10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

___________________________________________________________________________________________________________________________________________________

FORM 10-Q

_____________________________________________________________________________________________________________________________________________________

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

For the quarterly period ended March 31, 2019

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)255-5390

_________________________________________________________________________________________________

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  ý    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  ý    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	ý	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  ý

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

March 31, 2019 – Class A common stock	38,461,948
March 31, 2019 – Class B common stock	22,374,171

Quarterly Report on Form 10-Q
	FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES
	Index
	March 31, 2019
		Page Nos.
	Part I - Financial Information
Item 1.	Financial Statements (Unaudited)
	Consolidated Balance Sheets	3
	Consolidated Statements of Income	4
	Consolidated Statements of Comprehensive Income	5
	Consolidated Statements of Changes in Stockholders’ Equity	6
	Consolidated Statements of Cash Flows	7
	Notes to Unaudited Consolidated Financial Statements	9
Item 2.	Management's Discussion and Analysis of Financial Condition and Results of Operations	39
Item 3.	Quantitative and Qualitative Disclosures about Market Risk	54
Item 4.	Controls and Procedures	54
	Part II - Other Information
Item 1.	Legal Proceedings	54
Item 1A.	Risk Factors	54
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	55
Item 3.	Defaults Upon Senior Securities	55
Item 4.	Mine Safety Disclosures	55
Item 5.	Other Information	55
Item 6.	Exhibits	56
Signatures		57

2

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED BALANCE SHEETS (In millions, except share data) (Unaudited)
	March 31, 2019			December 31, 2018
Assets
Cash and due from banks	$	213.6		$	244.1
Interest bearing deposits in banks	741.5			577.8
Federal funds sold	0.1			0.1
Total cash and cash equivalents	955.2			822.0
Investment securities:
Available-for-sale	2,572.0			2,270.7
Held-to-maturity (estimated fair values of $118.0 and $400.7 at March 31, 2019 and December 31, 2018, respectively)	117.0			406.8
Total investment securities	2,689.0			2,677.5
Loans held for investment	8,459.2			8,470.4
Mortgage loans held for sale	34.0			33.3
Total loans	8,493.2			8,503.7
Less allowance for loan losses	72.4			73.0
Net loans	8,420.8			8,430.7
Goodwill	546.3			546.7
Company-owned life insurance	275.8			275.1
Premises and equipment, net of accumulated depreciation	298.2			245.2
Core deposit intangibles, net of accumulated amortization	54.6			56.9
Accrued interest receivable	46.5			44.9
Mortgage servicing rights, net of accumulated amortization and impairment reserve	27.9			27.7
Other real estate owned (“OREO”)	21.1			14.4
Other assets	162.8			159.1
Total assets	$	13,498.2		$	13,300.2
Liabilities and Stockholders’ Equity
Deposits:
Non-interest bearing	$	3,158.7		$	3,158.3
Interest bearing	7,656.0			7,522.4
Total deposits	10,814.7			10,680.7
Securities sold under repurchase agreements	672.6			712.4
Accounts payable and accrued expenses	142.6			94.1
Accrued interest payable	10.0			7.8
Deferred tax liability, net	18.7			8.6
Long-term debt	15.8			15.8
Subordinated debentures held by subsidiary trusts	86.9			86.9
Total liabilities	11,761.3			11,606.3
Stockholders’ equity:
Nonvoting noncumulative preferred stock without par value; authorized 100,000 shares; no shares issued and outstanding as of March 31, 2019 or December 31, 2018	—			—
Common stock	866.6			866.7
Retained earnings	874.7			851.8
Accumulated other comprehensive loss, net	(4.4		)	(24.6		)
Total stockholders’ equity	1,736.9			1,693.9
Total liabilities and stockholders’ equity	$	13,498.2		$	13,300.2

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 March 31,
	2019		2018
Interest income:
Interest and fees on loans	$	111.4	$	91.7
Interest and dividends on investment securities:
Taxable	15.1		13.2
Exempt from federal taxes	0.5		0.6
Interest on deposits in banks	3.6		2.1
Total interest income	130.6		107.6
Interest expense:
Interest on deposits	12.1		6.2
Interest on securities sold under repurchase agreements	1.0		0.4
Interest on other borrowed funds	—		0.1
Interest on other debt	0.3		0.2
Interest on subordinated debentures held by subsidiary trusts	1.2		0.9
Total interest expense	14.6		7.8
Net interest income	116.0		99.8
Provision for loan losses	3.7		2.1
Net interest income after provision for loan losses	112.3		97.7
Non-interest income:
Payment services revenues	9.4		10.5
Mortgage banking revenues	5.4		5.4
Wealth management revenues	6.1		5.9
Service charges on deposit accounts	5.0		5.6
Other service charges, commissions and fees	4.3		3.9
Investment securities gains (losses), net	—		—
Other income	4.3		3.9
Total non-interest income	34.5		35.2
Non-interest expense:
Salaries and wages	36.1		34.6
Employee benefits	14.4		11.3
Outsourced technology services	7.9		7.0
Occupancy, net	7.0		6.3
Furniture and equipment	3.5		3.1
OREO expense, net of income	0.1		0.2
Professional fees	1.9		1.2
FDIC insurance premiums	1.5		1.5
Mortgage servicing rights amortization	0.9		0.8
Core deposit intangibles amortization	2.3		1.8
Other expenses	15.9		15.8
Acquisition related expenses	2.3		2.3
Total non-interest expense	93.8		85.9
Income before income tax expense	53.0		47.0
Income tax expense	11.4		10.3
Net income	$	41.6	$	36.7
Earnings per common share (Basic)	$	0.69	$	0.65
Earnings per common share (Diluted)	$	0.69	$	0.65
Weighted average common shares outstanding (Basic)	60,311,171		56,241,201
Weighted average common shares outstanding (Diluted)	60,598,070		56,652,178

See accompanying notes to unaudited consolidated financial statements.

4

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (In millions) (Unaudited)
	Three Months Ended March 31,
	2019			2018
Net income	$	41.6		$	36.7
Other comprehensive income (loss), before tax:
Investment securities available-for sale:
Change in net unrealized gains (losses) during period	33.6			(23.7		)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(6.0		)	—
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	—			0.5
Defined benefit post-retirement benefits plans:
Change in net actuarial gain	(0.2		)	(0.1		)
Other comprehensive income (loss), before tax	27.4			(23.3		)
Deferred tax (expense) benefit related to other comprehensive income	(7.2		)	6.1
Other comprehensive income (loss), net of tax	20.2			(17.2		)
Comprehensive income, net of tax	$	61.8		$	19.5

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)
	Common stock			Retained earnings			Accumulated other comprehensive income (loss)			Total stockholders’ equity
Balance at December 31, 2018	$	866.7		$	851.8		$	(24.6	)	$	1,693.9
Net income	—			41.6			—			41.6
Other comprehensive income, net of tax expense	—			—			20.2			20.2
Common stock transactions:
38,753 common shares purchased and retired	(2.4		)	—			—			(2.4		)
200,028 non-vested common shares issued	—			—			—			—
5,385 non-vested common shares forfeited or canceled	—			—			—			—
56,982 stock options exercised, net of 19,004 shares tendered in payment of option price and income tax withholding amounts	0.4			—			—			0.4
Stock-based compensation expense	1.9			—			—			1.9
Common cash dividends declared ($0.31 per share)	—			(18.7		)	—			(18.7		)
Balance at March 31, 2019	$	866.6		$	874.7		$	(4.4	)	$	1,736.9
Balance at December 31, 2017	$	687.0		$	752.6		$	(12.0	)	$	1,427.6
Net income	—			36.7			—			36.7
Reclassification of the income tax effects of the Tax Cut and Jobs Act from AOCI	—			3.1			(3.1		)	—
Other comprehensive loss, net of tax expense	—			—			(17.2		)	(17.2		)
Common stock transactions:
21,700 common shares purchased and retired	(0.9		)	—			—			(0.9		)
204,991 non-vested common shares issued	—			—			—			—
16,581 non-vested common shares forfeited or canceled	—			—			—			—
67,146 stock options exercised, net of 20,469 shares tendered in payment of option price and income tax withholding amounts	0.8			—			—			0.8
Stock-based compensation expense	1.1			—			—			1.1
Common cash dividends declared ($0.28 per share)	—			(15.7		)	—			(15.7		)
Balance at March 31, 2018	$	688.0		$	776.7		$	(32.3	)	$	1,432.4

See accompanying notes to unaudited consolidated financial statements.

6

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (In millions) (Unaudited)
	Three Months Ended March 31,
	2019			2018
Cash flows from operating activities:
Net income	$	41.6		$	36.7
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	3.7			2.1
Depreciation and amortization	7.5			6.6
Net premium amortization on investment securities	2.0			2.8
Realized and unrealized net gains on mortgage banking activities	(4.7		)	(1.6		)
Net loss (gain) on sale of OREO	(0.4		)	—
Write-downs of OREO and other assets pending disposal	0.3			—
Deferred income tax expense	2.7			10.1
Net increase in cash surrender value of company-owned life insurance	(0.7		)	(1.3		)
Stock-based compensation expense	1.9			1.1
Originations of mortgage loans held for sale	(129.8		)	(204.1		)
Proceeds from sales of mortgage loans held for sale	132.7			218.8
Changes in operating assets and liabilities, net of effects of acquisition:
Increase in interest receivable	(1.6		)	(0.9		)
(Increase) decrease in other assets	(3.7		)	3.9
Increase in accrued interest payable	2.2			0.1
Decrease in accounts payable and accrued expenses	(6.1		)	(10.9		)
Net cash provided by operating activities	47.6			63.4
Cash flows from investing activities:
Purchases of investment securities:
Available-for-sale	(161.3		)	(212.9		)
Proceeds from maturities and pay-downs of investment securities:
Held-to-maturity	11.3			22.2
Available-for-sale	164.0			114.9
Extensions of credit to customers, net of repayments	(3.2		)	(53.3		)
Recoveries of loans charged-off	1.7			4.5
Proceeds from sale of OREO	1.8			0.3
Capital expenditures, net of sales	(2.2		)	(2.4		)
Net cash provided by (used in) investing activities	$	12.1		$	(126.7	)

7

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (continued) (In millions) (Unaudited)
	Three Months Ended March 31,
	2019			2018
Cash flows from financing activities:
Net increase (decrease) in deposits	$	134.0		$	91.0
Net (decrease) increase in securities sold under repurchase agreements	(39.8		)	(9.2		)
Net decrease in other borrowed funds	—			(20.0		)
Advances on long-term debt	—			2.6
Proceeds from issuance of common stock	0.4			0.8
Purchase and retirement of common stock	(2.4		)	(0.9		)
Dividends paid to common stockholders	(18.7		)	(15.7		)
Net cash provided by financing activities	73.5			48.6
Net increase (decrease) in cash and cash equivalents	133.2			(14.7		)
Cash and cash equivalents at beginning of period	822.0			758.9
Cash and cash equivalents at end of period	$	955.2		$	744.2
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$	—		$	4.6
Cash paid during the period for interest expense	12.4			7.7
Supplemental disclosures of non-cash investing and financing activities:
Amortization of unrealized gains and losses on transfers of securities	$	—		$	0.5
Right-of-use assets obtained in exchange for operating lease liabilities	54.6			—
Transfer of loans to other real estate owned	8.4			1.2
Capitalization of internally originated mortgage servicing rights	1.1			1.3

See accompanying notes to unaudited consolidated financial statements.

