	$	84.1	68.6	%
Employee benefits	19.6		12.9		6.7		51.9		60.2		43.7		16.5		37.8
Outsourced technology services	15.9		8.2		7.7		93.9		40.0		24.7		15.3		61.9
Occupancy, net	11.3		7.3		4.0		54.8		32.5		21.7		10.8		49.8
Furniture and equipment	5.8		4.5		1.3		28.9		17.0		13.0		4.0		30.8
OREO expense, net of income	—		—		—		NM		0.1		(0.1)		0.2		(200.0)
Professional fees	5.1		2.7		2.4		88.9		14.5		9.3		5.2		55.9
FDIC insurance premiums	4.1		1.7		2.4		141.2		10.2		4.8		5.4		112.5
Other intangibles amortization	4.1		2.4		1.7		70.8		11.8		7.4		4.4		59.5
Other expenses	31.4		17.6		13.8		78.4		82.7		49.6		33.1		66.7
Acquisition related expenses	4.0		6.6		(2.6)		(39.4)		115.0		6.6		108.4		100.0
Total non-interest expense	$	173.2	$	105.9	$	67.3	63.6	%	$	590.7	$	303.3	$	287.4	94.8	%

Salaries and wages expense increased $29.9 million, or 71.2%, to $71.9 million during the three months ended September 30, 2022, as compared to $42.0 million during the same period in 2021 and increased $84.1 million, or 68.6%, to $206.7 million during the nine months ended September 30, 2022 as compared to $122.6 million during the same period in 2021, primarily as a result of the additional employee-related expenses resulting from the acquisition of GWB and higher incentive accruals, which were partially offset by lower commission expenses.

Employee benefits expense increased $6.7 million, or 51.9%, to $19.6 million during the three months ended September 30, 2022, as compared to $12.9 million during the same period in 2021 and increased $16.5 million, or 37.8%, to $60.2 million during the nine months ended September 30, 2022 as compared to $43.7 million during the same period in 2021, primarily due to higher benefit costs related to the additional employees resulting from the GWB acquisition.

Outsourced technology services expense increased $7.7 million, or 93.9%, to $15.9 million during the three months ended September 30, 2022, as compared to $8.2 million during the same period in 2021 and increased $15.3 million, or 61.9%, to $40.0 million during the nine months ended September 30, 2022, as compared to $24.7 million during the same period in 2021. The increases are primarily due to technology costs associated with higher transaction volumes associated with the GWB acquisition.

The increases in occupancy, net expense, furniture and equipment, professional fees, FDIC insurance premiums, and other intangibles amortization during the three and the nine month periods ended September 30, 2022, as compared to the same periods in 2021 are primarily due to additional operating expenses, maintenance and repairs, depreciation and amortization, legal and consulting costs from the acquisition of additional banking offices as a result of the GWB acquisition.

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 increased $13.8 million, or 78.4%, to $31.4 million during the three months ended September 30, 2022, as compared to $17.6 million during the same period in 2021. Other expenses increased $33.1 million, or 66.7%, to $82.7 million during the nine months ended September 30, 2022, as compared to $49.6 million during the same period in 2021. Increases in other expenses in both periods are mainly attributable to the GWB acquisition and increases in travel, donations, postage, internet, telephone, insurance, credit and debit card processing, credit card rewards, and public relation and promotions expenses. The Company contributes 2% of its net income before tax, which also resulted in higher donations expense in both periods.

Income Tax Expense

Our effective tax rate was 20.7% for the three months ended September 30, 2022 compared to 22.4% for the three months ended September 30, 2021 and 20.9% for the nine months ended September 30, 2022 and 22.2% for the same period in 2021.

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Financial Condition        

Total Assets

Total assets increased $11,672.8 million, or 59.3%, to $31,344.7 million as of September 30, 2022, from $19,671.9 million as of December 31, 2021, primarily due to $13,353.3 million of assets acquired in the acquisition of GWB. Significant fluctuations in balance sheet accounts are discussed below. More information regarding the results as of December 31, 2021 can be found in our Annual Report on Form 10-K for the year ended December 31, 2021.

Loans Held for Sale

Loans held for sale consist of residential mortgage loans pending sale to investors in the secondary market and loans reclassified from loans held for investment due to management’s intent and decision to sell the loans. Loans held for sale increased $63.5 million, or 211.0%, to $93.6 million as of September 30, 2022, compared to $30.1 million as of December 31, 2021, primarily due to $217.0 million of certain agricultural and commercial loans transferred from loans held for investment to loans held for sale as a result of the GWB acquisition and a transfer of a commercial construction loan from loans held for investment during the third quarter of 2022, which was partially offset by resolutions of loans acquired from GWB and a decrease in mortgage loan refinance activity.

Loans Held for Investment, Net of Deferred Fees and Costs

Loans held for investment, net of deferred fees and costs, increased $8,271.8 million, or 88.6%, to $17,603.5 million as of September 30, 2022, as compared to $9,331.7 million as of December 31, 2021, primarily due to $7,705.0 million of loans acquired that were classified as held for investment in the GWB acquisition. Loans held for investment included PPP loans, net of deferred fees, of $5.9 million and $96.3 million as of September 30, 2022 and December 31, 2021, respectively. Excluding the impact of GWB acquired loans and PPP loans, loans held for investment as of September 30, 2022, increased $657.2 million from December 31, 2021, primarily driven by increases in real estate and commercial loans, partially offset by decreases in agricultural and consumer loans.

The following table presents the composition and comparison of loans held for investment, including the February 1, 2022 loans acquired from GWB:

									GWB Acquired Loans as of February 1, 2022
	September 30, 2022		December 31, 2021		$ Change		% Change
Real estate loans:
Commercial	$	8,026.9	$	3,971.5	$	4,055.4	102.1	%	$	3,968.8
Construction loans:
Land acquisition & development	393.2		247.8		145.4		58.7		116.4
Residential	501.4		262.0		239.4		91.4		122.1
Commercial	1,128.4		498.0		630.4		126.6		245.1
Total construction loans	2,023.0		1,007.8		1,015.2		100.7		483.6
Residential	2,127.7		1,538.2		589.5		38.3		495.0
Agricultural	800.9		213.9		587.0		274.4		631.8
Total real estate loans	12,978.5		6,731.4		6,247.1		92.8		5,579.2
Consumer loans:
Indirect	780.8		737.6		43.2		5.9		13.5
Direct and advance lines	155.0		129.2		25.8		20.0		17.0
Credit card	74.2		64.9		9.3		14.3		11.9
Total consumer loans	1,010.0		931.7		78.3		8.4		42.4
Commercial	2,966.1		1,475.5		1,490.6		101.0		1,503.3
Agricultural	658.2		203.9		454.3		222.8		580.1
Other, including overdrafts	3.8		1.5		2.3		153.3		—
Deferred loan fees and costs	(13.1)		(12.3)		(0.8)		6.5		—
Loans held for investment, net of deferred loan fees and costs	$	17,603.5	$	9,331.7	$	8,271.8	88.6	%	$	7,705.0

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Non-performing Assets

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 $54.5 million, or 218.9%, to $79.4 million, as of September 30, 2022, from $24.9 million as of December 31, 2021, primarily as a result of the loans acquired from GWB.

Accruing loans past due 90 days or more increased $3.8 million, or 135.7%.

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, 2022		Percent of Total		December 31, 2021		Percent of Total
Real estate:
Commercial	$	27.9	32.4	%	$	8.6	31.1	%
Construction:
Land acquisition and development	4.1		4.8		0.7		2.5
Residential	0.4		0.5		—		—
Total construction	4.5		5.2		0.7		2.5
Residential	7.6		8.8		3.0		10.8
Agricultural	16.3		19.0		4.9		17.7
Total real estate	56.3		65.5		17.2		62.1
Consumer	2.9		3.4		2.8		10.1
Commercial	13.5		15.7		6.1		22.0
Agricultural	13.3		15.5		1.6		5.8
Total non-performing loans	$	86.0	100.0	%	$	27.7	100.0	%

Non-performing assets. Non-performing assets include non-performing loans and OREO. The following table sets forth information regarding non-performing assets as of the dates indicated.

Other real estate owned increased $14.4 million, or 720.0%, to $16.4 million as of September 30, 2022, from $2.0 million as of December 31, 2021, primarily attributable to the $15.8 million of provisional other real estate owned acquired in the GWB acquisition, partially offset by dispositions.

Non-Performing Assets and Troubled Debt Restructurings
(Dollars in millions)	September 30, 2022			June 30, 2022			March 31, 2022			December 31, 2021			September 30, 2021
Non-performing loans:
Non-accrual loans	$	79.4		$	107.0		$	118.9		$	24.9		$	29.9
Accruing loans past due 90 days or more	6.6			2.9			2.7			2.8			5.2
Total non-performing loans	86.0			109.9			121.6			27.7			35.1
OREO	16.4			16.8			17.5			2.0			2.3
Total non-performing assets	$	102.4		$	126.7		$	139.1		$	29.7		$	37.4
Troubled debt restructurings not included above (1)	$	59.7		$	20.5		$	14.7		$	2.3		$	2.1
Non-accrual loans to loans held for investment	0.45		%	0.62		%	0.70		%	0.27		%	0.31		%
Non-performing loans to loans held for investment	0.49			0.64			0.72			0.30			0.36
Non-performing assets to loans held for investment and OREO	0.58			0.74			0.82			0.32			0.39
Non-performing assets to total assets	0.33			0.40			0.42			0.15			0.19

(1) Accruing loans modified in trouble debt restructurings are not considered non-performing loans as the loans are performing as agreed under their modified terms and management expects performance to continue.

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Allowance for Credit Losses

The Company performs a quarterly assessment of the adequacy of its allowance for credit losses in accordance with GAAP. The methodology used to assess the adequacy is consistently applied to the Company’s loans held for investment portfolio. 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, measured 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. 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 current and forecasted economic conditions on certain 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 loans which 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.

(2)Historical valuation allowances based on loan loss experience for similar loans with similar characteristics and trends. The Company applies probability of default and loss given default methodologies for all portfolio segments. The Company uses a transition matrix for probability of default components of the methodology and a historical average for the loss given default components of the methodology. The probability of default and loss given default is applied to the current principal balance as of the reporting date. The transition matrix determines the probability of default by tracking the historical movement of loans between loan risk tiers over a defined period of time. Loan transitions are measured by either internal ratings or delinquency status. Those loans tracked by ratings are generally commercial purpose including agricultural, commercial, and commercial real estate. Those loans tracked by delinquency are generally consumer in nature, with the exception of multi-family and credit cards. The loss given default used as the basis for the estimate of credit losses is comprised of the Company’s historical loss experiences from 2008 to the current period, based on a migration analysis of our historical loss experience, which is designed to account for credit deterioration. The model compares the most recent period losses to prior period defaults to calculate the loss given default, which is averaged over the historical observations.

(3)Qualitative allowances determined based on changes in the nature of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends, general economic conditions or forecasts, and other qualitative risk factors, both internal and external to us, including the incorporation of a one-year forecast period for economic conditions.     

As part of the qualitative adjustments, the Company considers future economic conditions over the one-year forecast period. There are 10 economic factors that are considered in our assessment which are compared against the Moody’s Analytics economic scenarios. The outcome of this analysis adjusts the one-year forecasted expectations which are incorporated into the qualitative adjustments. Other qualitative factors, including changes in loan and lending policies, underwriting standards and personnel, and assessments of portfolio loan quality, among others, are also considered. During the period ending September 30, 2022, other qualitative factors were adjusted based on our assessment of loan quality and sustained loan quality trends in certain loan categories, offset by a more conservative set of assumptions about the economic outlook.

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

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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 on loans acquired without evidence of credit deterioration. The Company established an allowance for credit losses and recorded a provision of $68.3 million on GWB non-PCD loans acquired. 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. On February 1, 2022, the Company established a provisional allowance for credit losses of $84.3 million, which was adjusted as a result of a fair value re-evaluation during the second quarter of 2022 by $24.8 million to $59.5 million on GWB PCD loans acquired. 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. The difference between the amortized cost basis and the unpaid principal balance of $31.2 million was established on GWB PCD loans acquired on February 1, 2022 and adjusted as a as a result of a fair value re-evaluation during the second quarter of 2022 by $8.4 million to $39.6 million. 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 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 on loans was $213.0 million, or 1.21% of loans held for investment as of September 30, 2022, including PPP loans, as compared to $122.3 million, or 1.31% of loans held for investment, as of December 31, 2021. The decrease in the percentage from December 31, 2021 is primarily a result of the improvement in the credit quality and sustained loan quality trends of our portfolio, partially offset by a more cautious economic forecast. The allowance for credit losses represents management’s estimate of expected credit losses in the loan portfolio expected over the life of the loan, including the incorporation of a one-year forecast period for economic conditions.

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 adequate to provide for known and inherent 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.

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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, 2022			Jun 30, 2022			Mar 31, 2022			Dec 31, 2021			Sep 30, 2021
Allowance for credit losses on loans:
Beginning balance	$	220.4		$	247.2		$	122.3		$	135.1		$	135.5
Provisional ACL recorded on PCD loans	—			(24.8)			84.3			—			—
Provision for (reversal of) credit losses	4.6			(1.7)			57.3			(10.1)			0.2
Charge offs:
Real estate
Commercial	5.8			—			5.1			—			—
Construction	6.6			—			2.7			1.1			—
Residential	0.1			—			0.1			—			—
Agricultural	—			0.1			0.1			0.7			—
Consumer	2.9			2.3			2.3			1.9			2.0
Commercial	0.8			1.2			4.3			1.1			0.1
Agricultural	—			0.1			5.3			—			—
Total charge-offs	16.2			3.7			19.9			4.8			2.1
Recoveries:
Real estate
Commercial	1.8			0.7			—			—			—
Construction	0.1			0.1			0.1			—			0.1
Residential	0.1			0.4			0.2			—			0.1
Consumer	1.2			1.4			1.4			1.1			1.1
Commercial	1.0			0.5			0.4			1.0			0.2
Agricultural	—			0.2			1.1			—			—
Total recoveries	4.2			3.4			3.2			2.1			1.5
Net charge-offs	12.0			0.3			16.7			2.7			0.6
Ending balance	$	213.0		$	220.4		$	247.2		$	122.3		$	135.1
Allowance for off-balance sheet credit losses:
Beginning balance	$	6.2		$	6.2		$	3.8		$	3.2		$	3.4
Provision for (reversal of) credit losses	3.5			—			2.4			0.6			(0.2)
Ending balance	$	9.7		$	6.2		$	6.2		$	3.8		$	3.2
Allowance for credit losses on investment securities:
Beginning balance	$	1.6		$	1.6		$	—		$	—		$	—
Provision for credit losses	0.3			—			1.6			—			—
Ending balance	$	1.9		$	1.6		$	1.6		$	—		$	—
Total allowance for credit losses	$	224.6		$	228.2		$	255.0		$	126.1		$	138.3
Total provision for (reversal of) credit losses	8.4			(1.7)			61.3			(9.5)			—
Loans held for investment	17,603.5			17,162.5			16,945.0			9,331.7			9,622.5
Average loans	17,543.8			17,220.4			14,460.6			9,512.3			9,805.2
Net loans charged-off to average loans, annualized	0.27		%	0.01		%	0.47		%	0.11		%	0.02		%
Allowance to non-accrual loans	268.26			205.98			207.91			491.16			451.84
Allowance to loans held for investment	1.21			1.28			1.46			1.31			1.40

65

Investment Securities

We manage our investment portfolio to obtain the highest yield possible, while meeting our risk tolerance and liquidity guidelines and 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, 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 increased $3,761.0 million, or 57.8%, to $10,269.1 million as of September 30, 2022, from $6,508.1 million as of December 31, 2021. The increase was primarily due to $2,699.0 million of securities acquired in the GWB acquisition and the redeployment of cash and cash equivalents into the securities portfolio. In conjunction with the acquisition of GWB, the Company transferred debt securities categorized as held-to-maturity with an estimated fair value of $10.9 million to the available-for-sale category classification and transferred debt securities categorized as available-for-sale with an estimated fair value of $463.6 million to the held-to-maturity classification during the first quarter of 2022.

During the second quarter of 2022, the Company terminated the $500.0 million, two-year forward starting, three-year pay-fixed interest rate swap, resulting in a $23.3 million gain. The gain associated with the $500.0 million interest rate swap was to be accreted into income through May 2026. However, the U.S. Treasury securities associated with the swap were sold on September 1, 2022 for a loss of $46.3 million. As such, the derivative gain was accreted through August 2022 and then in September 2022 the remaining derivative gain was recognized as income in investment securities gains (losses), for a net loss of $24.2 million. During the third quarter of 2022, the Company also 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.

As of September 30, 2022, the estimated duration of our investment portfolio was 3.9 years, as compared to 3.6 years as of December 31, 2021.

As of September 30, 2022, we had $2,065.2 million of investment securities that had been in a continuous loss position for more than twelve months. At September 30, 2022, the Company has an allowance for credit losses on held-to maturity securities classified as corporate and municipal securities of $1.9 million. There was no allowance for credit losses on held-to-maturity securities at December 31, 2021.

Goodwill

Goodwill increased $478.4 million, or 77.0%, to $1,100.0 million as of September 30, 2022, from $621.6 million as of December 31, 2021, attributable to the provisional goodwill recorded in conjunction with the acquisition of GWB.

Company-Owned Life Insurance

Company-owned life insurance increased $194.1 million, or 64.4%, to $495.6 million as of September 30, 2022, from $301.5 million as of December 31, 2021, attributable to provisional amounts recorded in conjunction with the acquisition of GWB.

Other Intangibles, Net of Accumulated Amortization

Other intangibles, net of accumulated amortization, increased $59.7 million, or 144.6%, to $101.0 million as of September 30, 2022, from $41.3 million as of December 31, 2021, attributable to provisional core deposit intangibles of $50.1 million and other customer relationship intangibles of $22.8 million recorded in conjunction with the acquisition of GWB, partially offset by the intangible related to health savings accounts that were sold during the second quarter of 2022 and amortization expense.

Premises and equipment

Premises and equipment, net of accumulated depreciation increased $145.8 million, or 48.7%, to $445.4 million as of September 30, 2022, from $299.6 million as of December 31, 2021, attributable to provisional amounts recorded in conjunction with the acquisition of GWB offset by depreciation expense.

66

Total Liabilities

Total liabilities increased $10,653.9 million, or 60.2%, to $28,339.2 million as of September 30, 2022, from $17,685.3 million as of December 31, 2021, primarily due to $12,108.4 million of liabilities assumed with the acquisition of GWB, which was partially offset by the redemption of the subordinated debt and payoff of the FHLB advances assumed with the acquisition of GWB. Significant fluctuations in liability accounts are discussed below.

Deposits

Our deposits consist of non-interest-bearing and interest-bearing demand, savings, individual retirement, and time deposit accounts. Total deposits increased $9,615.2 million, or 59.1%, to $25,884.8 million as of September 30, 2022, from $16,269.6 million as of December 31, 2021, primarily due to $11,688.0 million in deposit balances acquired as a result of the GWB acquisition. Exclusive of the $11,688.0 million of deposits acquired in the GWB acquisition on February 1, deposits subsequently decreased $2,072.8 million, or 12.7%, compared to December 31, 2021, largely due to a decrease in higher-cost, non-relationship deposits acquired from GWB, held in interest-bearing savings and time deposits, $250 and over.

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

Deposits
(Dollars in millions)	September 30, 2022		Percent of Total		December 31, 2021		Percent of Total
Non-interest-bearing demand	$	8,163.3	31.6	%	$	5,568.3	34.2	%
Interest bearing:
Demand	7,595.1		29.3		4,753.2		29.2
Savings	8,497.2		32.8		4,981.6		30.6
Time, $250 and over	319.3		1.2		186.7		1.2
Time, other (1)	1,309.9		5.1		779.8		4.8
Total interest bearing	17,721.5		68.4		10,701.3		65.8
Total deposits	$	25,884.8	100.0	%	$	16,269.6	100.0	%

(1)Included in “Time, other” are Certificate of Deposit Account Registry Service, or CDARS, deposits of $49.3 million and $104.5 million as of September 30, 2022 and December 31, 2021, respectively.

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 business. Repurchase agreement balances increased $24.5 million, or 2.3%, to $1,075.6 million as of September 30, 2022, from $1,051.1 million as of December 31, 2021. The increase is primarily related to $74.0 million in securities sold under repurchase agreements acquired from GWB in addition to the more typical fluctuations in repurchase agreement balances that correspond with fluctuations in the liquidity of the Company’s clients.

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses increased $304.5 million, or 205.2%, to $452.9 million as of September 30, 2022, from $148.4 million as of December 31, 2021, primarily attributable to $111.0 million of provisional amounts recorded in conjunction with the acquisition of GWB, the deferral of $34.0 million in payment service incentives primarily related to the GWB acquisition, and an increase in derivative liabilities of $110.3 million.

Other Borrowed Funds

Other borrowed funds increased $625.0 million as of September 30, 2022 compared to December 31, 2021, primarily due to the Company’s overnight borrowing with the Federal Home Loan Bank during the third quarter of 2022.

67

Subordinated debentures held by subsidiary trusts

Subordinated debentures held by subsidiary trusts increased $76.1 million, or 87.5%, to $163.1 million as of September 30, 2022, from $87.0 million as of December 31, 2021, primarily attributable to provisional amounts recorded in conjunction with the acquisition of GWB.

Deferred Tax Asset / Liability

As of September 30, 2022, we had a net deferred tax asset of $223.8 million, as compared to a net deferred tax liability of $9.3 million as of December 31, 2021, primarily due to the provisional net deferred tax asset benefit recorded in conjunction with the acquisition of GWB and the increase in our mark-to-market losses on investment securities.

Capital Resources and Liquidity Management

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 $1,018.9 million, or 51.3%, to $3,005.5 million as of September 30, 2022, from $1,986.6 million as of December 31, 2021, due to the issuance of additional Class A common stock as consideration for the acquisition of GWB and proceeds from stock option exercises and retention of earnings, which are partially offset by stock repurchases of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants, stock purchases pursuant to the new stock repurchase program (described below), other comprehensive loss, and cash dividends paid.

On October 24, 2022, the Company’s board of directors declared a dividend of $0.47 per common share, payable on November 18, 2022, to common stockholders of record as of November 8, 2022. The dividend equates to a 4.7% annual yield based on the $40.28 average closing pricing of the Company’s common stock during the third quarter of 2022.

On May 25, 2022, the Company’s board of directors adopted a stock repurchase program, terminating the program that had been in place since 2019 and had 1,889,158 shares of Class A common stock remaining to be purchased thereunder. Under the new stock repurchase program, the Company may repurchase up to 5.0 million of its outstanding shares of Class A common stock. Any repurchased shares will be returned to authorized but unissued shares of Class A common stock in accordance with Montana law.

During the three months ended September 30, 2022, the Company did repurchase 3,279,300 shares of our Class A common stock under the stock repurchase program at an average price of $40.59 per share. The shares of common stock repurchased during the period completes the 5.0 million shares authorized to be repurchased. The 5.0 million shares repurchased were purchased at an average per share cost of $39.48.

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, 2022 and December 31, 2021, 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, and the issuance of preferred or common securities.

68

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, debt financing, and increases in client deposits. 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.    

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.

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.        

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, 2021, the following update of the Company’s assessment of market risk as of September 30, 2022 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, 2021.

As of September 30, 2022, our simulation model predicted net interest income would increase 1.97% on an immediate plus 100 basis point parallel shock over the following twelve months, assuming a static balance sheet, which was lower than the previous increase of 7.68% as of December 31, 2021. Assuming a 2.0% gradual increase in interest rates during each of the next four consecutive quarters, net interest income would increase 2.43%, which was lower than the previous increase of 7.07% at December 31, 2021.

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, 2022, 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, 2022 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, 2022 that have materially affected, or are reasonably likely to materially affect, such control.

69

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, 2021 during the period covered by this quarterly report.

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, 2022.

(b) Not applicable.

(c) The following table provides information with respect to purchases made of our Class A 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, 2022. 

				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 (2)
July 2022	924,044	$	38.62	923,507	2,355,793
August 2022	394,355	40.53		394,206	1,961,587
September 2022	1,961,643	41.49		1,961,587	—
Total	3,280,042	$	40.59	3,279,300	—

(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 and purchases related to our stock repurchase program.

(2)    On May 25, 2022, the Company’s board of directors adopted a new stock repurchase program to replace the program that had been in place since 2019 and had 1,889,158 shares of Class A common stock remaining to be purchased thereunder. Under the new stock repurchase program, the Company was authorized to repurchase up to 5.0 million of its outstanding shares of Class A common stock, which was completed as of September 30, 2022.

Item 3.    Defaults upon Senior Securities

None.

Item 4.    Mine Safety Disclosures

Not applicable.

Item 5.    Other Information

None.

70

Item 6.    Exhibits

Exhibit Number		Description
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*		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.
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.

71

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 7, 2022	By:	/S/  KEVIN P. RILEY
			Kevin P. Riley President and Chief Executive Officer
Date:	November 7, 2022	By:	/S/  MARCY D. MUTCH
			Marcy D. Mutch Executive Vice President and Chief Financial Officer

72

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 7, 2022

/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 7, 2022

/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, 2022.

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 7, 2022.

/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

XML

Cover Page - shares	9 Months Ended
	Sep. 30, 2022	Oct. 31, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	001-34653
Entity Registrant Name	FIRST INTERSTATE BANCSYSTEM, INC.
Entity Incorporation, State or Country Code	MT
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	59116-0918
City Area Code	406
Local Phone Number	255-5311
Title of 12(b) Security	Class A common stock, no 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
Entity Common Stock, Shares Outstanding		104,447,711
Amendment Flag	false
Entity Central Index Key	0000860413
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3

XML

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Assets
Cash and due from banks	$ 390.4	$ 168.6
Interest bearing deposits in banks	201.4	2,176.1
Federal funds sold	0.1	0.1
Total cash and cash equivalents	591.9	2,344.8
Investment securities:
Available-for-sale, at estimated fair value	6,783.4	4,820.5
Held-to-maturity, net of allowance for credit losses of $1.9 and $0 at September 30, 2022 and December 31, 2021 (estimated fair values of $3,063.5 and $1,667.5 at September 30, 2022 and December 31, 2021)	3,485.7	1,687.6
Total investment securities	10,269.1	6,508.1
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	131.9	53.8
Loans held for sale	93.6	30.1
Loans held for investment, net of deferred fees and costs	17,603.5	9,331.7
Allowance for credit losses	213.0	122.3
Net loans held for investment	17,390.5	9,209.4
Goodwill	1,100.0	621.6
Bank Owned Life Insurance	495.6	301.5
Premises and equipment, net of accumulated depreciation	445.4	299.6
Other intangibles, net of accumulated amortization	101.0	41.3
Accrued interest receivable	106.4	47.4
Mortgage servicing rights, net of accumulated amortization and impairment reserve	31.8	28.2
Other real estate owned	16.4	2.0
Deferred tax assets	223.8	0.0
Other assets	347.3	184.1
Total assets	31,344.7	19,671.9
Deposits:
Non-interest bearing	8,163.3	5,568.3
Interest bearing	17,721.5	10,701.3
Total deposits	25,884.8	16,269.6
Securities sold under repurchase agreements	1,075.6	1,051.1
Accounts payable and accrued expenses	452.9	148.4
Accrued interest payable	7.4	3.7
Deferred tax liability, net	0.0	9.3
Long-term debt	120.7	112.4
Other Short-term Borrowings	625.0	0.0
Allowance for credit losses on off-balance sheet credit exposures	9.7	3.8
Subordinated debentures held by subsidiary trusts	163.1	87.0
Total liabilities	28,339.2	17,685.3
Stockholders’ equity:
Preferred stock, no par value; 100,000 shares authorized; none issued and outstanding	0.0	0.0
Common stock, no par value; 150,000,000 and 100,000,000 shares authorized at September 30, 2022 and December 31, 2021; 104,450,804 shares and 62,200,456 shares issued and outstanding, respectively	2,477.4	945.0
Retained earnings	1,035.8	1,052.6
Accumulated other comprehensive loss, net	(507.7)	(11.0)
Total stockholders’ equity	3,005.5	1,986.6
Total liabilities and stockholders’ equity	$ 31,344.7	$ 19,671.9

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Consolidated Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Investment securities:
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 1,900,000	$ 0
Estimated fair value	$ 3,063,500,000	$ 1,667,500,000
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)	104,450,804	62,200,456
Common Stock, Shares, Issued	104,450,804	62,200,456
Common Stock, Shares Authorized	150,000,000	100,000,000
Common Stock, Par or Stated Value Per Share	$ 0	$ 0
Preferred Stock, No Par Value	$ 0	$ 0
Other Short-term Borrowings	$ 625,000,000	$ 0
Class A Common Stock
Stockholders' equity:
Shares outstanding (in shares)		41,699,409

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Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Interest income:
Interest and fees on loans	$ 218.3	$ 111.9	$ 561.7	$ 325.1
Interest and dividends on investment securities:
Taxable	64.3	17.1	142.4	48.7
Exempt from federal taxes	1.4	1.4	4.1	4.2
Other Interest and Dividend Income	1.3	0.2	2.8	0.2
Interest on deposits in banks	1.4	0.7	6.5	1.7
Total interest income	286.7	131.3	717.5	379.9
Interest expense:
Interest on deposits	13.3	1.9	20.6	6.4
Interest on securities sold under repurchase agreements	0.8	0.1	1.4	0.3
Interest Expense, Other Short-term Borrowings	2.4	0.0	2.4	0.0
Interest on long-term debt	1.5	1.5	4.6	4.5
Interest on subordinated debentures held by subsidiary trusts	1.9	0.7	4.3	2.1
Total interest expense	19.9	4.2	33.3	13.3
Net interest income	266.8	127.1	684.2	366.6
Provision for (reversal of) credit losses	8.4	0.0	68.0	(5.1)
Net interest income after provision for (reversal of) credit losses	258.4	127.1	616.2	371.7
Non-interest income:
Payment Services Revenues	20.4	12.2	54.7	33.8
Mortgage banking revenues	2.7	11.6	16.1	32.8
Wealth management revenues	8.5	6.5	25.9	19.1
Service Charges on Deposit Accounts	5.7	4.4	19.7	12.1
Non-interest income	4.7	1.4	12.6	5.1
Debt Securities, Available-for-sale, Gain (Loss)	(24.2)	0.3	(24.4)	0.2
Other income	5.1	3.1	17.0	9.8
Total non-interest income	22.9	39.5	121.6	112.9
Non-interest expense:
Salaries and wages	71.9	42.0	206.7	122.6
Employee benefits	19.6	12.9	60.2	43.7
Outsourced technology services	15.9	8.2	40.0	24.7
Occupancy, net	11.3	7.3	32.5	21.7
Furniture and equipment	5.8	4.5	17.0	13.0
OREO expense, net of income	0.0	0.0	0.1	(0.1)
Professional fees	5.1	2.7	14.5	9.3
FDIC insurance premiums	4.1	1.7	10.2	4.8
Other intangibles amortization	4.1	2.4	11.8	7.4
Other expenses	31.4	17.6	82.7	49.6
Acquisition related expenses	4.0	6.6	115.0	6.6
Noninterest Expense	173.2	105.9	590.7	303.3
Income before income tax	108.1	60.7	147.1	181.3
Provision for income tax	22.4	13.6	30.7	40.3
Net income	$ 85.7	$ 47.1	$ 116.4	$ 141.0
Earnings per common share, basic (in dollars per share)	$ 0.80	$ 0.76	$ 1.13	$ 2.29
Earnings per common share, diluted (in dollars per share)	$ 0.80	$ 0.76	$ 1.13	$ 2.28
Weighted average common shares outstanding, basic (in shares)	106,525,974	61,673,656	102,879,422	61,641,342
Weighted average common shares outstanding, diluted (in shares)	106,589,699	61,747,972	102,935,360	61,732,822

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Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 85.7	$ 47.1	$ 116.4	$ 141.0
Other comprehensive loss, before tax:
Change in net unrealized loss during period	(236.4)	(13.4)	(650.6)	(81.0)
Reclassification adjustment for net loss (gain) included in income	24.2	(0.3)	24.4	(0.2)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0.0	0.0	0.2	0.0
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax	(1.7)	(2.5)	(25.6)	22.3
Change in unrealized (gain) loss on derivatives	(15.9)	3.2	(9.6)	2.3
Other comprehensive loss, before tax	(229.8)	(13.0)	(661.2)	(56.6)
Deferred tax benefit related to other comprehensive loss	51.9	3.2	164.5	14.3
Other comprehensive loss, net of tax	(177.9)	(9.8)	(496.7)	(42.3)
Comprehensive (loss) income, net of tax	$ (92.2)	$ 37.3	$ (380.3)	$ 98.7

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Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Retained earnings	Accumulated other comprehensive income (loss)
Equity, beginning balance at Dec. 31, 2020	$ 1,959.8	$ 941.1	$ 962.1	$ 56.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	141.0	0.0	141.0	0.0
Other comprehensive income (loss), net of tax expense	(42.3)	0.0	0.0	(42.3)
Common stock transactions:
Common shares purchased and retired	(5.4)	(5.4)	0.0	0.0
Common shares issued	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 options exercised, net of share tendered in payment of option price and income tax withholding amounts	0.4	0.4	0.0	0.0
Stock-based compensation expense	7.5	7.5	0.0	0.0
Common cash dividend declared	(76.2)	0.0	(76.2)	0.0
Equity, ending balance at Sep. 30, 2021	1,984.8	943.6	1,026.9	14.3
Equity, beginning balance at Jun. 30, 2021	1,970.9	941.6	1,005.2	24.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	47.1	0.0	47.1	0.0
Other comprehensive income (loss), net of tax expense	(9.8)	0.0	0.0	(9.8)
Common stock transactions:
Common shares purchased and retired	0.0	0.0	0.0	0.0
Common shares issued	0.0	0.0	0.0	0.0
Non-vested common shares issued	0.0	0.0	0.0	0.0
Stock-based compensation expense	2.0	2.0	0.0	0.0
Common cash dividend declared	(25.4)	0.0	(25.4)	0.0
Equity, ending balance at Sep. 30, 2021	1,984.8	943.6	1,026.9	14.3
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)
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 options exercised, net of share tendered in payment of option price and income tax withholding amounts	0.1	0.1	0.0	0.0
Stock-based compensation expense	8.7	8.7	0.0	0.0
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)
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 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)