8

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 (together, 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 March 31, 2019 and December 31, 2018, the results of operations for each of the three month periods ended March 31, 2019 and 2018, and cash flows and changes in stockholders’ equity for each of the three month periods ended March 31, 2019 and 2018, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2018 is derived from audited consolidated financial statements. Certain reclassifications, none of which were material, have been made to conform prior year financial statements to the March 31, 2019 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, 2018. Operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019.

Leases

We have leased branches and office space and have entered into various other agreements in conducting our business. At inception, we determine whether an agreement represents a lease and at commencement we evaluate each lease agreement to determine whether the lease is an operating or financing lease. Some of our lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses. As discussed in “Note 16 – Recent Authoritative Accounting Guidance” included in this report, we adopted ASU 2016-02, as of January 1, 2019.

Pursuant to ASU 2016-02, all of our long-term operating leases outstanding on December 31, 2018 continued to be classified as operating leases. Our capital lease outstanding at December 31, 2018 is classified as a financing lease. With the adoption of ASU 2016-02, we recorded an operating lease right-of-use asset, within the Premises and Equipment line item, and an operating lease liability, within the Other Liabilities line item, on our balance sheet. Right-of-use lease assets represent our right to use the underlying asset for the lease term and the lease obligation represents our commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit rate, we have used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as property taxes are expensed as incurred. Leases with an initial term of 12 months or less are not recorded on the balance sheet.

Prior to our adoption of ASU 2016-02, when our lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, we recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the statements of operations over the term of each lease. In cases where the lessor granted us leasehold improvement allowances that reduced our lease expense, we capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements.

9

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(2) Acquisitions

Idaho Independent Bank. On October 11, 2018, the Company entered into a definitive agreement to acquire all of the outstanding stock of Idaho Independent Bank (“IIBK”), a community bank headquartered in Coeur d' Alene, Idaho with 11 banking offices across Idaho. The acquisition was completed on April 8, 2019, and conversion of the data processing systems will occur in June 2019. Consideration for the acquisition was $157.3 million, consisting of the issuance of 3.871 million shares of the Company's Class A common stock valued at $40.64 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. Holders of each share of IIBK common stock received 0.50 shares of First Interstate Class A common stock for each share of IIBK common stock. Previously unvested IIBK restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close and included in the consideration.

Community 1^st Bank. On October 11, 2018, the Company also entered into a definitive agreement to acquire all of the outstanding stock of Community 1st Bank (“CMYF”), a community bank headquartered in Post Falls, Idaho with three banking offices in North Idaho. The acquisition was completed on April 8, 2019, and conversion of the data processing systems will occur in June 2019. Consideration for the acquisition was $18.8 million, consisting of the issuance of 0.463 million shares of the Company's Class A common stock valued at $40.64 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. Holders of each share of CMYF common stock received 0.3784 shares of First Interstate Class A common stock for each share of CMYF common stock. Previously unvested CMYF restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close and included in consideration.

Northwest Bancorporation, Inc. On April 25, 2018, the Company entered into a definitive agreement to acquire all of the outstanding stock of Northwest Bancorporation, Inc. (“Northwest”), the parent company of Inland Northwest Bank (“INB”), a Spokane, Washington based community bank with 20 banking offices across Idaho, Oregon and Washington. The acquisition was completed on August 16, 2018, and the Company merged INB with its existing bank subsidiary, First Interstate Bank, on November 9, 2018.

Consideration for the acquisition was $176.3 million, consisting of the issuance of 3.84 million shares of the Company's Class A common stock valued at $45.15 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. The Company paid approximately $3.0 million in cash related to Northwest warrants, which were included in the consideration paid. Holders of each share of Northwest common stock received 0.516 shares of First Interstate Class A common stock for each share of Northwest common stock. Additionally, all Northwest stock purchase warrants outstanding immediately prior to the close of the transaction were canceled in exchange for the right to receive a cash payment as provided in the Agreement. Previously unvested Northwest restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close.

The assets and liabilities of Northwest were provisionally recorded in the Company’s consolidated financial statements at their estimated fair values as of the acquisition date and will be finalized in the coming months. The excess value of the consideration paid over the fair value of assets acquired and liabilities assumed is recorded as provisional goodwill. The preliminary purchase price allocation resulted in provisional goodwill of $100.7 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 Northwest and the Company.

The following table summarizes the consideration paid, fair values of the Northwest assets acquired and liabilities assumed, and the resulting goodwill. The amounts reported for net deferred tax assets and goodwill are provisional pending completion of the Company's review of tax items.

10

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	As Recorded			Fair Value				As Recorded
As of August 16, 2018	by Northwest			Adjustments				by the Company
Assets acquired:
Cash and cash equivalents	$	31.2		$	—			$	31.2
Investment securities	3.1			—				3.1
Loans held for investment	727.9			(14.8		)	(1)	713.1
Allowance for loan loss	(8.0		)	8.0			(2)	—
Premises and equipment	14.5			—				14.5
Other real estate owned (“OREO”)	0.3			0.3				0.6
Core deposit intangible assets	2.4			13.3			(3)	15.7
Other assets	29.3			(10.0		)	(4)	19.3
Total assets acquired	800.7			(3.2		)		797.5
Liabilities assumed:
Deposits	696.1			0.2			(5)	696.3
Accounts payable and accrued expense	8.1			(0.4		)	(6)	7.7
Long term debt	13.0			0.1				13.1
Trust preferred securities	5.2			(0.8		)	(7)	4.4
Deferred tax liability, net	(1.2		)	1.6			(8)	0.4
Total liabilities assumed	721.2			0.7				721.9
Net assets acquired	$	79.5		$	(3.9	)		$	75.6
Consideration paid:
Cash								$	3.0
Class A common stock								173.3
Total consideration paid								176.3
Goodwill								$	100.7

Explanation of fair value adjustments and the removal of previously recorded fair value marks recorded by Northwest. Note adjustments to the marks for deferred tax assets and premises and equipment were made since the prior quarter, none of which were material. The adjustments had no impact on 2018 earnings and a net decrease to goodwill of $0.4 million from the December 31, 2018 reported balances.
(1)	Write down of the book value of loans to their estimated fair values. The fair value of the loans was estimated using cash flow projections based on the remaining maturity and repricing terms, adjusted for estimated future credit losses and prepayments and discounted to present value using a risk-adjusted market rate for similar loans. The fair value of collateral dependent loans acquired with deteriorated credit quality was estimated based on the Company’s analysis of the fair value of each loan’s underlying collateral, discounted using market-derived rates of return with consideration given to the period of time and costs associated with foreclosure and disposition of the collateral.
(2)	Adjustment to remove the Northwest allowance for loan losses at acquisition date, as the credit risk is included in the fair value adjustment for loans receivable described in (1) above.
(3)	Adjustment represents the value of the core deposit base assumed in the acquisition based upon valuation from an independent accounting and advisory firm.
(4)	Adjustment consists of reductions to the fair value of other items, including the removal of Northwest previously recorded goodwill.
(5)	Increase in book value of time deposits to their estimated fair values based upon interest rates of similar time deposits with similar terms on the date of acquisition based upon valuation from an independent accounting and advisory firm.
(6)	Decrease due to the write-off of off balance sheet reserves.
(7)	Write down of the book value of debt to the estimated fair values on the date of acquisition based upon favorable interest rates in the market.
(8)	Adjustment consists of the write-off of pre-existing deferred tax assets and purchase accounting adjustments as a result of the acquisition.

11

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Core deposit intangible assets of $15.7 million are being amortized using an accelerated method over the estimated useful lives of the related deposits of 10 years.

The Company acquired certain loans that are subject to Accounting Standards Codification ("ASC") Topic 310-30 "Loans and Debt Securities Acquired with Deteriorated Credit Quality." ASC Topic 310-30 provides recognition, measurement and disclosure guidance for acquired loans that have evidence of deterioration in credit quality since origination for which it is probable, at acquisition, the Company will be unable to collect all contractual amounts owed. For loans that meet the criteria stipulated in ASC Topic 310-30, the excess of all cash flows expected at acquisition over the initial fair value of the loans acquired ("accretable yield") is amortized to interest income over the expected remaining lives of the underlying loans using the effective interest method. The accretable yield will fluctuate due to changes in (i) estimated lives of underling credit-impaired loans, (ii) assumptions regarding future principal and interest amounts collected, and (iii) indices used to fair value variable rate loans.

Information regarding Northwest loans acquired deemed credit-impaired as of the August 16, 2018 acquisition date are as follows:

Contractually required principal and interest payments	$	27.5
Contractual cash flows not expected to be collected (“non-accretable discount”)	4.4
Cash flows expected to be collected	23.1
Interest component of cash flows expected to be collected (“accretable discount”)	3.2
Fair value of acquired credit-impaired loans	$	19.9

Information regarding Northwest acquired loans not deemed credit-impaired at the August 16, 2018 acquisition date are as follows:

Contractually required principal and interest payments	$	894.8
Contractual cash flows not expected to be collected	26.1
Fair value at acquisition	$	693.2

Unaudited pro forma consolidated revenues and net income as if the Northwest acquisition had occurred as of January 1, 2018, are not presented because the effect of this acquisition was not considered significant.