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Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Stockholders' Equity [Abstract]
Stock repurchased and retired (in shares)	3,280,042	574	5,039,784	128,038
Common shares issued (in shares)		1,782	46,913,370	19,081
Non-vested common shares issued (in shares)	251	12,620	453,690	241,307
Non-vested common shares forfeited (in shares)	27,443	2,324	94,735	39,993
stock options exercised (in shares)			17,807	42,987
Shares tendered (in shares)			4,877	6,177
Common dividends (in dollars per share)	$ 0.41	$ 0.41	$ 1.23	$ 1.23

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Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 85.7	$ 47.1	$ 116.4	$ 141.0
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for (reversal of) credit losses	8.4	0.0	68.0	(5.1)
Net gain on disposal of premises and equipment			(2.3)	(1.9)
Depreciation and amortization			41.4	33.4
Net premium amortization on investment securities			16.7	29.0
Net loss on investment securities transactions			24.4	(0.2)
Realized and unrealized net gains on mortgage banking activities			(8.1)	(19.1)
Net gain on sale of OREO			(0.4)	(0.2)
Write-downs of OREO and other assets pending disposal			0.2	0.0
Gain (Loss) on Extinguishment of Debt			(1.4)	0.0
Mortgage servicing rights recovery			(3.4)	(5.9)
Deferred taxes			(4.8)	4.6
Net increase in cash surrender value of company-owned life insurance			(7.6)	(4.1)
Stock-based compensation expense			8.7	7.5
Originations of mortgage loans held for sale			(369.5)	(596.6)
Proceeds from sales of mortgage loans held for sale			387.2	645.1
Changes in operating assets and liabilities:
Increase in interest receivable			(25.9)	(1.8)
Increase in other assets			(14.9)	(21.8)
Increase in accrued interest payable			1.3	0.8
Increase in accounts payable and accrued expenses			212.6	0.7
Net cash provided by operating activities			438.6	205.4
Purchases of investment securities:
Held-to-maturity			(1,316.0)	(1,069.5)
Available-for-sale			(2,521.2)	(1,891.4)
Proceeds from sales, maturities, and pay-downs of investment securities:
Held-to-maturity			304.8	163.9
Available-for-sale			1,753.6	747.8
Purchases of Federal Home Loan Bank and Federal Reserve Bank stock			115.8	0.0
Proceeds from Federal Home Loan Bank and Federal Reserve Bank stock			53.3	0.0
Extensions of credit to clients, net of repayments			(465.6)	172.5
Recoveries of loans charged-off			10.8	7.2
Proceeds from sale of OREO			2.0	1.1
Proceeds from the sale of Health Savings Accounts			1.4	0.0
Acquisition of bank and bank holding company, net of cash and cash equivalents received			2,006.9	0.0
Payments for (Proceeds from) Productive Assets			(27.2)	(5.5)
Net cash used in investing activities			(313.0)	(1,873.9)
Cash flows from financing activities:
Net (decrease) increase in deposits			(2,072.8)	1,790.3
Net increase (decrease) in securities sold under repurchase agreements			51.6	(83.9)
Proceeds from (Repayments of) Other Debt			625.0		$ 0.0
Repayments of long-term debt			(164.0)	0.0
Advances on long-term debt			14.4	0.0
Payments of Stock Issuance Costs			(0.8)	0.0
Proceeds from issuance of common stock, net			0.1	0.4
Purchase and retirement of common stock			(198.9)	(5.4)
Dividends paid to common stockholders			(133.1)	(76.2)
Net cash (used in) provided by financing activities			(1,878.5)	1,625.2
Net decrease in cash and cash equivalents			(1,752.9)	(43.3)
Cash and cash equivalents at beginning of period			2,344.8	2,276.8	2,276.8
Cash and cash equivalents at end of period	$ 591.9	$ 2,233.5	591.9	2,233.5	$ 2,344.8
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes			42.2	41.3
Cash paid during the period for interest expense			32.0	12.5
Supplemental disclosures of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities			22.9	0.8
Net change in unamortized (losses) gains on available-for-sale securities transferred into held-to-maturity			10.9	0.0
Debt Securities, Available-For-Sale, Transfer, Unrealized Gain (Loss)			463.6	672.2
Transfer of loans from held-for-sale to held for investment			19.8	0.0
Transfer of loans to held-for-sale			12.4	0.0
Transfer of loans to other real estate owned			0.4	0.7
Asset Acquisition, Consideration Transferred, Equity Interest Issued and Issuable			1,723.3	0.0
Capitalization of internally originated mortgage servicing rights			2.3	2.0
Investment securities			2,699.0	0.0
Securities Purchased under Agreements to Resell, Increase			101.1	0.0
Loans held for sale			217.0	0.0
Loans held for investment, net			7,645.5	0.0
Premises and equipment			144.7	0.0
Goodwill			478.4	0.0
Other Intangibles			72.9	0.0
Mortgage Servicing Rights			1.3	0.0
Company-owned life insurance			186.6	0.0
Noncash or Part Noncash Acquisition, Deferred Tax Assets Acquired			63.6	0.0
Noncash or Part Noncash Acquisition, Intangible Assets Acquired, Other Real Estate Owned			15.8	0.0
Other assets			198.9	0.0
Total noncash assets acquired			11,824.8	0.0
Noncash or Part Noncash Acquisition, Liabilities Assumed, Deposits			11,688.0	0.0
Securities sold under repurchase agreements			74.0	0.0
Accounts payable and accrued expenses			111.0	0.0
Long-term debt			159.3	0.0
Noncash or Part Noncash Acquisition, Liabilities Assumed, Trust preferred securities			76.1	0.0
Total liabilities assumed			$ 12,108.4	$ 0.0

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Basis of Presentation

9 Months Ended

Sep. 30, 2022

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., First Interstate Bank (“FIB”), and its other subsidiaries (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, 2022 and December 31, 2021, the results of operations, changes in stockholders’ equity, and cash flows for each of the three and the nine month periods ended September 30, 2022 and 2021, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2021 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, 2022 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, 2021, which includes a description of significant accounting policies. Operating results for the three and the nine months ended September 30, 2022 are not necessarily indicative of the results that may be expected for the year ending December 31, 2022.

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Acquisitions

9 Months Ended

Sep. 30, 2022

Business Combinations [Abstract]

Acquisitions

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. The acquisition of GWB 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 this 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. This determination is subject to refinement for up to one year after the closing date of the acquisition as additional information relative to the closing date fair values becomes available and such information is considered final, whichever is earlier.

The following table provides the provisional 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 as of September 30, 2022. We recorded the estimate of fair value based on initial valuations available 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 provisional goodwill of $478.4 million, which is not 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. Due to the recent closing of the transaction, all amounts reported are provisional pending the review of valuations obtained from third parties and other necessary information in support of related fair value accounting.

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 (“OREO”)	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	63.6
Other assets	198.9
Total assets acquired	13,353.3
Liabilities assumed:
Deposits	11,688.0
Securities sold under repurchase agreements	74.0
Accrued expenses and other liabilities	111.0
FHLB advances	122.9
Subordinated debt	36.4
Subordinated debentures held by subsidiary trusts	76.1
Total liabilities assumed	12,108.4
Net assets acquired	$	1,244.9
Consideration paid:
Class A common stock	1,723.3
Total consideration paid (1)	$	1,723.3
Goodwill	$	478.4

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

As of September 30, 2022, the Company recorded measurement period adjustments to the fair value marks. These adjustments included increases of $0.9 million in other assets and $0.9 million in accrued expenses and a decrease of $0.2 million in premises and equipment, which resulted in a net increase to goodwill of $0.2 million from the June 30, 2022 reported balances. The related impact to net income that would have been recognized in previous periods if the adjustments were recognized as of the acquisition date was not material to the consolidated financial statements.

The Company determined the fair value of loans, core deposit and customer relationship intangible assets, investment securities, premises and equipment, leases, mortgage servicing rights, deposits, FHLB advances, subordinated debt, and subordinated debentures held by subsidiary trusts with the assistance of third-party valuation specialists. The following is a description of the methods used to determine the fair values of significant assets and liabilities presented above.

Cash and cash equivalents

The carrying amount of these assets is a reasonable estimate of fair value based on the short-term nature of these assets.

Investment Securities

Fair values for securities are based on quoted market prices, where available. If quoted market prices are not available, fair value estimates are based on observable inputs including quoted market prices for similar instruments, quoted market prices that are not in an active market or other inputs that are observable in the market. In the absence of observable inputs, fair value is estimated based on pricing models and/or discounted cash flow methodologies.

Loans held for sale

The loans held for sale portfolio was recorded at fair value based on quotes or bids from third party investors.

Loans held for investment

A valuation of the loans held for investment portfolio was performed by a third party as of the acquisition date in accordance with ASC 820 to assess the fair value of the loan portfolio, considering adjustments for interest rate risk, required equity return, servicing, credit, and liquidity risk. The loans held for investment portfolio was segmented into two groups including purchase credit deteriorated (PCD) loans and non-PCD loans. The non-PCD loans were pooled based on similar characteristics, such as loan type, fixed or adjustable interest rates, payment type, index rate and caps/floors, and non-accrual status. The PCD loans were valued at the loan level with similar characteristics noted above. The fair value was calculated using a discounted cash flow analysis. The discount rate utilized to analyze fair value considered the cost of funds rate, capital charge, servicing costs, and liquidity premium, mostly based on industry standards.

The Company is required to record PCD assets, defined as a more-than-insignificant deterioration in credit quality since origination or issuance, at the purchase price plus the allowance for credit losses expected at the time of acquisition. Under this method, there is no credit loss expense affecting net income on acquisition of PCD assets. Changes in estimates of expected credit losses after acquisition are recognized in subsequent periods as credit loss expense (or reversal of credit loss expense) arise. Any non-credit discount or premium resulting from acquiring a pool of purchased financial assets with credit deterioration is allocated to each individual asset. At the acquisition date, the initial allowance for credit losses determined on a collective basis is allocated to individual assets to appropriately allocate any non-credit discount or premium. The non-credit discount or premium, after the adjustment for the allowance for credit losses, is accreted to interest income using the interest method based on the effective interest rate determined after the adjustment for credit losses at the adoption date. Information regarding loans acquired at the acquisition date as amended for measurement period adjustments as of September 30, 2022 were as follows:

(In millions)
PCD loans:
Unpaid principal balance	$	979.2
Principal amounts previously written off by GWB	(238.7)
Interest applied to principal by GWB	(18.1)
Adjusted unpaid principal balance	722.4
Credit discount	(69.2)
Discount attributable to other factors	(29.9)
Fair value	623.3
Allowance for credit losses	59.5
Amortized cost basis	682.8
Non-PCD loans:
Unpaid principal balance	7,107.9
Credit discount (1)	(76.5)
Non-credit discount	(9.2)
Fair value	7,022.2
Amortized cost basis	$	7,705.0
(1) Represents the best estimate of the contractual cash flows not expected to be collected as of the acquisition date.

Core deposit intangible

Core deposit intangible assets of $50.1 million on non-maturing deposits were determined by evaluating the underlying characteristics of the deposit relationships, including customer attrition, deposit interest rates and maintenance costs, and costs of alternative funding using the discounted cash flow approach. The core deposit intangibles represent the costs saved by the Company between maintaining the existing deposits and obtaining alternative funds over the life of the deposit base. These costs are amortized using an accelerated method over the estimated useful life of 10 years for the related deposits.

Premises and equipment

The fair values of premises are based on a market approach, using third-party appraisals and other analysis of value for land and premises.

Deposits

The fair values used for the demand and savings deposits equal the amounts payable on demand at the acquisition date. In determining the fair value of certificates of deposit, the cash flows of the contractual interest payments during the specific period of the certificates of deposit and scheduled principal payout were discounted to present value at market-based interest rates.

Customer relationship intangible

Customer relationship intangible assets of $22.8 million were determined using an excess earnings model associated with the expected fee income related to the underlying client relationships and is being amortized using the straight-line method over the estimated useful life of 12 years.

FHLB advances

The fair value of fixed rate Federal Home Loan Bank of Des Moines (“FHLB”) advances was determined using a discounted cash flow approach. The cash flows of the advances were projected based on scheduled payments of the fixed rate advances, which factored in prepayment fees. The cash flows were then discounted to present value using the FHLB rates as of February 1, 2022.

Subordinated debt and subordinated debentures held by subsidiary trusts

The fair value of subordinated debt and subordinated debentures held by subsidiary trusts was determined by using a discounted cash flow method using a market participant discount rate for similar instruments over the remaining terms.

Acquisition related expenses related to the GWB acquisition of $4.0 million and $115.0 million for the three and the nine month periods ended September 30, 2022, respectively, were included as a component of non-interest expense in the consolidated statements of income, of which none and approximately $26.8 million for the three and the nine month periods ended September 30, 2022, respectively, are acquisition related costs as defined by ASC 805. During the nine months ended September 30, 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, 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, First Interstate Bank, 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 and 2021 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		2021		2022		2021
Total revenues	$	314.0	$	295.8	$	883.5	$	909.1
Net income	$	90.3	$	110.9	$	267.8	$	177.0
Earnings per common share (Basic)	$	0.85	$	1.02	$	2.60	$	1.63
Earnings per common share (Diluted)	$	0.85	$	1.02	$	2.60	$	1.63

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Goodwill and Core Deposit Intangibles

9 Months Ended

Sep. 30, 2022

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

Goodwill

Management analyzes its goodwill for impairment on an annual basis and between annual tests in certain circumstances, such as upon material adverse changes in legal, business, regulatory, and economic factors. An impairment loss is recorded to the extent that the carrying amount of goodwill exceeds its implied fair value. The Company performed an impairment assessment as of July 1, 2022 and 2021 and concluded that there was no impairment to goodwill.

The following table details changes in the recorded amount of goodwill as of the dates indicated:

	As of September 30,
	September 30, 2022		December 31, 2021
Net carrying value at beginning of the period	$	621.6	$	621.6
Provisional additions to goodwill from acquisition	478.4		—
Net carrying value at end of period	$	1,100.0	$	621.6

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, 2022 and December 31, 2021:

As of September 30, 2022	CDI		OCRI		Total
Gross other intangible assets, at beginning of the period	$	106.0	$	—	$	106.0
Provisional amounts established through acquisition	50.1		22.8		72.9
Reductions due to sale of health savings accounts	(1.4)		—		(1.4)
Accumulated amortization	(75.2)		(1.3)		(76.5)
Net other intangible assets, end of period	$	79.5	$	21.5	$	101.0
December 31, 2021
Gross other intangible assets, at beginning of the period	$	106.0	$	—	$	106.0
Accumulated amortization	(64.7)		—		(64.7)
Net other intangible assets, end of period	$	41.3	$	—	$	41.3

The Company recorded $4.1 million and $2.4 million of other intangible asset amortization expense for the three months ended September 30, 2022 and 2021, respectively, and recorded $11.8 million and $7.4 million of other intangible asset amortization expense for the nine months ended September 30, 2022 and 2021, respectively

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:

Years Ending December 31,	CDI		OCRI		Total
2022 remaining	$	3.6	$	0.5	$	4.1
2023	13.7		1.9		15.6
2024	12.7		1.9		14.6
2025	11.8		1.9		13.7
2026	10.9		1.9		12.8
Thereafter	26.8		13.4		40.2
Total	$	79.5	$	21.5	$	101.0

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Investment Securities

9 Months Ended

Sep. 30, 2022

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, 2022	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	373.5	$	—	$	(36.7)	$	336.8
State, county, and municipal securities	317.8		—		(57.3)		260.5
Obligations of U.S. government agencies	216.3		—		(17.3)		199.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	4,852.2		0.2		(442.7)		4,409.7
Private mortgage-backed securities	270.3		—		(37.1)		233.2
Collateralized loan obligations	1,145.5		—		(40.4)		1,105.1
Corporate securities	272.6		—		(33.5)		239.1
Total	$	7,448.2	$	0.2	$	(665.0)	$	6,783.4

September 30, 2022	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	396.1	$	—	$	396.1	$	—	$	(10.6)	$	385.5
State, county, and municipal securities	184.0		(0.1)		183.9		0.2		(33.2)		150.9
Obligations of U.S. government agencies	350.8		—		350.8		—		(51.2)		299.6
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations (1)	2,476.6		—		2,476.6		—		(320.0)		2,156.6
Corporate securities	80.1		(1.8)		78.3		—		(7.4)		70.9
Total	$	3,487.6	$	(1.9)	$	3,485.7	$	0.2	$	(422.4)	$	3,063.5
(1) Amortized cost presented above include $20.8 million of unamortized losses and $15.2 million of unamortized gains in U.S. agency residential and commercial mortgage-backed securities and collateralized mortgage obligations related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity.

December 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	697.6	$	—	$	(12.9)	$	684.7
State, county, and municipal securities	434.7		2.1		(9.3)		427.5
Obligations of U.S. government agencies	356.0		0.1		(9.2)		346.9
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	2,027.3		14.1		(23.3)		2,018.1
Private mortgage-backed securities	174.4		0.1		(1.1)		173.4
Collateralized loan obligation	898.2		1.2		—		899.4
Corporate securities	271.1		3.0		(3.6)		270.5
Total	$	4,859.3	$	20.6	$	(59.4)	$	4,820.5

December 31, 2021	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
State, county, and municipal securities	$	67.6	$	—	$	67.6	$	2.0	$	(0.4)	$	69.2
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations(1)	1,609.0		—		1,609.0		13.2		(35.3)		1,586.9
Corporate securities	11.0		—		11.0		0.4		—		11.4
Total	$	1,687.6	$	—	$	1,687.6	$	15.6	$	(35.7)	$	1,667.5
(1) Amortized cost presented above include $20.1 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.

On February 1, 2022, in conjunction with the acquisition of GWB and under ASC 320, the Company transferred debt securities classified as held-to-maturity with an amortized cost of $10.7 million and an estimated fair value of $10.9 million to the available-for-sale category classification and transferred debt securities classified as available-for-sale with an amortized cost of $485.9 million and an estimated fair value of $463.6 million to the held-to-maturity classification to maintain the Company’s intended risk profile. The transfer of debt securities into the available-for-sale and held-to-maturity categories were recorded at fair value on the date of transfer. This discount, as well as the related unrealized loss in accumulated other comprehensive income, will be amortized into interest income as a yield adjustment over the remaining term of the securities. The amortization of the unrealized loss reported in accumulated other comprehensive (loss) income will offset the effect on interest income of the accretion of the discount. No gains or losses were recorded at the time of transfer.

The following tables show the gross unrealized losses and fair values of investment securities, aggregated by investment category, and the length of time individual investment securities have been in an unrealized loss position as of September 30, 2022 and December 31, 2021.

	Less than 12 Months				12 Months or More				Total
September 30, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	168.2	$	(5.1)	$	168.6	$	(31.6)	$	336.8	$	(36.7)
State, county, and municipal securities	110.6		(14.4)		136.4		(42.9)		247.0		(57.3)
Obligations of U.S. government agencies	152.4		(10.9)		45.9		(6.4)		198.3		(17.3)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	3,697.1		(308.8)		699.8		(133.9)		4,396.9		(442.7)
Private mortgage-backed securities	206.1		(32.3)		27.0		(4.8)		233.1		(37.1)
Collateralized loan obligations	1,076.1		(39.8)		29.0		(0.6)		1,105.1		(40.4)
Corporate securities	144.0		(10.4)		95.0		(23.1)		239.0		(33.5)
Total	$	5,554.5	$	(421.7)	$	1,201.7	$	(243.3)	$	6,756.2	$	(665.0)

	Less than 12 Months				12 Months or More				Total
December 31, 2021	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	684.7	$	(12.9)	$	—	$	—	$	684.7	$	(12.9)
State, county, and municipal securities	278.7		(9.1)		5.0		(0.2)		283.7		(9.3)
Obligations of U.S. government agencies	297.0		(8.9)		16.4		(0.3)		313.4		(9.2)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	1,262.8		(23.0)		26.4		(0.3)		1,289.2		(23.3)
Private mortgage-backed securities	127.2		(1.1)		—		—		127.2		(1.1)
Corporate securities	109.9		(3.3)		20.9		(0.3)		130.8		(3.6)
Total	$	2,760.3	$	(58.3)	$	68.7	$	(1.1)	$	2,829.0	$	(59.4)

As of September 30, 2022 and December 31, 2021, 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 acquired $2,356.9 million of available-for-sale securities and $342.1 million of held-to-maturity securities in connection with the acquisition of GWB. Such securities were evaluated and it was determined that there were no investment securities that met the definition of a PCD asset and none were classified as PCD upon acquisition.

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 may 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 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. The Company had no allowance for credit losses for available-for-sale investment securities as of September 30, 2022 and December 31, 2021.

As of September 30, 2022 and December 31, 2021, the Company had 1,239 and 285 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, 2022, 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 held-to-maturity securities classified as corporate and state, county, and municipal securities:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Beginning balance	$	1.6	$	—	$	—	$	—
Provision for credit loss expense	0.3		—		1.9		—
Ending balance of allowance for credit losses	$	1.9	$	—	$	1.9	$	—

There was no allowance for credit losses on held-to-maturity securities at December 31, 2021.

On a quarterly basis, the Company refreshes the credit quality 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, 2022	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	396.1	$	—	$	—	$	—	$	—	$	—	$	396.1
State, county, and municipal securities	69.4		93.8		12.0		—		—		8.8		184.0
Obligations of U.S. government agencies	350.8		—		—		—		—		—		350.8
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
FNMA/FHLMC	2,261.3		—		—		—		—		—		2,261.3
GNMA	215.3		—		—		—		—		—		215.3
Corporate securities	—		—		—		65.1		10.0		5.0		80.1
Total	$	3,292.9	$	93.8	$	12.0	$	65.1	$	10.0	$	13.8	$	3,487.6

December 31, 2021	AAA		AA		A		BBB		Not Rated		Total
State, county, and municipal securities	$	17.2	$	31.6	$	14.7	$	—	$	4.1	$	67.6
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
FNMA/FHLMC	1,439.1		—		—		—		—		1,439.1
GNMA	169.9		—		—		—		—		169.9
Corporate securities	—		—		4.0		7.0		—		11.0
Total	$	1,626.2	$	31.6	$	18.7	$	7.0	$	4.1	$	1,687.6

As of September 30, 2022 and December 31, 2021, the Company had $34.3 million and $16.6 million, respectively, of accrued interest receivable on the consolidated balance sheet. The Company does not consider accrued interest receivable in the carrying amount of financial assets held at the amortized cost basis or in the allowance for credit losses calculation.

As of September 30, 2022 and December 31, 2021, 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, 2022 and December 31, 2021, there were no collateral dependent available-for-sale or held-to-maturity securities.

There were no material gross realized gains and $46.3 million in gross realized losses on the disposition of available-for-sale investment securities, primarily related to the $500.0 million in US treasury notes, during the three months ended September 30, 2022. The gross realized losses were offset by $22.1 million in deferred gains realized related to the termination of the fair value derivative for a net realized loss of $24.2 million. For the nine months ended September 30, 2022, there were no material gross realized gains and $46.4 million in gross realized losses. For the three and the nine month periods ended September 30, 2021, there were no material gross realized gains and no material gross realized losses.

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, 2022	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	57.1	$	56.4	$	5.1	$	5.0
After one year but within five years	1,049.0		998.0		546.0		524.2
After five years but within ten years	1,918.3		1,710.2		797.1		695.2
After ten years	4,423.8		4,018.8		2,139.4		1,839.1
Total	$	7,448.2	$	6,783.4	$	3,487.6	$	3,063.5

As of September 30, 2022, the Company held investment securities callable within one year having amortized costs and estimated fair values of $777.7 million and $706.2 million, respectively. These investment securities are primarily included in the “after five years but within ten years” category in the table above. As of September 30, 2022, the Company had no callable structured notes.

As of September 30, 2022 and December 31, 2021, the Company has amortized costs of $4,836.7 million and $2,617.8 million, respectively, for investment securities pledged to secure public deposits and securities sold under repurchase agreements and had approximate fair values of $4,265.1 million and $2,610.8 million, as of September 30, 2022 and December 31, 2021, 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, 2022 and December 31, 2021, the Company held $131.9 million and $53.8 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, 2022

Loans Held for Sale [Abstract]

Loans Held for Sale

The following table presents loans held for sale by segment for the dates indicated:

	September 30, 2022		December 31, 2021
Loans Held for Sale:
Agricultural	$	63.0	$	—
Commercial construction	12.4		—
Residential real estate	18.2		30.1
Total loans held for sale	$	93.6	$	30.1

Residential real estate loans that the Company originated with the intent to sell are recorded at fair value. Conforming agency mortgage production is sold on a servicing retained basis. Certain loans, such as government guaranteed mortgage loans, are sold on a servicing released basis. The fair value of loans held for sale are primarily determined based on quoted prices for similar loans in active markets or outstanding commitments from third-party investors. Net unrealized losses, if any, are recorded as a valuation allowance and charged to non-interest income in the consolidated statements from operations. Net gains and losses on loan sales are recorded as a component of non-interest income.

As of September 30, 2022, loans held for sale included nonaccrual loans of $43.1 million, of which $30.7 million were agricultural loans and $12.4 million was a commercial construction loan. There were no loans held for sale that were considered a troubled debt restructuring as of September 30, 2022.

On February 1, 2022, in conjunction with the acquisition of GWB, agricultural loans with a carrying value of $155.8 million and commercial loans with a carrying value of $24.0 million were reclassified as loans held for sale from loans held for investment due to management’s intent and decision to sell the loans.

Subsequent to the acquisition date, agricultural loans with a carrying value of $19.8 million were reclassified from loans held for sale to loans held for investment due to management’s change in intent and decision not to sell the loans. On the date of transfer, the amortized cost exceeded the fair value of the loans due to credit deterioration. The Company recorded a charge-off of $5.1 million to the allowance for credit losses, which established a new aggregate cost basis for the loans of $14.7 million on the date of transfer. In addition to the reclassification of agricultural loans, subsequent to the acquisition date, the Company increased the fair value mark on loans held for sale of $35.1 million, transferred a $12.4 million legacy commercial construction loan from loans held for investment to loans held for sale, sold $23.4 million of commercial loans, and recorded $108.7 million of net repayments and discounted pay-offs.

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Loans Held for Investment

9 Months Ended

Sep. 30, 2022

Receivables [Abstract]

Loans

Loans Held for Investment

The following table presents loans by segment as of the dates indicated:

	September 30, 2022		December 31, 2021
Real estate loans:
Commercial	$	8,026.9	$	3,971.5
Construction loans:
Land acquisition & development	393.2		247.8
Residential	501.4		262.0
Commercial	1,128.4		498.0
Total construction loans	2,023.0		1,007.8
Residential	2,127.7		1,538.2
Agricultural	800.9		213.9
Total real estate loans	12,978.5		6,731.4
Consumer loans:
Indirect	780.8		737.6
Direct and advance lines	155.0		129.2
Credit card	74.2		64.9
Total consumer loans	1,010.0		931.7
Commercial	2,966.1		1,475.5
Agricultural	658.2		203.9
Other, including overdrafts	3.8		1.5
Loans held for investment	17,616.6		9,344.0
Deferred loan fees and costs	(13.1)		(12.3)
Loans held for investment, net of deferred fees and costs	17,603.5		9,331.7
Allowance for credit losses	(213.0)		(122.3)
Net loans held for investment	$	17,390.5	$	9,209.4

Allowance for Credit Losses

The following tables represent, by loan portfolio segment, the activity in the allowance for credit losses for loans held for investment:

Three Months Ended September 30, 2022	Beginning Balance		Provisional ACL Recorded for PCD loans		Provision for (reversal of) Credit Losses		Loans Charged-Off		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
(1) Amounts presented exclude the allowance for credit losses related to unfunded commitments. These amounts are included in Note “Financial Instruments with Off-Balance Sheet Risk” and the allowance for credit losses related to investment securities which are included in Note “Investment Securities” included in this report.

Nine Months Ended September 30, 2022	Beginning Balance		Provisional ACL Recorded for PCD loans		Provision for (reversal of) Credit Losses (2)		Loans Charged-Off		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
Total 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 are exclusive of the allowance for credit losses related to unfunded commitments which are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.
(2) Amounts include $68.3 million related to the acquired GWB non-PCD loans.

Three Months Ended September 30, 2021	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	22.9	$	1.1	$	—	$	—	$	24.0
Owner occupied	16.6		(0.6)		—		—		16.0
Multi-family	11.6		0.2		—		—		11.8
Total commercial real estate	51.1		0.7		—		—		51.8
Construction:
Land acquisition & development	1.0		(0.2)		—		0.1		0.9
Residential construction	1.5		0.3		—		—		1.8
Commercial construction	8.0		(1.3)		—		—		6.7
Total construction	10.5		(1.2)		—		0.1		9.4
Residential real estate:
Residential 1-4 family	13.4		(0.2)		—		—		13.2
Home equity and HELOC	1.4		(0.1)		—		0.1		1.4
Total residential real estate	14.8		(0.3)		—		0.1		14.6
Agricultural real estate	3.0		0.1		—		—		3.1
Total real estate	79.4		(0.7)		—		0.2		78.9
Consumer:
Indirect	15.8		(0.1)		(0.8)		0.5		15.4
Direct and advance lines	4.6		0.5		(0.8)		0.4		4.7
Credit card	1.6		0.4		(0.4)		0.2		1.8
Total consumer	22.0		0.8		(2.0)		1.1		21.9
Commercial:
Commercial and floor plans	29.0		0.3		(0.1)		0.2		29.4
Commercial purpose secured by 1-4 family	4.4		(0.2)		—		—		4.2
Credit card	0.3		—		—		—		0.3
Total commercial	33.7		0.1		(0.1)		0.2		33.9
Agricultural:
Agricultural	0.4		—		—		—		0.4
Total agricultural	0.4		—		—		—		0.4
Total allowance for credit losses	$	135.5	$	0.2	$	(2.1)	$	1.5	$	135.1
(1) Amounts presented exclude the allowance for credit losses related to unfunded commitments. These amounts are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.

Nine Months Ended September 30, 2021	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	25.5	$	(1.6)	$	—	$	0.1	$	24.0
Owner occupied	18.3		—		(2.3)		—		16.0
Multi-family	11.0		0.8		—		—		11.8
Total commercial real estate	54.8		(0.8)		(2.3)		0.1		51.8
Construction:
Land acquisition & development	1.3		(0.8)		(0.1)		0.5		0.9
Residential construction	1.6		0.3		(0.1)		—		1.8
Commercial construction	7.3		(0.6)		(0.1)		0.1		6.7
Total construction	10.2		(1.1)		(0.3)		0.6		9.4
Residential real estate:
Residential 1-4 family	11.4		1.8		—		—		13.2
Home equity and HELOC	1.4		(0.2)		(0.1)		0.3		1.4
Total residential real estate	12.8		1.6		(0.1)		0.3		14.6
Agricultural real estate	2.7		0.4		—		—		3.1
Total real estate	80.5		0.1		(2.7)		1.0		78.9
Consumer:
Indirect	16.7		(0.3)		(2.9)		1.9		15.4
Direct and advance lines	4.6		1.2		(2.0)		0.9		4.7
Credit card	2.6		—		(1.4)		0.6		1.8
Total consumer	23.9		0.9		(6.3)		3.4		21.9
Commercial:
Commercial and floor plans	34.2		(4.9)		(2.2)		2.3		29.4
Commercial purpose secured by 1-4 family	4.7		(0.8)		(0.1)		0.4		4.2
Credit card	0.3		0.2		(0.3)		0.1		0.3
Total commercial	39.2		(5.5)		(2.6)		2.8		33.9
Agricultural:
Agricultural	0.7		(0.1)		(0.2)		—		0.4
Total agricultural	0.7		(0.1)		(0.2)		—		0.4
Total allowance for credit losses	$	144.3	$	(4.6)	$	(11.8)	$	7.2	$	135.1
(1) Amounts presented are exclusive of the allowance for credit losses related to unfunded commitments which are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.

Collateral-Dependent Financial Loans

A collateral-dependent financial loan relies solely on the operation or sale of the collateral for repayment. In evaluating the overall risk associated with a loan, the Company considers (1) character, overall financial condition and resources, and payment record of the borrower; (2) the prospects for support from any financially responsible guarantors; and (3) the nature and degree of protection provided by the cash flow and value of any underlying collateral. The loan may become collateral-dependent when 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 amortized cost basis of collateral-dependent loans by class of loans as of the dates indicated:

	Collateral Type
As of September 30, 2022	Business Assets		Real Property		Other		Total
Real estate	$	2.2	$	39.1	$	—	$	41.3
Commercial	1.4		4.9		—		6.3
Agricultural	0.3		9.7		—		10.0
Total collateral-dependent	$	3.9	$	53.7	$	—	$	57.6

	Collateral Type
As of December 31, 2021	Business Assets		Real Property		Other		Total
Real estate	$	1.2	$	7.0	$	—	$	8.2
Commercial	1.8		1.0		—		2.8
Agricultural	—		0.7		—		0.7
Total collateral-dependent	$	3.0	$	8.7	$	—	$	11.7

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 greater than 90 days past due continue to accrue interest. The following tables present the contractual aging of the Company’s recorded amortized cost basis in loans by portfolio as of the dates indicated.

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of September 30, 2022	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate
Commercial	$	9.7	$	2.7	$	1.4	$	13.8	$	7,986.6	$	26.5	$	8,026.9
Construction:
Land acquisition & development	0.6		0.4		0.2		1.2		388.1		3.9		393.2
Residential	3.9		—		0.4		4.3		497.1		—		501.4
Commercial	6.8		—		—		6.8		1,121.6		—		1,128.4
Total construction loans	11.3		0.4		0.6		12.3		2,006.8		3.9		2,023.0
Residential	1.1		3.4		1.2		5.7		2,115.6		6.4		2,127.7
Agricultural	1.3		—		0.7		2.0		783.3		15.6		800.9
Total real estate loans	23.4		6.5		3.9		33.8		12,892.3		52.4		12,978.5
Consumer:
Indirect consumer	6.0		1.3		0.2		7.5		771.3		2.0		780.8
Other consumer	0.7		0.2		0.1		1.0		153.9		0.1		155.0
Credit card	0.6		0.4		0.5		1.5		72.7		—		74.2
Total consumer loans	7.3		1.9		0.8		10.0		997.9		2.1		1,010.0
Commercial	9.5		1.7		1.8		13.0		2,941.4		11.7		2,966.1
Agricultural	2.1		0.1		0.1		2.3		642.7		13.2		658.2
Other, including overdrafts	—		—		—		—		3.8		—		3.8
Loans held for investment	$	42.3	$	10.2	$	6.6	$	59.1	$	17,478.1	$	79.4	$	17,616.6

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2021	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate
Commercial	$	1.1	$	1.0	$	0.6	$	2.7	$	3,960.8	$	8.0	$	3,971.5
Construction:
Land acquisition & development	0.2		—		—		0.2		246.9		0.7		247.8
Residential	4.2		—		—		4.2		257.8		—		262.0
Commercial	—		—		—		—		498.0		—		498.0
Total construction loans	4.4		—		—		4.4		1,002.7		0.7		1,007.8
Residential	3.0		0.8		0.1		3.9		1,531.4		2.9		1,538.2
Agricultural	1.9		0.2		—		2.1		206.9		4.9		213.9
Total real estate loans	10.4		2.0		0.7		13.1		6,701.8		16.5		6,731.4
Consumer:
Indirect consumer	5.1		1.4		0.4		6.9		729.0		1.7		737.6
Other consumer	0.5		0.2		0.1		0.8		128.3		0.1		129.2
Credit card	0.6		0.2		0.5		1.3		63.6		—		64.9
Total consumer loans	6.2		1.8		1.0		9.0		920.9		1.8		931.7
Commercial	4.9		0.7		1.1		6.7		1,463.8		5.0		1,475.5
Agricultural	0.7		—		—		0.7		201.6		1.6		203.9
Other, including overdrafts	—		—		—		—		1.5		—		1.5
Loans held for investment	$	22.2	$	4.5	$	2.8	$	29.5	$	9,289.6	$	24.9	$	9,344.0

(1) As of September 30, 2022 and December 31, 2021, 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, 2022 and 2021, respectively. There were $0.6 million and no reversals of accrued interest at September 30, 2022 and September 30, 2021. respectively.

Troubled Debt Restructurings

Modifications of performing 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 and typically include adjustments such as changes to interest rates, the implementation of interest only periods of less than twelve months, the deferment of short-term payments, and extension of amortization periods. A loan modification is considered a troubled debt restructuring if the borrower is experiencing financial difficulties and the Company, for economic or legal reasons, grants a concession to the borrower that it would not under other circumstances. Certain troubled loans are on non-accrual status at the time of debt restructuring. These restructured loans may be returned to accrual status if the borrower has exhibited sustained repayment performance in compliance with the restructuring agreement for a period of at least six months and the Company is reasonably assured of the borrower’s future performance. If the troubled debt restructuring meets these performance criteria, and the interest rate granted at the modification date is equal to or greater than the rate that the Company might grant for a new loan at the same time at comparable risk, then the loan will be reclassified to performing status and the accrual of interest will resume. Loans that return to performing status will continue to be evaluated individually for credit deterioration in the ordinary course of business.

The Company renegotiated loans in troubled debt restructurings in the amount of $68.1 million as of September 30, 2022, of which $8.4 million were included in non-accrual loans and $59.7 million were on accrual status. As of September 30, 2022, the Company allocated $0.4 million of its allowance for credit losses to these loans. The Company had no material commitments to lend additional funds to borrowers whose existing loans had been renegotiated or classified as non-accrual.

The Company renegotiated loans in troubled debt restructurings in the amount of $6.2 million as of December 31, 2021, of which $3.9 million were included in non-accrual loans and $2.3 million were on accrual status. As of December 31, 2021, the Company allocated $0.1 million of its allowance for credit losses to these loans. The Company had no material commitments to lend additional funds to borrowers whose existing loans had been renegotiated or classified as non-accrual.

The Company had $48.1 million and $71.7 million of new troubled debt restructurings during the three and the nine months ended September 30, 2022, respectively.

	Number of Notes	Type of Concession								Principal Balance at Restructure
Three Months Ended September 30, 2022		Interest only period		Extension of term or amortization schedule		Interest rate adjustment		Other (1)
Commercial real estate	1	$	—	$	—	$	—	$	46.1	$	46.1
Agricultural real estate	1	—		0.1		—		—		0.1
Commercial	1	—		1.9		—		—		1.9
Total loans restructured during period	3	$	—	$	2.0	$	—	$	46.1	$	48.1
(1) Other includes concessions that reduce or defer payments for a specified period of time and/or concessions that do not fit into other designated categories.
	Number of Notes	Type of Concession								Principal Balance at Restructure
Nine Months Ended September 30, 2022		Interest only period		Extension of term or amortization schedule		Interest rate adjustment		Other (1)
Commercial real estate	4	$	3.2	$	4.2	$	—	$	46.3	$	53.7
Residential real estate	2	—		0.6		—		—		0.6
Agriculture real estate	2	—		9.0		—		—		9.0
Commercial	3	—		1.9		—		0.6		2.5
Agriculture	1	—		—		—		5.9		5.9
Total loans restructured during period	12	$	3.2	$	15.7	$	—	$	52.8	$	71.7
(1) Other includes concessions that reduce or defer payments for a specified period of time and/or concessions that do not fit into other designated categories.

For troubled debt restructurings that were on non-accrual status or otherwise deemed collateral-dependent before a modification, the Company may record an allowance for credit losses depending on the circumstances. In periods after modification, the Company continues to evaluate all troubled debt restructurings for possible credit deterioration and, where deterioration is observed, recognizes credit loss through the allowance. Additionally, the Company continues to work these loans through the credit cycle through charge-off, pay-off, or foreclosure. Financial effects of modifications of troubled debt restructurings may include principal loan forgiveness or other charge-offs directly related to the restructuring. The Company had $5.7 million in charge-offs directly related to modifying an acquired PCD loan, for which a troubled debt restructuring was initiated during the three and the nine months ended September 30, 2022. The Company had no charge-offs directly related to troubled debt restructurings during the three and the nine months ended September 30, 2021.

The Company had no material troubled debt restructurings resulting in payment default during the previous 12 months ended September 30, 2022. The Company considers a payment default to occur on troubled debt restructurings when the loan is 90 days or more past due or the loan is placed on non-accrual status after the modification.

The Company modified the terms of certain other loans with a total recorded investment of $191.4 million as of September 30, 2022, where the loan did not meet the definition of a troubled debt restructuring and the borrowers had not been experiencing financial difficulties or there were delays in a payment considered to be insignificant. The Company determines whether a borrower is experiencing financial difficulty by evaluating the probability that the borrower will be in payment default on any of its debt in the foreseeable future without the modification as required under the Company’s internal underwriting policy.

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 the date of the acquisition with the purchase price (or initial fair value of the loans) as amended for measurement period adjustments as of September 30, 2022:

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 GWB PCD loans acquired 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 managed 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 loan losses of the following segments based on the aforementioned risk scale for the periods indicated:

	September 30, 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	$	784.9	$	784.8	$	666.7	$	463.9	$	279.4	$	913.3	$	27.5	$	3,920.5
Special mention	6.0		4.4		0.4		4.7		8.3		19.8		—		43.6
Substandard	3.5		33.2		10.7		18.9		20.1		9.5		—		95.9
Doubtful	—		—		—		—		1.8		—		—		1.8
Total	$	794.4	$	822.4	$	677.8	$	487.5	$	309.6	$	942.6	$	27.5	$	4,061.8
Commercial real estate owner occupied:
Pass	$	621.4	$	757.4	$	552.2	$	282.9	$	177.4	$	589.9	$	16.3	$	2,997.5
Special mention	5.2		8.8		1.5		11.1		2.8		9.8		0.3		39.5
Substandard	12.1		3.0		2.3		4.6		2.8		17.8		0.4		43.0
Doubtful	0.4		1.5		—		—		7.9		2.0		—		11.8
Total	$	639.1	$	770.7	$	556.0	$	298.6	$	190.9	$	619.5	$	17.0	$	3,091.8
Commercial multi-family:
Pass	$	267.4	$	209.6	$	188.8	$	52.5	$	35.7	$	115.7	$	1.5	$	871.2
Special mention	—		—		—		—		—		1.8		—		1.8
Substandard	—		—		—		—		—		0.3		—		0.3
Total	$	267.4	$	209.6	$	188.8	$	52.5	$	35.7	$	117.8	$	1.5	$	873.3
Land, acquisition and development:
Pass	$	122.7	$	141.0	$	31.7	$	25.6	$	12.4	$	30.1	$	17.7	$	381.2
Special mention	6.7		—		—		—		0.2		0.3		—		7.2
Substandard	—		0.8		0.2		—		—		0.6		—		1.6
Doubtful	—		3.2		—		—		—		—		—		3.2
Total	$	129.4	$	145.0	$	31.9	$	25.6	$	12.6	$	31.0	$	17.7	$	393.2
Residential construction:
Pass	$	104.2	$	133.9	$	0.4	$	9.2	$	0.4	$	5.5	$	247.0	$	500.6
Substandard	—		0.4		—		—		—		0.4		—		0.8
Total	$	104.2	$	134.3	$	0.4	$	9.2	$	0.4	$	5.9	$	247.0	$	501.4
Commercial construction:
Pass	$	358.1	$	469.0	$	180.9	$	76.2	$	0.5	$	—	$	15.6	$	1,100.3
Special mention	2.1		—		23.1		—		—		—		—		25.2
Substandard	2.9		—		—		—		—		—		—		2.9
Total	$	363.1	$	469.0	$	204.0	$	76.2	$	0.5	$	—	$	15.6	$	1,128.4
Agricultural real estate:
Pass	$	162.5	$	175.6	$	119.5	$	67.3	$	48.0	$	111.9	$	28.7	$	713.5
Special mention	2.0		2.8		2.3		2.3		9.6		3.3		11.2		33.5
Substandard	1.1		13.9		3.6		3.4		3.2		14.2		11.4		50.8
Doubtful	—		—		3.1		—		—		—		—		3.1
Total	$	165.6	$	192.3	$	128.5	$	73.0	$	60.8	$	129.4	$	51.3	$	800.9
Commercial and floor plans:
Pass	$	415.9	$	406.3	$	233.4	$	138.5	$	130.3	$	178.9	$	707.5	$	2,210.8
Special mention	10.1		9.6		2.1		3.9		1.4		5.2		64.5		96.8
Substandard	8.0		1.2		3.4		2.7		3.5		2.4		6.6		27.8
Doubtful	0.3		4.7		—		—		—		—		—		5.0
Total	$	434.3	$	421.8	$	238.9	$	145.1	$	135.2	$	186.5	$	778.6	$	2,340.4

	September 30, 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	$	155.8	$	140.4	$	71.6	$	31.4	$	31.0	$	43.2	$	29.9	$	503.3
Special mention	0.2		1.1		2.3		0.2		1.5		0.3		—		5.6
Substandard	0.2		0.3		0.1		0.3		0.9		1.2		0.1		3.1
Total	$	156.2	$	141.8	$	74.0	$	31.9	$	33.4	$	44.7	$	30.0	$	512.0
Agricultural:
Pass	$	107.6	$	70.9	$	35.0	$	12.8	$	9.9	$	1.5	$	356.3	$	594.0
Special mention	1.5		3.4		0.6		1.2		0.7		—		12.1		19.5
Substandard	23.1		6.5		5.0		0.9		4.2		1.1		1.4		42.2
Doubtful	—		0.6		—		—		—		—		—		0.6
Total	$	132.2	$	81.4	$	40.6	$	14.9	$	14.8	$	2.6	$	369.8	$	656.3

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial real estate non-owner occupied:
Pass	$	507.9	$	452.2	$	237.9	$	150.4	$	76.3	$	409.0	$	15.3	$	1,849.0
Special mention	0.2		3.1		2.1		—		—		3.6		—		9.0
Substandard	3.9		15.3		2.3		0.7		1.0		12.4		—		35.6
Total	$	512.0	$	470.6	$	242.3	$	151.1	$	77.3	$	425.0	$	15.3	$	1,893.6
Commercial real estate owner occupied:
Pass	$	452.7	$	314.9	$	235.0	$	151.0	$	94.5	$	322.5	$	14.2	$	1,584.8
Special mention	1.3		3.2		1.5		7.4		3.5		13.8		—		30.7
Substandard	3.8		4.3		4.7		5.4		2.7		20.3		—		41.2
Total	$	457.8	$	322.4	$	241.2	$	163.8	$	100.7	$	356.6	$	14.2	$	1,656.7
Commercial multi-family:
Pass	$	129.1	$	118.6	$	43.9	$	15.4	$	36.0	$	76.7	$	1.5	$	421.2
Total	$	129.1	$	118.6	$	43.9	$	15.4	$	36.0	$	76.7	$	1.5	$	421.2
Land, acquisition and development:
Pass	$	113.0	$	41.5	$	34.2	$	14.8	$	19.8	$	20.8	$	1.2	$	245.3
Special mention	—		0.1		—		—		0.1		0.3		—		0.5
Substandard	0.8		0.2		—		0.6		0.3		0.1		—		2.0
Total	$	113.8	$	41.8	$	34.2	$	15.4	$	20.2	$	21.2	$	1.2	$	247.8
Residential construction:
Pass	$	112.4	$	7.0	$	13.7	$	0.9	$	—	$	—	$	127.2	$	261.2
Substandard	—		0.4		—		—		0.4		—		—		0.8
Total	$	112.4	$	7.4	$	13.7	$	0.9	$	0.4	$	—	$	127.2	$	262.0
Commercial construction:
Pass	$	209.7	$	141.4	$	118.8	$	27.6	$	—	$	0.5	$	—	$	498.0
Total	$	209.7	$	141.4	$	118.8	$	27.6	$	—	$	0.5	$	—	$	498.0

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Agricultural real estate:
Pass	$	58.3	$	36.9	$	35.1	$	22.6	$	11.8	$	28.1	$	4.9	$	197.7
Special mention	0.1		1.3		1.2		0.1		0.1		0.9		0.9		4.6
Substandard	4.0		0.4		1.0		0.6		1.3		4.3		—		11.6
Total	$	62.4	$	38.6	$	37.3	$	23.3	$	13.2	$	33.3	$	5.8	$	213.9
Commercial and floor plans:
Pass	$	394.2	$	165.7	$	94.5	$	73.5	$	47.1	$	91.3	$	224.7	$	1,091.0
Special mention	0.8		11.4		0.8		0.8		3.0		2.3		7.0		26.1
Substandard	1.3		2.8		1.6		2.6		0.6		4.1		2.6		15.6
Total	$	396.3	$	179.9	$	96.9	$	76.9	$	50.7	$	97.7	$	234.3	$	1,132.7
Commercial purpose secured by 1-4 family:
Pass	$	94.9	$	55.0	$	27.8	$	23.1	$	15.3	$	32.2	$	14.4	$	262.7
Special mention	—		0.2		0.2		0.5		0.1		0.6		—		1.6
Substandard	1.3		1.2		0.6		0.6		0.2		1.3		0.1		5.3
Total	$	96.2	$	56.4	$	28.6	$	24.2	$	15.6	$	34.1	$	14.5	$	269.6
Agricultural:
Pass	$	35.1	$	16.2	$	9.0	$	5.4	$	2.1	$	1.6	$	108.9	$	178.3
Special mention	0.2		4.1		0.1		0.4		0.6		0.3		7.0		12.7
Substandard	4.9		0.7		0.6		2.5		—		0.1		2.6		11.4
Total	$	40.2	$	21.0	$	9.7	$	8.3	$	2.7	$	2.0	$	118.5	$	202.4

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, and loans modified under troubled debt restructurings are considered nonperforming for purposes of credit quality evaluation. The following tables present the recorded investment of our other loan portfolios based on the credit risk profile of loans that are performing and loans that are nonperforming as of the periods indicated:

	September 30, 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	$	195.3	$	466.3	$	550.2	$	102.3	$	32.6	$	230.2	$	—	$	1,576.9
Nonperforming	—		0.2		0.4		0.5		0.4		3.4		—		4.9
Total	$	195.3	$	466.5	$	550.6	$	102.8	$	33.0	$	233.6	$	—	$	1,581.8
Consumer home equity and HELOC:
Performing	$	14.9	$	8.7	$	5.4	$	4.4	$	5.7	$	17.6	$	486.5	$	543.2
Nonperforming	0.5		0.3		0.1		0.1		0.1		1.2		0.4		2.7
Total	$	15.4	$	9.0	$	5.5	$	4.5	$	5.8	$	18.8	$	486.9	$	545.9
Consumer indirect:
Performing	$	279.0	$	194.9	$	144.5	$	69.0	$	39.5	$	51.7	$	—	$	778.6
Nonperforming	0.2		0.6		0.4		0.3		0.2		0.5		—		2.2
Total	$	279.2	$	195.5	$	144.9	$	69.3	$	39.7	$	52.2	$	—	$	780.8
Consumer direct and advance line:
Performing	$	45.0	$	36.2	$	20.9	$	10.5	$	7.9	$	9.7	$	24.6	$	154.8
Nonperforming	—		0.1		—		—		—		0.1		—		0.2
Total	$	45.0	$	36.3	$	20.9	$	10.5	$	7.9	$	9.8	$	24.6	$	155.0

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Residential 1-4 family:
Performing	$	360.9	$	477.0	$	74.7	$	27.5	$	25.7	$	176.5	$	—	$	1,142.3
Nonperforming	—		0.3		—		—		0.2		0.8		—		1.3
Total	$	360.9	$	477.3	$	74.7	$	27.5	$	25.9	$	177.3	$	—	$	1,143.6
Consumer home equity and HELOC:
Performing	$	11.1	$	7.0	$	3.7	$	4.8	$	3.6	$	12.0	$	350.7	$	392.9
Nonperforming	0.3		—		0.3		—		0.6		0.5		—		1.7
Total	$	11.4	$	7.0	$	4.0	$	4.8	$	4.2	$	12.5	$	350.7	$	394.6
Consumer indirect:
Performing	$	272.6	$	208.6	$	108.3	$	64.0	$	37.0	$	45.0	$	—	$	735.5
Nonperforming	0.5		0.5		0.4		0.2		0.1		0.4		—		2.1
Total	$	273.1	$	209.1	$	108.7	$	64.2	$	37.1	$	45.4	$	—	$	737.6
Consumer direct and advance line:
Performing	$	42.5	$	27.9	$	15.0	$	13.3	$	5.8	$	7.6	$	16.9	$	129.0
Nonperforming	0.1		—		—		0.1		—		—		—		0.2
Total	$	42.6	$	27.9	$	15.0	$	13.4	$	5.8	$	7.6	$	16.9	$	129.2

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 September 30, 2022	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	73.8	$	113.3	$	1.9	$	189.0
Nonperforming	0.4		0.4		—		0.8
Total credit card	$	74.2	$	113.7	$	1.9	$	189.8

As of December 31, 2021	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	64.4	$	73.1	$	1.5	$	139.0
Nonperforming	0.5		0.1		—		0.6
Total credit card	$	64.9	$	73.2	$	1.5	$	139.6

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, 2022 or 2021.

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Other Real Estate Owned

9 Months Ended

Sep. 30, 2022

Repossessed Assets [Abstract]

Other Real Estate Owned

Other Real Estate Owned

Other real estate owned 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 other real estate owned is reflected in the following table:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Beginning balance	$	16.8	$	2.0	$	2.0	$	2.5
Acquired through acquisition	—		—		15.8		—
Additions	0.3		0.4		0.4		0.7
Valuation adjustments	(0.2)		—		(0.2)		—
Dispositions	(0.5)		(0.1)		(1.6)		(0.9)
Ending balance	$	16.4	$	2.3	$	16.4	$	2.3

The carrying value of foreclosed residential real estate properties included in other real estate owned was not material as of September 30, 2022 and December 31, 2021. The Company had 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, 2022 and December 31, 2021.

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Derivatives and Hedging Activities

9 Months Ended

Sep. 30, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative and Hedging Activities

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 marked to market through earnings. In addition to the effects of the change in market interest rate, the fair value measurement of the derivative also contemplates the expected cash flows to be received from the counterparty from the future sale of the loan.

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 marked to market through earnings and are not designated as accounting hedges during the interest rate lock commitment period and through the duration of the forward loan sales contracts. Exclusive of the fair value component associated with the projected cash flows from the loan delivery to the investor, the changes in fair value related to movements in market rates of the interest rate lock commitments and the forward loan sales contracts generally move in opposite directions, and the net impact of changes in these valuations on net income during the loan commitment period is generally inconsequential. When the loan is funded to the borrower, the interest rate lock commitment derivative expires, and the Company records a loan held for sale. The forward loan sales contract acts as a hedge against the variability in cash to be received from the loan sale. The changes in measurement of the estimated fair values of the interest rate lock commitments and forward loan sales contracts are included in mortgage banking revenues in the accompanying consolidated statements of income.

The Company also enters into certain interest rate swap contracts that are not designated as hedging instruments. These derivative contracts relate to transactions in which the Company enters into an interest rate swap with a client while at the same time entering into an offsetting interest rate swap with a third-party financial institution. Because the Company acts as an intermediary for the client, changes in the fair value of the underlying derivative contracts 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 expense and to manage its exposure to interest rate movements. To accomplish this objective, 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 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 variable-rate borrowings (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. 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.

For derivatives 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 (loss) income and subsequently reclassified into interest expense in the same period(s) during which the hedged transaction affects earnings. Amounts reported in accumulated other comprehensive (loss) income related to derivatives will be reclassified as interest expense when interest payments are made on the Company’s variable-rate liabilities. During the next twelve months, the Company estimates that no material amounts 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 2021, the Company entered into two forward starting, fixed interest rate fair value hedges associated with U.S. Treasury securities. During the second quarter of 2022, the Company terminated the $500.0 million, two-year forward starting, three-year pay-fixed interest rate swap, resulting in a $23.3 million gain. The gain associated with the $500.0 million interest rate swap was to be accreted into income through May 2026. However, the U.S. Treasury securities associated with the swap were sold during the third quarter of 2022. As such, the gain was accreted through August 2022 and then in September 2022 the remaining gain was recognized as income. 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 balance sheet related to cumulative basis adjustment for fair value hedges for the periods indicated:

	September 30, 2022				December 31, 2021
	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	$	—	$	—	$	695.6	$	(4.4)

Non-designated Hedge Derivatives

Derivatives not designated as 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 enters into these credit risk participation agreements in instances in which the Company is 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 balance sheet.

	September 30, 2022					December 31, 2021
	Notional Amount		Balance Sheet Location	Estimated Fair Value		Notional Amount		Balance Sheet Location	Estimated Fair Value
Derivatives designated as hedges:
Interest rate swap contracts	—			—		700.0			4.1
Derivatives not designated as hedges:
Interest rate swap contracts	1,743.3			42.1		913.9			22.2
Interest rate lock commitments	—			—		77.3			1.8
Forward loan sales contracts	32.3			0.6		—			—
Derivative assets in the balance sheet	$	1,775.6	Other Assets	$	42.7	$	1,691.2	Other Assets	$	28.1
Derivatives designated as hedges:
Interest rate collars	$	300.0		$	5.6	$	—		$	—
Interest rate swap contracts	—			—		87.6			0.1
Derivatives not designated as hedges:
Interest rate swap contracts	1,743.3			163.7		913.9			18.1
Risk participation agreements	107.2			0.1		—			—
Interest rate lock commitments	25.9			0.5		—			—
Forward loan sales contracts	—			—		102.4			—
Derivative liabilities in the balance sheet	$	2,176.4	Accrued Expenses	$	169.9	$	1,103.9	Accrued Expenses	$	18.2

There was a $5.6 million unrealized fair value loss on derivative instruments in accumulated other comprehensive loss during the three and the nine months ended September 30, 2022. There were no material effects of derivative instruments in fair value or cash flow hedge accounting on accumulated other comprehensive (loss) income during the three and the nine months ended 2021.

There were no material effects from the Company’s fair value or cash flow hedged derivative financial instruments on the income statement during the three and the nine months ended September 30, 2022 or 2021.

The table below presents the effect of the Company’s derivative financial instruments that are not designated as hedging instruments on the income statement for the periods indicated:

	Three Months Ended September 30,					Nine Months Ended September 30,
		2022		2021			2022		2021
	Location of (Loss) Gain Recognized in Income on Derivative	Amount of (Loss) Gain Recognized in Income on Derivative				Location of (Loss) Gain Recognized in Income on Derivative	Amount of (Loss) Gain Recognized in Income on Derivative
Interest rate lock commitments	Mortgage banking revenues	$	(0.2)	$	1.3	Mortgage banking revenues	$	(1.7)	$	1.7

The Company recorded swap fee revenues of $2.5 million and $0.4 million for the three months ended September 30, 2022 and September 30, 2021, respectively, and $5.6 million and $1.6 million for the nine months ended September 30, 2022 and September 30, 2021, respectively. The Company includes swap fee revenues in other service charges, commissions, and fees.

The tables below present the gross presentation, the effects of offsetting, and a net presentation of the Company’s derivatives as of the periods indicated:

	September 30, 2022
	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	$	42.1	$	—	$	42.1	$	—	$	42.1	$	—
Mortgage related derivatives	0.6		—		0.6		—		—		0.6
Total derivatives	42.7		—		42.7		—		42.1		0.6
Total assets	$	42.7	$	—	$	42.7	$	—	$	42.1	$	0.6
(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	$	169.3	$	—	$	169.3	$	—	$	5.6	$	163.7
Risk participation agreements	0.1		—		0.1		—		—		0.1
Mortgage related derivatives	0.5		—		0.5		—		—		0.5
Total derivatives	169.9		—		169.9		—		5.6		164.3
Repurchase agreements	1,075.6		—		1,075.6		—		1,075.6		—
Total liabilities	$	1,245.5	$	—	$	1,245.5	$	—	$	1,081.2	$	164.3

	December 31, 2021
	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	$	26.3	$	—	$	26.3	$	—	$	8.0	$	18.3
Mortgage related derivatives	1.8		—		1.8		—		—		1.8
Total derivatives	28.1		—		28.1		—		8.0		20.1
Total assets	$	28.1	$	—	$	28.1	$	—	$	8.0	$	20.1
	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	$	18.2	$	—	$	18.2	$	—	$	—	$	18.2
Total derivatives	18.2		—		18.2		—		—		18.2
Repurchase agreements	1,051.1		—		1,051.1		—		1,051.1		—
Total liabilities	$	1,069.3	$	—	$	1,069.3	$	—	$	1,051.1	$	18.2

Credit-risk-related Contingent Feature

The Company has agreements with each of its derivative counterparties that contain a provision where if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations.

The Company has agreements with certain of its derivative counterparties that contain a provision where if the Company fails to maintain its status as a well / adequately capitalized institution, then in certain instances the Company could be required to post additional capital and in certain instances the counterparty would have the right to terminate the derivative positions and the Company would be required to settle its obligations under the agreements.

As of September 30, 2022, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, was $5.6 million related to these agreements. As of September 30, 2022, the Company has minimum collateral posting thresholds with certain of its derivative counterparties and has not posted excess collateral. If the Company had breached any of these provisions at September 30, 2022, it could have been required to settle its obligations under the agreements at their termination value of $5.6 million.

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Capital Stock

9 Months Ended

Sep. 30, 2022

Equity [Abstract]

Capital Stock

Capital Stock

On February 1, 2022, the Company issued 46,879,601 shares of its Class A common stock with an aggregate value of approximately $1.7 billion as consideration for the acquisition of Great Western. During the nine months ended September 30, 2022 and 2021, the Company also issued 33,769 shares and 19,081 shares, respectively, of its Class A common stock to directors for their annual service on the Company's board of directors. The aggregate value of the shares issued to directors is included in employee benefits in the consolidated statement of income and in stock-based compensation expense in the consolidated statements of changes in stockholders' equity.

On March 25, 2022, all outstanding shares of the Company’s Class B common stock automatically converted into shares of the Company’s Class A common stock on a one-for-one basis, pursuant to the terms of the Company’s Third Amended and Restated Articles of Incorporation, as amended (the “Charter”). No additional shares of Class B common stock are permitted to be issued. The conversion occurred automatically pursuant to the Company’s Charter because the number of the Company’s outstanding shares of Class B common stock represented on March 25, 2022, the record date for determining the shareholders of the Company entitled to notice of, and to vote at, the Company’s 2022 Annual Meeting of Shareholders, was less than twenty percent (20%) of the aggregate number of all of the outstanding shares of Class A common stock and Class B common stock of the Company. The former holders of Class B common stock now hold Class A common stock with the same voting powers, preferences, rights and qualifications, limitations and restrictions as the other holders of Class A common stock. All shares of the Company’s outstanding capital stock are now composed solely of shares of Class A common stock and are entitled to one vote per share. The Company’s Class A common stock will continue to trade on the NASDAQ Stock Market under the ticker symbol “FIBK”.

On May 25, 2022, the Company’s board of directors adopted a new stock repurchase program to replace the program that had been in place since 2019 and had 1,889,158 shares of Class A common stock remaining to be purchased thereunder. Under the new stock repurchase program, the Company may repurchase up to 5.0 million of its outstanding shares of Class A common stock. There were 3,279,300 shares repurchased and retired under the new 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. The shares of common stock repurchased during the period completes the 5.0 million shares authorized to be repurchased. The 5.0 million shares repurchased during the nine months ended September 30, 2022 were purchased at a total cost of $197.4 million, including costs and commissions, at an average per share cost of $39.48.

All other stock repurchases during the nine months ended September 30, 2022 and 2021, 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.

The Company had 104,450,804 shares of Class A common stock outstanding as of September 30, 2022. The Company had 41,699,409 shares of Class A common stock and 20,501,047 shares of Class B common stock outstanding as of December 31, 2021.

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Earnings per Common Share

9 Months Ended

Sep. 30, 2022

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,
	2022		2021		2022		2021
Net income	$	85.7	$	47.1	$	116.4	$	141.0
Weighted average common shares outstanding for basic earnings per share computation	106,525,974		61,673,656		102,879,422		61,641,342
Dilutive effects of stock-based compensation	63,725		74,316		55,938		91,480
Weighted average common shares outstanding for diluted earnings per common share computation	106,589,699		61,747,972		102,935,360		61,732,822
Basic earnings per common share	$	0.80	$	0.76	$	1.13	$	2.29
Diluted earnings per common share	$	0.80	$	0.76	$	1.13	$	2.28
Anti-dilutive unvested time restricted stock	48,871		89,142		51,161		88,677

The Company had 481,567 and 355,981 shares of unvested restricted stock as of September 30, 2022 and 2021, 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, 2022

Banking and Thrift, Other Disclosures [Abstract]

Regulatory Capital

Regulatory Capital

As of September 30, 2022 and December 31, 2021, 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, 2022 and December 31, 2021 are presented in the following tables: 

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(1)
September 30, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,820.2	12.50	%	$	1,804.7	8.00	%	$	2,368.7	10.50	%	$	2,255.9	10.00	%
FIB	2,704.8		12.01		1,801.1		8.00		2,363.9		10.50		2,251.4		10.00
Tier 1 risk-based capital:
Consolidated	2,366.8		10.49		1,353.5		6.00		1,917.5		8.50		1,804.7		8.00
FIB	2,508.9		11.14		1,350.8		6.00		1,913.7		8.50		1,801.1		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,366.8		10.49		1,015.1		4.50		1,579.1		7.00		1,466.3		6.50
FIB	2,508.9		11.14		1,013.1		4.50		1,576.0		7.00		1,463.4		6.50
Leverage capital ratio:
Consolidated	2,366.8		7.67		1,234.4		4.00		1,234.4		4.00		1,543.0		5.00
FIB	2,508.9		8.14		1,232.2		4.00		1,232.2		4.00		1,540.2		5.00

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(1)
December 31, 2021	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,659.3	14.11	%	$	940.9	8.00	%	$	1,235.0	10.50	%	$	1,176.2	10.00	%
FIB	1,472.5		12.56		938.0		8.00		1,231.1		10.50		1,172.5		10.00
Tier 1 risk-based capital:
Consolidated	1,469.0		12.49		705.7		6.00		999.7		8.50		940.9		8.00
FIB	1,382.2		11.79		703.5		6.00		996.6		8.50		938.0		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,384.8		11.77		529.3		4.50		823.3		7.00		764.5		6.50
FIB	1,382.2		11.79		527.6		4.50		820.8		7.00		762.1		6.50
Leverage capital ratio:
Consolidated	1,469.0		7.68		765.5		4.00		765.5		4.00		956.9		5.00
FIB	1,382.2		7.24		764.1		4.00		764.1		4.00		955.1		5.00

(1) 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 the Current Expected Credit Loss accounting standard (“CECL”), or ASC 326, 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 transitioning 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, 2022

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, 2022, the Company had commitments under construction contracts of $1.6 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 $1.0 million of sold residential mortgage loans with recourse provisions still in effect as of September 30, 2022.

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Financial Instruments with Off-Balance Sheet Risk

9 Months Ended

Sep. 30, 2022

Financial Instruments with Off-Balance Sheet Risk [Abstract]

Financial Instruments with Off-Balance Sheet Risk

Financial Instruments with Off-Balance Sheet RiskIn 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,
	2022		2021		2022		2021
Beginning balance	$	6.2	$	3.4	$	3.8	$	3.7
Provision for (reversal of) credit loss expense	3.5		(0.2)		5.9		(0.5)
Ending balance of allowance for off-balance sheet credit losses	$	9.7	$	3.2	$	9.7	$	3.2

	September 30, 2022		December 31, 2021
Unused credit card lines	$	814.9	$	681.6
Commitments to extend credit	5,011.0		2,539.8
Standby letter of credit	92.4		57.5

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Other Comprehensive Income/Loss

9 Months Ended

Sep. 30, 2022

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,	2022		2021		2022		2021		2022		2021
Investment securities available-for sale:
Change in net unrealized loss during period	$	(236.4)	$	(13.4)	$	(53.4)	$	(3.3)	$	(183.0)	$	(10.1)
Reclassification adjustment for net loss (gain) included in net income	24.2		(0.3)		5.5		(0.1)		18.7		(0.2)
Net change in unamortized (gains) losses on available-for-sale securities transferred into held-to-maturity	(1.7)		(2.5)		(0.4)		(0.6)		(1.3)		(1.9)
Change in net unrealized gain (loss) on derivatives	(15.9)		3.2		(3.6)		0.8		(12.3)		2.4
Total other comprehensive loss	$	(229.8)	$	(13.0)	$	(51.9)	$	(3.2)	$	(177.9)	$	(9.8)

	Pre-tax				Tax Expense (Benefit)				Net of Tax
Nine Months Ended September 30,	2022		2021		2022		2021		2022		2021
Investment securities available-for sale:
Change in net unrealized loss during period	$	(650.6)	$	(81.0)	$	(161.3)	$	(20.5)	$	(489.3)	$	(60.5)
Reclassification adjustment for net loss (gain) included in net income	24.4		(0.2)		5.5		(0.1)		18.9		(0.1)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0.2		—		0.1		—		0.1		—
Net change in unamortized (gains) losses on available-for-sale securities transferred into held-to-maturity	(25.6)		22.3		(6.3)		5.7		(19.3)		16.6
Change in net unrealized gain (loss) on derivatives	(9.6)		2.3		(2.5)		0.6		(7.1)		1.7
Total other comprehensive loss	$	(661.2)	$	(56.6)	$	(164.5)	$	(14.3)	$	(496.7)	$	(42.3)

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

	September 30, 2022		December 31, 2021
Net unrealized loss on investment securities available-for-sale	$	(499.1)	$	(29.0)
Net unrealized (loss) gain on investment securities transferred to held-to-maturity	(4.4)		15.0
Net unrealized gain on derivatives	(4.2)		3.0
Net accumulated other comprehensive loss	$	(507.7)	$	(11.0)

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Fair Value Measurements

9 Months Ended

Sep. 30, 2022

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, 2022 and 2021.