The accompanying consolidated statements of income for the three months ended March 31, 2019, include the results of operations of the acquired entity from the August 16, 2018 acquisition date. The acquired entity continued to operate as INB until November 9, 2018 at which point INB’s operations were integrated with the Company’s operations, and INB merged with FIB.

The Company recorded $2.3 million and $2.3 million in pre-tax acquisition related expenses for the three months ended March 31, 2019 and 2018. These costs are incorporated in non-interest expenses in the Company’s consolidated statements of income.

	Three Months Ended March 31, 2019		Three Months Ended March 31, 2018
Legal and Professional Fees	$	0.3	$	0.5
Employee Expenses	0.6		0.1
Technology Conversion and Contract Termination	0.8		1.5
Other	0.6		0.2
Total Acquisition Related Expenses	$	2.3	$	2.3

12

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(3) Goodwill and Core Deposit Intangibles

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, 2018 and 2017 and concluded that there was no impairment to goodwill.

Goodwill

	As of March 31,
	2019			2018
Net carrying value at beginning of three month period	$	546.7		$	444.7
Measurement period adjustment to previously recorded goodwill	(0.4		)	0.9
Net carrying value at end of period	$	546.3		$	445.6

Core deposit intangibles (“CDI”)

	As of March 31,
	2019			2018
Gross CDI, beginning of period	$	89.7		$	74.0
Accumulated amortization	(35.1		)	(26.7		)
Net CDI, end of period	$	54.6		$	47.3

The Company recorded $2.3 million and $1.8 million of CDI amortization expense for the three months ended March 31, 2019 and 2018.

CDI are evaluated for impairment if events and circumstances indicate a possible impairment and are amortized using an accelerated method based on the estimated weighted average useful lives of the related deposits, which is generally ten years.

The following table provides the estimated future CDI amortization expense:

Years Ending December 31,
2019 remaining	$	6.6
2020	8.1
2021	7.5
2022	6.9
2023	6.3
Thereafter	19.2
Total	$	54.6

13

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(4)     Investment Securities

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

March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	4.0	$	—	$	—		$	4.0
State, county and municipal securities	77.7		0.8		(0.1		)	78.4
Obligations of U.S. government agencies	601.4		0.3		(4.0		)	597.7
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	1,735.9		9.4		(12.4		)	1,732.9
Private mortgage-backed securities	66.2		—		(0.9		)	65.3
Corporate securities	92.1		0.2		(0.3		)	92.0
Other investments	1.7		—		—			1.7
Total	$	2,579.0	$	10.7	$	(17.7	)	$	2,572.0

March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held-to-Maturity:
State, county and municipal securities	$	67.6	$	1.5	$	(0.2	)	$	68.9
Obligations of U.S. government agencies	19.8		—		(0.2		)	19.6
U.S agency residential mortgage-backed securities & collateralized mortgage obligations	1.3		—		—			1.3
Corporate securities	28.2		—		(0.1		)	28.1
Other investments	0.1		—		—			0.1
Total	$	117.0	$	1.5	$	(0.5	)	$	118.0

December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	2.6	$	—	$	—		$	2.6
Obligations of U.S. government agencies	569.3		0.1		(10.2		)	559.2
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	1,566.4		2.5		(24.1		)	1,544.8
Private mortgage-backed securities	72.0		—		(1.8		)	70.2
Corporate securities	92.9		—		(1.0		)	91.9
Other investments	2.0		—		—			2.0
Total	$	2,305.2	$	2.6	$	(37.1	)	$	2,270.7

December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held-to-Maturity:
State, county and municipal securities	$	150.9	$	1.8	$	(0.9	)	$	151.8
Obligations of U.S. government agencies	19.8		—		(0.3		)	19.5
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	189.7		0.3		(6.5		)	183.5
Corporate securities	46.3		0.1		(0.6		)	45.8
Other investments	0.1		—		—			0.1
Total	$	406.8	$	2.2	$	(8.3	)	$	400.7

14

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

At December 31, 2018, we had $406.8 million of investment securities classified as held to maturity. As a result of the adoption of ASU 2017-12 discussed in “Note 16 – Recent Authoritative Accounting Guidance” included in this report, the Company transferred investment securities classified as held-to-maturity to investment securities available-for-sale. At the time of transfer, the amortized cost and fair value of these securities totaled $281.1 million and $275.0 million, respectively. In addition, the unrealized loss of $6.0 million was recorded in the consolidated statement of comprehensive income.

There were no material gross realized gains and losses from the disposition of available-for-sale investment securities for the three month periods ended March 31, 2019 and 2018.

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 a continuous unrealized loss position, as of March 31, 2019 and December 31, 2018:

	Less than 12 Months					12 Months or More					Total
March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Available-for-Sale:
State, county and municipal securities	$	—	$	—		$	16.2	$	(0.1	)	$	16.2	$	(0.1	)
Obligations of U.S. government agencies	336.8		(2.8		)	129.7		(1.2		)	466.5		(4.0		)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	535.9		(6.9		)	450.3		(5.5		)	986.2		(12.4		)
Private mortgage-backed securities	—		—			64.5		(0.9		)	64.5		(0.9		)
Corporate securities	—		—			36.9		(0.3		)	36.9		(0.3		)
Total	$	872.7	$	(9.7	)	$	697.6	$	(8.0	)	$	1,570.3	$	(17.7	)

	Less than 12 Months					12 Months or More					Total
March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Held-to-Maturity:
State, county and municipal securities	$	9.0	$	(0.1	)	$	16.6	$	(0.1	)	$	25.6	$	(0.2	)
Obligations of U.S. government agencies	19.6		(0.2		)	—		—			19.6		(0.2		)
Corporate securities	—		—			28.0		(0.1		)	28.0		(0.1		)
Total	$	28.6	$	(0.3	)	$	44.6	$	(0.2	)	$	73.2	$	(0.5	)

	Less than 12 Months					12 Months or More					Total
December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Available-for-Sale:
Obligations of U.S. government agencies	$	363.1	$	(7.9	)	$	154.5	$	(2.3	)	$	517.6	$	(10.2	)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	735.2		(14.5		)	503.7		(9.6		)	1,238.9		(24.1		)
Private mortgage-backed securities	—		—			69.4		(1.8		)	69.4		(1.8		)
Corporate securities	24.9		(0.2		)	51.4		(0.8		)	76.3		(1.0		)
Total	$	1,123.2	$	(22.6	)	$	779.0	$	(14.5	)	$	1,902.2	$	(37.1	)

15

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, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Held-to-Maturity:
State, county and municipal securities	$	25.9	$	(0.3	)	$	57.1	$	(0.6	)	$	83.0	$	(0.9	)
Obligations of U.S. government agencies	19.5		(0.3		)	—		—			19.5		(0.3		)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	45.0		(2.2		)	120.2		(4.3		)	165.2		(6.5		)
Corporate securities	—		—			39.6		(0.6		)	39.6		(0.6		)
Total	$	90.4	$	(2.8	)	$	216.9	$	(5.5	)	$	307.3	$	(8.3	)

The investment portfolio is evaluated quarterly for other-than-temporary declines in the market value of each individual investment security. The Company had 551 and 760 individual investment securities that were in an unrealized loss position as of March 31, 2019 and December 31, 2018, respectively, related primarily to fluctuations in the current interest rates. As of March 31, 2019, the Company had the intent and ability to hold these investment securities for a period of time sufficient to allow for an anticipated recovery. Furthermore, the Company does not have the intent to sell any of the available-for-sale securities in the above table and it is more likely than not that the Company will not have to sell any securities before a recovery in cost. No impairment losses were recorded during the three month periods ended March 31, 2019 or 2018.

Maturities of investment securities at March 31, 2019 are shown below. 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
March 31, 2019	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	497.2	$	496.0	$	44.9	$	44.8
After one year but within five years	1,509.8		1,504.9		44.2		44.1
After five years but within ten years	395.3		395.5		24.3		25.5
After ten years	176.7		175.6		3.6		3.6
Total	$	2,579.0	$	2,572.0	$	117.0	$	118.0

As of March 31, 2019, the Company had investment securities callable within one year with amortized costs and estimated fair values of $121.3 million and $121.5 million, respectively. These investment securities are primarily included in the after one year but within five years category in the table above. As of March 31, 2019, the Company had callable structured notes with amortized costs and estimated fair values of $2.0 million and $2.0 million, respectively. These callable structured notes, which are classified as available-for-sale, are included in the after one year but within five years category in the table above.

16

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(5) Loans

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

	March 31, 2019		December 31, 2018
Real estate loans:
Commercial	$	3,255.8	$	3,235.4
Construction:
Land acquisition & development	292.7		321.6
Residential	233.1		242.8
Commercial	312.1		274.3
Total construction loans	837.9		838.7
Residential	1,529.5		1,542.0
Agricultural	210.4		217.4
Total real estate loans	5,833.6		5,833.5
Consumer:
Indirect consumer	775.7		787.8
Other consumer	194.1		200.6
Credit card	77.2		81.8
Total consumer loans	1,047.0		1,070.2
Commercial	1,342.1		1,310.3
Agricultural	234.7		254.8
Other, including overdrafts	1.8		1.6
Loans held for investment	8,459.2		8,470.4
Mortgage loans held for sale	34.0		33.3
Total loans	$	8,493.2	$	8,503.7

17

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The following tables present the Company’s recorded investment and contractual aging of the Company’s recorded investment in loans by class as of the dates indicated. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due.

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of March 31, 2019	Past Due		Past Due		Past Due		Past Due		Loans		Loans		Loans
Real estate
Commercial	$	12.6	$	7.2	$	2.5	$	22.3	$	3,222.4	$	11.1	$	3,255.8
Construction:
Land acquisition & development	1.2		0.7		0.4		2.3		286.6		3.8		292.7
Residential	2.2		—		—		2.2		229.6		1.3		233.1
Commercial	—		—		—		—		311.9		0.2		312.1
Total construction loans	3.4		0.7		0.4		4.5		828.1		5.3		837.9
Residential	4.6		1.6		0.2		6.4		1,517.2		5.9		1,529.5
Agricultural	4.0		0.9		0.3		5.2		202.8		2.4		210.4
Total real estate loans	24.6		10.4		3.4		38.4		5,770.5		24.7		5,833.6
Consumer:
Indirect consumer	6.5		1.1		0.5		8.1		765.6		2.0		775.7
Other consumer	1.4		0.7		0.3		2.4		191.2		0.5		194.1
Credit card	0.6		0.5		0.7		1.8		75.4		—		77.2
Total consumer loans	8.5		2.3		1.5		12.3		1,032.2		2.5		1,047.0
Commercial	4.0		4.1		1.7		9.8		1,317.0		15.3		1,342.1
Agricultural	1.3		1.3		0.5		3.1		229.0		2.6		234.7
Other, including overdrafts	—		—		—		—		1.8		—		1.8
Loans held for investment	38.4		18.1		7.1		63.6		8,350.5		45.1		8,459.2
Mortgage loans originated for sale	—		—		—		—		34.0		—		34.0
Total loans	$	38.4	$	18.1	$	7.1	$	63.6	$	8,384.5	$	45.1	$	8,493.2

18

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2018	Past Due		Past Due		Past Due		Past Due		Loans		Loans		Loans
Real estate
Commercial	$	10.4	$	1.0	$	0.8	$	12.2	$	3,214.0	$	9.2	$	3,235.4
Construction:
Land acquisition & development	1.6		0.1		0.2		1.9		316.0		3.7		321.6
Residential	1.0		0.4		—		1.4		240.4		1.0		242.8
Commercial	0.4		—		—		0.4		273.7		0.2		274.3
Total construction loans	3.0		0.5		0.2		3.7		830.1		4.9		838.7
Residential	8.8		1.1		0.2		10.1		1,525.3		6.6		1,542.0
Agricultural	2.2		—		—		2.2		202.6		12.6		217.4
Total real estate loans	24.4		2.6		1.2		28.2		5,772.0		33.3		5,833.5
Consumer:
Indirect consumer	6.8		2.1		0.4		9.3		776.8		1.7		787.8
Other consumer	1.4		0.5		0.1		2.0		198.1		0.5		200.6
Credit card	0.9		0.4		0.8		2.1		79.7		—		81.8
Total consumer loans	9.1		3.0		1.3		13.4		1,054.6		2.2		1,070.2
Commercial	8.3		1.2		1.3		10.8		1,283.7		15.8		1,310.3
Agricultural	2.1		0.3		—		2.4		249.4		3.0		254.8
Other, including overdrafts	—		—		—		—		1.6		—		1.6
Loans held for investment	43.9		7.1		3.8		54.8		8,361.3		54.3		8,470.4
Mortgage loans originated for sale	—		—		—		—		33.3		—		33.3
Total loans	$	43.9	$	7.1	$	3.8	$	54.8	$	8,394.6	$	54.3	$	8,503.7

Loans from business combinations included in the tables above include certain loans that had evidence of deterioration in credit quality since origination and for which it was probable, at acquisition, that all contractually required payments would not be collected.

The following table displays the outstanding unpaid balances and accrual status of loans acquired with credit impairment as of the dates indicated:    

	March 31, 2019		December 31, 2018
Outstanding balance	$	40.9	$	43.4
Carrying value
Loans on accrual status	28.0		30.2
Total carrying value	$	28.0	$	30.2

The following table summarizes changes in the accretable yield for loans acquired deemed credit impaired for the three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	8.9		$	7.3
Accretion income	(0.7		)	(0.7		)
Reductions due to exit events	(0.3		)	(0.2		)
Reclassifications from non-accretable differences	0.5			0.8
Ending balance	$	8.4		$	7.2

19

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Acquired loans that met the criteria for non-accrual of interest prior to acquisition were considered performing upon acquisition. If interest on non-accrual loans had been accrued, such income would have been approximately $0.6 million and $0.8 million for the three months ended March 31, 2019 and 2018, respectively.

The Company considers impaired loans to include all originated loans, except consumer loans, that are risk rated as doubtful, or have been placed on non-accrual status or renegotiated in troubled debt restructurings, and all loans acquired with evidence of deterioration in credit quality and for which it was probable, at acquisition, that the Company would be unable to collect all contractual amounts owed. The following tables present information on the Company’s recorded investment in impaired loans as of the dates indicated:

As of March 31, 2019	Unpaid Total Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
Real estate:
Commercial	$	27.0	$	10.7	$	10.6	$	21.3	$	0.7
Construction:
Land acquisition & development	10.0		0.4		3.4		3.8		0.3
Residential	1.5		0.9		0.4		1.3		—
Commercial	0.6		0.1		—		0.1		—
Total construction loans	12.1		1.4		3.8		5.2		0.3
Residential	8.9		4.2		3.3		7.5		0.5
Agricultural	2.7		2.4		0.2		2.6		—
Total real estate loans	50.7		18.7		17.9		36.6		1.5
Commercial	24.3		5.8		14.0		19.8		5.1
Agricultural	5.0		1.6		3.2		4.8		0.5
Total	$	80.0	$	26.1	$	35.1	$	61.2	$	7.1

As of December 31, 2018	Unpaid Total Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
Real estate:
Commercial	$	22.2	$	8.6	$	7.7	$	16.3	$	0.7
Construction:
Land acquisition & development	10.0		0.4		3.5		3.9		0.2
Residential	1.1		0.6		0.4		1.0		0.1
Commercial	0.7		0.2		—		0.2		—
Total construction loans	11.8		1.2		3.9		5.1		0.3
Residential	8.8		5.7		2.0		7.7		0.3
Agricultural	12.9		12.5		0.2		12.7		—
Total real estate loans	55.7		28.0		13.8		41.8		1.3
Commercial	24.1		5.5		14.4		19.9		5.2
Agricultural	3.2		2.5		0.6		3.1		0.3
Total	$	83.0	$	36.0	$	28.8	$	64.8	$	6.8

20

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The following table presents the average recorded investment in and income recognized on impaired loans for the periods indicated:

	Three Months Ended March 31,
	2019				2018
	Average Recorded Investment		Income Recognized		Average Recorded Investment		Income Recognized
Real estate	$	39.3	$	—	$	56.1	$	—
Commercial	19.9		—		22.1		—
Agricultural	3.9		—		1.5		—
Total	$	63.1	$	—	$	79.7	$	—

Interest payments received on non-accrual impaired loans are applied to principal. Interest income is subsequently recognized only to the extent cash payments are received in excess of principal due. If interest on impaired loans had been accrued, interest income on impaired loans would have been approximately $0.6 million and $0.8 million for the three months ended March 31, 2019 and 2018, respectively.

Collateralized impaired loans are generally recorded at the fair value of the underlying collateral using discounted cash flows, independent appraisals and management estimates based upon current market conditions. For loans measured under the present value of cash flows method, the change in present value attributable to the passage of time, if applicable, is recognized in the provision for loan losses and thus no interest income is recognized.

Modifications of performing loans are made in the ordinary course of business and are completed on a case-by-case basis as negotiated with the borrower. Loan modifications typically include interest rate changes, interest only periods of less than twelve months, short-term payment deferrals and extension of amortization periods to provide payment relief. 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 otherwise consider. Certain troubled debt restructurings are on non-accrual status at the time of restructuring and may be returned to accrual status after considering the borrower’s sustained repayment performance in accordance with the restructuring agreement for a period of at least six months and management is reasonably assured of future performance. If the troubled debt restructuring meets these performance criteria and the interest rate granted at the modification is equal to or greater than the rate that the Company was willing to accept at the time of the restructuring for a new loan with comparable risk, then the loan will return to performing status and the accrual of interest will resume, although they continue to be individually evaluated for impairment and disclosed as impaired loans.

The Company had loans renegotiated in troubled debt restructurings of $22.7 million as of March 31, 2019, of which $16.9 million were included in non-accrual loans and $5.8 million were on accrual status. The Company had loans renegotiated in troubled debt restructurings of $23.4 million as of December 31, 2018, of which $17.8 million were included in non-accrual loans and $5.6 million were on accrual status.

The Company had no material troubled debt restructurings that occurred during the three months ended March 31, 2019.

For troubled debt restructurings that were on non-accrual status or otherwise deemed impaired before the modification, a specific reserve may already be recorded. In periods subsequent to modification, the Company continues to evaluate all troubled debt restructurings for possible impairment and recognizes impairment through the allowance. Additionally these loans continue to work their way 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 no charge-offs directly related to modifying troubled debt restructurings during the three months ended March 31, 2019 or 2018.

21

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The Company had no material troubled debt restructurings during the previous 12 months for which there was a payment default during the three months ended March 31, 2019. The Company considers a payment default to occur on troubled debt restructurings when the loan is 90 days or more past due or was placed on non-accrual status after the modification.

At March 31, 2019, there were no material commitments to lend additional funds to borrowers whose existing loans have been renegotiated or are classified as non-accrual.

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. The Company adheres to a Uniform Classification System developed jointly by the various bank regulatory agencies to internally risk rate loans. The Uniform Classification System defines three broad categories of criticized assets, which the Company uses as credit quality indicators:

Other Assets Especially Mentioned — includes loans that exhibit weaknesses in financial condition, loan structure or documentation, which if not promptly corrected, may lead to the development of abnormal risk elements.

Substandard — includes loans that are inadequately protected by the current sound worth and paying capacity of the borrower. Although the primary source of repayment for a substandard loan is not currently 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 to a point where collection or liquidation in full, on the basis of currently existing facts, conditions and values, is highly questionable and improbable. Doubtful loans are required to be placed on non-accrual status and are assigned specific loss exposure.

Company management undertakes the same process for assigning risk ratings to acquired loans as it does for originated loans. Acquired loans rated as substandard or lower or that were on non-accrual status or designated as troubled debt restructurings at the time of acquisition are deemed to be acquired credit impaired loans accounted for under ASC Topic 310-30, regardless of whether they are classified as performing or non-performing loans.