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 transfers between fair value hierarchy levels during the three and the nine months ended September 30, 2022 and 2021.

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 other things. 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 three-month LIBOR forward curve to estimate variable rate cash inflows and the Secured Overnight Financing Rate 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 as well as ours. 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, 2022	Balance		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	$	336.8	$	336.8	$	—	$	—
State, county, and municipal securities	260.5			—	260.5			—
Obligations of U.S. government agencies	199.0			—	199.0			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	4,409.7			—	4,409.7			—
Private mortgage-backed securities	233.2			—	233.2			—
Collateralized loan obligations	1,105.1			—	1,105.1			—
Corporate securities	239.1			—	239.1			—
Loans held for sale	93.6			—	93.6			—
Derivative assets:
Interest rate swap contracts	42.1			—	42.1			—
Forward loan sale contracts	0.6			—	0.6			—
Derivative liabilities:
Interest rate collars	5.6			—	5.6			—
Interest rate swap contracts	163.7			—	163.7			—
Risk participation agreements	0.1			—	0.1			—
Interest rate lock commitments	0.5			—	0.5			—
Deferred compensation plan assets	19.0			—	19.0			—
Deferred compensation plan liabilities	19.0			—	19.0			—

			Fair Value Measurements at Reporting Date Using
As of December 31, 2021	Balance		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	$	684.7	$	684.7	$	—	$	—
State, county and municipal securities	427.5			—	427.5			—
Obligations of U.S. government agencies	346.9			—	346.9			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	2,018.1			—	2,018.1			—
Private mortgage-backed securities	173.4			—	173.4			—
Collateralized loan obligations	899.4			—	899.4			—
Corporate securities	270.5			—	270.5			—
Loans held for sale	30.1			—	30.1			—
Derivative assets:
Interest rate swap contracts	26.3			—	26.3			—
Interest rate lock commitments	1.8			—	1.8			—
Derivative liabilities
Interest rate swap contracts	18.2			—	18.2			—
Deferred compensation plan assets	21.4			—	21.4			—
Deferred compensation plan liabilities	21.4			—	21.4			—

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, 2022	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral dependent loans	$	57.6	$	—	$	—	$	57.6
Other real estate owned	16.4			—		—	16.4
Long-lived assets to be disposed of by sale	6.7			—		—	6.7
				Fair Value Measurements at Reporting Date Using
As of December 31, 2021	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral dependent loans	$	11.7	$	—	$	—	$	11.7
Other real estate owned	2.0			—		—	2.0
Long-lived assets to be disposed of by sale	1.3			—		—	1.3

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, 2022 and December 31, 2021, the Company had collateral-dependent loans with a carrying and fair value of $57.6 million and $11.7 million, respectively.

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 no material write downs on OREO properties during the nine months ended September 30, 2022 and 2021, 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, 2022, the Company had long-lived assets to be disposed of by sale with carrying and fair values aggregating $6.7 million, with no write-downs charged to other expense. As of December 31, 2021, the Company had long-lived assets to be disposed of by sale with carrying and fair values aggregating $1.3 million, with no write-downs charged to other expense.         

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, 2022		December 31, 2021		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Collateral dependent loans	$	57.6	$	11.7	Appraisal	Appraisal adjustment	1%	-	18%	(7%)
Other real estate owned	16.4		2.0		Appraisal	Appraisal adjustment	0%	-	0%	0%
Long-lived assets to be disposed of by sale	6.7		1.3		Appraisal	Appraisal adjustment	0%	-	0%	0%

The Company is required to disclose the fair value of financial instruments for which it is practical to estimate fair value. The methodologies for estimating the fair value of financial instruments that are measured at fair value on a recurring or non-recurring basis are discussed above. The methodologies for estimating the fair value of other financial instruments are discussed below. For financial instruments bearing a variable interest rate where no credit risk exists, it is presumed that recorded book values are reasonable estimates of fair value.        

Financial Assets. Carrying values of cash, cash equivalents, and accrued interest receivable approximate fair values due to the liquid and/or short-term nature of these instruments. Fair values for investment securities held-to-maturity are obtained from an independent pricing service, which considers observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the investment’s terms and conditions, among other things. Fair values of fixed rate loans and variable rate loans that reprice on an infrequent basis are estimated by discounting future cash flows using current interest rates at which similar loans with similar terms would be made to borrowers of similar credit quality using an exit price notion. Carrying values of variable rate loans that reprice frequently, and with no change in credit risk, approximate the fair values of these instruments.

Financial Liabilities. The fair values of demand deposits, savings accounts, securities sold under repurchase agreements, and accrued interest payable are the amounts that are payable on demand at the reporting date. The fair values of fixed-maturity certificates of deposit are estimated using external market rates that are currently offered for deposits that have similar remaining maturities. The fair values of derivative liabilities are obtained from an independent pricing service, which considers observable data that may include the three-month LIBOR forward curve, the federal funds effective swap rate and cash flows, among other things. The carrying values of the interest-bearing demand notes to the United States Treasury are deemed an approximation of fair values due to the frequent repayment and repricing at market rates. The fixed and floating rate subordinated debentures, floating rate subordinated term loan, notes payable to the FHLB, 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, 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	$	591.9	$	591.9	$	591.9	$	—	$	—
Investment debt securities available-for-sale	6,783.4		6,783.4		336.8		6,446.6		—
Investment debt securities held-to-maturity	3,485.7		3,063.5		385.5		2,678.0		—
Accrued interest receivable	106.4		106.4		—		106.4		—
Mortgage servicing rights, net	31.8		36.6		—		36.6		—
Loans held for sale	93.6		93.6		—		93.6		—
Net loans held for investment	17,390.5		17,293.6		—		17,236.0		57.6
Derivative assets	42.7		42.7		—		42.7		—
Deferred compensation plan assets	19.0		19.0		—		19.0		—
Total financial assets	$	28,545.0	$	28,030.7	$	1,314.2	$	26,658.9	$	57.6
Financial liabilities:
Total deposits, excluding time deposits	$	24,255.6	$	24,255.6	$	24,255.6	$	—	$	—
Time deposits	1,629.2		1,587.2		—		1,587.2		—
Securities sold under repurchase agreements	1,075.6		1,075.6		—		1,075.6		—
Other borrowed funds	625.0		625.0		—		625.0		—
Accrued interest payable	7.4		7.4		—		7.4		—
Long-term debt	120.7		116.7		—		116.7		—
Subordinated debentures held by subsidiary trusts	163.1		157.1		—		157.1		—
Derivative liabilities	169.9		169.9		—		169.9		—
Deferred compensation plan liabilities	19.0		19.0		—		19.0		—
Total financial liabilities	$	28,065.5	$	28,013.5	$	24,255.6	$	3,757.9	$	—

					Fair Value Measurements at Reporting Date Using
As of December 31, 2021	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	$	2,344.8	$	2,344.8	$	2,344.8	$	—	$	—
Investment debt securities available-for-sale	4,820.5		4,820.5		684.7		4,135.8		—
Investment debt securities held-to-maturity	1,687.6		1,667.5		—		1,667.5		—
Accrued interest receivable	47.4		47.4		—		47.4		—
Mortgage servicing rights, net	28.2		28.2		—		28.2		—
Loans held for sale	30.1		30.1		—		30.1		—
Net loans held for investment	9,209.4		9,254.3		—		9,242.6		11.7
Derivative assets	28.1		28.1		—		28.1		—
Deferred compensation plan assets	21.4		21.4		—		21.4		—
Total financial assets	$	18,217.5	$	18,242.3	$	3,029.5	$	15,201.1	$	11.7
Financial liabilities:
Total deposits, excluding time deposits	$	15,303.1	$	15,303.1	$	15,303.1	$	—	$	—
Time deposits	966.5		963.1		—		963.1		—
Securities sold under repurchase agreements	1,051.1		1,051.1		—		1,051.1		—
Accrued interest payable	3.7		3.7		—		3.7		—
Long-term debt	112.4		120.7		—		120.7		—
Subordinated debentures held by subsidiary trusts	87.0		85.5		—		85.5		—
Derivative liabilities	18.2		18.2		—		18.2		—
Deferred compensation plan liabilities	21.4		21.4		—		21.4		—
Total financial liabilities	$	17,563.4	$	17,566.8	$	15,303.1	$	2,263.7	$	—

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Other Borrowed Funds	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Long-Term Debt	At September 30, 2022, the Company had $625.0 million in outstanding Federal Home Loan Bank (“FHLB”) borrowings consisting of $550.0 million in 3.29% variable rate overnight borrowings and $75.0 million in 3.20% fixed rate one-month borrowings, as compared to no outstanding borrowings from the FHLB at December 31, 2021. The Company has a remaining borrowing capacity at FHLB of $3,962.4 million. The borrowings are collateralized by certain loans with an advance equivalent collateral value of $4,588.0 million.

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Recent Authoritative Accounting Guidance

9 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Recent Authoritative Accounting Guidance

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. The Company is currently evaluating the impact of the adoption of other expedients in the standard and does not anticipate it will have a significant impact on the Company’s financial position or results of operations.

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 (including periods after December 31, 2022). 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.

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. Early adoption is permitted, including in any interim period, for public business entities for periods for which financial statements have not yet been issued, and for all other entities for periods for which financial statements have not yet been made available for issuance. 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.

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. Entities should apply the amendments prospectively to business combinations that occur after the effective date. Early adoption in an interim period is permitted for public business entities, with the effect of adopting the amendments related to basis adjustments reflected as of the beginning of the fiscal year of adoption. 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.

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. Entities should apply the amendments prospectively except for the transition method related to the recognition and measurement of TDRs, an entity has the option to apply a modified retrospective transition method, resulting in a cumulative-effect adjustment to retained earnings in the period of adoption. Early adoption of the amendments are permitted, including adoption in an interim period. If an entity elects to early adopt the amendments in an interim period, the guidance should be applied as of the beginning of the fiscal year that includes the interim period. An entity may elect to early adopt the amendments about TDRs and related disclosure enhancements separately from the amendments related to vintage disclosures. 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.

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Subsequent Events

9 Months Ended

Sep. 30, 2022

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, 2022, the Company declared a quarterly dividend to common shareholders of $0.47 per share, to be paid on November 18, 2022 to shareholders of record as of November 8, 2022.

No other undisclosed events requiring recognition or disclosure were identified.

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Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2022

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, 2022 and 2021.

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 transfers between fair value hierarchy levels during the three and the nine months ended September 30, 2022 and 2021.

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 other things. 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 three-month LIBOR forward curve to estimate variable rate cash inflows and the Secured Overnight Financing Rate 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 as well as ours. 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 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. The Company is currently evaluating the impact of the adoption of other expedients in the standard and does not anticipate it will have a significant impact on the Company’s financial position or results of operations.

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 (including periods after December 31, 2022). 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.

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. Early adoption is permitted, including in any interim period, for public business entities for periods for which financial statements have not yet been issued, and for all other entities for periods for which financial statements have not yet been made available for issuance. 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.

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. Entities should apply the amendments prospectively to business combinations that occur after the effective date. Early adoption in an interim period is permitted for public business entities, with the effect of adopting the amendments related to basis adjustments reflected as of the beginning of the fiscal year of adoption. 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.

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. Entities should apply the amendments prospectively except for the transition method related to the recognition and measurement of TDRs, an entity has the option to apply a modified retrospective transition method, resulting in a cumulative-effect adjustment to retained earnings in the period of adoption. Early adoption of the amendments are permitted, including adoption in an interim period. If an entity elects to early adopt the amendments in an interim period, the guidance should be applied as of the beginning of the fiscal year that includes the interim period. An entity may elect to early adopt the amendments about TDRs and related disclosure enhancements separately from the amendments related to vintage disclosures. 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.

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Accounting Changes and Error Corrections (Policies)

9 Months Ended

Sep. 30, 2022

Accounting Changes and Error Corrections [Abstract]

Recent Authoritative Accounting Guidance

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. The Company is currently evaluating the impact of the adoption of other expedients in the standard and does not anticipate it will have a significant impact on the Company’s financial position or results of operations.

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 (including periods after December 31, 2022). 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.

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. Early adoption is permitted, including in any interim period, for public business entities for periods for which financial statements have not yet been issued, and for all other entities for periods for which financial statements have not yet been made available for issuance. 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.

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. Entities should apply the amendments prospectively to business combinations that occur after the effective date. Early adoption in an interim period is permitted for public business entities, with the effect of adopting the amendments related to basis adjustments reflected as of the beginning of the fiscal year of adoption. 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.

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. Entities should apply the amendments prospectively except for the transition method related to the recognition and measurement of TDRs, an entity has the option to apply a modified retrospective transition method, resulting in a cumulative-effect adjustment to retained earnings in the period of adoption. Early adoption of the amendments are permitted, including adoption in an interim period. If an entity elects to early adopt the amendments in an interim period, the guidance should be applied as of the beginning of the fiscal year that includes the interim period. An entity may elect to early adopt the amendments about TDRs and related disclosure enhancements separately from the amendments related to vintage disclosures. 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.

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Acquisitions (Tables)

9 Months Ended

Sep. 30, 2022

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table provides the provisional 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 as of September 30, 2022. We recorded the estimate of fair value based on initial valuations available 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 provisional goodwill of $478.4 million, which is not 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. Due to the recent closing of the transaction, all amounts reported are provisional pending the review of valuations obtained from third parties and other necessary information in support of related fair value accounting.

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 (“OREO”)	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	63.6
Other assets	198.9
Total assets acquired	13,353.3
Liabilities assumed:
Deposits	11,688.0
Securities sold under repurchase agreements	74.0
Accrued expenses and other liabilities	111.0
FHLB advances	122.9
Subordinated debt	36.4
Subordinated debentures held by subsidiary trusts	76.1
Total liabilities assumed	12,108.4
Net assets acquired	$	1,244.9
Consideration paid:
Class A common stock	1,723.3
Total consideration paid (1)	$	1,723.3
Goodwill	$	478.4

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

Financing Receivable, Purchased

The non-credit discount or premium, after the adjustment for the allowance for credit losses, is accreted to interest income using the interest method based on the effective interest rate determined after the adjustment for credit losses at the adoption date. Information regarding loans acquired at the acquisition date as amended for measurement period adjustments as of September 30, 2022 were as follows:

(In millions)
PCD loans:
Unpaid principal balance	$	979.2
Principal amounts previously written off by GWB	(238.7)
Interest applied to principal by GWB	(18.1)
Adjusted unpaid principal balance	722.4
Credit discount	(69.2)
Discount attributable to other factors	(29.9)
Fair value	623.3
Allowance for credit losses	59.5
Amortized cost basis	682.8
Non-PCD loans:
Unpaid principal balance	7,107.9
Credit discount (1)	(76.5)
Non-credit discount	(9.2)
Fair value	7,022.2
Amortized cost basis	$	7,705.0
(1) Represents the best estimate of the contractual cash flows not expected to be collected as of the acquisition date.

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 and 2021 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		2021		2022		2021
Total revenues	$	314.0	$	295.8	$	883.5	$	909.1
Net income	$	90.3	$	110.9	$	267.8	$	177.0
Earnings per common share (Basic)	$	0.85	$	1.02	$	2.60	$	1.63
Earnings per common share (Diluted)	$	0.85	$	1.02	$	2.60	$	1.63

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Goodwill and Core Deposit Intangibles (Tables)

9 Months Ended

Sep. 30, 2022

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The following table details changes in the recorded amount of goodwill as of the dates indicated:

	As of September 30,
	September 30, 2022		December 31, 2021
Net carrying value at beginning of the period	$	621.6	$	621.6
Provisional additions to goodwill from acquisition	478.4		—
Net carrying value at end of period	$	1,100.0	$	621.6

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, 2022 and December 31, 2021:

As of September 30, 2022	CDI		OCRI		Total
Gross other intangible assets, at beginning of the period	$	106.0	$	—	$	106.0
Provisional amounts established through acquisition	50.1		22.8		72.9
Reductions due to sale of health savings accounts	(1.4)		—		(1.4)
Accumulated amortization	(75.2)		(1.3)		(76.5)
Net other intangible assets, end of period	$	79.5	$	21.5	$	101.0
December 31, 2021
Gross other intangible assets, at beginning of the period	$	106.0	$	—	$	106.0
Accumulated amortization	(64.7)		—		(64.7)
Net other intangible assets, end of period	$	41.3	$	—	$	41.3

Schedule of Future Amortization Expense

The following table provides the estimated aggregate future amortization expense of other intangible assets:

Years Ending December 31,	CDI		OCRI		Total
2022 remaining	$	3.6	$	0.5	$	4.1
2023	13.7		1.9		15.6
2024	12.7		1.9		14.6
2025	11.8		1.9		13.7
2026	10.9		1.9		12.8
Thereafter	26.8		13.4		40.2
Total	$	79.5	$	21.5	$	101.0

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Investment Securities (Tables)

9 Months Ended

Sep. 30, 2022

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, 2022	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	373.5	$	—	$	(36.7)	$	336.8
State, county, and municipal securities	317.8		—		(57.3)		260.5
Obligations of U.S. government agencies	216.3		—		(17.3)		199.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	4,852.2		0.2		(442.7)		4,409.7
Private mortgage-backed securities	270.3		—		(37.1)		233.2
Collateralized loan obligations	1,145.5		—		(40.4)		1,105.1
Corporate securities	272.6		—		(33.5)		239.1
Total	$	7,448.2	$	0.2	$	(665.0)	$	6,783.4

September 30, 2022	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	396.1	$	—	$	396.1	$	—	$	(10.6)	$	385.5
State, county, and municipal securities	184.0		(0.1)		183.9		0.2		(33.2)		150.9
Obligations of U.S. government agencies	350.8		—		350.8		—		(51.2)		299.6
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations (1)	2,476.6		—		2,476.6		—		(320.0)		2,156.6
Corporate securities	80.1		(1.8)		78.3		—		(7.4)		70.9
Total	$	3,487.6	$	(1.9)	$	3,485.7	$	0.2	$	(422.4)	$	3,063.5
(1) Amortized cost presented above include $20.8 million of unamortized losses and $15.2 million of unamortized gains in U.S. agency residential and commercial mortgage-backed securities and collateralized mortgage obligations related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity.

December 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	697.6	$	—	$	(12.9)	$	684.7
State, county, and municipal securities	434.7		2.1		(9.3)		427.5
Obligations of U.S. government agencies	356.0		0.1		(9.2)		346.9
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	2,027.3		14.1		(23.3)		2,018.1
Private mortgage-backed securities	174.4		0.1		(1.1)		173.4
Collateralized loan obligation	898.2		1.2		—		899.4
Corporate securities	271.1		3.0		(3.6)		270.5
Total	$	4,859.3	$	20.6	$	(59.4)	$	4,820.5

December 31, 2021	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
State, county, and municipal securities	$	67.6	$	—	$	67.6	$	2.0	$	(0.4)	$	69.2
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations(1)	1,609.0		—		1,609.0		13.2		(35.3)		1,586.9
Corporate securities	11.0		—		11.0		0.4		—		11.4
Total	$	1,687.6	$	—	$	1,687.6	$	15.6	$	(35.7)	$	1,667.5
(1) Amortized cost presented above include $20.1 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.

Gross Unrealized Losses and Fair Values of Investment Securities

The following tables show the gross unrealized losses and fair values of investment securities, aggregated by investment category, and the length of time individual investment securities have been in an unrealized loss position as of September 30, 2022 and December 31, 2021.

	Less than 12 Months				12 Months or More				Total
September 30, 2022	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	168.2	$	(5.1)	$	168.6	$	(31.6)	$	336.8	$	(36.7)
State, county, and municipal securities	110.6		(14.4)		136.4		(42.9)		247.0		(57.3)
Obligations of U.S. government agencies	152.4		(10.9)		45.9		(6.4)		198.3		(17.3)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	3,697.1		(308.8)		699.8		(133.9)		4,396.9		(442.7)
Private mortgage-backed securities	206.1		(32.3)		27.0		(4.8)		233.1		(37.1)
Collateralized loan obligations	1,076.1		(39.8)		29.0		(0.6)		1,105.1		(40.4)
Corporate securities	144.0		(10.4)		95.0		(23.1)		239.0		(33.5)
Total	$	5,554.5	$	(421.7)	$	1,201.7	$	(243.3)	$	6,756.2	$	(665.0)

	Less than 12 Months				12 Months or More				Total
December 31, 2021	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	684.7	$	(12.9)	$	—	$	—	$	684.7	$	(12.9)
State, county, and municipal securities	278.7		(9.1)		5.0		(0.2)		283.7		(9.3)
Obligations of U.S. government agencies	297.0		(8.9)		16.4		(0.3)		313.4		(9.2)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations	1,262.8		(23.0)		26.4		(0.3)		1,289.2		(23.3)
Private mortgage-backed securities	127.2		(1.1)		—		—		127.2		(1.1)
Corporate securities	109.9		(3.3)		20.9		(0.3)		130.8		(3.6)
Total	$	2,760.3	$	(58.3)	$	68.7	$	(1.1)	$	2,829.0	$	(59.4)

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

The following table presents the activity in the allowance for credit losses related to held-to-maturity securities classified as corporate and state, county, and municipal securities:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Beginning balance	$	1.6	$	—	$	—	$	—
Provision for credit loss expense	0.3		—		1.9		—
Ending balance of allowance for credit losses	$	1.9	$	—	$	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, 2022	AAA		AA		A		BBB		BB		Not Rated		Total
U.S. Treasury notes	$	396.1	$	—	$	—	$	—	$	—	$	—	$	396.1
State, county, and municipal securities	69.4		93.8		12.0		—		—		8.8		184.0
Obligations of U.S. government agencies	350.8		—		—		—		—		—		350.8
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
FNMA/FHLMC	2,261.3		—		—		—		—		—		2,261.3
GNMA	215.3		—		—		—		—		—		215.3
Corporate securities	—		—		—		65.1		10.0		5.0		80.1
Total	$	3,292.9	$	93.8	$	12.0	$	65.1	$	10.0	$	13.8	$	3,487.6

December 31, 2021	AAA		AA		A		BBB		Not Rated		Total
State, county, and municipal securities	$	17.2	$	31.6	$	14.7	$	—	$	4.1	$	67.6
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
FNMA/FHLMC	1,439.1		—		—		—		—		1,439.1
GNMA	169.9		—		—		—		—		169.9
Corporate securities	—		—		4.0		7.0		—		11.0
Total	$	1,626.2	$	31.6	$	18.7	$	7.0	$	4.1	$	1,687.6

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, 2022	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	57.1	$	56.4	$	5.1	$	5.0
After one year but within five years	1,049.0		998.0		546.0		524.2
After five years but within ten years	1,918.3		1,710.2		797.1		695.2
After ten years	4,423.8		4,018.8		2,139.4		1,839.1
Total	$	7,448.2	$	6,783.4	$	3,487.6	$	3,063.5

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Loans Held for Sale (Tables)

9 Months Ended

Sep. 30, 2022

Receivables [Abstract]

Loans Held For Sale (Table)

The following table presents loans held for sale by segment for the dates indicated:

	September 30, 2022		December 31, 2021
Loans Held for Sale:
Agricultural	$	63.0	$	—
Commercial construction	12.4		—
Residential real estate	18.2		30.1
Total loans held for sale	$	93.6	$	30.1

XML

Loans Held for Investment (Tables)

9 Months Ended

Sep. 30, 2022

Receivables [Abstract]

Schedule of Loans by Class

The following table presents loans by segment as of the dates indicated:

	September 30, 2022		December 31, 2021
Real estate loans:
Commercial	$	8,026.9	$	3,971.5
Construction loans:
Land acquisition & development	393.2		247.8
Residential	501.4		262.0
Commercial	1,128.4		498.0
Total construction loans	2,023.0		1,007.8
Residential	2,127.7		1,538.2
Agricultural	800.9		213.9
Total real estate loans	12,978.5		6,731.4
Consumer loans:
Indirect	780.8		737.6
Direct and advance lines	155.0		129.2
Credit card	74.2		64.9
Total consumer loans	1,010.0		931.7
Commercial	2,966.1		1,475.5
Agricultural	658.2		203.9
Other, including overdrafts	3.8		1.5
Loans held for investment	17,616.6		9,344.0
Deferred loan fees and costs	(13.1)		(12.3)
Loans held for investment, net of deferred fees and costs	17,603.5		9,331.7
Allowance for credit losses	(213.0)		(122.3)
Net loans held for investment	$	17,390.5	$	9,209.4

Schedule of Allowance for Loan Losses by Portfolio Segment

The following tables represent, by loan portfolio segment, the activity in the allowance for credit losses for loans held for investment:

Three Months Ended September 30, 2022	Beginning Balance		Provisional ACL Recorded for PCD loans		Provision for (reversal of) Credit Losses		Loans Charged-Off		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
(1) Amounts presented exclude the allowance for credit losses related to unfunded commitments. These amounts are included in Note “Financial Instruments with Off-Balance Sheet Risk” and the allowance for credit losses related to investment securities which are included in Note “Investment Securities” included in this report.

Nine Months Ended September 30, 2022	Beginning Balance		Provisional ACL Recorded for PCD loans		Provision for (reversal of) Credit Losses (2)		Loans Charged-Off		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
Total 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 are exclusive of the allowance for credit losses related to unfunded commitments which are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.
(2) Amounts include $68.3 million related to the acquired GWB non-PCD loans.

Three Months Ended September 30, 2021	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	22.9	$	1.1	$	—	$	—	$	24.0
Owner occupied	16.6		(0.6)		—		—		16.0
Multi-family	11.6		0.2		—		—		11.8
Total commercial real estate	51.1		0.7		—		—		51.8
Construction:
Land acquisition & development	1.0		(0.2)		—		0.1		0.9
Residential construction	1.5		0.3		—		—		1.8
Commercial construction	8.0		(1.3)		—		—		6.7
Total construction	10.5		(1.2)		—		0.1		9.4
Residential real estate:
Residential 1-4 family	13.4		(0.2)		—		—		13.2
Home equity and HELOC	1.4		(0.1)		—		0.1		1.4
Total residential real estate	14.8		(0.3)		—		0.1		14.6
Agricultural real estate	3.0		0.1		—		—		3.1
Total real estate	79.4		(0.7)		—		0.2		78.9
Consumer:
Indirect	15.8		(0.1)		(0.8)		0.5		15.4
Direct and advance lines	4.6		0.5		(0.8)		0.4		4.7
Credit card	1.6		0.4		(0.4)		0.2		1.8
Total consumer	22.0		0.8		(2.0)		1.1		21.9
Commercial:
Commercial and floor plans	29.0		0.3		(0.1)		0.2		29.4
Commercial purpose secured by 1-4 family	4.4		(0.2)		—		—		4.2
Credit card	0.3		—		—		—		0.3
Total commercial	33.7		0.1		(0.1)		0.2		33.9
Agricultural:
Agricultural	0.4		—		—		—		0.4
Total agricultural	0.4		—		—		—		0.4
Total allowance for credit losses	$	135.5	$	0.2	$	(2.1)	$	1.5	$	135.1
(1) Amounts presented exclude the allowance for credit losses related to unfunded commitments. These amounts are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.

Nine Months Ended September 30, 2021	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate:
Commercial real estate:
Non-owner occupied	$	25.5	$	(1.6)	$	—	$	0.1	$	24.0
Owner occupied	18.3		—		(2.3)		—		16.0
Multi-family	11.0		0.8		—		—		11.8
Total commercial real estate	54.8		(0.8)		(2.3)		0.1		51.8
Construction:
Land acquisition & development	1.3		(0.8)		(0.1)		0.5		0.9
Residential construction	1.6		0.3		(0.1)		—		1.8
Commercial construction	7.3		(0.6)		(0.1)		0.1		6.7
Total construction	10.2		(1.1)		(0.3)		0.6		9.4
Residential real estate:
Residential 1-4 family	11.4		1.8		—		—		13.2
Home equity and HELOC	1.4		(0.2)		(0.1)		0.3		1.4
Total residential real estate	12.8		1.6		(0.1)		0.3		14.6
Agricultural real estate	2.7		0.4		—		—		3.1
Total real estate	80.5		0.1		(2.7)		1.0		78.9
Consumer:
Indirect	16.7		(0.3)		(2.9)		1.9		15.4
Direct and advance lines	4.6		1.2		(2.0)		0.9		4.7
Credit card	2.6		—		(1.4)		0.6		1.8
Total consumer	23.9		0.9		(6.3)		3.4		21.9
Commercial:
Commercial and floor plans	34.2		(4.9)		(2.2)		2.3		29.4
Commercial purpose secured by 1-4 family	4.7		(0.8)		(0.1)		0.4		4.2
Credit card	0.3		0.2		(0.3)		0.1		0.3
Total commercial	39.2		(5.5)		(2.6)		2.8		33.9
Agricultural:
Agricultural	0.7		(0.1)		(0.2)		—		0.4
Total agricultural	0.7		(0.1)		(0.2)		—		0.4
Total allowance for credit losses	$	144.3	$	(4.6)	$	(11.8)	$	7.2	$	135.1
(1) Amounts presented are exclusive of the allowance for credit losses related to unfunded commitments which are included in Note “Financial Instruments with Off-Balance Sheet Risk” included in this report.

Schedule of Recorded Investment in Impaired Loans

The following tables present the amortized cost basis of collateral-dependent loans by class of loans as of the dates indicated:

	Collateral Type
As of September 30, 2022	Business Assets		Real Property		Other		Total
Real estate	$	2.2	$	39.1	$	—	$	41.3
Commercial	1.4		4.9		—		6.3
Agricultural	0.3		9.7		—		10.0
Total collateral-dependent	$	3.9	$	53.7	$	—	$	57.6

	Collateral Type
As of December 31, 2021	Business Assets		Real Property		Other		Total
Real estate	$	1.2	$	7.0	$	—	$	8.2
Commercial	1.8		1.0		—		2.8
Agricultural	—		0.7		—		0.7
Total collateral-dependent	$	3.0	$	8.7	$	—	$	11.7

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 greater than 90 days past due continue to accrue interest. The following tables present the contractual aging of the Company’s recorded amortized cost basis in loans by portfolio as of the dates indicated.

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of September 30, 2022	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate
Commercial	$	9.7	$	2.7	$	1.4	$	13.8	$	7,986.6	$	26.5	$	8,026.9
Construction:
Land acquisition & development	0.6		0.4		0.2		1.2		388.1		3.9		393.2
Residential	3.9		—		0.4		4.3		497.1		—		501.4
Commercial	6.8		—		—		6.8		1,121.6		—		1,128.4
Total construction loans	11.3		0.4		0.6		12.3		2,006.8		3.9		2,023.0
Residential	1.1		3.4		1.2		5.7		2,115.6		6.4		2,127.7
Agricultural	1.3		—		0.7		2.0		783.3		15.6		800.9
Total real estate loans	23.4		6.5		3.9		33.8		12,892.3		52.4		12,978.5
Consumer:
Indirect consumer	6.0		1.3		0.2		7.5		771.3		2.0		780.8
Other consumer	0.7		0.2		0.1		1.0		153.9		0.1		155.0
Credit card	0.6		0.4		0.5		1.5		72.7		—		74.2
Total consumer loans	7.3		1.9		0.8		10.0		997.9		2.1		1,010.0
Commercial	9.5		1.7		1.8		13.0		2,941.4		11.7		2,966.1
Agricultural	2.1		0.1		0.1		2.3		642.7		13.2		658.2
Other, including overdrafts	—		—		—		—		3.8		—		3.8
Loans held for investment	$	42.3	$	10.2	$	6.6	$	59.1	$	17,478.1	$	79.4	$	17,616.6

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2021	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)		Loans
Real estate
Commercial	$	1.1	$	1.0	$	0.6	$	2.7	$	3,960.8	$	8.0	$	3,971.5
Construction:
Land acquisition & development	0.2		—		—		0.2		246.9		0.7		247.8
Residential	4.2		—		—		4.2		257.8		—		262.0
Commercial	—		—		—		—		498.0		—		498.0
Total construction loans	4.4		—		—		4.4		1,002.7		0.7		1,007.8
Residential	3.0		0.8		0.1		3.9		1,531.4		2.9		1,538.2
Agricultural	1.9		0.2		—		2.1		206.9		4.9		213.9
Total real estate loans	10.4		2.0		0.7		13.1		6,701.8		16.5		6,731.4
Consumer:
Indirect consumer	5.1		1.4		0.4		6.9		729.0		1.7		737.6
Other consumer	0.5		0.2		0.1		0.8		128.3		0.1		129.2
Credit card	0.6		0.2		0.5		1.3		63.6		—		64.9
Total consumer loans	6.2		1.8		1.0		9.0		920.9		1.8		931.7
Commercial	4.9		0.7		1.1		6.7		1,463.8		5.0		1,475.5
Agricultural	0.7		—		—		0.7		201.6		1.6		203.9
Other, including overdrafts	—		—		—		—		1.5		—		1.5
Loans held for investment	$	22.2	$	4.5	$	2.8	$	29.5	$	9,289.6	$	24.9	$	9,344.0

(1) As of September 30, 2022 and December 31, 2021, 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, 2022 and 2021, respectively. There were $0.6 million and no reversals of accrued interest at September 30, 2022 and September 30, 2021. respectively.

Financing Receivable, Troubled Debt Restructuring

The Company had $48.1 million and $71.7 million of new troubled debt restructurings during the three and the nine months ended September 30, 2022, respectively.