The following tables present the Company’s recorded investment in criticized loans by class and credit quality indicator based on the most recent analysis performed as of the dates indicated:

As of March 31, 2019	Other Assets Especially Mentioned		Substandard		Doubtful		Total Criticized Loans
Real estate:
Commercial	$	100.4	$	90.9	$	2.8	$	194.1
Construction:
Land acquisition & development	5.1		2.2		3.4		10.7
Residential	0.9		2.2		0.9		4.0
Commercial	1.8		4.1		—		5.9
Total construction loans	7.8		8.5		4.3		20.6
Residential	2.6		8.9		1.9		13.4
Agricultural	15.7		18.0		0.1		33.8
Total real estate loans	126.5		126.3		9.1		261.9
Consumer:
Indirect consumer	0.3		2.7		0.1		3.1
Direct consumer	0.3		0.8		0.1		1.2
Total consumer loans	0.6		3.5		0.2		4.3
Commercial	42.3		46.5		11.3		100.1
Agricultural	16.8		18.3		1.1		36.2
Total	$	186.2	$	194.6	$	21.7	$	402.5

22

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

As of December 31, 2018	Other Assets Especially Mentioned		Substandard		Doubtful		Total Criticized Loans
Real estate:
Commercial	$	102.5	$	87.4	$	2.9	$	192.8
Construction:
Land acquisition & development	5.0		7.0		3.3		15.3
Residential	2.8		2.0		0.4		5.2
Commercial	1.7		3.9		—		5.6
Total construction loans	9.5		12.9		3.7		26.1
Residential	3.0		10.8		0.7		14.5
Agricultural	9.0		24.0		0.1		33.1
Total real estate loans	124.0		135.1		7.4		266.5
Consumer:
Indirect consumer	0.7		2.1		0.1		2.9
Direct consumer	0.3		0.8		0.1		1.2
Total consumer loans	1.0		2.9		0.2		4.1
Commercial	39.4		45.8		11.8		97.0
Agricultural	14.4		17.8		1.5		33.7
Total	$	178.8	$	201.6	$	20.9	$	401.3

The Company maintains a credit review function, which is independent of the credit approval process, to assess assigned internal risk classifications and monitor compliance with internal lending policies and procedures.

Written action plans with firm target dates for resolution of identified problems are maintained and reviewed on a quarterly basis for all categories of criticized loans.

(6) Allowance for Loan Losses

The following tables present a summary of changes in the allowance for loan losses by portfolio segment for the periods indicated:

Three Months Ended March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Allowance for loan losses:
Beginning balance	$	31.0		$	8.7		$	31.3		$	2.0		$	—	$	73.0
Provision charged to operating expense	(1.7		)	2.0			3.6			(0.2		)	—		3.7
Less loans charged-off	(2.1		)	(3.0		)	(0.8		)	(0.1		)	—		(6.0		)
Add back recoveries of loans previously    charged-off	0.2			1.1			0.4			—			—		1.7
Ending balance	$	27.4		$	8.8		$	34.5		$	1.7		$	—	$	72.4
As of March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Allowance for loan losses:
Loans individually evaluated for impairment	$	1.5		$	—		$	5.1		$	0.5		$	—	$	7.1
Loans collectively evaluated for impairment	25.9			8.8			29.4			1.2			—		65.3
Allowance for loan losses	$	27.4		$	8.8		$	34.5		$	1.7		$	—	$	72.4
As of March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Loans held for investment:
Individually evaluated for impairment	$	36.6		$	—		$	19.8		$	4.8		$	—	$	61.2
Collectively evaluated for impairment	5,797.0			1,047.0			1,322.3			229.9			1.8		8,398.0
Total loans held for investment	$	5,833.6		$	1,047.0		$	1,342.1		$	234.7		$	1.8	$	8,459.2

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 March 31, 2018	Real Estate			Consumer			Commercial			Agriculture		Other		Total
Allowance for loan losses:
Beginning balance	$	31.7		$	8.7		$	30.5		$	1.2	$	—	$	72.1
Provision charged to operating expense	1.8			0.7			(0.7		)	0.3		—		2.1
Less loans charged-off	(0.8		)	(2.7		)	(1.7		)	—		—		(5.2		)
Add back recoveries of loans previously    charged-off	1.2			1.1			2.0			0.2		—		4.5
Ending balance	$	33.9		$	7.8		$	30.1		$	1.7	$	—	$	73.5

As of December 31, 2018	Real Estate		Consumer		Commercial		Agriculture		Other		Total
Allowance for loan losses:
Loans individually evaluated for impairment	$	1.3	$	—	$	5.2	$	0.3	$	—	$	6.8
Loans collectively evaluated for impairment	29.7		8.7		26.1		1.7		—		66.2
Allowance for loan losses	$	31.0	$	8.7	$	31.3	$	2.0	$	—	$	73.0
As of December 31, 2018	Real Estate		Consumer		Commercial		Agriculture		Other		Total
Loans held for investment:
Individually evaluated for impairment	$	41.8	$	—	$	19.9	$	3.1	$	—	$	64.8
Collectively evaluated for impairment	5,791.7		1,070.2		1,290.4		251.7		1.6		8,405.6
Total loans held for investment	$	5,833.5	$	1,070.2	$	1,310.3	$	254.8	$	1.6	$	8,470.4

The Company performs a quarterly assessment of the adequacy of its allowance for loan losses in accordance with GAAP. The methodology used to assess the adequacy is consistently applied to the Company’s loan portfolio and consists of three elements: (1) specific valuation allowances based on probable losses on impaired loans; (2) historical valuation allowances based on loan loss experience for similar loans with similar characteristics and trends; and (3) general valuation allowances determined based on changes in the nature of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends, general economic conditions and other qualitative risk factors both internal and external to the Company.

Specific allowances are established for loans where management has determined that probability of a loss exists by analyzing the borrower’s ability to repay amounts owed, collateral deficiencies and any relevant qualitative or economic factors impacting the loan. Historical valuation allowances are determined by applying percentage loss factors to the credit exposures from outstanding loans. For commercial, agricultural and real estate loans, loss factors are applied based on the internal risk classifications of these loans. For consumer loans, loss factors are applied on a portfolio basis. For commercial, agriculture and real estate loans, loss factor percentages are based on a migration analysis of our historical loss experience, designed to account for credit deterioration. For consumer loans, the loss factor percentages are based on a three-year loss history for the 2018 period and on a one-year loss history for the comparable periods. The loan loss rates for 2018 also incorporate the available loss history data from Bank of the Cascades prior to the merger date to represent a consolidated institutional loss rate for both originated and acquired portfolios. General valuation allowances are determined by evaluating, on a quarterly basis, changes in the nature and volume of the loan portfolio, overall portfolio quality, industry concentrations, current economic and regulatory conditions and the estimated impact of these factors on historical loss rates.

An allowance for loan losses is established for loans acquired deemed credit impaired and for which the Company projects a decrease in the expected cash flows in periods subsequent to the acquisition of such loans. As of March 31, 2019 and December 31, 2018, the Company’s allowance for loan losses included $0.9 million and $0.8 million related to loans acquired credit impaired.

24

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(7) Other Real Estate Owned

Information with respect to the Company’s other real estate owned follows:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	14.4		$	10.1
Additions	8.4			1.2
Valuation adjustments	(0.3		)	—
Dispositions	(1.4		)	(0.3		)
Ending balance	$	21.1		$	11.0

The carrying values of foreclosed residential real estate properties included in other real estate owned were $1.7 million and $2.0 million as of March 31, 2019 and December 31, 2018, respectively. The Company had $0.5 million of consumer mortgage loans collateralized by residential real estate property that were in the process of foreclosure as of March 31, 2019 and $0.4 million as of December 31, 2018.

(8) Derivatives and Hedging Activities

The Company 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 customer 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 customer, 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.

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

25

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The notional amounts and estimated fair values of the Company’s derivatives are presented in the following table. Fair value estimates are obtained from third parties and are based on pricing models.

	March 31, 2019				December 31, 2018
	Notional Amount		Estimated Fair Value		Notional Amount		Estimated Fair Value
Derivative Assets (included in other assets on the consolidated balance sheets):
Non-hedging interest rate derivatives:
Interest rate swap contracts	$	449.2	$	12.7	$	403.3	$	8.8
Interest rate lock commitments	76.9		1.9		51.0		1.3
Total derivative assets	$	526.1	$	14.6	$	454.3	$	10.1
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Non-hedging interest rate derivatives:
Interest rate swap contracts	$	449.2	$	12.7	$	403.3	$	8.8
Forward loan sales contracts	90.4		0.8		64.6		0.6
Total derivative liabilities	$	539.6	$	13.5	$	467.9	$	9.4

Derivative assets and liabilities are recorded at fair value on the balance sheet and do not take into account the effects of master netting arrangements. Master netting arrangements allow the Company to settle all contracts held with a single counterparty on a net basis and to offset net contract position with related collateral where applicable.

The following table illustrates the potential effect of the Company’s master netting arrangements, by type of financial instrument, on the Company’s consolidated balance sheets as of March 31, 2019 and December 31, 2018:

	March 31, 2019
	Gross Amounts Recognized		Gross Amounts Offset in the Balance Sheet		Net Amounts in the Balance Sheet		Financial Instruments		Fair Value of Financial Collateral in the Balance Sheet		Net Amount
Financial Assets
Interest rate swap contracts	$	12.7	$	—	$	12.7	$	2.0	$	7.5	$	3.2
Mortgage related derivatives	1.9		—		1.9		—		—		1.9
Total derivatives	14.6		—		14.6		2.0		7.5		5.1
Total assets	$	14.6	$	—	$	14.6	$	2.0	$	7.5	$	5.1
Financial Liabilities
Interest rate swap contracts	$	12.7	$	—	$	12.7	$	2.0	$	0.2	$	10.5
Mortgage related derivatives	0.8		—		0.8		—		—		0.8
Total derivatives	13.5		—		13.5		2.0		0.2		11.3
Repurchase agreements	672.6		—		672.6		—		672.6		—
Total liabilities	$	686.1	$	—	$	686.1	$	2.0	$	672.8	$	11.3

26

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

	December 31, 2018
	Gross Amounts Recognized		Gross Amounts Offset in the Balance Sheet		Net Amounts in the Balance Sheet		Financial Instruments		Fair Value of Financial Collateral in the Balance Sheet		Net Amount
Financial Assets
Interest rate swap contracts	$	8.8	$	—	$	8.8	$	2.7	$	2.4	$	3.7
Mortgage related derivatives	1.3		—		1.3		—		—		1.3
Total derivatives	10.1		—		10.1		2.7		2.4		5.0
Total assets	$	10.1	$	—	$	10.1	$	2.7	$	2.4	$	5.0
Financial Liabilities
Interest rate swap contracts	$	8.8	$	—	$	8.8	$	2.7	$	4.1	$	2.0
Mortgage related derivatives	0.6		—		0.6		—		—		0.6
Total derivatives	9.4		—		9.4		2.7		4.1		2.6
Repurchase agreements	712.4		—		712.4		—		712.4		—
Total liabilities	$	721.8	$	—	$	721.8	$	2.7	$	716.5	$	2.6

The following table presents the pre-tax gains or losses related to derivative contracts that were recorded in other non-interest income in the Company’s statements of income for the periods indicated:

	Three Months Ended March 31,
	2019		2018
Non-hedging interest rate derivatives:
Amount of gain recognized in other non-interest income	$	—	$	0.3
Amount of net fee income recognized in other non-interest income	0.8		0.5
Amount of net gains recognized in mortgage banking revenues	0.4		(0.1		)

(9) Capital Stock

The Company had 38,461,948 shares of Class A common stock and 22,374,171 shares of Class B common stock outstanding as of March 31, 2019. The Company had 38,169,575 shares of Class A common stock and 22,453,672 shares of Class B common stock outstanding as of December 31, 2018.

During the three months ended March 31, 2019 and 2018, the Company did not repurchase any shares of its Class A common stock other than stock repurchases which 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.

(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.

27

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

The following table sets forth the computation of basic and diluted earnings per share for the three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019		2018
Net income	$	41.6	$	36.7
Weighted average common shares outstanding for basic earnings per share computation	60,311,171		56,241,201
Dilutive effects of stock-based compensation	286,899		410,977
Weighted average common shares outstanding for diluted earnings per common share computation	60,598,070		56,652,178
Basic earnings per common share	$	0.69	$	0.65
Diluted earnings per common share	$	0.69	$	0.65
Anti-dilutive unvested time restricted stock	121,452		139,943

The Company had 154,387 and 164,019 shares of unvested restricted stock as of March 31, 2019 and 2018, respectively, that were not included in the computation of diluted earnings per common share because performance conditions for vesting had not been met.

(11) Regulatory Capital

On July 2, 2013, the Board of Governors of the Federal Reserve Bank issued a final rule implementing a revised regulatory capital framework for U.S. banks in accordance with the Basel III international accord and satisfying related mandates under the Dodd-Frank Wall Street Reform and Consumer Protection Act. The revised regulatory capital framework (the “Basel III Capital Rules”) substantially revised the risk-based capital requirements applicable to bank holding companies and depository institutions by defining the components of capital and addressing other issues affecting the numerator in banking institutions’ regulatory capital ratios, addressing risk weights and other issues affecting the denominator in banking institutions’ regulatory capital ratios and replacing the existing risk-weighting approach with a more risk-sensitive approach. The Basel III Capital Rules became effective for the Company on January 1, 2015, subject to a phase-in period for certain provisions. The capital conservation buffer required under Basel III began to phase in starting January 1, 2016 and became fully implemented on January 1, 2019.

28

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

As of March 31, 2019 and December 31, 2018, 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 March 31, 2019 and December 31, 2018 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)
March 31, 2019	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,310.3	13.23	%	$	792.4	8.000	%	$	1,040.0	10.50	%	$	990.5	10.00	%
FIB	1,201.4		12.16		790.2		8.000		1,037.1		10.50		987.8		10.00
Tier 1 risk-based capital:
Consolidated	1,237.9		12.50		594.3		6.000		841.9		8.50		792.4		8.00
FIB	1,129.0		11.43		592.7		6.000		839.6		8.50		790.2		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,153.7		11.65		445.7		4.500		693.4		7.00		643.8		6.50
FIB	1,129.0		11.43		444.5		4.500		691.4		7.00		642.0		6.50
Leverage capital ratio:
Consolidated	1,237.9		9.76		507.5		4.000		507.5		4.00		634.4		5.00
FIB	1,129.0		8.92		506.3		4.000		506.3		4.00		632.8		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, 2018	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,285.0	12.99	%	$	791.2	8.00	%	$	976.6	9.875	%	$	989.0	10.00	%
FIB	1,184.5		12.01		788.8		8.00		973.7		9.875		986.0		10.00
Tier 1 risk-based capital:
Consolidated	1,212.0		12.26		593.4		6.00		778.8		7.875		791.2		8.00
FIB	1,111.6		11.27		591.6		6.00		776.5		7.875		788.8		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,127.8		11.40		445.0		4.50		630.5		6.375		642.8		6.50
FIB	1,111.6		11.27		443.7		4.50		628.6		6.375		640.9		6.50
Leverage capital ratio:
Consolidated	1,212.0		9.47		511.9		4.00		511.9		4.000		639.9		5.00
FIB	1,111.6		8.97		495.9		4.00		495.9		4.000		619.8		5.00

(1) The ratios for 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 entity and has presented the ratios as if they also applied on a consolidated basis.

(12) Commitments and Contingencies

In the normal course of business, the Company is involved in various other claims and litigation. In the opinion of management, following consultation with legal counsel, the ultimate liability or disposition thereof of all other 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 March 31, 2019, the Company had commitments under construction contracts of $1.5 million.

29

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Residential mortgage loans sold to investors in the secondary market are sold with varying recourse provisions. Essentially all of 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; unmarketability; etc. 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 $1.5 million of sold residential mortgage loans with recourse provisions still in effect as of March 31, 2019.

(13) Financial Instruments with Off-Balance Sheet Risk

The Company is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit. Commitments to extend credit are agreements to lend to a customer as 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. At March 31, 2019, commitments to extend credit to existing and new borrowers approximated $2,637.1 million, which included $720.7 million on unused credit card lines and $1,058.9 million with commitment maturities beyond one year.

Standby letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. At March 31, 2019, the Company had outstanding standby letters of credit of $47.6 million. The estimated fair value of the obligation undertaken by the Company in issuing the standby letters of credit is included in other liabilities in the Company’s consolidated balance sheet.

(14) Other Comprehensive Income/Loss

The gross amounts of each component of other comprehensive income and the related tax effects are as follows:

	Pre-tax						Tax Expense (Benefit)						Net of Tax
Three Months Ended March 31,	2019			2018			2019			2018			2019			2018
Investment securities available-for sale:
Change in net unrealized gains during period	$	33.6		$	(23.7	)	$	8.8		$	(6.2	)	$	24.8		$	(17.5	)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(6.0		)	—			(1.6		)	—			(4.4		)	—
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	—			0.5			—			0.2			—			0.3
Defined benefits post-retirement benefit plan:
Change in net actuarial (gain) loss	(0.2		)	(0.1		)	—			(0.1		)	(0.2		)	—
Total other comprehensive income (loss)	$	27.4		$	(23.3	)	$	7.2		$	(6.1	)	$	20.2		$	(17.2	)

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

	March 31, 2019			December 31, 2018
Net unrealized gain (loss) on investment securities available-for-sale	$	(5.1	)	$	(25.5	)
Net actuarial gain (loss) on defined benefit post-retirement benefit plans	0.7			0.9
Net accumulated other comprehensive gain (loss)	$	(4.4	)	$	(24.6	)

(15) Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or 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.

30

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 that may be used 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 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, and therefore are classified within Level 2 of the valuation hierarchy. The Company’s policy is to recognize transfers between levels as of the end of the reporting period. There were no transfers between Level 1 and Level 2 during the three months ended March 31, 2019 and 2018.

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 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.

Interest Rate Swap Contracts. Fair values for derivative interest rate swap contracts 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 3 month LIBOR forward curve to estimate variable rate cash inflows and the federal funds effective swap 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 from each other, was not significant in the reported periods. The Company also obtains and compares the reasonableness of the pricing from an independent third party.

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.

31

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Deferred Compensation Plan Assets and Liabilities. The fair values of deferred compensation plan assets 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 liabilities measured at fair value on a recurring basis are as follows:

			Fair Value Measurements at Reporting Date Using
As of March 31, 2019	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	$	4.0	$	—	$	4.0	$	—
State, county and municipal securities	78.4			—	78.4			—
Obligations of U.S. government agencies	597.7			—	597.7			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	1,732.9			—	1,732.9			—
Private mortgage-backed securities	65.3			—	65.3			—
Corporate securities	92.0			—	92.0			—
Other investments	1.7			—	1.7			—
Loans held for sale	34.0			—	34.0			—
Derivative assets:
Interest rate swap contracts	12.7			—	12.7			—
Interest rate lock commitments	1.9			—	1.9			—
Derivative liabilities:
Interest rate swap contracts	12.7			—	12.7			—
Forward loan sale contracts	0.8			—	0.8			—
Deferred compensation plan assets	12.4			—	12.4			—
Deferred compensation plan liabilities	$	12.4	$	—	$	12.4	$	—

32

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, 2018	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	$	2.6	$	—	$	2.6	$	—
Obligations of U.S. government agencies	559.2			—	559.2			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	1,544.8			—	1,544.8			—
Private mortgage-backed securities	70.2			—	70.2			—
Corporate securities	91.9			—	91.9			—
Other investments	2.0			—	2.0			—
Loans held for sale	33.3			—	33.3			—
Derivative assets:
Interest rate swap contracts	8.8			—	8.8			—
Interest rate lock commitments	1.3			—	1.3			—
Derivative liabilities
Interest rate swap contracts	8.8			—	8.8			—
Forward loan sales contracts	0.6			—	0.6			—
Deferred compensation plan assets	12.1			—	12.1			—
Deferred compensation plan liabilities	$	12.1	$	—	$	12.1	$	—

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 impairment. 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 March 31, 2019	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Impaired loans	$	30.9	$	—	$	—	$	30.9
Other real estate owned	2.0			—		—	2.0
Long-lived assets to be disposed of by sale	$	5.5	$	—	$	—	$	5.5
				Fair Value Measurements at Reporting Date Using
As of December 31, 2018	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Impaired loans	$	24.1	$	—	$	—	$	24.1
Other real estate owned	0.6			—		—	0.6
Long-lived assets to be disposed of by sale	$	4.9	$	—	$	—	$	4.9

33

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Impaired Loans. Collateralized impaired loans are reported at the fair value of the underlying collateral if repayment is expected solely from collateral. The impaired loans are reported at fair value through specific valuation allowance allocations. In addition, when it is determined that the fair value of an impaired 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 loan losses. Collateral values are estimated using independent appraisals and management estimates of current market conditions. As of March 31, 2019, certain impaired loans with a carrying value of $44.2 million were reduced by specific valuation allowance allocations of $7.1 million and partial loan charge-offs of $6.2 million resulting in a reported fair value of $30.9 million. As of December 31, 2018, certain impaired loans with a carrying value of $36.3 million were reduced by specific valuation allowance allocations of $6.8 million and partial loan charge-offs of $5.4 million resulting in a reported fair value of $24.1 million.