	Number of Notes	Type of Concession								Principal Balance at Restructure
Three Months Ended September 30, 2022		Interest only period		Extension of term or amortization schedule		Interest rate adjustment		Other (1)
Commercial real estate	1	$	—	$	—	$	—	$	46.1	$	46.1
Agricultural real estate	1	—		0.1		—		—		0.1
Commercial	1	—		1.9		—		—		1.9
Total loans restructured during period	3	$	—	$	2.0	$	—	$	46.1	$	48.1
(1) Other includes concessions that reduce or defer payments for a specified period of time and/or concessions that do not fit into other designated categories.
	Number of Notes	Type of Concession								Principal Balance at Restructure
Nine Months Ended September 30, 2022		Interest only period		Extension of term or amortization schedule		Interest rate adjustment		Other (1)
Commercial real estate	4	$	3.2	$	4.2	$	—	$	46.3	$	53.7
Residential real estate	2	—		0.6		—		—		0.6
Agriculture real estate	2	—		9.0		—		—		9.0
Commercial	3	—		1.9		—		0.6		2.5
Agriculture	1	—		—		—		5.9		5.9
Total loans restructured during period	12	$	3.2	$	15.7	$	—	$	52.8	$	71.7
(1) Other includes concessions that reduce or defer payments for a specified period of time and/or concessions that do not fit into other designated categories.

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 the date of the acquisition with the purchase price (or initial fair value of the loans) as amended for measurement period adjustments as of September 30, 2022:

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 GWB PCD loans acquired 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 loan losses of the following segments based on the aforementioned risk scale for the periods indicated:

	September 30, 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	$	784.9	$	784.8	$	666.7	$	463.9	$	279.4	$	913.3	$	27.5	$	3,920.5
Special mention	6.0		4.4		0.4		4.7		8.3		19.8		—		43.6
Substandard	3.5		33.2		10.7		18.9		20.1		9.5		—		95.9
Doubtful	—		—		—		—		1.8		—		—		1.8
Total	$	794.4	$	822.4	$	677.8	$	487.5	$	309.6	$	942.6	$	27.5	$	4,061.8
Commercial real estate owner occupied:
Pass	$	621.4	$	757.4	$	552.2	$	282.9	$	177.4	$	589.9	$	16.3	$	2,997.5
Special mention	5.2		8.8		1.5		11.1		2.8		9.8		0.3		39.5
Substandard	12.1		3.0		2.3		4.6		2.8		17.8		0.4		43.0
Doubtful	0.4		1.5		—		—		7.9		2.0		—		11.8
Total	$	639.1	$	770.7	$	556.0	$	298.6	$	190.9	$	619.5	$	17.0	$	3,091.8
Commercial multi-family:
Pass	$	267.4	$	209.6	$	188.8	$	52.5	$	35.7	$	115.7	$	1.5	$	871.2
Special mention	—		—		—		—		—		1.8		—		1.8
Substandard	—		—		—		—		—		0.3		—		0.3
Total	$	267.4	$	209.6	$	188.8	$	52.5	$	35.7	$	117.8	$	1.5	$	873.3
Land, acquisition and development:
Pass	$	122.7	$	141.0	$	31.7	$	25.6	$	12.4	$	30.1	$	17.7	$	381.2
Special mention	6.7		—		—		—		0.2		0.3		—		7.2
Substandard	—		0.8		0.2		—		—		0.6		—		1.6
Doubtful	—		3.2		—		—		—		—		—		3.2
Total	$	129.4	$	145.0	$	31.9	$	25.6	$	12.6	$	31.0	$	17.7	$	393.2
Residential construction:
Pass	$	104.2	$	133.9	$	0.4	$	9.2	$	0.4	$	5.5	$	247.0	$	500.6
Substandard	—		0.4		—		—		—		0.4		—		0.8
Total	$	104.2	$	134.3	$	0.4	$	9.2	$	0.4	$	5.9	$	247.0	$	501.4
Commercial construction:
Pass	$	358.1	$	469.0	$	180.9	$	76.2	$	0.5	$	—	$	15.6	$	1,100.3
Special mention	2.1		—		23.1		—		—		—		—		25.2
Substandard	2.9		—		—		—		—		—		—		2.9
Total	$	363.1	$	469.0	$	204.0	$	76.2	$	0.5	$	—	$	15.6	$	1,128.4
Agricultural real estate:
Pass	$	162.5	$	175.6	$	119.5	$	67.3	$	48.0	$	111.9	$	28.7	$	713.5
Special mention	2.0		2.8		2.3		2.3		9.6		3.3		11.2		33.5
Substandard	1.1		13.9		3.6		3.4		3.2		14.2		11.4		50.8
Doubtful	—		—		3.1		—		—		—		—		3.1
Total	$	165.6	$	192.3	$	128.5	$	73.0	$	60.8	$	129.4	$	51.3	$	800.9
Commercial and floor plans:
Pass	$	415.9	$	406.3	$	233.4	$	138.5	$	130.3	$	178.9	$	707.5	$	2,210.8
Special mention	10.1		9.6		2.1		3.9		1.4		5.2		64.5		96.8
Substandard	8.0		1.2		3.4		2.7		3.5		2.4		6.6		27.8
Doubtful	0.3		4.7		—		—		—		—		—		5.0
Total	$	434.3	$	421.8	$	238.9	$	145.1	$	135.2	$	186.5	$	778.6	$	2,340.4

	September 30, 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	$	155.8	$	140.4	$	71.6	$	31.4	$	31.0	$	43.2	$	29.9	$	503.3
Special mention	0.2		1.1		2.3		0.2		1.5		0.3		—		5.6
Substandard	0.2		0.3		0.1		0.3		0.9		1.2		0.1		3.1
Total	$	156.2	$	141.8	$	74.0	$	31.9	$	33.4	$	44.7	$	30.0	$	512.0
Agricultural:
Pass	$	107.6	$	70.9	$	35.0	$	12.8	$	9.9	$	1.5	$	356.3	$	594.0
Special mention	1.5		3.4		0.6		1.2		0.7		—		12.1		19.5
Substandard	23.1		6.5		5.0		0.9		4.2		1.1		1.4		42.2
Doubtful	—		0.6		—		—		—		—		—		0.6
Total	$	132.2	$	81.4	$	40.6	$	14.9	$	14.8	$	2.6	$	369.8	$	656.3

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Commercial real estate non-owner occupied:
Pass	$	507.9	$	452.2	$	237.9	$	150.4	$	76.3	$	409.0	$	15.3	$	1,849.0
Special mention	0.2		3.1		2.1		—		—		3.6		—		9.0
Substandard	3.9		15.3		2.3		0.7		1.0		12.4		—		35.6
Total	$	512.0	$	470.6	$	242.3	$	151.1	$	77.3	$	425.0	$	15.3	$	1,893.6
Commercial real estate owner occupied:
Pass	$	452.7	$	314.9	$	235.0	$	151.0	$	94.5	$	322.5	$	14.2	$	1,584.8
Special mention	1.3		3.2		1.5		7.4		3.5		13.8		—		30.7
Substandard	3.8		4.3		4.7		5.4		2.7		20.3		—		41.2
Total	$	457.8	$	322.4	$	241.2	$	163.8	$	100.7	$	356.6	$	14.2	$	1,656.7
Commercial multi-family:
Pass	$	129.1	$	118.6	$	43.9	$	15.4	$	36.0	$	76.7	$	1.5	$	421.2
Total	$	129.1	$	118.6	$	43.9	$	15.4	$	36.0	$	76.7	$	1.5	$	421.2
Land, acquisition and development:
Pass	$	113.0	$	41.5	$	34.2	$	14.8	$	19.8	$	20.8	$	1.2	$	245.3
Special mention	—		0.1		—		—		0.1		0.3		—		0.5
Substandard	0.8		0.2		—		0.6		0.3		0.1		—		2.0
Total	$	113.8	$	41.8	$	34.2	$	15.4	$	20.2	$	21.2	$	1.2	$	247.8
Residential construction:
Pass	$	112.4	$	7.0	$	13.7	$	0.9	$	—	$	—	$	127.2	$	261.2
Substandard	—		0.4		—		—		0.4		—		—		0.8
Total	$	112.4	$	7.4	$	13.7	$	0.9	$	0.4	$	—	$	127.2	$	262.0
Commercial construction:
Pass	$	209.7	$	141.4	$	118.8	$	27.6	$	—	$	0.5	$	—	$	498.0
Total	$	209.7	$	141.4	$	118.8	$	27.6	$	—	$	0.5	$	—	$	498.0

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Agricultural real estate:
Pass	$	58.3	$	36.9	$	35.1	$	22.6	$	11.8	$	28.1	$	4.9	$	197.7
Special mention	0.1		1.3		1.2		0.1		0.1		0.9		0.9		4.6
Substandard	4.0		0.4		1.0		0.6		1.3		4.3		—		11.6
Total	$	62.4	$	38.6	$	37.3	$	23.3	$	13.2	$	33.3	$	5.8	$	213.9
Commercial and floor plans:
Pass	$	394.2	$	165.7	$	94.5	$	73.5	$	47.1	$	91.3	$	224.7	$	1,091.0
Special mention	0.8		11.4		0.8		0.8		3.0		2.3		7.0		26.1
Substandard	1.3		2.8		1.6		2.6		0.6		4.1		2.6		15.6
Total	$	396.3	$	179.9	$	96.9	$	76.9	$	50.7	$	97.7	$	234.3	$	1,132.7
Commercial purpose secured by 1-4 family:
Pass	$	94.9	$	55.0	$	27.8	$	23.1	$	15.3	$	32.2	$	14.4	$	262.7
Special mention	—		0.2		0.2		0.5		0.1		0.6		—		1.6
Substandard	1.3		1.2		0.6		0.6		0.2		1.3		0.1		5.3
Total	$	96.2	$	56.4	$	28.6	$	24.2	$	15.6	$	34.1	$	14.5	$	269.6
Agricultural:
Pass	$	35.1	$	16.2	$	9.0	$	5.4	$	2.1	$	1.6	$	108.9	$	178.3
Special mention	0.2		4.1		0.1		0.4		0.6		0.3		7.0		12.7
Substandard	4.9		0.7		0.6		2.5		—		0.1		2.6		11.4
Total	$	40.2	$	21.0	$	9.7	$	8.3	$	2.7	$	2.0	$	118.5	$	202.4

The following tables present the recorded investment of our other loan portfolios based on the credit risk profile of loans that are performing and loans that are nonperforming as of the periods indicated:

	September 30, 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	$	195.3	$	466.3	$	550.2	$	102.3	$	32.6	$	230.2	$	—	$	1,576.9
Nonperforming	—		0.2		0.4		0.5		0.4		3.4		—		4.9
Total	$	195.3	$	466.5	$	550.6	$	102.8	$	33.0	$	233.6	$	—	$	1,581.8
Consumer home equity and HELOC:
Performing	$	14.9	$	8.7	$	5.4	$	4.4	$	5.7	$	17.6	$	486.5	$	543.2
Nonperforming	0.5		0.3		0.1		0.1		0.1		1.2		0.4		2.7
Total	$	15.4	$	9.0	$	5.5	$	4.5	$	5.8	$	18.8	$	486.9	$	545.9
Consumer indirect:
Performing	$	279.0	$	194.9	$	144.5	$	69.0	$	39.5	$	51.7	$	—	$	778.6
Nonperforming	0.2		0.6		0.4		0.3		0.2		0.5		—		2.2
Total	$	279.2	$	195.5	$	144.9	$	69.3	$	39.7	$	52.2	$	—	$	780.8
Consumer direct and advance line:
Performing	$	45.0	$	36.2	$	20.9	$	10.5	$	7.9	$	9.7	$	24.6	$	154.8
Nonperforming	—		0.1		—		—		—		0.1		—		0.2
Total	$	45.0	$	36.3	$	20.9	$	10.5	$	7.9	$	9.8	$	24.6	$	155.0

	December 31, 2021
	Term Loans Amortized Cost Basis by Origination Year
Risk by Collateral	2021		2020		2019		2018		2017		Prior		Revolving Loans Amortized Cost Basis		Total
Residential 1-4 family:
Performing	$	360.9	$	477.0	$	74.7	$	27.5	$	25.7	$	176.5	$	—	$	1,142.3
Nonperforming	—		0.3		—		—		0.2		0.8		—		1.3
Total	$	360.9	$	477.3	$	74.7	$	27.5	$	25.9	$	177.3	$	—	$	1,143.6
Consumer home equity and HELOC:
Performing	$	11.1	$	7.0	$	3.7	$	4.8	$	3.6	$	12.0	$	350.7	$	392.9
Nonperforming	0.3		—		0.3		—		0.6		0.5		—		1.7
Total	$	11.4	$	7.0	$	4.0	$	4.8	$	4.2	$	12.5	$	350.7	$	394.6
Consumer indirect:
Performing	$	272.6	$	208.6	$	108.3	$	64.0	$	37.0	$	45.0	$	—	$	735.5
Nonperforming	0.5		0.5		0.4		0.2		0.1		0.4		—		2.1
Total	$	273.1	$	209.1	$	108.7	$	64.2	$	37.1	$	45.4	$	—	$	737.6
Consumer direct and advance line:
Performing	$	42.5	$	27.9	$	15.0	$	13.3	$	5.8	$	7.6	$	16.9	$	129.0
Nonperforming	0.1		—		—		0.1		—		—		—		0.2
Total	$	42.6	$	27.9	$	15.0	$	13.4	$	5.8	$	7.6	$	16.9	$	129.2

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

As of September 30, 2022	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	73.8	$	113.3	$	1.9	$	189.0
Nonperforming	0.4		0.4		—		0.8
Total credit card	$	74.2	$	113.7	$	1.9	$	189.8

As of December 31, 2021	Consumer		Commercial		Agricultural		Total
Credit Card:
Performing	$	64.4	$	73.1	$	1.5	$	139.0
Nonperforming	0.5		0.1		—		0.6
Total credit card	$	64.9	$	73.2	$	1.5	$	139.6

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Other Real Estate Owned (Tables)

9 Months Ended

Sep. 30, 2022

Repossessed Assets [Abstract]

Other Real Estate Owned Roll Forward

Other real estate owned 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 other real estate owned is reflected in the following table:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Beginning balance	$	16.8	$	2.0	$	2.0	$	2.5
Acquired through acquisition	—		—		15.8		—
Additions	0.3		0.4		0.4		0.7
Valuation adjustments	(0.2)		—		(0.2)		—
Dispositions	(0.5)		(0.1)		(1.6)		(0.9)
Ending balance	$	16.4	$	2.3	$	16.4	$	2.3

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Derivatives and Hedging Activities (Tables)

9 Months Ended

Sep. 30, 2022

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 balance sheet related to cumulative basis adjustment for fair value hedges for the periods indicated:

	September 30, 2022				December 31, 2021
	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	$	—	$	—	$	695.6	$	(4.4)

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 balance sheet.

	September 30, 2022					December 31, 2021
	Notional Amount		Balance Sheet Location	Estimated Fair Value		Notional Amount		Balance Sheet Location	Estimated Fair Value
Derivatives designated as hedges:
Interest rate swap contracts	—			—		700.0			4.1
Derivatives not designated as hedges:
Interest rate swap contracts	1,743.3			42.1		913.9			22.2
Interest rate lock commitments	—			—		77.3			1.8
Forward loan sales contracts	32.3			0.6		—			—
Derivative assets in the balance sheet	$	1,775.6	Other Assets	$	42.7	$	1,691.2	Other Assets	$	28.1
Derivatives designated as hedges:
Interest rate collars	$	300.0		$	5.6	$	—		$	—
Interest rate swap contracts	—			—		87.6			0.1
Derivatives not designated as hedges:
Interest rate swap contracts	1,743.3			163.7		913.9			18.1
Risk participation agreements	107.2			0.1		—			—
Interest rate lock commitments	25.9			0.5		—			—
Forward loan sales contracts	—			—		102.4			—
Derivative liabilities in the balance sheet	$	2,176.4	Accrued Expenses	$	169.9	$	1,103.9	Accrued Expenses	$	18.2

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 income statement for the periods indicated:

	Three Months Ended September 30,					Nine Months Ended September 30,
		2022		2021			2022		2021
	Location of (Loss) Gain Recognized in Income on Derivative	Amount of (Loss) Gain Recognized in Income on Derivative				Location of (Loss) Gain Recognized in Income on Derivative	Amount of (Loss) Gain Recognized in Income on Derivative
Interest rate lock commitments	Mortgage banking revenues	$	(0.2)	$	1.3	Mortgage banking revenues	$	(1.7)	$	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 periods indicated:

	September 30, 2022
	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	$	42.1	$	—	$	42.1	$	—	$	42.1	$	—
Mortgage related derivatives	0.6		—		0.6		—		—		0.6
Total derivatives	42.7		—		42.7		—		42.1		0.6
Total assets	$	42.7	$	—	$	42.7	$	—	$	42.1	$	0.6
(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	$	169.3	$	—	$	169.3	$	—	$	5.6	$	163.7
Risk participation agreements	0.1		—		0.1		—		—		0.1
Mortgage related derivatives	0.5		—		0.5		—		—		0.5
Total derivatives	169.9		—		169.9		—		5.6		164.3
Repurchase agreements	1,075.6		—		1,075.6		—		1,075.6		—
Total liabilities	$	1,245.5	$	—	$	1,245.5	$	—	$	1,081.2	$	164.3

	December 31, 2021
	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	$	26.3	$	—	$	26.3	$	—	$	8.0	$	18.3
Mortgage related derivatives	1.8		—		1.8		—		—		1.8
Total derivatives	28.1		—		28.1		—		8.0		20.1
Total assets	$	28.1	$	—	$	28.1	$	—	$	8.0	$	20.1
	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	$	18.2	$	—	$	18.2	$	—	$	—	$	18.2
Total derivatives	18.2		—		18.2		—		—		18.2
Repurchase agreements	1,051.1		—		1,051.1		—		1,051.1		—
Total liabilities	$	1,069.3	$	—	$	1,069.3	$	—	$	1,051.1	$	18.2

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Earnings per Common Share (Tables)

9 Months Ended

Sep. 30, 2022

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,
	2022		2021		2022		2021
Net income	$	85.7	$	47.1	$	116.4	$	141.0
Weighted average common shares outstanding for basic earnings per share computation	106,525,974		61,673,656		102,879,422		61,641,342
Dilutive effects of stock-based compensation	63,725		74,316		55,938		91,480
Weighted average common shares outstanding for diluted earnings per common share computation	106,589,699		61,747,972		102,935,360		61,732,822
Basic earnings per common share	$	0.80	$	0.76	$	1.13	$	2.29
Diluted earnings per common share	$	0.80	$	0.76	$	1.13	$	2.28
Anti-dilutive unvested time restricted stock	48,871		89,142		51,161		88,677

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Regulatory Capital (Tables)

9 Months Ended

Sep. 30, 2022

Banking and Thrift, Other Disclosures [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, 2022 and December 31, 2021 are presented in the following tables: 

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(1)
September 30, 2022	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	2,820.2	12.50	%	$	1,804.7	8.00	%	$	2,368.7	10.50	%	$	2,255.9	10.00	%
FIB	2,704.8		12.01		1,801.1		8.00		2,363.9		10.50		2,251.4		10.00
Tier 1 risk-based capital:
Consolidated	2,366.8		10.49		1,353.5		6.00		1,917.5		8.50		1,804.7		8.00
FIB	2,508.9		11.14		1,350.8		6.00		1,913.7		8.50		1,801.1		8.00
Common equity tier 1 risk-based capital:
Consolidated	2,366.8		10.49		1,015.1		4.50		1,579.1		7.00		1,466.3		6.50
FIB	2,508.9		11.14		1,013.1		4.50		1,576.0		7.00		1,463.4		6.50
Leverage capital ratio:
Consolidated	2,366.8		7.67		1,234.4		4.00		1,234.4		4.00		1,543.0		5.00
FIB	2,508.9		8.14		1,232.2		4.00		1,232.2		4.00		1,540.2		5.00

	Actual				Minimum Required for Capital Adequacy Purposes				For Capital Adequacy Purposes Plus Capital Conservation Buffer				Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements(1)
December 31, 2021	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,659.3	14.11	%	$	940.9	8.00	%	$	1,235.0	10.50	%	$	1,176.2	10.00	%
FIB	1,472.5		12.56		938.0		8.00		1,231.1		10.50		1,172.5		10.00
Tier 1 risk-based capital:
Consolidated	1,469.0		12.49		705.7		6.00		999.7		8.50		940.9		8.00
FIB	1,382.2		11.79		703.5		6.00		996.6		8.50		938.0		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,384.8		11.77		529.3		4.50		823.3		7.00		764.5		6.50
FIB	1,382.2		11.79		527.6		4.50		820.8		7.00		762.1		6.50
Leverage capital ratio:
Consolidated	1,469.0		7.68		765.5		4.00		765.5		4.00		956.9		5.00
FIB	1,382.2		7.24		764.1		4.00		764.1		4.00		955.1		5.00

(1) 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, 2022

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,
	2022		2021		2022		2021
Beginning balance	$	6.2	$	3.4	$	3.8	$	3.7
Provision for (reversal of) credit loss expense	3.5		(0.2)		5.9		(0.5)
Ending balance of allowance for off-balance sheet credit losses	$	9.7	$	3.2	$	9.7	$	3.2

	September 30, 2022		December 31, 2021
Unused credit card lines	$	814.9	$	681.6
Commitments to extend credit	5,011.0		2,539.8
Standby letter of credit	92.4		57.5

XML

Other Comprehensive Income/Loss (Tables)

9 Months Ended

Sep. 30, 2022

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,	2022		2021		2022		2021		2022		2021
Investment securities available-for sale:
Change in net unrealized loss during period	$	(236.4)	$	(13.4)	$	(53.4)	$	(3.3)	$	(183.0)	$	(10.1)
Reclassification adjustment for net loss (gain) included in net income	24.2		(0.3)		5.5		(0.1)		18.7		(0.2)
Net change in unamortized (gains) losses on available-for-sale securities transferred into held-to-maturity	(1.7)		(2.5)		(0.4)		(0.6)		(1.3)		(1.9)
Change in net unrealized gain (loss) on derivatives	(15.9)		3.2		(3.6)		0.8		(12.3)		2.4
Total other comprehensive loss	$	(229.8)	$	(13.0)	$	(51.9)	$	(3.2)	$	(177.9)	$	(9.8)

	Pre-tax				Tax Expense (Benefit)				Net of Tax
Nine Months Ended September 30,	2022		2021		2022		2021		2022		2021
Investment securities available-for sale:
Change in net unrealized loss during period	$	(650.6)	$	(81.0)	$	(161.3)	$	(20.5)	$	(489.3)	$	(60.5)
Reclassification adjustment for net loss (gain) included in net income	24.4		(0.2)		5.5		(0.1)		18.9		(0.1)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	0.2		—		0.1		—		0.1		—
Net change in unamortized (gains) losses on available-for-sale securities transferred into held-to-maturity	(25.6)		22.3		(6.3)		5.7		(19.3)		16.6
Change in net unrealized gain (loss) on derivatives	(9.6)		2.3		(2.5)		0.6		(7.1)		1.7
Total other comprehensive loss	$	(661.2)	$	(56.6)	$	(164.5)	$	(14.3)	$	(496.7)	$	(42.3)

Schedule of Accumulated Other Comprehensive Income (Loss)

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

	September 30, 2022		December 31, 2021
Net unrealized loss on investment securities available-for-sale	$	(499.1)	$	(29.0)
Net unrealized (loss) gain on investment securities transferred to held-to-maturity	(4.4)		15.0
Net unrealized gain on derivatives	(4.2)		3.0
Net accumulated other comprehensive loss	$	(507.7)	$	(11.0)

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Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2022

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, 2022	Balance		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	$	336.8	$	336.8	$	—	$	—
State, county, and municipal securities	260.5			—	260.5			—
Obligations of U.S. government agencies	199.0			—	199.0			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	4,409.7			—	4,409.7			—
Private mortgage-backed securities	233.2			—	233.2			—
Collateralized loan obligations	1,105.1			—	1,105.1			—
Corporate securities	239.1			—	239.1			—
Loans held for sale	93.6			—	93.6			—
Derivative assets:
Interest rate swap contracts	42.1			—	42.1			—
Forward loan sale contracts	0.6			—	0.6			—
Derivative liabilities:
Interest rate collars	5.6			—	5.6			—
Interest rate swap contracts	163.7			—	163.7			—
Risk participation agreements	0.1			—	0.1			—
Interest rate lock commitments	0.5			—	0.5			—
Deferred compensation plan assets	19.0			—	19.0			—
Deferred compensation plan liabilities	19.0			—	19.0			—

			Fair Value Measurements at Reporting Date Using
As of December 31, 2021	Balance		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	$	684.7	$	684.7	$	—	$	—
State, county and municipal securities	427.5			—	427.5			—
Obligations of U.S. government agencies	346.9			—	346.9			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	2,018.1			—	2,018.1			—
Private mortgage-backed securities	173.4			—	173.4			—
Collateralized loan obligations	899.4			—	899.4			—
Corporate securities	270.5			—	270.5			—
Loans held for sale	30.1			—	30.1			—
Derivative assets:
Interest rate swap contracts	26.3			—	26.3			—
Interest rate lock commitments	1.8			—	1.8			—
Derivative liabilities
Interest rate swap contracts	18.2			—	18.2			—
Deferred compensation plan assets	21.4			—	21.4			—
Deferred compensation plan liabilities	21.4			—	21.4			—

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, 2022	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral dependent loans	$	57.6	$	—	$	—	$	57.6
Other real estate owned	16.4			—		—	16.4
Long-lived assets to be disposed of by sale	6.7			—		—	6.7
				Fair Value Measurements at Reporting Date Using
As of December 31, 2021	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Collateral dependent loans	$	11.7	$	—	$	—	$	11.7
Other real estate owned	2.0			—		—	2.0
Long-lived assets to be disposed of by sale	1.3			—		—	1.3

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, 2022		December 31, 2021		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Collateral dependent loans	$	57.6	$	11.7	Appraisal	Appraisal adjustment	1%	-	18%	(7%)
Other real estate owned	16.4		2.0		Appraisal	Appraisal adjustment	0%	-	0%	0%
Long-lived assets to be disposed of by sale	6.7		1.3		Appraisal	Appraisal adjustment	0%	-	0%	0%

Fair Value, by Balance Sheet Grouping

The estimated fair values of financial instruments that are reported in the Company’s consolidated balance sheets, and are segregated by the level of the valuation inputs within the fair value hierarchy that are utilized to measure fair value, are as follows:

					Fair Value Measurements at Reporting Date Using
As of September 30, 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	$	591.9	$	591.9	$	591.9	$	—	$	—
Investment debt securities available-for-sale	6,783.4		6,783.4		336.8		6,446.6		—
Investment debt securities held-to-maturity	3,485.7		3,063.5		385.5		2,678.0		—
Accrued interest receivable	106.4		106.4		—		106.4		—
Mortgage servicing rights, net	31.8		36.6		—		36.6		—
Loans held for sale	93.6		93.6		—		93.6		—
Net loans held for investment	17,390.5		17,293.6		—		17,236.0		57.6
Derivative assets	42.7		42.7		—		42.7		—
Deferred compensation plan assets	19.0		19.0		—		19.0		—
Total financial assets	$	28,545.0	$	28,030.7	$	1,314.2	$	26,658.9	$	57.6
Financial liabilities:
Total deposits, excluding time deposits	$	24,255.6	$	24,255.6	$	24,255.6	$	—	$	—
Time deposits	1,629.2		1,587.2		—		1,587.2		—
Securities sold under repurchase agreements	1,075.6		1,075.6		—		1,075.6		—
Other borrowed funds	625.0		625.0		—		625.0		—
Accrued interest payable	7.4		7.4		—		7.4		—
Long-term debt	120.7		116.7		—		116.7		—
Subordinated debentures held by subsidiary trusts	163.1		157.1		—		157.1		—
Derivative liabilities	169.9		169.9		—		169.9		—
Deferred compensation plan liabilities	19.0		19.0		—		19.0		—
Total financial liabilities	$	28,065.5	$	28,013.5	$	24,255.6	$	3,757.9	$	—

					Fair Value Measurements at Reporting Date Using
As of December 31, 2021	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	$	2,344.8	$	2,344.8	$	2,344.8	$	—	$	—
Investment debt securities available-for-sale	4,820.5		4,820.5		684.7		4,135.8		—
Investment debt securities held-to-maturity	1,687.6		1,667.5		—		1,667.5		—
Accrued interest receivable	47.4		47.4		—		47.4		—
Mortgage servicing rights, net	28.2		28.2		—		28.2		—
Loans held for sale	30.1		30.1		—		30.1		—
Net loans held for investment	9,209.4		9,254.3		—		9,242.6		11.7
Derivative assets	28.1		28.1		—		28.1		—
Deferred compensation plan assets	21.4		21.4		—		21.4		—
Total financial assets	$	18,217.5	$	18,242.3	$	3,029.5	$	15,201.1	$	11.7
Financial liabilities:
Total deposits, excluding time deposits	$	15,303.1	$	15,303.1	$	15,303.1	$	—	$	—
Time deposits	966.5		963.1		—		963.1		—
Securities sold under repurchase agreements	1,051.1		1,051.1		—		1,051.1		—
Accrued interest payable	3.7		3.7		—		3.7		—
Long-term debt	112.4		120.7		—		120.7		—
Subordinated debentures held by subsidiary trusts	87.0		85.5		—		85.5		—
Derivative liabilities	18.2		18.2		—		18.2		—
Deferred compensation plan liabilities	21.4		21.4		—		21.4		—
Total financial liabilities	$	17,563.4	$	17,566.8	$	15,303.1	$	2,263.7	$	—

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Acquisitions - Narrative (Details) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Feb. 01, 2022 USD ($) office $ / shares shares	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 1,100.0		$ 1,100.0		$ 621.6	$ 621.6
Estimated useful lives of related deposits				12 years
Acquisition related expenses		4.0	$ 6.6	$ 115.0	$ 6.6
Goodwill, Period Increase (Decrease)		0.2
Core Deposits
Business Acquisition [Line Items]
Estimated useful lives of related deposits	10 years			10 years
Great Western Bank
Business Acquisition [Line Items]
Number of banking offices acquired | office	174
Total consideration exchanged	$ 1,723.3
Goodwill	478.4
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	46,879,601
Price per share of First Interstate Class A common stock (in dollars per share) | $ / shares	$ 36.76
Great Western Bank | Customer Relationships
Business Acquisition [Line Items]
Estimated useful lives of related deposits	12 years
Acquisition related costs as defined by ASC 805
Business Acquisition [Line Items]
Acquisition related expenses		$ 0.0		$ 26.8

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Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Feb. 01, 2022	Sep. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
Liabilities assumed:
Goodwill		$ 1,100,000	$ 621,600	$ 621,600
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 (“OREO”)	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	63,600
Other assets	198,900
Total assets acquired	13,353,300
Liabilities assumed:
Deposits	11,688,000
Securities sold under repurchase agreements	74,000
Accrued expenses and other liabilities	111,000
FHLB advances	122,900
Subordinated debt	36,400
Subordinated debentures held by subsidiary trusts	76,100
Total liabilities assumed	12,108,400
Net assets acquired	1,244,900
Class A common stock	1,723,300
Total consideration paid (1)	1,723,300
Goodwill	478,400
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
Great Western Bank
Business Acquisition [Line Items]
Unpaid principal balance	979.2
Credit discount	69.2
Discount attributable to other factors	29.9
Purchase price (initial fair value)	623.3
Allowance for credit losses	59.5
Amortized cost basis	$ 682.8

XML

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
Great Western Bank
Business Acquisition [Line Items]
Unpaid principal balance	979.2
Principal amounts previously written off by GWB	(238.7)
Interest applied to principal by GWB	(18.1)
Adjusted unpaid principal balance	722.4
Credit discount	(69.2)
Discount attributable to other factors	(29.9)
Purchase price (initial fair value)	623.3
Allowance for credit losses	59.5
Amortized cost basis	682.8
Unpaid principal balance	7,107.9
Credit discount (1)	(76.5)
Non-credit discount	(9.2)
Fair value	7,022.2
Amortized cost basis	$ 7,705.0

XML

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, 2021	Sep. 30, 2022	Sep. 30, 2021
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 0.85	$ 1.02	$ 2.60	$ 1.63
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 0.85	$ 1.02	$ 2.60	$ 1.63
Great Western Bank
Business Acquisition [Line Items]
Total revenues	$ 314.0	$ 295.8	$ 883.5	$ 909.1
Net income	$ 90.3	$ 110.9	$ 267.8	$ 177.0

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Schedule of Adjustments to Goodwill (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2022	Jun. 30, 2022
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)	$ 0.2
Accrued expenses and other liabilties
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)	0.9
Loans held for sale
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)		$ 35.1
Premises and equipment
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)	(0.2)
Deferred tax assets
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)	$ 0.9

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Goodwill and Core Deposit Intangibles - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	Feb. 01, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of goodwill				$ 0
Goodwill [Line Items]
Amortization of intangible assets		$ 4,100,000	$ 2,400,000	$ 11,800,000	$ 7,400,000
Weighted average useful lives of related deposits				12 years
Core Deposits
Goodwill [Line Items]
Weighted average useful lives of related deposits	10 years			10 years

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Goodwill and Core Deposit Intangibles - Goodwill Carrying Value (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Net carrying value at beginning of the period	$ 621.6	$ 621.6
Provisional additions to goodwill from acquisition	478.4	0.0
Net carrying value at end of period	$ 1,100.0	$ 621.6

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Goodwill and Core Deposit Intangibles - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
2023	$ 15.6
Finite-lived Intangible Assets [Roll Forward]
Gross other intangible assets, at beginning of the period		$ 106.0	$ 106.0
Provisional amounts established through acquisition	72.9
Finite-Lived Intangible Assets, Period Increase (Decrease)	(1.4)
Accumulated amortization	(76.5)	(64.7)
Net other intangible assets, end of period	101.0	41.3
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2023	13.7
Finite-lived Intangible Assets [Roll Forward]
Gross other intangible assets, at beginning of the period		106.0	106.0
Provisional amounts established through acquisition	50.1
Finite-Lived Intangible Assets, Period Increase (Decrease)	(1.4)
Accumulated amortization	(75.2)	(64.7)
Net other intangible assets, end of period	79.5	41.3
OCRI
Finite-Lived Intangible Assets [Line Items]
2023	1.9
Finite-lived Intangible Assets [Roll Forward]
Gross other intangible assets, at beginning of the period		0.0	$ 0.0
Provisional amounts established through acquisition	22.8
Finite-Lived Intangible Assets, Period Increase (Decrease)	0.0
Accumulated amortization	(1.3)	0.0
Net other intangible assets, end of period	$ 21.5	$ 0.0