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 loan 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 $0.3 million and zero write downs on OREO properties during the three months ended March 31, 2019 and 2018, 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 March 31, 2019, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $6.0 million, which was reduced by write-downs of $0.5 million, resulting in a fair value of $5.5 million. As of December 31, 2018, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $5.4 million, reduced by write-downs of $0.5 million, resulting in a fair value of $4.9 million.         

The following table presents additional quantitative information about assets measured at fair value on a non-recurring basis and for which the Company has utilized Level 3 inputs to determine fair values:

	Fair Value As of
	March 31, 2019		December 31, 2018		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Impaired loans	$	30.9	$	24.1	Appraisal	Appraisal adjustment	0%	-	26%	(13%)
Other real estate owned	2.0		0.6		Appraisal	Appraisal adjustment	8%	-	96%	(39%)
Long-lived assets to be disposed of by sale	$	5.5	$	4.9	Appraisal	Appraisal adjustment	0%	-	43%	(10%)

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.

34

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

Financial Liabilities. The fair values of demand deposits, savings accounts, securities sold under repurchase agreements and accrued interest payable are the amounts payable on demand at the reporting date. The fair values of fixed-maturity certificates of deposit are estimated using external market rates currently offered for deposits with 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 with 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, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, are as follows:

					Fair Value Measurements at Reporting Date Using
As of March 31, 2019	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	$	955.2	$	955.2	$	955.2	$	—	$	—
Investment debt securities available-for-sale	2,572.0		2,572.0		—		2,572.0		—
Investment debt securities held-to-maturity	117.0		118.0		—		118.0		—
Accrued interest receivable	46.5		46.5		—		46.5		—
Mortgage servicing rights, net	27.9		40.5		—		40.5		—
Loans held for sale	34.0		34.0		—		34.0		—
Net loans held for investment	8,386.8		8,408.6		—		8,377.7		30.9
Derivative assets	14.6		14.6		—		14.6		—
Deferred compensation plan assets	12.4		12.4		—		12.4		—
Total financial assets	$	12,166.4	$	12,201.8	$	955.2	$	11,215.7	$	30.9
Financial liabilities:
Total deposits, excluding time deposits	$	9,408.3	$	9,408.3	$	9,408.3	$	—	$	—
Time deposits	1,406.4		1,393.2		—		1,393.2		—
Securities sold under repurchase agreements	672.6		672.6		—		672.6		—
Accrued interest payable	10.0		10.0		—		10.0		—
Long-term debt	15.8		13.9		—		13.9		—
Subordinated debentures held by subsidiary trusts	86.9		85.1		—		85.1		—
Derivative liabilities	13.5		13.5		—		13.5		—
Deferred compensation plan liabilities	12.4		12.4		—		12.4		—
Total financial liabilities	$	11,625.9	$	11,609.0	$	9,408.3	$	2,200.7	$	—

35

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, 2018	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	$	822.0	$	822.0	$	822.0	$	—	$	—
Investment debt securities available-for-sale	2,270.7		2,270.7		—		2,270.7		—
Investment debt securities held-to-maturity	406.8		400.7		—		400.7		—
Accrued interest receivable	44.9		44.9		—		44.9		—
Mortgage servicing rights, net	27.7		42.4		—		42.4		—
Loans held for sale	33.3		33.3		—		33.3		—
Net loans held for investment	8,397.4		8,439.7		—		8,415.6		24.1
Derivative assets	10.1		10.1		—		10.1		—
Deferred compensation plan assets	12.1		12.1		—		12.1		—
Total financial assets	$	12,025.0	$	12,075.9	$	822.0	$	11,229.8	$	24.1
Financial liabilities:
Total deposits, excluding time deposits	$	9,363.7	$	9,363.7	$	9,363.7	$	—	$	—
Time deposits	1,317.0		1,299.0		—		1,299.0		—
Securities sold under repurchase agreements	712.4		712.4		—		712.4		—
Accrued interest payable	7.8		7.8		—		7.8		—
Long-term debt	15.8		13.0		—		13.0		—
Subordinated debentures held by subsidiary trusts	86.9		84.9		—		84.9		—
Derivative liabilities	9.4		9.4		—		9.4		—
Deferred compensation plan liabilities	12.1		12.1		—		12.1		—
Total financial liabilities	$	11,525.1	$	11,502.3	$	9,363.7	$	2,138.6	$	—

(16) Recent Authoritative Accounting Guidance

ASU 2016-02, “Leases (Topic 842).” In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” Under the new guidance, lessees will be required to recognize a lease liability and a right of use asset for all leases (with the exception of short-term leases) at the commencement date of the lease and disclose key information about leasing arrangements.  Accounting by lessors is largely unchanged. In July 2018, the FASB issued ASU 2018-11 to provide entities with an additional (and optional) transition method to adopt the new leases standard. Under this new transition method, an entity initially applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Additionally, in December 2018, the FASB issued ASU 2018-20, “Leases (Topic 842) - Narrow-Scope Improvements for Lessors,” which provides for certain policy elections and changes lessor accounting for sales and similar taxes and certain lessor costs. Upon adoption of ASU 2016-02, ASU 2018-11 and ASU 2018-20 on January 1, 2019, the Company recognized right-of-use assets and related lease liabilities totaling $54.6 million and $54.6 million, respectively, with an immaterial impact on its consolidated results of operations and liquidity. The Company elected to apply certain practical expedients provided under ASU 2016-02 whereby we did not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases and (iii) initial direct costs for any existing leases. The Company elected the hindsight practical expedient to determine the lease term for existing leases. We also did not apply the recognition requirements of ASU 2016-02 to any short-term leases (as defined by related accounting guidance). Lease and non-lease components are accounted for separately as the amounts are readily determinable under our lease contracts.

36

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendments in ASU 2016-13 require a financial asset or group of financial assets measured at amortized cost basis to be presented on a company’s financial statements at the net amount expected to be collected based on historical experience, current conditions and reasonable and supportable forecasts. ASU 2016-13 requires a company’s income statement to reflect the measurement of credit losses for newly recognized financial assets as well as the expected increases or decreases of expected credit losses that have taken place during the period. The amendments in ASU 2016-13 require that the allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination be measured at amortized cost basis with the initial allowance for credit losses added to the purchase price rather than being reported as a credit loss expense. ASU 2016-13 also requires that credit losses relating to available-for-sale debt securities be recorded through an allowance for credit losses. The amendments in ASU 2016-13 are effective for the Company for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The amendments will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period. A prospective transition approach is required for debt securities for which other-than-temporary impairment was recognized before the effective date. Amounts previously recognized in accumulated other comprehensive income as of the date of adoption that relate to improvement in cash flows expected to be collected will continue to be accreted into income over the remaining life of the asset. Recoveries of amounts previously written off relating to improvements in cash flows after the date of adoption will be recorded in earnings when received. We are currently evaluating the potential impact of ASU 2016-13 on our financial statements, which will be effective on January 1, 2020. We have formed a cross-functional working group comprised of individuals from various functional areas including credit, risk management, finance and information technology, among others. We are currently working through our implementation plan which includes assessment and documentation of processes, internal controls and data sources; model development and documentation; and system configuration, among other things. We are in the process of implementing a third-party vendor solution. The adoption of ASU 2016-13 could result in an increase in the allowance for loan losses as a result of changing from an “incurred loss” model, which encompasses allowances for current known and inherent losses within the portfolio, to an “expected loss” model, which encompasses allowances for losses expected to be incurred over the life of the portfolio. The adoption will also necessitate that we establish an allowance for expected credit losses for certain debt securities and other financial assets. While we are currently unable to reasonably estimate the impact of adopting ASU 2016-13, we expect that the impact of adoption will be significantly influenced by the composition, characteristics and quality of our loan and securities portfolios as well as the prevailing economic conditions and forecasts as of the adoption date.

ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” The amendments in ASU 2017-08 shorten the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The new guidance does not change the accounting for purchased callable debt securities held at a discount; the discount continues to be amortized to maturity. ASU No. 2017-08 is effective for interim and annual reporting periods beginning after December 15, 2018. As the Company amortized premiums on callable debt securities to the earliest call date, the amendments in ASU 2017-08 became effective for the Company on January 1, 2019, and did not have a significant impact on the Company’s consolidated financial statements, results of operations or liquidity.

ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12). The purpose of this updated guidance is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. In addition, this ASU makes certain targeted improvements to simplify the application of the hedge accounting, including to derivative instruments as well as allow a one-time election to reclassify fixed-rate, prepayable debt securities from a held-to-maturity classification to an available-for-sale classification. ASU 2017-12 is effective for public business entities for fiscal years beginning after December 15, 2018. Guidance related to existing cash flow hedges and, if elected, fair value hedges is to be applied under a modified retrospective approach and guidance related to amended presentation and disclosures is to be applied under a prospective approach. Upon adoption of ASU 2017-12 on January 1, 2019, the guidance did not have an impact on the Company's derivatives and, thus, no adjustments were made related to derivatives. In conjunction with the adoption of ASU 2017-12, the Company made the transition election to reclassify $281.1 million in book value of securities, that qualified, from held-to-maturity to available-for-sale.

37

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement.” In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement: Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (ASU 2018-13). The amendments in this Update removes, modifies, and adds to the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in the Concepts Statement, including the consideration of costs and benefits. The amendments in this Update are effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. An entity is permitted to early adopt any removed or modified disclosures upon issuance of this Update and delay adoption of the additional disclosures until their effective date. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements disclosures.

ASU 2018-14, “Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans.” In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General: Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans (ASU 2018-14). The amendments in this Update remove disclosures that no longer are considered cost beneficial, clarify the specific requirements of disclosures, and add disclosure requirements identified as relevant. Although narrow in scope, the amendments are considered an important part of the Board’s efforts to improve the effectiveness of disclosures in the notes to financial statements by applying concepts in the Concepts Statement. The amendments in this Update are effective for fiscal years ending after December 15, 2020, for public business entities. Early adoption is permitted. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements disclosures.

ASU 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other- Internal-Use Software (Subtopic 350-40). The amendments in this Update clarifies certain aspects of ASU 2015-05, “Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement,” which was issued in April 2015. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the Update. The amendments in this Update are effective for fiscal years beginning after December 15, 2019, for public business entities. Early adoption is permitted. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements disclosures.