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Goodwill and Core Deposit Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
2022 remaining	$ 4.1
2023	15.6
2024	14.6
2025	13.7
2026	12.8
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	40.2
Total	101.0	$ 41.3
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2022 remaining	3.6
2023	13.7
2024	12.7
2025	11.8
2026	10.9
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	26.8
Total	79.5	41.3
OCRI
Finite-Lived Intangible Assets [Line Items]
2022 remaining	0.5
2023	1.9
2024	1.9
2025	1.9
2026	1.9
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	13.4
Total	$ 21.5	$ 0.0

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Investment Securities - Amortized Cost and Approximate Fair Values of Investment Securities (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Jun. 30, 2022	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Available-for-Sale:
Amortized Cost	$ 7,448,200,000	$ 4,859,300,000
Gross Unrealized Gains	200,000	20,600,000
Gross Unrealized Losses	(665,000,000.0)	(59,400,000)
Estimated Fair Value	6,783,400,000	4,820,500,000
Held-to-Maturity:
Amortized Cost	3,487,600,000	1,687,600,000
Allowance for Credit Losses	(1,900,000)	0	$ (1,600,000)	$ 0	$ 0	$ 0
Net Carrying Amount	3,485,700,000	1,687,600,000
Gross Unrealized Gains	200,000	15,600,000
Gross Unrealized Losses	(422,400,000)	(35,700,000)
Estimated Fair Value	3,063,500,000	1,667,500,000
U.S. Treasury notes
Available-for-Sale:
Amortized Cost	373,500,000	697,600,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(36,700,000)	(12,900,000)
Estimated Fair Value	336,800,000	684,700,000
Held-to-Maturity:
Amortized Cost	396,100,000
Allowance for Credit Losses	0
Net Carrying Amount	396,100,000
Gross Unrealized Gains	0
Gross Unrealized Losses	(10,600,000)
Estimated Fair Value	385,500,000
State, county, and municipal securities
Available-for-Sale:
Amortized Cost	317,800,000	434,700,000
Gross Unrealized Gains	0	2,100,000
Gross Unrealized Losses	(57,300,000)	(9,300,000)
Estimated Fair Value	260,500,000	427,500,000
Held-to-Maturity:
Amortized Cost	184,000,000.0	67,600,000
Allowance for Credit Losses	(100,000)	0
Net Carrying Amount	183,900,000	67,600,000
Gross Unrealized Gains	200,000	2,000,000.0
Gross Unrealized Losses	(33,200,000)	(400,000)
Estimated Fair Value	150,900,000	69,200,000
Obligations of U.S. government agencies
Available-for-Sale:
Amortized Cost	216,300,000	356,000,000.0
Gross Unrealized Gains	0	100,000
Gross Unrealized Losses	(17,300,000)	(9,200,000)
Estimated Fair Value	199,000,000.0	346,900,000
Held-to-Maturity:
Amortized Cost	350,800,000
Allowance for Credit Losses	0
Net Carrying Amount	350,800,000
Gross Unrealized Gains	0
Gross Unrealized Losses	(51,200,000)
Estimated Fair Value	299,600,000
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
Available-for-Sale:
Amortized Cost	4,852,200,000	2,027,300,000
Gross Unrealized Gains	200,000	14,100,000
Gross Unrealized Losses	(442,700,000)	(23,300,000)
Estimated Fair Value	4,409,700,000	2,018,100,000
Held-to-Maturity:
Amortized Cost	2,476,600,000	1,609,000,000
Allowance for Credit Losses	0	0
Net Carrying Amount	2,476,600,000	1,609,000,000
Gross Unrealized Gains	0	13,200,000
Gross Unrealized Losses	(320,000,000.0)	(35,300,000)
Estimated Fair Value	2,156,600,000	1,586,900,000
Debt Securities, Held-To-Maturity, Transfer, Unamortized Gain	15,200,000	20,100,000
Debt Securities, Held-To-Maturity, Transfer, Unamortized Loss	(20,800,000)
Private mortgage-backed securities
Available-for-Sale:
Amortized Cost	270,300,000	174,400,000
Gross Unrealized Gains	0	100,000
Gross Unrealized Losses	(37,100,000)	(1,100,000)
Estimated Fair Value	233,200,000	173,400,000
Collateralized Loan Obligations
Available-for-Sale:
Amortized Cost	1,145,500,000	898,200,000
Gross Unrealized Gains	0	1,200,000
Gross Unrealized Losses	(40,400,000)	0
Estimated Fair Value	1,105,100,000	899,400,000
Corporate Debt Securities
Available-for-Sale:
Amortized Cost	272,600,000	271,100,000
Gross Unrealized Gains	0	3,000,000.0
Gross Unrealized Losses	(33,500,000)	(3,600,000)
Estimated Fair Value	239,100,000	270,500,000
Held-to-Maturity:
Amortized Cost	80,100,000	11,000,000.0
Allowance for Credit Losses	(1,800,000)	0
Net Carrying Amount	78,300,000	11,000,000.0
Gross Unrealized Gains	0	400,000
Gross Unrealized Losses	(7,400,000)	0
Estimated Fair Value	$ 70,900,000	$ 11,400,000

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Investment Securities - Gross Unrealized Losses and Fair Values of Investment Securities (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Available-for-Sale:
Fair Value, Less than 12 Months	$ 5,554.5	$ 2,760.3
Gross Unrealized Losses, Less than 12 Months	(421.7)	(58.3)
Fair Value, 12 Months or Longer	1,201.7	68.7
Gross Unrealized Losses, 12 Months or Longer	(243.3)	(1.1)
Fair Value, Total	6,756.2	2,829.0
Gross Unrealized Losses, Total	(665.0)	(59.4)
US Treasury Notes Securities
Available-for-Sale:
Fair Value, Less than 12 Months	168.2
Gross Unrealized Losses, Less than 12 Months	(5.1)
Fair Value, 12 Months or Longer	168.6
Gross Unrealized Losses, 12 Months or Longer	(31.6)
Fair Value, Total	336.8
Gross Unrealized Losses, Total	(36.7)
U.S. Treasury notes
Available-for-Sale:
Fair Value, Less than 12 Months		684.7
Gross Unrealized Losses, Less than 12 Months		(12.9)
Fair Value, 12 Months or Longer		0.0
Gross Unrealized Losses, 12 Months or Longer		0.0
Fair Value, Total		684.7
Gross Unrealized Losses, Total		(12.9)
State, county, and municipal securities
Available-for-Sale:
Fair Value, Less than 12 Months	110.6	278.7
Gross Unrealized Losses, Less than 12 Months	(14.4)	(9.1)
Fair Value, 12 Months or Longer	136.4	5.0
Gross Unrealized Losses, 12 Months or Longer	(42.9)	(0.2)
Fair Value, Total	247.0	283.7
Gross Unrealized Losses, Total	(57.3)	(9.3)
Obligations of U.S. government agencies
Available-for-Sale:
Fair Value, Less than 12 Months	152.4	297.0
Gross Unrealized Losses, Less than 12 Months	(10.9)	(8.9)
Fair Value, 12 Months or Longer	45.9	16.4
Gross Unrealized Losses, 12 Months or Longer	(6.4)	(0.3)
Fair Value, Total	198.3	313.4
Gross Unrealized Losses, Total	(17.3)	(9.2)
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
Available-for-Sale:
Fair Value, Less than 12 Months	3,697.1	1,262.8
Gross Unrealized Losses, Less than 12 Months	(308.8)	(23.0)
Fair Value, 12 Months or Longer	699.8	26.4
Gross Unrealized Losses, 12 Months or Longer	(133.9)	(0.3)
Fair Value, Total	4,396.9	1,289.2
Gross Unrealized Losses, Total	(442.7)	(23.3)
Private mortgage-backed securities
Available-for-Sale:
Fair Value, Less than 12 Months	206.1	127.2
Gross Unrealized Losses, Less than 12 Months	(32.3)	(1.1)
Fair Value, 12 Months or Longer	27.0	0.0
Gross Unrealized Losses, 12 Months or Longer	(4.8)	0.0
Fair Value, Total	233.1	127.2
Gross Unrealized Losses, Total	(37.1)	(1.1)
Collateralized Loan Obligations
Available-for-Sale:
Fair Value, Less than 12 Months	1,076.1
Gross Unrealized Losses, Less than 12 Months	(39.8)
Fair Value, 12 Months or Longer	29.0
Gross Unrealized Losses, 12 Months or Longer	(0.6)
Fair Value, Total	1,105.1
Gross Unrealized Losses, Total	(40.4)
Corporate Debt Securities
Available-for-Sale:
Fair Value, Less than 12 Months	144.0	109.9
Gross Unrealized Losses, Less than 12 Months	(10.4)	(3.3)
Fair Value, 12 Months or Longer	95.0	20.9
Gross Unrealized Losses, 12 Months or Longer	(23.1)	(0.3)
Fair Value, Total	239.0	130.8
Gross Unrealized Losses, Total	$ (33.5)	$ (3.6)

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Investment Securities - Narrative (Details)		3 Months Ended		9 Months Ended
	Feb. 01, 2022 USD ($)	Sep. 30, 2022 USD ($) Investments	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Investments	Sep. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($) Investments	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Transfer, Amount	$ 10,700,000
Debt Securities, Held-To-Maturity, After Allowance For Credit Loss, Transfer, Amount	10,900,000
Debt Securities, Available-For-Sale, Amortized Cost, after Allowance for Credit Loss, Transfer, Amount	485,900,000
Debt Securities, Available-For-Sale, after Allowance for Credit Loss, Transfer, Amount	463,600,000
Debt Securities, Held-to-maturity, Transfer to Trading, Unrealized Gain (Loss)	0
Allowance for Credit Losses		$ 0		$ 0			$ 0
Debt Securities, Held-to-maturity, Allowance for Credit Loss		1,900,000	$ 0	1,900,000	$ 0	$ 1,600,000	0	$ 0	$ 0
Interest Receivable		106,400,000		106,400,000			47,400,000
Debt Securities, Available-for-sale, Realized Gain		0	0	0	0
Debt Securities, Available-for-sale, Realized Loss		46,300,000	$ 0	46,400,000	$ 0
Debt Securities, Available-for-sale, Amortized Cost		7,448,200,000		7,448,200,000			4,859,300,000
Securities Sold under Agreements to Repurchase, Fair Value of Collateral		4,836,700,000		4,836,700,000			2,617,800,000
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure		$ 4,265,100,000		$ 4,265,100,000			$ 2,610,800,000
Investment securities in an unrealized loss position (securities) | Investments		1,239		1,239			285
Great Western Bank
Schedule of Held-to-maturity Securities [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Debt Securities, Available-For-Sale	2,356,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Debt Securities, Held-To-Maturity	$ 342,100,000
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		$ 777,700,000		$ 777,700,000
Fair value of investment securities callable after one year but within five years		706,200,000		706,200,000
Callable structured notes amortized costs		$ 0		$ 0

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Investment Securities - Held-To-Maturity Allowance For Credit Loss (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 1,600,000	$ 0	$ 0	$ 0
Provision for credit loss expense	300,000	0	1,900,000	0
Ending balance of allowance for credit losses	$ 1,900,000	$ 0	$ 1,900,000	$ 0

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Investment Securities - Credit Quality Indicators (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	$ 3,487.6	$ 1,687.6
AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	3,292.9	1,626.2
AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	93.8	31.6
A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	12.0	18.7
BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	65.1	7.0
Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	13.8	4.1
BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	10.0
U.S. Treasury notes
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	396.1
U.S. Treasury notes | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	396.1
U.S. Treasury notes | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
U.S. Treasury notes | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
U.S. Treasury notes | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
U.S. Treasury notes | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
U.S. Treasury notes | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
State, county, and municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	184.0	67.6
State, county, and municipal securities | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	69.4	17.2
State, county, and municipal securities | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	93.8	31.6
State, county, and municipal securities | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	12.0	14.7
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	8.8	4.1
State, county, and municipal securities | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
Obligations of U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	350.8
Obligations of U.S. government agencies | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	350.8
Obligations of U.S. government agencies | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
Obligations of U.S. government agencies | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
Obligations of U.S. government agencies | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
Obligations of U.S. government agencies | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
Obligations of U.S. government agencies | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
Corporate securities
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	80.1	11.0
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	4.0
Corporate securities | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	65.1	7.0
Corporate securities | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	5.0	0.0
Corporate securities | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	10.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	2,476.6	1,609.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | FNMA/FHLMC
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	2,261.3	1,439.1
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | FNMA/FHLMC | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	2,261.3	1,439.1
U.S. agency residential & commercial mortgage-backed securities & 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
U.S. agency residential & commercial mortgage-backed securities & 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
U.S. agency residential & commercial mortgage-backed securities & 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
U.S. agency residential & commercial mortgage-backed securities & 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
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | FNMA/FHLMC | BB Rating
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | GNMA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	215.3	169.9
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | GNMA | AAA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	215.3	169.9
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | GNMA | AA
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | GNMA | A
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | GNMA | BBB
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	0.0
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations | GNMA | Not Rated
Schedule of Held-to-maturity Securities [Line Items]
Investment securities classified as held to maturity	0.0	$ 0.0
U.S. agency residential & commercial mortgage-backed securities & 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, 2022	Dec. 31, 2021
Available-for-Sale, Amortized Cost
Available-for-Sale Amortized Cost, Within One Year	$ 57.1
Available-for-Sale Amortized Cost, After One Year but Within Five Years	1,049.0
Available-for-Sale Amortized Cost, After Five Years but Within Ten Years	1,918.3
Available-for-Sale Amortized Cost, After Ten Years	4,423.8
Amortized Cost	7,448.2	$ 4,859.3
Available-for-Sale, Estimated Fair Value
Available-for-Sale Estimated Fair Value, Within One Year	56.4
Available-for-Sale Estimated Fair Value, After One Year but Within Five Years	998.0
Available-for-Sale Estimated Fair Value, After Five Years but Within Ten Years	1,710.2
Available-for-Sale Estimated Fair Value, After Ten Years	4,018.8
Available-for-Sale, Estimated Fair Value	6,783.4	4,820.5
Held-to-Maturity, Amortized Cost
Held-to-Maturity Amortized Cost, Within One Year	5.1
Held-to-Maturity Amortized Cost, After One Year but Within Five Years	546.0
Held-to-Maturity Amortized Cost, After Five Years but Within Ten Years	797.1
Held-to-Maturity Amortized Cost, After Ten Years	2,139.4
Amortized Cost	3,487.6	1,687.6
Held-to-Maturity, Estimated Fair Value
Held-to-Maturity Estimated Fair Value, Within One Year	5.0
Held-to-Maturity Estimated Fair Value, After One Year but Within Five Years	524.2
Held-to-Maturity Estimated Fair Value, After Five Years but Within Ten Years	695.2
Held-to-Maturity Estimated Fair Value, After Ten Years	1,839.1
Held-to-Maturity, Estimated Fair Value	3,063.5	1,667.5
Securities Sold under Agreements to Repurchase [Abstract]
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	4,836.7	2,617.8
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	$ 4,265.1	$ 2,610.8

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Loans Held for Sale - Narrative (Details) - USD ($)		3 Months Ended			9 Months Ended
	Feb. 01, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Mortgage loans held for sale		$ 93,600,000			$ 93,600,000		$ 30,100,000
Nonaccrual loans		43,100,000			43,100,000
Loans held for sale considered a troubled debt restructuring					0
Transfer of loans to held-for-sale					12,400,000	$ 0
Transfer of loans from held-for-sale to held for investment					19,800,000	$ 0
Allowance for loan losses, charge-off				$ 5,100,000
Goodwill, Period Increase (Decrease)		200,000
Proceeds from Collection of Loans Held-for-sale			$ 108,700,000
Loans held for sale
Debt Securities, Available-for-sale [Line Items]
Goodwill, Period Increase (Decrease)			35,100,000
Commercial
Debt Securities, Available-for-sale [Line Items]
Nonaccrual loans		11,700,000			11,700,000		5,000,000.0
Proceeds from Sale of Loans Held-for-sale		12,400,000	$ 23,400,000
Agricultural
Debt Securities, Available-for-sale [Line Items]
Transfer of loans from held-for-sale to held for investment				19,800,000
Cost basis after charge-off				$ 14,700,000
Residential
Debt Securities, Available-for-sale [Line Items]
Mortgage loans held for sale		18,200,000			18,200,000		30,100,000
Agricultural
Debt Securities, Available-for-sale [Line Items]
Mortgage loans held for sale		63,000,000.0			63,000,000.0		0
Nonaccrual loans		30,700,000			30,700,000
Transfer of loans to held-for-sale	$ 155,800,000
Commercial construction
Debt Securities, Available-for-sale [Line Items]
Transfer of loans to held-for-sale	$ 24,000,000
Commercial construction
Debt Securities, Available-for-sale [Line Items]
Mortgage loans held for sale		12,400,000			12,400,000		$ 0
Nonaccrual loans		$ 12,400,000			$ 12,400,000

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Loans Held for Investment - Schedule of Loans by Segment (Details) - USD ($) $ in Millions	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Deferred loan fees and costs	$ (13.1)		$ (12.3)
Loans held for investment, net of deferred fees and costs	17,603.5		9,331.7
Allowance for credit losses	(213.0)	$ (220.4)	(122.3)	$ (135.1)	$ (135.5)	$ (144.3)
Net loans held for investment	17,390.5		9,209.4
Commercial real estate
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(73.7)	(89.5)	(43.9)	(51.8)	(51.1)	(54.8)
Financing Receivable, Loan in Process	13.8		2.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	8,026.9		3,971.5
Commercial real estate | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	9.7		1.1
Commercial real estate | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.7		1.0
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	1.4		0.6
Commercial real estate | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	7,986.6		3,960.8
Land acquisition & development
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(0.7)	(0.8)	(0.5)	(0.9)	(1.0)	(1.3)
Financing Receivable, Loan in Process	1.2		0.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	393.2		247.8
Land acquisition & development | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.6		0.2
Land acquisition & development | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		0.0
Land acquisition & development | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.2		0.0
Land acquisition & development | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	388.1		246.9
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(3.1)	(3.4)	(2.4)	(1.8)	(1.5)	(1.6)
Financing Receivable, Loan in Process	4.3		4.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	501.4		262.0
Residential | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	3.9		4.2
Residential | 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
Residential | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		0.0
Residential | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	497.1		257.8
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(24.7)	(14.9)	(6.0)	(6.7)	(8.0)	(7.3)
Financing Receivable, Loan in Process	6.8		0.0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,128.4		498.0
Commercial | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.8		0.0
Commercial | 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
Commercial | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.0		0.0
Commercial | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1,121.6		498.0
Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	12.3		4.4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,023.0		1,007.8
Total construction loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	11.3		4.4
Total construction loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.4		0.0
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	0.6		0.0
Total construction loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,006.8		1,002.7
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(20.7)	(19.7)	(14.6)	(14.6)	(14.8)	(12.8)
Financing Receivable, Loan in Process	5.7		3.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,127.7		1,538.2
Residential | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.1		3.0
Residential | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	3.4		0.8
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	1.2		0.1
Residential | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,115.6		1,531.4
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(5.8)	(5.4)	(1.9)	(3.1)	(3.0)	(2.7)
Financing Receivable, Loan in Process	2.0		2.1
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	800.9		213.9
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.3		1.9
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.0		0.2
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	0.7		0.0
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	783.3		206.9
Total real estate loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(128.7)	(133.7)	(69.3)	(78.9)	(79.4)	(80.5)
Financing Receivable, Loan in Process	33.8		13.1
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	12,978.5		6,731.4
Total real estate loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	23.4		10.4
Total real estate loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.5		2.0
Total real estate 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	3.9		0.7
Total real estate loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	12,892.3		6,701.8
Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(14.1)	(13.1)	(14.3)	(15.4)	(15.8)	(16.7)
Financing Receivable, Loan in Process	7.5		6.9
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	780.8		737.6
Indirect consumer | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	6.0		5.1
Indirect consumer | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.3		1.4
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	0.2		0.4
Indirect consumer | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	771.3		729.0
Direct and advance lines
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(5.3)	(5.0)	(4.6)	(4.7)	(4.6)	(4.6)
Financing Receivable, Loan in Process	1.0		0.8
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	155.0		129.2
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	0.7		0.5
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		0.2
Direct and advance lines | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		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	153.9		128.3
Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(2.4)	(2.2)	(2.2)	(1.8)	(1.6)	(2.6)
Financing Receivable, Loan in Process	1.5		1.3
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	74.2		64.9
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		0.6
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		0.2
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		0.5
Credit card | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	72.7		63.6
Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(21.8)	(20.3)	(21.1)	(21.9)	(22.0)	(23.9)
Financing Receivable, Loan in Process	10.0		9.0
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,010.0		931.7
Total consumer loans | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	7.3		6.2
Total consumer loans | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.9		1.8
Total consumer loans | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.8		1.0
Total consumer loans | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	997.9		920.9
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(58.5)	(59.9)	(31.6)	(33.9)	(33.7)	(39.2)
Financing Receivable, Loan in Process	13.0		6.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,966.1		1,475.5
Commercial | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	9.5		4.9
Commercial | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	1.7		0.7
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	1.8		1.1
Commercial | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2,941.4		1,463.8
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Allowance for credit losses	(4.0)	$ (6.5)	(0.3)	$ (0.4)	$ (0.4)	$ (0.7)
Financing Receivable, Loan in Process	2.3		0.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	658.2		203.9
Agricultural | 30 to 59 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	2.1		0.7
Agricultural | 60 to 89 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		0.0
Agricultural | Equal to or Greater than 90 Days Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	0.1		0.0
Agricultural | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	642.7		201.6
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	3.8		1.5
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	3.8		1.5
Loans And Leases Held For Investment [Member]
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	59.1		29.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	17,616.6		9,344.0
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	42.3		22.2
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	10.2		4.5
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	6.6		2.8
Loans And Leases Held For Investment [Member] | Financial Asset, Not Past Due
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Financing Receivable, Loan in Process	$ 17,478.1		$ 9,289.6

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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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 220.4	$ 135.5	$ 122.3	$ 144.3
Provisional ACL Recorded for PCD loans	0.0		59.5
Provision for (reversal of) credit losses	8.4	0.0	68.0	(5.1)
Loans Charged-Off	(16.2)	(2.1)	(39.8)	(11.8)
Recoveries Collected	4.2	1.5	10.8	7.2
Ending balance	213.0	135.1	213.0	135.1
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	4.6	0.2	60.2	(4.6)
Great Western Bank
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	68.3
Non-owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	29.5	22.9	17.3	25.5
Provisional ACL Recorded for PCD loans	0.0		17.2
Provision for (reversal of) credit losses	(5.5)	1.1	(7.6)	(1.6)
Loans Charged-Off	(0.1)	0.0	(3.0)	0.0
Recoveries Collected	0.0	0.0	0.0	0.1
Ending balance	23.9	24.0	23.9	24.0
Owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	26.6	16.6	13.3	18.3
Provisional ACL Recorded for PCD loans	0.0		9.5
Provision for (reversal of) credit losses	(3.7)	(0.6)	2.3	0.0
Loans Charged-Off	0.0	0.0	(2.2)	(2.3)
Recoveries Collected	1.8	0.0	1.8	0.0
Ending balance	24.7	16.0	24.7	16.0
Multi-family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	33.4	11.6	13.3	11.0
Provisional ACL Recorded for PCD loans	0.0		10.9
Provision for (reversal of) credit losses	(2.6)	0.2	5.9	0.8
Loans Charged-Off	(5.7)	0.0	(5.7)	0.0
Recoveries Collected	0.0	0.0	0.7	0.0
Ending balance	25.1	11.8	25.1	11.8
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	89.5	51.1	43.9	54.8
Provisional ACL Recorded for PCD loans	0.0		37.6
Provision for (reversal of) credit losses	(11.8)	0.7	0.6	(0.8)
Loans Charged-Off	(5.8)	0.0	(10.9)	(2.3)
Recoveries Collected	1.8	0.0	2.5	0.1
Ending balance	73.7	51.8	73.7	51.8
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6.5	0.4	0.3	0.7
Provisional ACL Recorded for PCD loans	0.0		4.5
Provision for (reversal of) credit losses	(2.5)	0.0	3.3	(0.1)
Loans Charged-Off	0.0	0.0	(5.4)	(0.2)
Recoveries Collected	0.0	0.0	1.3	0.0
Ending balance	4.0	0.4	4.0	0.4
Commercial and floor plans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	54.1	29.0	27.1	34.2
Provisional ACL Recorded for PCD loans	0.0		11.2
Provision for (reversal of) credit losses	(2.2)	0.3	18.1	(4.9)
Loans Charged-Off	(0.5)	(0.1)	(5.8)	(2.2)
Recoveries Collected	1.0	0.2	1.8	2.3
Ending balance	52.4	29.4	52.4	29.4
Commercial purpose secured by 1-4 family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5.5	4.4	4.4	4.7
Provisional ACL Recorded for PCD loans	0.0		0.2
Provision for (reversal of) credit losses	0.4	(0.2)	1.2	(0.8)
Loans Charged-Off	0.0	0.0	0.0	(0.1)
Recoveries Collected	0.0	0.0	0.1	0.4
Ending balance	5.9	4.2	5.9	4.2
Land acquisition & development
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0.8	1.0	0.5	1.3
Provisional ACL Recorded for PCD loans	0.0		3.4
Provision for (reversal of) credit losses	(0.2)	(0.2)	(0.8)	(0.8)
Loans Charged-Off	0.0	0.0	(2.7)	(0.1)
Recoveries Collected	0.1	0.1	0.3	0.5
Ending balance	0.7	0.9	0.7	0.9
Residential construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3.4	1.5	2.4	1.6
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	(0.3)	0.3	0.7	0.3
Loans Charged-Off	0.0	0.0	0.0	(0.1)
Recoveries Collected	0.0	0.0	0.0	0.0
Ending balance	3.1	1.8	3.1	1.8
Commercial construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	14.9	8.0	6.0	7.3
Provisional ACL Recorded for PCD loans	0.0		0.2
Provision for (reversal of) credit losses	16.4	(1.3)	25.1	(0.6)
Loans Charged-Off	(6.6)	0.0	(6.6)	(0.1)
Recoveries Collected	0.0	0.0	0.0	0.1
Ending balance	24.7	6.7	24.7	6.7
Total construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	19.1	10.5	8.9	10.2
Provisional ACL Recorded for PCD loans	0.0		3.6
Provision for (reversal of) credit losses	15.9	(1.2)	25.0	(1.1)
Loans Charged-Off	(6.6)	0.0	(9.3)	(0.3)
Recoveries Collected	0.1	0.1	0.3	0.6
Ending balance	28.5	9.4	28.5	9.4
Residential 1-4 family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	18.2	13.4	13.4	11.4
Provisional ACL Recorded for PCD loans	0.0		0.1
Provision for (reversal of) credit losses	0.9	(0.2)	5.4	1.8
Loans Charged-Off	0.0	0.0	(0.1)	0.0
Recoveries Collected	0.0	0.0	0.3	0.0
Ending balance	19.1	13.2	19.1	13.2
Home equity and HELOC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1.5	1.4	1.2	1.4
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	0.1	(0.1)	0.1	(0.2)
Loans Charged-Off	(0.1)	0.0	(0.1)	(0.1)
Recoveries Collected	0.1	0.1	0.4	0.3
Ending balance	1.6	1.4	1.6	1.4
Residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	19.7	14.8	14.6	12.8
Provisional ACL Recorded for PCD loans	0.0		0.1
Provision for (reversal of) credit losses	1.0	(0.3)	5.5	1.6
Loans Charged-Off	(0.1)	0.0	(0.2)	(0.1)
Recoveries Collected	0.1	0.1	0.7	0.3
Ending balance	20.7	14.6	20.7	14.6
Agricultural
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5.4	3.0	1.9	2.7
Provisional ACL Recorded for PCD loans	0.0		2.3
Provision for (reversal of) credit losses	0.4	0.1	1.7	0.4
Loans Charged-Off	0.0	0.0	(0.2)	0.0
Recoveries Collected	0.0	0.0	0.1	0.0
Ending balance	5.8	3.1	5.8	3.1
Total real estate loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	133.7	79.4	69.3	80.5
Provisional ACL Recorded for PCD loans	0.0		43.6
Provision for (reversal of) credit losses	5.5	(0.7)	32.8	0.1
Loans Charged-Off	(12.5)	0.0	(20.6)	(2.7)
Recoveries Collected	2.0	0.2	3.6	1.0
Ending balance	128.7	78.9	128.7	78.9
Indirect consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	13.1	15.8	14.3	16.7
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	1.6	(0.1)	0.9	(0.3)
Loans Charged-Off	(1.2)	(0.8)	(2.9)	(2.9)
Recoveries Collected	0.6	0.5	1.8	1.9
Ending balance	14.1	15.4	14.1	15.4
Direct and advance lines
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5.0	4.6	4.6	4.6
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	1.3	0.5	1.7	1.2
Loans Charged-Off	(1.4)	(0.8)	(2.8)	(2.0)
Recoveries Collected	0.4	0.4	1.8	0.9
Ending balance	5.3	4.7	5.3	4.7
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2.2	1.6	2.2	2.6
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	0.3	0.4	1.6	0.0
Loans Charged-Off	(0.3)	(0.4)	(1.8)	(1.4)
Recoveries Collected	0.2	0.2	0.4	0.6
Ending balance	2.4	1.8	2.4	1.8
Total consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	20.3	22.0	21.1	23.9
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	3.2	0.8	4.2	0.9
Loans Charged-Off	(2.9)	(2.0)	(7.5)	(6.3)
Recoveries Collected	1.2	1.1	4.0	3.4
Ending balance	21.8	21.9	21.8	21.9
Credit card
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0.3	0.3	0.1	0.3
Provisional ACL Recorded for PCD loans	0.0		0.0
Provision for (reversal of) credit losses	0.2	0.0	0.6	0.2
Loans Charged-Off	(0.3)	0.0	(0.5)	(0.3)
Recoveries Collected	0.0	0.0	0.0	0.1
Ending balance	0.2	0.3	0.2	0.3
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	59.9	33.7	31.6	39.2
Provisional ACL Recorded for PCD loans	0.0		11.4
Provision for (reversal of) credit losses	(1.6)	0.1	19.9	(5.5)
Loans Charged-Off	(0.8)	(0.1)	(6.3)	(2.6)
Recoveries Collected	1.0	0.2	1.9	2.8
Ending balance	$ 58.5	$ 33.9	$ 58.5	$ 33.9

XML

Loans Held for Investment - Schedule of Allowance for Credit Losses for Loans Held for Investment (Details)		3 Months Ended		9 Months Ended
	Feb. 01, 2022 USD ($)	Sep. 30, 2022 USD ($) Investments	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Investments	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) Investments
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		$ 220,400,000	$ 135,500,000	$ 122,300,000	$ 144,300,000
Provision charged to operating expense		8,400,000	0	68,000,000.0	(5,100,000)
Loans Charged-Off		(16,200,000)	(2,100,000)	(39,800,000)	(11,800,000)
Ending balance		213,000,000.0	135,100,000	213,000,000.0	135,100,000
Provisional ACL Recorded for PCD loans		0		59,500,000
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)		4,600,000	200,000	60,200,000	(4,600,000)
Financing Receivable, Allowance for Credit Loss, Recovery		4,200,000	1,500,000	10,800,000	7,200,000
Interest Receivable		106,400,000		106,400,000		$ 47,400,000
Debt Securities, Available-for-sale, Realized Loss		46,300,000	0	46,400,000	0
Debt Securities, Held-To-Maturity, After Allowance For Credit Loss, Transfer, Amount	$ 10,900,000
Debt Securities, Available-For-Sale, Amortized Cost, after Allowance for Credit Loss, Transfer, Amount	485,900,000
Debt Securities, Available-For-Sale, after Allowance for Credit Loss, Transfer, Amount	463,600,000
Debt Securities, Held-to-maturity, Transfer to Trading, Unrealized Gain (Loss)	0
Allowance for Credit Losses		$ 0		$ 0		$ 0
Investment securities in an unrealized loss position (securities) | Investments		1,239		1,239		285
Debt Securities, Available-for-sale, Realized Gain		$ 0	0	$ 0	0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral		4,836,700,000		4,836,700,000		$ 2,617,800,000
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure		4,265,100,000		4,265,100,000		2,610,800,000
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Transfer, Amount	10,700,000
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		777,700,000		777,700,000
Fair value of investment securities callable after one year but within five years		706,200,000		706,200,000
Callable structured notes amortized costs		0		0
Great Western Bank
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)		68,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Debt Securities, Available-For-Sale	2,356,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Debt Securities, Held-To-Maturity	$ 342,100,000
Debt Securities
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Interest Receivable		34,300,000		34,300,000		$ 16,600,000
Commercial Real Estate Non Owner Occupied Loans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		29,500,000	22,900,000	17,300,000	25,500,000
Provision charged to operating expense		(5,500,000)	1,100,000	(7,600,000)	(1,600,000)
Loans Charged-Off		(100,000)	0	(3,000,000.0)	0
Ending balance		23,900,000	24,000,000.0	23,900,000	24,000,000.0
Provisional ACL Recorded for PCD loans		0		17,200,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	0	100,000
Agricultural Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		6,500,000	400,000	300,000	700,000
Provision charged to operating expense		(2,500,000)	0	3,300,000	(100,000)
Loans Charged-Off		0	0	(5,400,000)	(200,000)
Ending balance		4,000,000.0	400,000	4,000,000.0	400,000
Provisional ACL Recorded for PCD loans		0		4,500,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	1,300,000	0
Commercial and Floor Plans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		54,100,000	29,000,000.0	27,100,000	34,200,000
Provision charged to operating expense		(2,200,000)	300,000	18,100,000	(4,900,000)
Loans Charged-Off		(500,000)	(100,000)	(5,800,000)	(2,200,000)
Ending balance		52,400,000	29,400,000	52,400,000	29,400,000
Provisional ACL Recorded for PCD loans		0		11,200,000
Financing Receivable, Allowance for Credit Loss, Recovery		1,000,000.0	200,000	1,800,000	2,300,000
Commercial Real Estate Owner Occupied [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		26,600,000	16,600,000	13,300,000	18,300,000
Provision charged to operating expense		(3,700,000)	(600,000)	2,300,000	0
Loans Charged-Off		0	0	(2,200,000)	(2,300,000)
Ending balance		24,700,000	16,000,000.0	24,700,000	16,000,000.0
Provisional ACL Recorded for PCD loans		0		9,500,000
Financing Receivable, Allowance for Credit Loss, Recovery		1,800,000	0	1,800,000	0
Commercial Real Estate Multi-family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		33,400,000	11,600,000	13,300,000	11,000,000.0
Provision charged to operating expense		(2,600,000)	200,000	5,900,000	800,000
Loans Charged-Off		(5,700,000)	0	(5,700,000)	0
Ending balance		25,100,000	11,800,000	25,100,000	11,800,000
Provisional ACL Recorded for PCD loans		0		10,900,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	700,000	0
Commercial real estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		89,500,000	51,100,000	43,900,000	54,800,000
Provision charged to operating expense		(11,800,000)	700,000	600,000	(800,000)
Loans Charged-Off		(5,800,000)	0	(10,900,000)	(2,300,000)
Ending balance		73,700,000	51,800,000	73,700,000	51,800,000
Provisional ACL Recorded for PCD loans		0		37,600,000
Financing Receivable, Allowance for Credit Loss, Recovery		1,800,000	0	2,500,000	100,000
Land Acquisition And Development Construction Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		800,000	1,000,000.0	500,000	1,300,000
Provision charged to operating expense		(200,000)	(200,000)	(800,000)	(800,000)
Loans Charged-Off		0	0	(2,700,000)	(100,000)
Ending balance		700,000	900,000	700,000	900,000
Provisional ACL Recorded for PCD loans		0		3,400,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	100,000	300,000	500,000
Residential construction
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		3,400,000	1,500,000	2,400,000	1,600,000
Provision charged to operating expense		(300,000)	300,000	700,000	300,000
Loans Charged-Off		0	0	0	(100,000)
Ending balance		3,100,000	1,800,000	3,100,000	1,800,000
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		14,900,000	8,000,000.0	6,000,000.0	7,300,000
Provision charged to operating expense		16,400,000	(1,300,000)	25,100,000	(600,000)
Loans Charged-Off		(6,600,000)	0	(6,600,000)	(100,000)
Ending balance		24,700,000	6,700,000	24,700,000	6,700,000
Provisional ACL Recorded for PCD loans		0		200,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	0	100,000
Construction Loans [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19,100,000	10,500,000	8,900,000	10,200,000
Provision charged to operating expense		15,900,000	(1,200,000)	25,000,000.0	(1,100,000)
Loans Charged-Off		(6,600,000)	0	(9,300,000)	(300,000)
Ending balance		28,500,000	9,400,000	28,500,000	9,400,000
Provisional ACL Recorded for PCD loans		0		3,600,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	100,000	300,000	600,000
Residential Real Estate 1-4 Family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		18,200,000	13,400,000	13,400,000	11,400,000
Provision charged to operating expense		900,000	(200,000)	5,400,000	1,800,000
Loans Charged-Off		0	0	(100,000)	0
Ending balance		19,100,000	13,200,000	19,100,000	13,200,000
Provisional ACL Recorded for PCD loans		0		100,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	300,000	0
Home Equity Line of Credit [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		1,500,000	1,400,000	1,200,000	1,400,000
Provision charged to operating expense		100,000	(100,000)	100,000	(200,000)
Loans Charged-Off		(100,000)	0	(100,000)	(100,000)
Ending balance		1,600,000	1,400,000	1,600,000	1,400,000
Provisional ACL Recorded for PCD loans		0		0
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	100,000	400,000	300,000
Residential Real Estate [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		19,700,000	14,800,000	14,600,000	12,800,000
Provision charged to operating expense		1,000,000.0	(300,000)	5,500,000	1,600,000
Loans Charged-Off		(100,000)	0	(200,000)	(100,000)
Ending balance		20,700,000	14,600,000	20,700,000	14,600,000
Provisional ACL Recorded for PCD loans		0		100,000
Financing Receivable, Allowance for Credit Loss, Recovery		100,000	100,000	700,000	300,000
Agricultural Real Estate Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,400,000	3,000,000.0	1,900,000	2,700,000
Provision charged to operating expense		400,000	100,000	1,700,000	400,000
Loans Charged-Off		0	0	(200,000)	0
Ending balance		5,800,000	3,100,000	5,800,000	3,100,000
Provisional ACL Recorded for PCD loans		0		2,300,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	100,000	0
Real Estate Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		133,700,000	79,400,000	69,300,000	80,500,000
Provision charged to operating expense		5,500,000	(700,000)	32,800,000	100,000
Loans Charged-Off		(12,500,000)	0	(20,600,000)	(2,700,000)
Ending balance		128,700,000	78,900,000	128,700,000	78,900,000
Provisional ACL Recorded for PCD loans		0		43,600,000
Financing Receivable, Allowance for Credit Loss, Recovery		2,000,000.0	200,000	3,600,000	1,000,000.0
Consumer Indirect Financing Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		13,100,000	15,800,000	14,300,000	16,700,000
Provision charged to operating expense		1,600,000	(100,000)	900,000	(300,000)
Loans Charged-Off		(1,200,000)	(800,000)	(2,900,000)	(2,900,000)
Ending balance		14,100,000	15,400,000	14,100,000	15,400,000
Provisional ACL Recorded for PCD loans		0		0
Financing Receivable, Allowance for Credit Loss, Recovery		600,000	500,000	1,800,000	1,900,000
Direct consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,000,000.0	4,600,000	4,600,000	4,600,000
Provision charged to operating expense		1,300,000	500,000	1,700,000	1,200,000
Loans Charged-Off		(1,400,000)	(800,000)	(2,800,000)	(2,000,000.0)
Ending balance		5,300,000	4,700,000	5,300,000	4,700,000
Provisional ACL Recorded for PCD loans		0		0
Financing Receivable, Allowance for Credit Loss, Recovery		400,000	400,000	1,800,000	900,000
Credit Card Receivable [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		2,200,000	1,600,000	2,200,000	2,600,000
Provision charged to operating expense		300,000	400,000	1,600,000	0
Loans Charged-Off		(300,000)	(400,000)	(1,800,000)	(1,400,000)
Ending balance		2,400,000	1,800,000	2,400,000	1,800,000
Provisional ACL Recorded for PCD loans		0		0
Financing Receivable, Allowance for Credit Loss, Recovery		200,000	200,000	400,000	600,000
Consumer
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		20,300,000	22,000,000.0	21,100,000	23,900,000
Provision charged to operating expense		3,200,000	800,000	4,200,000	900,000
Loans Charged-Off		(2,900,000)	(2,000,000.0)	(7,500,000)	(6,300,000)
Ending balance		21,800,000	21,900,000	21,800,000	21,900,000
Provisional ACL Recorded for PCD loans		0		0
Financing Receivable, Allowance for Credit Loss, Recovery		1,200,000	1,100,000	4,000,000.0	3,400,000
Commercial Purpose secured by 1-4 Family [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		5,500,000	4,400,000	4,400,000	4,700,000
Provision charged to operating expense		400,000	(200,000)	1,200,000	(800,000)
Loans Charged-Off		0	0	0	(100,000)
Ending balance		5,900,000	4,200,000	5,900,000	4,200,000
Provisional ACL Recorded for PCD loans		0		200,000
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	100,000	400,000
Commercial Borrower [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		300,000	300,000	100,000	300,000
Provision charged to operating expense		200,000	0	600,000	200,000
Loans Charged-Off		(300,000)	0	(500,000)	(300,000)
Ending balance		200,000	300,000	200,000	300,000
Provisional ACL Recorded for PCD loans		0		0
Financing Receivable, Allowance for Credit Loss, Recovery		0	0	0	100,000
Commercial Portfolio Segment [Member]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance		59,900,000	33,700,000	31,600,000	39,200,000
Provision charged to operating expense		(1,600,000)	100,000	19,900,000	(5,500,000)
Loans Charged-Off		(800,000)	(100,000)	(6,300,000)	(2,600,000)
Ending balance		58,500,000	33,900,000	58,500,000	33,900,000
Provisional ACL Recorded for PCD loans		0		11,400,000
Financing Receivable, Allowance for Credit Loss, Recovery		$ 1,000,000.0	$ 200,000	$ 1,900,000	$ 2,800,000

XML

Loans Held for Investment - Schedule of Contractual Aging of Loans by Portfolio (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Nonaccrual loans	$ 43,100,000		$ 43,100,000
Financing Receivable, Nonaccrual, Interest Income			0		$ 0
Impaired Financing Receivable, Interest Income, Accrual Method	0	$ 0	0	$ 0
Accrued interest reversal			600,000
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13,800,000		13,800,000		2,700,000
Nonaccrual loans	26,500,000		26,500,000		8,000,000.0
Land acquisition & development
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,200,000		1,200,000		200,000
Nonaccrual loans	3,900,000		3,900,000		700,000
Residential construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	4,300,000		4,300,000		4,200,000
Nonaccrual loans	0		0		0
Commercial construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6,800,000		6,800,000		0
Nonaccrual loans	0		0		0
Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	12,300,000		12,300,000		4,400,000
Nonaccrual loans	3,900,000		3,900,000		700,000
Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	5,700,000		5,700,000		3,900,000
Nonaccrual loans	6,400,000		6,400,000		2,900,000
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,000,000.0		2,000,000.0		2,100,000
Nonaccrual loans	15,600,000		15,600,000		4,900,000
Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	33,800,000		33,800,000		13,100,000
Nonaccrual loans	52,400,000		52,400,000		16,500,000
Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	7,500,000		7,500,000		6,900,000
Nonaccrual loans	2,000,000.0		2,000,000.0		1,700,000
Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,000,000.0		1,000,000.0		800,000
Nonaccrual loans	100,000		100,000		100,000
Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,500,000		1,500,000		1,300,000
Nonaccrual loans	0		0		0
Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	10,000,000.0		10,000,000.0		9,000,000.0
Nonaccrual loans	2,100,000		2,100,000		1,800,000
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	13,000,000.0		13,000,000.0		6,700,000
Nonaccrual loans	11,700,000		11,700,000		5,000,000.0
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,300,000		2,300,000		700,000
Nonaccrual loans	13,200,000		13,200,000		1,600,000
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	59,100,000		59,100,000		29,500,000
Nonaccrual loans	79,400,000		79,400,000		24,900,000
30 to 59 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9,700,000		9,700,000		1,100,000
30 to 59 Days Past Due | Land acquisition & development
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	600,000		600,000		200,000
30 to 59 Days Past Due | Residential construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3,900,000		3,900,000		4,200,000
30 to 59 Days Past Due | Commercial construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6,800,000		6,800,000		0
30 to 59 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	11,300,000		11,300,000		4,400,000
30 to 59 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,100,000		1,100,000		3,000,000.0
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,300,000		1,300,000		1,900,000
30 to 59 Days Past Due | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	23,400,000		23,400,000		10,400,000
30 to 59 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6,000,000.0		6,000,000.0		5,100,000
30 to 59 Days Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	700,000		700,000		500,000
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		600,000
30 to 59 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	7,300,000		7,300,000		6,200,000
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	9,500,000		9,500,000		4,900,000
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,100,000		2,100,000		700,000
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	42,300,000		42,300,000		22,200,000
60 to 89 Days Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,700,000		2,700,000		1,000,000.0
60 to 89 Days Past Due | Land acquisition & development
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	400,000		400,000		0
60 to 89 Days Past Due | Residential construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
60 to 89 Days Past Due | Commercial construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
60 to 89 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	400,000		400,000		0
60 to 89 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3,400,000		3,400,000		800,000
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		200,000
60 to 89 Days Past Due | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	6,500,000		6,500,000		2,000,000.0
60 to 89 Days Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,300,000		1,300,000		1,400,000
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		200,000
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		200,000
60 to 89 Days Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,900,000		1,900,000		1,800,000
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,700,000		1,700,000		700,000
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	100,000		100,000		0
60 to 89 Days Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
60 to 89 Days Past Due | Loans And Leases Held For Investment [Member]
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	10,200,000		10,200,000		4,500,000
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	1,400,000		1,400,000		600,000
Equal to or Greater than 90 Days Past Due | Land acquisition & development
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	200,000		200,000		0
Equal to or Greater than 90 Days Past Due | Residential construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	400,000		400,000		0
Equal to or Greater than 90 Days Past Due | Commercial construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	0		0		0
Equal to or Greater than 90 Days Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	600,000		600,000		0
Equal to or Greater than 90 Days Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,200,000		1,200,000		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	700,000		700,000		0
Equal to or Greater than 90 Days Past Due | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3,900,000		3,900,000		700,000
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	200,000		200,000		400,000
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	100,000		100,000		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		500,000
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	800,000		800,000		1,000,000.0
Equal to or Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,800,000		1,800,000		1,100,000
Equal to or Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	100,000		100,000		0
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	6,600,000		6,600,000		2,800,000
Financial Asset, Not Past Due | Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	7,986,600,000		7,986,600,000		3,960,800,000
Financial Asset, Not Past Due | Land acquisition & development
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	388,100,000		388,100,000		246,900,000
Financial Asset, Not Past Due | Residential construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	497,100,000		497,100,000		257,800,000
Financial Asset, Not Past Due | Commercial construction
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	1,121,600,000		1,121,600,000		498,000,000.0
Financial Asset, Not Past Due | Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,006,800,000		2,006,800,000		1,002,700,000
Financial Asset, Not Past Due | Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,115,600,000		2,115,600,000		1,531,400,000
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	783,300,000		783,300,000		206,900,000
Financial Asset, Not Past Due | Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	12,892,300,000		12,892,300,000		6,701,800,000
Financial Asset, Not Past Due | Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	771,300,000		771,300,000		729,000,000.0
Financial Asset, Not Past Due | Direct and advance lines
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	153,900,000		153,900,000		128,300,000
Financial Asset, Not Past Due | Credit card
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	72,700,000		72,700,000		63,600,000
Financial Asset, Not Past Due | Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	997,900,000		997,900,000		920,900,000
Financial Asset, Not Past Due | Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	2,941,400,000		2,941,400,000		1,463,800,000
Financial Asset, Not Past Due | Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	642,700,000		642,700,000		201,600,000
Financial Asset, Not Past Due | Other, including overdrafts
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Loan in Process	3,800,000		3,800,000		1,500,000
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	$ 17,478,100,000		$ 17,478,100,000		$ 9,289,600,000

XML

Loans Held for Investment - Schedule of Troubled Debt Restructurings (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022 USD ($) note	Sep. 30, 2022 USD ($) note
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	3	12
Troubled debt restructurings	$ 48.1	$ 71.7
Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	3.2
Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	2.0	15.7
Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 46.1	$ 52.8
Commercial Real Estate
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	1	4
Troubled debt restructurings	$ 46.1	$ 53.7
Commercial Real Estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	3.2
Commercial Real Estate | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	4.2
Commercial Real Estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Commercial Real Estate | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 46.1	$ 46.3
Residential
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note		2
Troubled debt restructurings		$ 0.6
Residential | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Residential | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.6
Residential | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Residential | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		$ 0.0
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	1	2
Troubled debt restructurings	$ 0.1	$ 9.0
Agricultural | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Agricultural | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.1	9.0
Agricultural | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Agricultural | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 0.0	$ 0.0
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note	1	3
Troubled debt restructurings	$ 1.9	$ 2.5
Commercial | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Commercial | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	1.9	1.9
Commercial | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	0.0	0.0
Commercial | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings	$ 0.0	$ 0.6
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Number of Notes | note		1
Troubled debt restructurings		$ 5.9
Agricultural | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Agricultural | Extension of term or amortization schedule
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Agricultural | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		0.0
Agricultural | Other Loan Restructuring Modification
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings		$ 5.9

XML

Loans Held for Investment - Schedule of Recorded Investment in Criticized Loans by Class and Credit Quality Indicator (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Impaired financing receivable, recorded investment	$ 191,400,000		$ 191,400,000
Commitments to purchase or sell	0	$ 0	0	$ 0
Proceeds from sale of loans held-for-investment	0	$ 0	0	$ 0
Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	794,400,000		794,400,000		$ 512,000,000.0
2021	822,400,000		822,400,000		470,600,000
2020	677,800,000		677,800,000		242,300,000
2019	487,500,000		487,500,000		151,100,000
2018	309,600,000		309,600,000		77,300,000
Prior	942,600,000		942,600,000		425,000,000.0
Revolving Loans Amortized Cost Basis	27,500,000		27,500,000		15,300,000
Total	4,061,800,000		4,061,800,000		1,893,600,000
Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	129,400,000		129,400,000		113,800,000
2021	145,000,000.0		145,000,000.0		41,800,000
2020	31,900,000		31,900,000		34,200,000
2019	25,600,000		25,600,000		15,400,000
2018	12,600,000		12,600,000		20,200,000
Prior	31,000,000.0		31,000,000.0		21,200,000
Revolving Loans Amortized Cost Basis	17,700,000		17,700,000		1,200,000
Total	393,200,000		393,200,000		247,800,000
Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	104,200,000		104,200,000		112,400,000
2021	134,300,000		134,300,000		7,400,000
2020	400,000		400,000		13,700,000
2019	9,200,000		9,200,000		900,000
2018	400,000		400,000		400,000
Prior	5,900,000		5,900,000		0
Revolving Loans Amortized Cost Basis	247,000,000.0		247,000,000.0		127,200,000
Total	501,400,000		501,400,000		262,000,000.0
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	363,100,000		363,100,000		209,700,000
2021	469,000,000.0		469,000,000.0		141,400,000
2020	204,000,000.0		204,000,000.0		118,800,000
2019	76,200,000		76,200,000		27,600,000
2018	500,000		500,000		0
Prior	0		0		500,000
Revolving Loans Amortized Cost Basis	15,600,000		15,600,000		0
Total	1,128,400,000		1,128,400,000		498,000,000.0
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	165,600,000		165,600,000		62,400,000
2021	192,300,000		192,300,000		38,600,000
2020	128,500,000		128,500,000		37,300,000
2019	73,000,000.0		73,000,000.0		23,300,000
2018	60,800,000		60,800,000		13,200,000
Prior	129,400,000		129,400,000		33,300,000
Revolving Loans Amortized Cost Basis	51,300,000		51,300,000		5,800,000
Total	800,900,000		800,900,000		213,900,000
Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	279,200,000		279,200,000		273,100,000
2021	195,500,000		195,500,000		209,100,000
2020	144,900,000		144,900,000		108,700,000
2019	69,300,000		69,300,000		64,200,000
2018	39,700,000		39,700,000		37,100,000
Prior	52,200,000		52,200,000		45,400,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	780,800,000		780,800,000		737,600,000
Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	45,000,000.0		45,000,000.0		42,600,000
2021	36,300,000		36,300,000		27,900,000
2020	20,900,000		20,900,000		15,000,000.0
2019	10,500,000		10,500,000		13,400,000
2018	7,900,000		7,900,000		5,800,000
Prior	9,800,000		9,800,000		7,600,000
Revolving Loans Amortized Cost Basis	24,600,000		24,600,000		16,900,000
Total	155,000,000.0		155,000,000.0		129,200,000
Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	189,800,000		189,800,000		139,600,000
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022					40,200,000
2021					21,000,000.0
2020					9,700,000
2019					8,300,000
2018					2,700,000
Prior					2,000,000.0
Revolving Loans Amortized Cost Basis					118,500,000
Total					202,400,000
Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	639,100,000		639,100,000		457,800,000
2021	770,700,000		770,700,000		322,400,000
2020	556,000,000.0		556,000,000.0		241,200,000
2019	298,600,000		298,600,000		163,800,000
2018	190,900,000		190,900,000		100,700,000
Prior	619,500,000		619,500,000		356,600,000
Revolving Loans Amortized Cost Basis	17,000,000.0		17,000,000.0		14,200,000
Total	3,091,800,000		3,091,800,000		1,656,700,000
Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	267,400,000		267,400,000		129,100,000
2021	209,600,000		209,600,000		118,600,000
2020	188,800,000		188,800,000		43,900,000
2019	52,500,000		52,500,000		15,400,000
2018	35,700,000		35,700,000		36,000,000.0
Prior	117,800,000		117,800,000		76,700,000
Revolving Loans Amortized Cost Basis	1,500,000		1,500,000		1,500,000
Total	873,300,000		873,300,000		421,200,000
Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	434,300,000		434,300,000		396,300,000
2021	421,800,000		421,800,000		179,900,000
2020	238,900,000		238,900,000		96,900,000
2019	145,100,000		145,100,000		76,900,000
2018	135,200,000		135,200,000		50,700,000
Prior	186,500,000		186,500,000		97,700,000
Revolving Loans Amortized Cost Basis	778,600,000		778,600,000		234,300,000
Total	2,340,400,000		2,340,400,000		1,132,700,000
Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	156,200,000		156,200,000		96,200,000
2021	141,800,000		141,800,000		56,400,000
2020	74,000,000.0		74,000,000.0		28,600,000
2019	31,900,000		31,900,000		24,200,000
2018	33,400,000		33,400,000		15,600,000
Prior	44,700,000		44,700,000		34,100,000
Revolving Loans Amortized Cost Basis	30,000,000.0		30,000,000.0		14,500,000
Total	512,000,000.0		512,000,000.0		269,600,000
Agriculture Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	132,200,000		132,200,000
2021	81,400,000		81,400,000
2020	40,600,000		40,600,000
2019	14,900,000		14,900,000
2018	14,800,000		14,800,000
Prior	2,600,000		2,600,000
Revolving Loans Amortized Cost Basis	369,800,000		369,800,000
Total	656,300,000		656,300,000
Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	195,300,000		195,300,000		360,900,000
2021	466,500,000		466,500,000		477,300,000
2020	550,600,000		550,600,000		74,700,000
2019	102,800,000		102,800,000		27,500,000
2018	33,000,000.0		33,000,000.0		25,900,000
Prior	233,600,000		233,600,000		177,300,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	1,581,800,000		1,581,800,000		1,143,600,000
Consumer Home Equity and HELOC
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	15,400,000		15,400,000		11,400,000
2021	9,000,000.0		9,000,000.0		7,000,000.0
2020	5,500,000		5,500,000		4,000,000.0
2019	4,500,000		4,500,000		4,800,000
2018	5,800,000		5,800,000		4,200,000
Prior	18,800,000		18,800,000		12,500,000
Revolving Loans Amortized Cost Basis	486,900,000		486,900,000		350,700,000
Total	545,900,000		545,900,000		394,600,000
Pass | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	784,900,000		784,900,000		507,900,000
2021	784,800,000		784,800,000		452,200,000
2020	666,700,000		666,700,000		237,900,000
2019	463,900,000		463,900,000		150,400,000
2018	279,400,000		279,400,000		76,300,000
Prior	913,300,000		913,300,000		409,000,000.0
Revolving Loans Amortized Cost Basis	27,500,000		27,500,000		15,300,000
Total	3,920,500,000		3,920,500,000		1,849,000,000
Pass | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	122,700,000		122,700,000		113,000,000.0
2021	141,000,000.0		141,000,000.0		41,500,000
2020	31,700,000		31,700,000		34,200,000
2019	25,600,000		25,600,000		14,800,000
2018	12,400,000		12,400,000		19,800,000
Prior	30,100,000		30,100,000		20,800,000
Revolving Loans Amortized Cost Basis	17,700,000		17,700,000		1,200,000
Total	381,200,000		381,200,000		245,300,000
Pass | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	104,200,000		104,200,000		112,400,000
2021	133,900,000		133,900,000		7,000,000.0
2020	400,000		400,000		13,700,000
2019	9,200,000		9,200,000		900,000
2018	400,000		400,000		0
Prior	5,500,000		5,500,000		0
Revolving Loans Amortized Cost Basis	247,000,000.0		247,000,000.0		127,200,000
Total	500,600,000		500,600,000		261,200,000
Pass | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	358,100,000		358,100,000		209,700,000
2021	469,000,000.0		469,000,000.0		141,400,000
2020	180,900,000		180,900,000		118,800,000
2019	76,200,000		76,200,000		27,600,000
2018	500,000		500,000		0
Prior	0		0		500,000
Revolving Loans Amortized Cost Basis	15,600,000		15,600,000		0
Total	1,100,300,000		1,100,300,000		498,000,000.0
Pass | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	162,500,000		162,500,000		58,300,000
2021	175,600,000		175,600,000		36,900,000
2020	119,500,000		119,500,000		35,100,000
2019	67,300,000		67,300,000		22,600,000
2018	48,000,000.0		48,000,000.0		11,800,000
Prior	111,900,000		111,900,000		28,100,000
Revolving Loans Amortized Cost Basis	28,700,000		28,700,000		4,900,000
Total	713,500,000		713,500,000		197,700,000
Pass | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022					35,100,000
2021					16,200,000
2020					9,000,000.0
2019					5,400,000
2018					2,100,000
Prior					1,600,000
Revolving Loans Amortized Cost Basis					108,900,000
Total					178,300,000
Pass | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	621,400,000		621,400,000		452,700,000
2021	757,400,000		757,400,000		314,900,000
2020	552,200,000		552,200,000		235,000,000.0
2019	282,900,000		282,900,000		151,000,000.0
2018	177,400,000		177,400,000		94,500,000
Prior	589,900,000		589,900,000		322,500,000
Revolving Loans Amortized Cost Basis	16,300,000		16,300,000		14,200,000
Total	2,997,500,000		2,997,500,000		1,584,800,000
Pass | Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	267,400,000		267,400,000		129,100,000
2021	209,600,000		209,600,000		118,600,000
2020	188,800,000		188,800,000		43,900,000
2019	52,500,000		52,500,000		15,400,000
2018	35,700,000		35,700,000		36,000,000.0
Prior	115,700,000		115,700,000		76,700,000
Revolving Loans Amortized Cost Basis	1,500,000		1,500,000		1,500,000
Total	871,200,000		871,200,000		421,200,000
Pass | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	415,900,000		415,900,000		394,200,000
2021	406,300,000		406,300,000		165,700,000
2020	233,400,000		233,400,000		94,500,000
2019	138,500,000		138,500,000		73,500,000
2018	130,300,000		130,300,000		47,100,000
Prior	178,900,000		178,900,000		91,300,000
Revolving Loans Amortized Cost Basis	707,500,000		707,500,000		224,700,000
Total	2,210,800,000		2,210,800,000		1,091,000,000
Pass | Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	155,800,000		155,800,000		94,900,000
2021	140,400,000		140,400,000		55,000,000.0
2020	71,600,000		71,600,000		27,800,000
2019	31,400,000		31,400,000		23,100,000
2018	31,000,000.0		31,000,000.0		15,300,000
Prior	43,200,000		43,200,000		32,200,000
Revolving Loans Amortized Cost Basis	29,900,000		29,900,000		14,400,000
Total	503,300,000		503,300,000		262,700,000
Pass | Agriculture Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	107,600,000		107,600,000
2021	70,900,000		70,900,000
2020	35,000,000.0		35,000,000.0
2019	12,800,000		12,800,000
2018	9,900,000		9,900,000
Prior	1,500,000		1,500,000
Revolving Loans Amortized Cost Basis	356,300,000		356,300,000
Total	594,000,000.0		594,000,000.0
Other Assets Especially Mentioned | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	6,000,000.0		6,000,000.0		200,000
2021	4,400,000		4,400,000		3,100,000
2020	400,000		400,000		2,100,000
2019	4,700,000		4,700,000		0
2018	8,300,000		8,300,000		0
Prior	19,800,000		19,800,000		3,600,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	43,600,000		43,600,000		9,000,000.0
Other Assets Especially Mentioned | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	6,700,000		6,700,000		0
2021	0		0		100,000
2020	0		0		0
2019	0		0		0
2018	200,000		200,000		100,000
Prior	300,000		300,000		300,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	7,200,000		7,200,000		500,000
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	2,100,000		2,100,000
2021	0		0
2020	23,100,000		23,100,000
2019	0		0
2018	0		0
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	25,200,000		25,200,000
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	2,000,000.0		2,000,000.0		100,000
2021	2,800,000		2,800,000		1,300,000
2020	2,300,000		2,300,000		1,200,000
2019	2,300,000		2,300,000		100,000
2018	9,600,000		9,600,000		100,000
Prior	3,300,000		3,300,000		900,000
Revolving Loans Amortized Cost Basis	11,200,000		11,200,000		900,000
Total	33,500,000		33,500,000		4,600,000
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022					200,000
2021					4,100,000
2020					100,000
2019					400,000
2018					600,000
Prior					300,000
Revolving Loans Amortized Cost Basis					7,000,000.0
Total					12,700,000
Other Assets Especially Mentioned | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	5,200,000		5,200,000		1,300,000
2021	8,800,000		8,800,000		3,200,000
2020	1,500,000		1,500,000		1,500,000
2019	11,100,000		11,100,000		7,400,000
2018	2,800,000		2,800,000		3,500,000
Prior	9,800,000		9,800,000		13,800,000
Revolving Loans Amortized Cost Basis	300,000		300,000		0
Total	39,500,000		39,500,000		30,700,000
Other Assets Especially Mentioned | Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0
2021	0		0
2020	0		0
2019	0		0
2018	0		0
Prior	1,800,000		1,800,000
Revolving Loans Amortized Cost Basis	0		0
Total	1,800,000		1,800,000
Other Assets Especially Mentioned | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	10,100,000		10,100,000		800,000
2021	9,600,000		9,600,000		11,400,000
2020	2,100,000		2,100,000		800,000
2019	3,900,000		3,900,000		800,000
2018	1,400,000		1,400,000		3,000,000.0
Prior	5,200,000		5,200,000		2,300,000
Revolving Loans Amortized Cost Basis	64,500,000		64,500,000		7,000,000.0
Total	96,800,000		96,800,000		26,100,000
Other Assets Especially Mentioned | Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	200,000		200,000		0
2021	1,100,000		1,100,000		200,000
2020	2,300,000		2,300,000		200,000
2019	200,000		200,000		500,000
2018	1,500,000		1,500,000		100,000
Prior	300,000		300,000		600,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	5,600,000		5,600,000		1,600,000
Other Assets Especially Mentioned | Agriculture Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	1,500,000		1,500,000
2021	3,400,000		3,400,000
2020	600,000		600,000
2019	1,200,000		1,200,000
2018	700,000		700,000
Prior	0		0
Revolving Loans Amortized Cost Basis	12,100,000		12,100,000
Total	19,500,000		19,500,000
Substandard | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	3,500,000		3,500,000		3,900,000
2021	33,200,000		33,200,000		15,300,000
2020	10,700,000		10,700,000		2,300,000
2019	18,900,000		18,900,000		700,000
2018	20,100,000		20,100,000		1,000,000.0
Prior	9,500,000		9,500,000		12,400,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	95,900,000		95,900,000		35,600,000
Substandard | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0		800,000
2021	800,000		800,000		200,000
2020	200,000		200,000		0
2019	0		0		600,000
2018	0		0		300,000
Prior	600,000		600,000		100,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	1,600,000		1,600,000		2,000,000.0
Substandard | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0		0
2021	400,000		400,000		400,000
2020	0		0		0
2019	0		0		0
2018	0		0		400,000
Prior	400,000		400,000		0
Revolving Loans Amortized Cost Basis	0		0		0
Total	800,000		800,000		800,000
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	2,900,000		2,900,000
2021	0		0
2020	0		0
2019	0		0
2018	0		0
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	2,900,000		2,900,000
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	1,100,000		1,100,000		4,000,000.0
2021	13,900,000		13,900,000		400,000
2020	3,600,000		3,600,000		1,000,000.0
2019	3,400,000		3,400,000		600,000
2018	3,200,000		3,200,000		1,300,000
Prior	14,200,000		14,200,000		4,300,000
Revolving Loans Amortized Cost Basis	11,400,000		11,400,000		0
Total	50,800,000		50,800,000		11,600,000
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022					4,900,000
2021					700,000
2020					600,000
2019					2,500,000
2018					0
Prior					100,000
Revolving Loans Amortized Cost Basis					2,600,000
Total					11,400,000
Substandard | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	12,100,000		12,100,000		3,800,000
2021	3,000,000.0		3,000,000.0		4,300,000
2020	2,300,000		2,300,000		4,700,000
2019	4,600,000		4,600,000		5,400,000
2018	2,800,000		2,800,000		2,700,000
Prior	17,800,000		17,800,000		20,300,000
Revolving Loans Amortized Cost Basis	400,000		400,000		0
Total	43,000,000.0		43,000,000.0		41,200,000
Substandard | Multi-family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0
2021	0		0
2020	0		0
2019	0		0
2018	0		0
Prior	300,000		300,000
Revolving Loans Amortized Cost Basis	0		0
Total	300,000		300,000
Substandard | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	8,000,000.0		8,000,000.0		1,300,000
2021	1,200,000		1,200,000		2,800,000
2020	3,400,000		3,400,000		1,600,000
2019	2,700,000		2,700,000		2,600,000
2018	3,500,000		3,500,000		600,000
Prior	2,400,000		2,400,000		4,100,000
Revolving Loans Amortized Cost Basis	6,600,000		6,600,000		2,600,000
Total	27,800,000		27,800,000		15,600,000
Substandard | Commercial purpose secured by 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	200,000		200,000		1,300,000
2021	300,000		300,000		1,200,000
2020	100,000		100,000		600,000
2019	300,000		300,000		600,000
2018	900,000		900,000		200,000
Prior	1,200,000		1,200,000		1,300,000
Revolving Loans Amortized Cost Basis	100,000		100,000		100,000
Total	3,100,000		3,100,000		5,300,000
Substandard | Agriculture Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	23,100,000		23,100,000
2021	6,500,000		6,500,000
2020	5,000,000.0		5,000,000.0
2019	900,000		900,000
2018	4,200,000		4,200,000
Prior	1,100,000		1,100,000
Revolving Loans Amortized Cost Basis	1,400,000		1,400,000
Total	42,200,000		42,200,000
Doubtful | Non-owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0
2021	0		0
2020	0		0
2019	0		0
2018	1,800,000		1,800,000
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	1,800,000		1,800,000
Doubtful | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0
2021	3,200,000		3,200,000
2020	0		0
2019	0		0
2018	0		0
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	3,200,000		3,200,000
Doubtful | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0
2021	0		0
2020	3,100,000		3,100,000
2019	0		0
2018	0		0
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	3,100,000		3,100,000
Doubtful | Owner occupied
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	400,000		400,000
2021	1,500,000		1,500,000
2020	0		0
2019	0		0
2018	7,900,000		7,900,000
Prior	2,000,000.0		2,000,000.0
Revolving Loans Amortized Cost Basis	0		0
Total	11,800,000		11,800,000
Doubtful | Commercial and floor plans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	300,000		300,000
2021	4,700,000		4,700,000
2020	0		0
2019	0		0
2018	0		0
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	5,000,000.0		5,000,000.0
Doubtful | Agriculture Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0
2021	600,000		600,000
2020	0		0
2019	0		0
2018	0		0
Prior	0		0
Revolving Loans Amortized Cost Basis	0		0
Total	600,000		600,000
Performing | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	279,000,000.0		279,000,000.0		272,600,000
2021	194,900,000		194,900,000		208,600,000
2020	144,500,000		144,500,000		108,300,000
2019	69,000,000.0		69,000,000.0		64,000,000.0
2018	39,500,000		39,500,000		37,000,000.0
Prior	51,700,000		51,700,000		45,000,000.0
Revolving Loans Amortized Cost Basis	0		0		0
Total	778,600,000		778,600,000		735,500,000
Performing | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	45,000,000.0		45,000,000.0		42,500,000
2021	36,200,000		36,200,000		27,900,000
2020	20,900,000		20,900,000		15,000,000.0
2019	10,500,000		10,500,000		13,300,000
2018	7,900,000		7,900,000		5,800,000
Prior	9,700,000		9,700,000		7,600,000
Revolving Loans Amortized Cost Basis	24,600,000		24,600,000		16,900,000
Total	154,800,000		154,800,000		129,000,000.0
Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	189,000,000.0		189,000,000.0		139,000,000.0
Performing | Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	195,300,000		195,300,000		360,900,000
2021	466,300,000		466,300,000		477,000,000.0
2020	550,200,000		550,200,000		74,700,000
2019	102,300,000		102,300,000		27,500,000
2018	32,600,000		32,600,000		25,700,000
Prior	230,200,000		230,200,000		176,500,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	1,576,900,000		1,576,900,000		1,142,300,000
Performing | Consumer Home Equity and HELOC
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	14,900,000		14,900,000		11,100,000
2021	8,700,000		8,700,000		7,000,000.0
2020	5,400,000		5,400,000		3,700,000
2019	4,400,000		4,400,000		4,800,000
2018	5,700,000		5,700,000		3,600,000
Prior	17,600,000		17,600,000		12,000,000.0
Revolving Loans Amortized Cost Basis	486,500,000		486,500,000		350,700,000
Total	543,200,000		543,200,000		392,900,000
Nonperforming | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	200,000		200,000		500,000
2021	600,000		600,000		500,000
2020	400,000		400,000		400,000
2019	300,000		300,000		200,000
2018	200,000		200,000		100,000
Prior	500,000		500,000		400,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	2,200,000		2,200,000		2,100,000
Nonperforming | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0		100,000
2021	100,000		100,000		0
2020	0		0		0
2019	0		0		100,000
2018	0		0		0
Prior	100,000		100,000		0
Revolving Loans Amortized Cost Basis	0		0		0
Total	200,000		200,000		200,000
Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	800,000		800,000		600,000
Nonperforming | Residential 1-4 family
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0		0
2021	200,000		200,000		300,000
2020	400,000		400,000		0
2019	500,000		500,000		0
2018	400,000		400,000		200,000
Prior	3,400,000		3,400,000		800,000
Revolving Loans Amortized Cost Basis	0		0		0
Total	4,900,000		4,900,000		1,300,000
Nonperforming | Consumer Home Equity and HELOC
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	500,000		500,000		300,000
2021	300,000		300,000		0
2020	100,000		100,000		300,000
2019	100,000		100,000		0
2018	100,000		100,000		600,000
Prior	1,200,000		1,200,000		500,000
Revolving Loans Amortized Cost Basis	400,000		400,000		0
Total	2,700,000		2,700,000		1,700,000
Agriculture Portfolio Segment [Member] | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	1,900,000		1,900,000		1,500,000
Agriculture Portfolio Segment [Member] | Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	1,900,000		1,900,000		1,500,000
Agriculture Portfolio Segment [Member] | Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	0		0		0
Commercial | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	113,700,000		113,700,000		73,200,000
Commercial | Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	113,300,000		113,300,000		73,100,000
Commercial | Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	400,000		400,000		100,000
Total consumer loans | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	74,200,000		74,200,000		64,900,000
Total consumer loans | Performing | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	73,800,000		73,800,000		64,400,000
Total consumer loans | Nonperforming | Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
2022	$ 400,000		$ 400,000		$ 500,000

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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

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Loans Held for Investment - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	$ (8.4)	$ 0.0	$ (68.0)	$ 5.1
Accounts Receivable, Allowance for Credit Loss	213.0	135.1	213.0	135.1	$ 220.4	$ 122.3	$ 135.5	$ 144.3
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal)	4.6	0.2	60.2	(4.6)
Balance of defaulted loans under trouble debt restructurings	0.0		0.0
Impaired Financing Receivable, Interest Income, Accrual Method	0.0	0.0	0.0	0.0
Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	(5.5)	0.7	(32.8)	(0.1)
Accounts Receivable, Allowance for Credit Loss	128.7	78.9	128.7	78.9	133.7	69.3	79.4	80.5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	12,978.5		12,978.5			6,731.4
Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	1.6	(0.1)	(19.9)	5.5
Accounts Receivable, Allowance for Credit Loss	58.5	33.9	58.5	33.9	59.9	31.6	33.7	39.2
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,966.1		2,966.1			1,475.5
Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Provision charged to operating expense	2.5	0.0	(3.3)	0.1
Accounts Receivable, Allowance for Credit Loss	4.0	$ 0.4	4.0	$ 0.4	$ 6.5	0.3	$ 0.4	$ 0.7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	658.2		658.2			203.9
Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	57.6		57.6			11.7
Collateral [Member] | Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	41.3		41.3			8.2
Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	6.3		6.3			2.8
Collateral [Member] | Agricultural
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	10.0		10.0			0.7
Business Assets [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	3.9		3.9			3.0
Business Assets [Member] | Collateral [Member] | Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2.2		2.2			1.2
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	1.4		1.4			1.8
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	0.3		0.3			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	53.7		53.7			8.7
Real Property [Member] | Collateral [Member] | Total real estate loans
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	39.1		39.1			7.0
Real Property [Member] | Collateral [Member] | Commercial
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	4.9		4.9			1.0
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	9.7		9.7			0.7
Other Property [Member] | Collateral [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	0.0		0.0			0.0
Other Property [Member] | Collateral [Member] | Total real estate 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
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] | 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

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Loans Held for Investment - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Receivables [Abstract]
Loans renegotiated in troubled debt restructurings	$ 68,100,000		$ 68,100,000		$ 6,200,000
Troubled restructurings included in non-accrual loans	8,400,000		8,400,000		3,900,000
Loans renegotiated in troubled debt restructurings, accrual loans	59,700,000		59,700,000		2,300,000
Financing receivable, after allowance for credit loss, noncurrent	400,000		400,000		100,000
Troubled debt restructurings	48,100,000		71,700,000
Charge-offs directly related to modifying troubled debt restructurings	5,700,000		5,700,000
Balance of defaulted loans under trouble debt restructurings	0		0
Impaired financing receivable, recorded investment	191,400,000		191,400,000
Commitments to purchase or sell	0	$ 0	0	$ 0
Proceeds from sale of loans held-for-investment	0	$ 0	0	$ 0
Interest Receivable	$ 106,400,000		$ 106,400,000		$ 47,400,000

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Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Real Estate Acquired Through Foreclosure [Roll Forward]
Beginning balance	$ 16.8	$ 2.0	$ 2.0	$ 2.5
Acquired through acquisition	0.0	0.0	15.8	0.0
Additions	0.3	0.4	0.4	0.7
Dispositions	(0.5)	(0.1)	(1.6)	(0.9)
Ending balance	16.4	$ 2.3	16.4	$ 2.3
Carrying values of foreclosed residential real estate properties	0.0		0.0
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 0.0		$ 0.0

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Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	$ 1,775.6	$ 1,691.2
Derivative Asset, Estimated Fair Value	42.7	28.1
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	2,176.4	1,103.9
Derivative Liabilities, Estimated Fair Value	169.9	18.2
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	1,743.3	913.9
Derivative Asset, Estimated Fair Value	42.1	22.2
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	1,743.3	913.9
Derivative Liabilities, Estimated Fair Value	163.7	18.1
Not Designated as Hedging Instrument | Interest rate lock commitments
Derivative Assets (included in other assets on the consolidated balance sheets):
Derivative Asset, Notional Amount	0.0	77.3
Derivative Asset, Estimated Fair Value	0.0	1.8
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	25.9	0.0
Derivative Liabilities, Estimated Fair Value	0.5	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	32.3	0.0
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	0.0	102.4
Derivative Liabilities, Estimated Fair Value	0.0	0.0
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	700.0
Derivative Asset, Estimated Fair Value	0.0	4.1
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Derivative Liabilities, Notional Amount	0.0	87.6
Derivative Liabilities, Estimated Fair Value	$ 0.0	$ 0.1

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Derivatives and Hedging Activities - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Financial Assets
Gross Amounts Recognized	$ 42.7		$ 42.7		$ 28.1
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	42.7		42.7		28.1
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	42.1		42.1		8.0
Net Amount	0.6		0.6		20.1
Financial Liabilities
Gross Amounts Recognized	169.9		169.9		18.2
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	169.9		169.9		18.2
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	5.6		5.6		0.0
Net Amount	164.3		164.3		18.2
Repurchase agreements
Gross Amounts Recognized					1,051.1
Gross Amounts Offset in the Balance Sheet					0.0
Net Amounts in the Balance Sheet	1,075.6		1,075.6		1,051.1
Financial Instruments					0.0
Fair Value of Financial Collateral in the Balance Sheet					1,051.1
Net Amount					0.0
Total assets and liabilities
Gross Amounts Recognized	1,245.5		1,245.5		1,069.3
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	1,245.5		1,245.5		1,069.3
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	1,081.2		1,081.2		1,051.1
Net Amount	164.3		164.3		18.2
Derivative Liability, Notional Amount	2,176.4		2,176.4		1,103.9
Not Designated as Hedging Instrument
Total assets and liabilities
Amount of net gains recognized in mortgage banking revenues	(0.2)	$ 1.3	(1.7)	$ 1.7
Interest Rate Swap
Financial Assets
Gross Amounts Recognized	42.1		42.1		26.3
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	42.1		42.1		26.3
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	42.1		42.1		8.0
Net Amount	0.0		0.0		18.3
Financial Liabilities
Gross Amounts Recognized	169.3		169.3		18.2
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	169.3		169.3		18.2
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	5.6		5.6		0.0
Net Amount	163.7		163.7		18.2
Interest Rate Swap | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	1,743.3		1,743.3		913.9
Mortgage Related Derivatives
Financial Assets
Gross Amounts Recognized	0.6		0.6		1.8
Gross Amounts Offset in the Balance Sheet	0.0		0.0		0.0
Net Amounts in the Balance Sheet	0.6		0.6		1.8
Financial Instruments	0.0		0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	0.0		0.0		0.0
Net Amount	0.6		0.6		1.8
Financial Liabilities
Gross Amounts Recognized	0.5		0.5
Gross Amounts Offset in the Balance Sheet	0.0		0.0
Net Amounts in the Balance Sheet	0.5		0.5
Financial Instruments	0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	0.0		0.0
Net Amount	0.5		0.5
Risk Participation Agreements
Financial Liabilities
Gross Amounts Recognized	0.1		0.1
Gross Amounts Offset in the Balance Sheet	0.0		0.0
Net Amounts in the Balance Sheet	0.1		0.1
Financial Instruments	0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	0.0		0.0
Net Amount	0.1		0.1
Risk Participation Agreements | Not Designated as Hedging Instrument
Total assets and liabilities
Derivative Liability, Notional Amount	107.2		107.2		$ 0.0
Repurchase Agreements
Repurchase agreements
Gross Amounts Recognized	1,075.6		1,075.6
Gross Amounts Offset in the Balance Sheet	0.0		0.0
Net Amounts in the Balance Sheet	1,075.6		1,075.6
Financial Instruments	0.0		0.0
Fair Value of Financial Collateral in the Balance Sheet	1,075.6		1,075.6
Net Amount	$ 0.0		$ 0.0

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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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Derivative [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 0.0		$ 0.0
Derivative Instruments and Hedges, Assets	0.0		0.0		$ 695.6
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	0.0		0.0		(4.4)
Financial Instruments	0.0		0.0		0.0
Derivative Asset, Notional Amount	1,775.6		1,775.6		1,691.2
Derivative Asset, Estimated Fair Value	42.7		42.7		28.1
Derivative Liability, Notional Amount	2,176.4		2,176.4		1,103.9
Derivative Liabilities, Estimated Fair Value	169.9		169.9		18.2
two-year forward starting, three-year pay fixed interest rate swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	500.0		500.0
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	23.3		23.3
Collateral Pledged
Derivative [Line Items]
Derivative, Fair Value, Net	5.6		5.6
Financial Instruments	0.0		0.0
Not Designated as Hedging Instrument
Derivative [Line Items]
Amount of net fee income recognized in other non-interest income	2.5	$ 0.4	5.6	$ 1.6
Amount of net gains recognized in mortgage banking revenues	(0.2)	1.3	(1.7)	1.7
Interest Rate Swap
Derivative [Line Items]
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		700.0
Derivative Asset, Estimated Fair Value	0.0		0.0		4.1
Derivative Liability, Notional Amount	0.0		0.0		87.6
Derivative Liabilities, Estimated Fair Value	0.0		0.0		0.1
Interest Rate Swap | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	1,743.3		1,743.3		913.9
Derivative Asset, Estimated Fair Value	42.1		42.1		22.2
Derivative Liability, Notional Amount	1,743.3		1,743.3		913.9
Derivative Liabilities, Estimated Fair Value	163.7		163.7		18.1
Risk Participation Agreements
Derivative [Line Items]
Financial Instruments	0.0		0.0
Risk Participation Agreements | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Liability, Notional Amount	107.2		107.2		0.0
Derivative Liabilities, Estimated Fair Value	0.1		0.1		0.0
Forward Contracts | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative, Fair Value, Net	0.6		0.6		0.0
Derivative Asset, Notional Amount	32.3		32.3		0.0
Derivative Liability, Notional Amount	0.0		0.0		102.4
Derivative Liabilities, Estimated Fair Value	0.0		0.0		0.0
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount	0.0		0.0		77.3
Derivative Asset, Estimated Fair Value	0.0		0.0		1.8
Derivative Liability, Notional Amount	25.9		25.9		0.0
Derivative Liabilities, Estimated Fair Value	0.5		0.5		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		0.0
Derivative Liabilities, Estimated Fair Value	5.6		5.6		$ 0.0
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	$ 5.6	$ 0.0	$ 5.6	$ 0.0

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Derivative Instruments and Hedging Activities - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	$ 0.0		$ 0.0		$ 695.6
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	0.0		0.0		$ (4.4)
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 | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	5.6	$ 0.0	5.6	$ 0.0
Interest Rate Collars
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	300.0		300.0
two-year forward starting, three-year pay fixed interest rate swap
Derivative [Line Items]
Derivative Instruments and Hedges, Assets	500.0		500.0
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	23.3		23.3
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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Capital Stock (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Feb. 01, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	May 25, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Shares outstanding (in shares)		104,450,804		104,450,804			62,200,456
Common shares issued (in shares)			1,782	46,913,370	19,081
Stock repurchased and retired (in shares)		3,280,042	574	5,039,784	128,038
Stock Repurchased and Retired During Period, Value		$ 133.0	$ 0.0	$ 198.9	$ 5.4
Shares repurchased, average cost per share (in dollars per share)		$ 40.59		$ 39.48
Accelerated Share Repurchases, Adjustment to Recorded Amount		$ 133.1		$ 197.4
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)							41,699,409
Stock Repurchase Program, Number of Shares Authorized to be Repurchased						5,000,000
Stock repurchased and retired (in shares)		3,279,300
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased						1,889,158
Class A Common Stock | Great Western Bank
Class of Stock [Line Items]
Number of shares issued as consideration (in shares)	46,879,601
Class B Common Stock
Class of Stock [Line Items]
Shares outstanding (in shares)							20,501,047
Director [Member]
Class of Stock [Line Items]
Common shares issued (in shares)				33,769	19,081

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Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 85.7	$ 47.1	$ 116.4	$ 141.0
Weighted average common shares outstanding for basic earnings per share computation (in shares)	106,525,974	61,673,656	102,879,422	61,641,342
Dilutive effects of stock-based compensation (in shares)	63,725	74,316	55,938	91,480
Weighted average common shares outstanding for diluted earnings per common share computation (in shares)	106,589,699	61,747,972	102,935,360	61,732,822
Basic earnings per common share (in dollars per share)	$ 0.80	$ 0.76	$ 1.13	$ 2.29
Diluted earnings per common share (in dollars per share)	$ 0.80	$ 0.76	$ 1.13	$ 2.28
Restricted Stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)	48,871	89,142	51,161	88,677
Unvested restricted stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock (in shares)			481,567	355,981

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Regulatory Capital (Details) $ in Millions	Jan. 01, 2020 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained Earnings (Accumulated Deficit)		$ 1,035.8	$ 1,052.6
Total risk-based capital:
Actual, Amount		$ 2,820.2	$ 1,659.3
Actual, Ratio		0.1250	0.1411
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,804.7	$ 940.9
Minimum Required for Capital Adequacy Purposes, Ratio		0.0800	0.0800
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 2,368.7	$ 1,235.0
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		10.50%	10.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 2,255.9	$ 1,176.2
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		$ 1,015.1	$ 529.3
Tier 1 risk-based capital:
Actual, Amount		$ 2,366.8	$ 1,469.0
Actual, Ratio		0.1049	0.1249
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,353.5	$ 705.7
Minimum Required for Capital Adequacy Purposes, Ratio		0.0600	0.0600
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,917.5	$ 999.7
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		8.50%	8.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,804.7	$ 940.9
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		0.1049	0.1177
Banking Regulation, Common Equity Tier One Risk-Based Capital, Well Capitalized, Minimum		$ 1,466.3	$ 764.5
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		2,366.8	1,384.8
Common equity tier 1 risk-based capital:
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,579.1	$ 823.3
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		7.00%	7.00%
Leverage capital ratio:
Actual, Amount		$ 2,366.8	$ 1,469.0
Actual, Ratio		0.0767	0.0768
Banking Regulation, Tier One Leverage Capital, Capital Adequacy, Minimum		$ 1,234.4	$ 765.5
Capital Adequacy Purposes and Conservation Buffer, Ratio		0.0400	0.0400
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,543.0	$ 956.9
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		$ 2,704.8	$ 1,472.5
Actual, Ratio		0.1201	0.1256
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,801.1	$ 938.0
Minimum Required for Capital Adequacy Purposes, Ratio		0.0800	0.0800
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 2,363.9	$ 1,231.1
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		10.50%	10.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 2,251.4	$ 1,172.5
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		$ 1,013.1	$ 527.6
Tier 1 risk-based capital:
Actual, Amount		$ 2,508.9	$ 1,382.2
Actual, Ratio		0.1114	0.1179
Minimum Required for Capital Adequacy Purposes, Amount		$ 1,350.8	$ 703.5
Minimum Required for Capital Adequacy Purposes, Ratio		0.0600	0.0600
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,913.7	$ 996.6
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		8.50%	8.50%
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,801.1	$ 938.0
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		0.1114	0.1179
Banking Regulation, Common Equity Tier One Risk-Based Capital, Well Capitalized, Minimum		$ 1,463.4	$ 762.1
Banking Regulation, Common Equity Tier One Risk-Based Capital, Actual		2,508.9	1,382.2
Common equity tier 1 risk-based capital:
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Amount		$ 1,576.0	$ 820.8
For Capital Adequacy Purposes Plus Capital Conservation Buffer, Ratio		7.00%	7.00%
Leverage capital ratio:
Actual, Amount		$ 2,508.9	$ 1,382.2
Actual, Ratio		0.0814	0.0724
Banking Regulation, Tier One Leverage Capital, Capital Adequacy, Minimum		$ 1,232.2	$ 764.1
Capital Adequacy Purposes and Conservation Buffer, Ratio		0.0400	0.0400
Minimum to Be Well Capitalized Under Prompt Corrective Action Requirements, Amount		$ 1,540.2	$ 955.1
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	Oct. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Shares outstanding (in shares)		104,450,804	62,200,456
Entity Common Stock, Shares Outstanding	104,447,711
Class A Common Stock
Loss Contingencies [Line Items]
Shares outstanding (in shares)			41,699,409
Mortgage Loans Held For Sale [Member]
Loss Contingencies [Line Items]
Mortgage loans with recourse provision in effect		$ 1.0
Construction Contracts
Loss Contingencies [Line Items]
Commitments under construction contracts		$ 1.6

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Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Entity Information [Line Items]
Off-Balance Sheet, Credit Loss, Liability	$ 9.7	$ 3.2	$ 9.7	$ 3.2	$ 6.2	$ 3.8	$ 3.4	$ 3.7
Provision for (reversal of) credit loss expense	(4.6)	(0.2)	(60.2)	4.6
Credit Extension Commitments	5,011.0		5,011.0			2,539.8
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	814.9		814.9			681.6
Standby Letter of Credit
Entity Information [Line Items]
Credit Extension Commitments	92.4		92.4			$ 57.5
Cumulative effect, period of adoption, adjusted balance
Entity Information [Line Items]
Provision for (reversal of) credit loss expense	$ 3.5	$ (0.2)	$ 5.9	$ (0.5)

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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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investment securities available-for sale:
Change in net unrealized gain during period, pre-tax	$ (236.4)	$ (13.4)	$ (650.6)	$ (81.0)
Change in net unrealized gain during period, tax expense (benefit)	(53.4)	(3.3)	(161.3)	(20.5)
Change in net unrealized gain during period, net of tax	(183.0)	(10.1)	(489.3)	(60.5)
Reclassification adjustment for net gains included in income, pre-tax	24.2	(0.3)	24.4	(0.2)
Reclassification adjustment for net gains included in income, tax expense (benefit)	5.5	(0.1)	5.5	(0.1)
Reclassification adjustment for net gains included in income, net of tax	18.7	(0.2)	18.9	(0.1)
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, pre-tax	(1.7)	(2.5)	(25.6)	22.3
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	(0.4)	(0.6)	(6.3)	5.7
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, net of tax	(1.3)	(1.9)	(19.3)	16.6
Unrealized loss on derivatives, pre-tax	(15.9)	3.2	(9.6)	2.3
Unrealized loss on derivatives, tax expense (benefit)	(3.6)	0.8	(2.5)	0.6
Unrealized loss on derivatives, net of tax	(12.3)	2.4	(7.1)	1.7
Other comprehensive loss, before tax	(229.8)	(13.0)	(661.2)	(56.6)
Other Comprehensive Income (Loss), tax expense (benefit)	(51.9)	(3.2)	(164.5)	(14.3)
Other Comprehensive Income (Loss), Net of Tax	$ (177.9)	$ (9.8)	(496.7)	(42.3)
Other than Temporary Impairment Losses, Investments, Reclassification Adjustment of Noncredit Portion from Held-to-maturity to Available-for-sale Securities, before Tax			$ 0.2	$ 0.0

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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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ 3,005.5	$ 1,984.8	$ 3,005.5	$ 1,984.8	$ 1,986.6	$ 3,271.9	$ 1,970.9	$ 1,959.8
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax					15.0
Net unrealized gain (loss) on derivatives	(12.3)	2.4	(7.1)	1.7
Other than Temporary Impairment Losses, Investments, Reclassification Adjustment of Noncredit Portion from Held-to-maturity to Available-for-sale Securities, before Tax			0.2	0.0
Change in net unrealized gain during period, pre-tax	(236.4)	(13.4)	(650.6)	(81.0)
Change in net unrealized gain during period, tax expense (benefit)	(53.4)	(3.3)	(161.3)	(20.5)
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(183.0)	(10.1)	(489.3)	(60.5)
Reclassification adjustment for net loss (gain) included in income	24.2	(0.3)	24.4	(0.2)
Reclassification adjustment for net gains included in income, tax expense (benefit)	5.5	(0.1)	5.5	(0.1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	18.7	(0.2)	18.9	(0.1)
Other Comprehensive Loss, Held-to-maturity Security, Reclassification Adjustment from AOCI for Noncredit Portion of OTTI, Sale, Tax			0.1	0.0
Other Comprehensive Loss, Held-to-maturity Security, Reclassification Adjustment from AOCI for Noncredit Portion of OTTI, Sale, after Tax			0.1	0.0
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), before Tax	(1.7)	(2.5)	(25.6)	22.3
Amortization of unrealized gains on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	(0.4)	(0.6)	(6.3)	5.7
OCI, Debt Securities, Available-for-Sale, Transfer to Held-to-Maturity, Adjustment from AOCI for Amortization of Gain (Loss), after Tax	(1.3)	(1.9)	(19.3)	16.6
Unrealized loss on derivatives, pre-tax	(15.9)	3.2	(9.6)	2.3
Unrealized loss on derivatives, tax expense (benefit)	(3.6)	0.8	(2.5)	0.6
Other comprehensive loss, before tax	(229.8)	(13.0)	(661.2)	(56.6)
Other Comprehensive Income (Loss), tax expense (benefit)	(51.9)	(3.2)	(164.5)	(14.3)
Other Comprehensive Income (Loss), Net of Tax	(177.9)	(9.8)	(496.7)	(42.3)
Net unrealized loss on investment securities available-for-sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	(499.1)		(499.1)		(29.0)
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax			(4.4)
Net unrealized gain on derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss) on derivatives			(4.2)		3.0
Net accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total stockholders’ equity	$ (507.7)	$ 14.3	$ (507.7)	$ 14.3	$ (11.0)	$ (329.8)	$ 24.1	$ 56.6

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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
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
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
Investment debt securities available-for-sale	6,783.4		6,783.4		$ 4,820.5
Derivative assets	42.7		42.7		28.1
Derivative liabilities	169.9		169.9		18.2
Write downs	(0.2)	$ 0.0	(0.2)	$ 0.0
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	93.6		93.6		30.1
Deferred compensation plan assets	19.0		19.0		21.4
Deferred compensation plan liabilities	19.0		19.0		21.4
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		0.0
Deferred compensation plan assets	0.0		0.0		0.0
Deferred compensation plan liabilities	0.0		0.0		0.0
U.S. Treasury notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	336.8		336.8		684.7
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	336.8		336.8		684.7
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	0.0		0.0		0.0
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
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	260.5		260.5		427.5
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	260.5		260.5		427.5
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
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	199.0		199.0		346.9
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	199.0		199.0		346.9
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
U.S. agency residential & commercial mortgage-backed securities & collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	4,409.7		4,409.7		2,018.1
U.S. agency residential & commercial mortgage-backed securities & 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
U.S. agency residential & commercial mortgage-backed securities & 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	4,409.7		4,409.7		2,018.1
U.S. agency residential & commercial mortgage-backed securities & 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
Private mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	233.2		233.2		173.4
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	233.2		233.2		173.4
Private mortgage-backed securities | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	0.0		0.0		0.0
Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	239.1		239.1		270.5
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	239.1		239.1		270.5
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					11.7
Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	1,105.1		1,105.1		899.4
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	1,105.1		1,105.1		899.4
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
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	6,783.4		6,783.4		4,820.5
Derivative assets	42.7		42.7		28.1
Derivative liabilities	169.9		169.9		18.2
Deferred compensation plan assets	19.0		19.0		21.4
Deferred compensation plan liabilities	19.0		19.0		21.4
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	93.6		93.6		30.1
Deferred compensation plan assets	19.0		19.0		21.4
Deferred compensation plan liabilities	19.0		19.0		21.4
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	336.8		336.8		684.7
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	6,446.6		6,446.6		4,135.8
Derivative assets	42.7		42.7		28.1
Derivative liabilities	169.9		169.9		18.2
Deferred compensation plan assets	19.0		19.0		21.4
Deferred compensation plan liabilities	19.0		19.0		21.4
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	336.8		336.8		684.7
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	260.5		260.5		427.5
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	199.0		199.0		346.9
Estimated Fair Value | U.S. agency residential & commercial mortgage-backed securities & 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	4,409.7		4,409.7		2,018.1
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	233.2		233.2		173.4
Estimated Fair Value | Corporate securities | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	239.1		239.1		270.5
Estimated Fair Value | 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	57.6		57.6		11.7
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	1,105.1		1,105.1		899.4
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale	6,783.4		6,783.4		4,820.5
Derivative assets	42.7		42.7		28.1
Derivative liabilities	169.9		169.9		18.2
Deferred compensation plan assets	19.0		19.0		21.4
Deferred compensation plan liabilities	19.0		19.0		21.4
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	57.6		57.6		11.7
Long-lived assets to be disposed of by sale	6.7		6.7		1.3
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	42.1		42.1		26.3
Derivative liabilities	169.3		169.3		18.2
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	42.1		42.1		26.3
Derivative liabilities	163.7		163.7		18.2
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	42.1		42.1		26.3
Derivative liabilities	163.7		163.7		18.2
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 assets					0.0
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 assets					1.8
Derivative liabilities	0.5		0.5
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 assets					0.0
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 assets					1.8
Derivative liabilities	0.5		0.5
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		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	0.6		0.6
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		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	0.6		0.6
Risk Participation Agreements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0.1		0.1
Risk Participation Agreements | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0.0		0.0
Risk Participation Agreements | Significant Other Observable Inputs (Level 2) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0.1		0.1
Risk Participation Agreements | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0.0		0.0
Risk Participation Agreements | Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0.1		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
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	5.6		5.6
Interest Rate Collars | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0.0		0.0
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	5.6		5.6
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	6.7		6.7		1.3
Long-lived assets to be disposed of by sale | Estimated Fair Value | 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	$ 6.7		$ 6.7		$ 1.3

XML

Fair Value Measurements - Fair Value Inputs, Quantitative Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Material write downs	$ 0.2	$ 0.0	$ 0.2	$ 0.0
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	57.6		57.6		$ 11.7
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					11.7
Collateral dependent loans | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Collateral dependent loans	$ 57.6		$ 57.6		11.7
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	0.01		0.01
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	0.18		0.18
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 | 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	16.4		16.4		2.0
Other real estate owned | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Other real estate owned	$ 16.4		$ 16.4		2.0
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		0
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		0
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		0
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	6.7		6.7		1.3
Long-lived assets to be disposed of by sale | Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Long-lived assets to be disposed of by sale	$ 6.7		$ 6.7		$ 1.3
Long-lived assets to be disposed of by sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0
Long-lived assets to be disposed of by sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0
Long-lived assets to be disposed of by sale | Discount Rate | Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount rate	0		0

XML

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments by Level of Valuation Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financial assets:
Investment debt securities available-for-sale	$ 6,783.4	$ 4,820.5
Investment debt securities held-to-maturity	3,063.5	1,667.5
Derivative assets	42.7	28.1
Financial liabilities:
Derivative liabilities	169.9	18.2
Estimated Fair Value
Financial assets:
Cash and cash equivalents	591.9	2,344.8
Investment debt securities available-for-sale	6,783.4	4,820.5
Investment debt securities held-to-maturity	3,063.5	1,667.5
Accrued interest receivable	106.4	47.4
Mortgage servicing rights, net	36.6	28.2
Loans held for sale	93.6	30.1
Net loans held for investment	17,293.6	9,254.3
Derivative assets	42.7	28.1
Deferred compensation plan assets	19.0	21.4
Total financial assets	28,030.7	18,242.3
Financial liabilities:
Total deposits, excluding time deposits	24,255.6	15,303.1
Time deposits	1,587.2	963.1
Securities sold under repurchase agreements	1,075.6	1,051.1
Other Borrowings	625.0
Accrued interest payable	7.4	3.7
Long-term debt	116.7	120.7
Subordinated debentures held by subsidiary trusts	157.1	85.5
Derivative liabilities	169.9	18.2
Deferred compensation plan liabilities	19.0	21.4
Total financial liabilities	28,013.5	17,566.8
Carrying Amount
Financial assets:
Cash and cash equivalents	591.9	2,344.8
Investment debt securities available-for-sale	6,783.4	4,820.5
Investment debt securities held-to-maturity	3,485.7	1,687.6
Accrued interest receivable	106.4	47.4
Mortgage servicing rights, net	31.8	28.2
Loans held for sale	93.6	30.1
Net loans held for investment	17,390.5	9,209.4
Derivative assets	42.7	28.1
Deferred compensation plan assets	19.0	21.4
Total financial assets	28,545.0	18,217.5
Financial liabilities:
Total deposits, excluding time deposits	24,255.6	15,303.1
Time deposits	1,629.2	966.5
Securities sold under repurchase agreements	1,075.6	1,051.1
Other Borrowings	625.0
Accrued interest payable	7.4	3.7
Long-term debt	120.7	112.4
Subordinated debentures held by subsidiary trusts	163.1	87.0
Derivative liabilities	169.9	18.2
Deferred compensation plan liabilities	19.0	21.4
Total financial liabilities	28,065.5	17,563.4
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	591.9	2,344.8
Investment debt securities available-for-sale	336.8	684.7
Investment debt securities held-to-maturity	385.5	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	1,314.2	3,029.5
Financial liabilities:
Total deposits, excluding time deposits	24,255.6	15,303.1
Time deposits	0.0	0.0
Securities sold under repurchase agreements	0.0	0.0
Other Borrowings	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	24,255.6	15,303.1
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	6,446.6	4,135.8
Investment debt securities held-to-maturity	2,678.0	1,667.5
Accrued interest receivable	106.4	47.4
Mortgage servicing rights, net	36.6	28.2
Loans held for sale	93.6	30.1
Net loans held for investment	17,236.0	9,242.6
Derivative assets	42.7	28.1
Deferred compensation plan assets	19.0	21.4
Total financial assets	26,658.9	15,201.1
Financial liabilities:
Total deposits, excluding time deposits	0.0	0.0
Time deposits	1,587.2	963.1
Securities sold under repurchase agreements	1,075.6	1,051.1
Other Borrowings	625.0
Accrued interest payable	7.4	3.7
Long-term debt	116.7	120.7
Subordinated debentures held by subsidiary trusts	157.1	85.5
Derivative liabilities	169.9	18.2
Deferred compensation plan liabilities	19.0	21.4
Total financial liabilities	3,757.9	2,263.7
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	0.0	0.0
Net loans held for investment	57.6	11.7
Derivative assets	0.0	0.0
Deferred compensation plan assets	0.0	0.0
Total financial assets	57.6	11.7
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
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

Other Borrowed Funds - Narrative (Details) $ in Millions	Sep. 30, 2022 USD ($)
Short-term Debt, Percentage Bearing Variable Interest Rate	329.00%
Short-term Debt, Percentage Bearing Fixed Interest Rate	320.00%
Debt Instrument, Unused Borrowing Capacity, Amount	$ 3,962.4
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	4,588.0
Variable Rate [Member]
Other Borrowings	550.0
Fixed Rate [Member]
Other Borrowings	$ 75.0

XML

Subsequent Events (Details)	Oct. 24, 2022 $ / shares
Class A Common Stock | Subsequent Event
Subsequent Event [Line Items]
Dividend amount per share (in dollars)	$ 0.47