ASU 2018-16, “Derivatives and Hedging (Topic 815) - Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes.” In October 2018, the FASB issued ASU 2018-16, Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes. The amendments in this Update permit use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes under Topic 815 in addition to the interest rates on direct U.S. Treasury obligations, the LIBOR swap rate, the OIS rate based on the Fed Funds Effective Rate and the Securities Industry and Financial Markets Association (SIFMA) Municipal Swap Rate. The amendments in ASU 2018-16 became effective for the Company in conjunction with the adoption of ASU 2017-12 on January 1, 2019, and did not have a significant impact on the Company’s consolidated financial statements, results of operations or liquidity.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

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

(17)    Subsequent Events

Subsequent events have been evaluated for potential recognition and disclosure through the date financial statements were filed with the SEC. On May 3, 2019, the Company declared a quarterly dividend to common shareholders of $0.31 per share, to be paid on May 23, 2019 to shareholders of record as of May 13, 2019.

No other undisclosed events requiring recognition or disclosure were identified.

Item 2.

MANAGEMENT’S DISCUSSION AND ANALYSIS OF

FINANCIAL CONDITION AND RESULTS OF OPERATIONS

The following discussion should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2018, including the audited financial statements contained therein, filed with the Securities and Exchange Commission, or SEC.

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 (“FIB”), 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 First Interstate Bank.

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

“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, 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,” “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. The following factors, among others, may cause actual results to differ materially from current expectations in the forward-looking statements, including those set forth in this report: political, legal, regulatory, and general economic or business conditions, either nationally or regionally; geopolitical uncertainties throughout the world; weather-related, and other adverse climate or other conditions that may impact our business and our customers’ business; changes in the interest rate environment or interest rate changes made by the Federal Reserve; credit performance of our loan portfolio; adequacy of the allowance for loan losses and access to low-cost funding sources; the unavailability of LIBOR; impairment of goodwill; dependence on the Company’s management team and ability to attract and retain qualified employees; governmental regulation and changes in regulatory, tax and accounting rules and interpretations; stringent capital requirements; future FDIC insurance premium increases; CFPB restrictions on our ability to originate and sell mortgage loans; cyber-security risks, including items such as “denial of service,” “hacking” and “identity theft”; unfavorable resolution to litigation and regulatory proceedings; liquidity risks and technological innovations; inability to grow organically or through acquisitions; impairment of collateral underlying our loans; environmental remediation and other costs associated with repossessed properties; ineffective internal operational controls; competition; meeting market demand with current and new products; reliance on external vendors; soundness of other financial institutions; failure of technology and failure to effectively implement technology-driven products and services; risks associated with introducing and implementing new lines of business, products or services; failure to execute on strategic or operational plans, including the ability to complete mergers and acquisitions or fully achieve expected costs savings or revenue growth associated with mergers and acquisitions; deposit attrition, customer loss and/or revenue loss following completed acquisitions; anti-takeover provisions; changes in dividend policy and the inability of our bank subsidiary to pay dividends; the uninsured nature of any investment in Class A or Class B common stock; decline in market price and volatility of Class A and Class B common stock; voting control of Class B common stock stockholders; controlled company status; dilution as a result of future equity issuances; and subordination of common stock to Company debt.

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A more detailed discussion of each of the foregoing risks is included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. These factors and the other risk factors described in the Company’s periodic and current reports filed with the SEC from time to time, however, are not necessarily all of the important factors that could cause the Company’s actual results, performance, or achievements to differ materially from those expressed in or implied by any of the Company’s forward-looking statements. Other unknown or unpredictable factors also could harm the Company’s results. Investors and others are encouraged to read the more detailed discussion of the Company’s risks contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

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 and included in the Company’s periodic reports filed with the SEC under the Securities Exchange Act of 1934, as amended under the caption “Risk Factors.” Interested parties are urged to read in their entirety such risk factors prior to making any investment decisions 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 laws. 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 incorporated as a Montana corporation in 1971, and headquartered in Billings, Montana. Our Class A common stock is listed on the NASDAQ stock market under the symbol “FIBK.” As of March 31, 2019, we had consolidated assets of $13.5 billion, deposits of $10.8 billion, loans of $8.5 billion and total stockholders’ equity of $1.7 billion. We currently operate 147 banking offices, including detached drive-up facilities, in communities across Idaho, Montana, Oregon, South Dakota, Washington, and Wyoming in addition to Internet and mobile banking services. Through our bank subsidiary, FIB, we deliver a comprehensive range of banking products and services to individuals, businesses, municipalities and other entities throughout our market areas. Our customers participate in a wide variety of industries, including agriculture, construction, education, energy, governmental services, healthcare, mining, professional services, retail, technology, tourism, and wholesale trade.

Our Business            

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 investments. We also derive income from non-interest sources such as fees received in connection with various lending and deposit services; trust, employee benefit, investment, and insurance services; mortgage loan originations, sales and servicing; merchant and electronic banking services; and from time to time, gains on sales of assets. Our principal expenses include interest expense on deposits and borrowings, operating expenses, provisions for loan losses, and income tax expense.

Our loan portfolio consists of a mix of real estate, consumer, commercial, agricultural, and other loans, including fixed and variable rate loans. Our real estate loans comprise commercial real estate, construction (including residential, commercial and land development loans), residential, agricultural, and other real estate loans. Fluctuations in the loan portfolio are directly related to the economies of the communities we serve. While each loan originated must meet minimum underwriting standards established in our credit policies, lending officers are granted discretion within pre-approved limits in approving and pricing loans to assure that the banking offices are responsive to competitive issues and community needs in each market area. We fund our loan portfolio primarily with the core deposits from our customers, generally without utilizing brokered deposits and with minimal reliance on wholesale funding sources.     

Recent Trends and Developments

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

On October 11, 2018, the Company entered into a definitive agreement to acquire all of the outstanding stock of IIBK, a community bank headquartered in Coeur d' Alene, Idaho with 11 banking offices across Idaho. The acquisition was completed on April 8, 2019, and conversion of the data processing systems will occur in June 2019. Consideration for the acquisition was $157.3 million, consisting of the issuance of 3.87 million shares of the Company's Class A common stock valued at $40.64 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. Holders of each share of IIBK common stock received 0.50 shares of First Interstate Class A common stock for each share of IIBK common stock. Previously unvested IIBK restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close.

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On October 11, 2018, the Company also entered into a definitive agreement to acquire all of the outstanding stock of CMYF, a community bank headquartered in Post Falls, Idaho with three banking offices in North Idaho. The acquisition was completed on April 8, 2019, and conversion of the data processing systems will occur in June 2019. Consideration for the acquisition was $18.8 million, consisting of the issuance of 0.46 million shares of the Company's Class A common stock valued at $40.64 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. Holders of each share of CMYF common stock received 0.3784 shares of First Interstate Class A common stock for each share of CMYF common stock. Previously unvested CMYF restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close.

On August 16, 2018, the Company completed its acquisition of Northwest, the parent company of INB, a Spokane, Washington based community bank with 20 banking offices across Idaho, Oregon, and Washington. The Company merged INB with its existing bank subsidiary, FIB, on November 9, 2018. Consideration for the acquisition included $176.3 million, consisting of the issuance of 3.84 million shares of the Company's Class A common stock valued at $45.15 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. The Company paid approximately $3.0 million in cash related to Northwest warrants, which were included in the consideration paid. Holders of each share of Northwest common stock received 0.516 shares of First Interstate Class A common stock for each share of Northwest common stock. Additionally, all Northwest stock purchase warrants outstanding immediately prior to the close of the transaction were canceled in exchange for the right to receive a cash payment as provided in the Agreement. Previously unvested Northwest restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close.

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 both our own historical levels and the financial condition and performance of comparable banking institutions in our region and nationally.

Results of Operations

Principal tools we use in managing and evaluating our results of operations include tracking performance as measured by certain metrics including return on average equity, net interest income, non-interest income, non-interest expense, and net income. Net interest income is affected by a number of factors such as the level of interest rates, changes in interest rates, and changes in the volume and composition of interest earning assets and interest bearing liabilities. 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.

The impact of funding, including non-interest bearing deposit sources, is captured in the net interest margin, which is calculated as net interest income divided by average earning assets. We evaluate our net interest income by assessing the yields on our loans and other earning assets, the costs of our deposits and other funding sources, and the levels of our net interest spread and net interest margin.

We seek to increase our non-interest income over time, and we evaluate our non-interest income relative to the trends of the individual types of non-interest income in view of prevailing market conditions.

We manage our non-interest expenses in consideration of growth opportunities and our community banking model that emphasizes customer service and responsiveness. We evaluate our non-interest expense on factors that include our non-interest expense relative to our average assets, our efficiency ratio and the trends of the individual categories of non-interest expense.

Finally, we seek to increase our net income and provide favorable shareholder returns over time, and we evaluate our net income relative to the performance of similar bank holding companies on factors that include return on average assets, return on average equity, total shareholder return, and growth in earnings.

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Financial Condition

Managing and evaluating our financial condition, we focus on liquidity, the diversification and quality of our loans, the adequacy of our allowance for loan losses, the diversification and terms of our deposits and other funding sources, the re-pricing characteristics and maturities of our assets and liabilities, including potential interest rate exposure, and the adequacy of our capital levels. We seek to maintain sufficient levels of cash and investment securities to meet potential payment and funding obligations, and we evaluate our liquidity on factors that include the levels of cash and highly liquid assets relative to our liabilities, the quality and maturities of our investment securities, the ratio of loans to deposits and any reliance on brokered certificates of deposit or other wholesale funding sources.

We seek to maintain a diverse and high quality loan portfolio and evaluate our asset quality on factors that include the allocation of our loans among loan types, credit exposure to any single borrower or industry type, non-performing assets as a percentage of total loans and OREO, and loan charge-offs as a percentage of average loans. We seek to maintain our allowance for loan losses at a level adequate to absorb probable losses inherent in our loan portfolio at each balance sheet date, and we evaluate the level of our allowance for loan losses relative to our overall loan portfolio and the level of non-performing loans and potential charge-offs.        

We seek to fund our assets primarily using core customer deposits spread among various deposit categories, and we evaluate our deposit and funding mix on factors that include the allocation of our deposits among deposit types, the level of our non-interest bearing deposits, the ratio of our core deposits (i.e. excluding time deposits above $100,000) to our total deposits, and our reliance on brokered deposits or other wholesale funding sources, such as borrowings from other banks or agencies. We seek to manage the mix, maturities and re-pricing characteristics of our assets and liabilities to maintain relative stability of our net interest rate margin in a changing interest rate environment, and we evaluate our asset-liability management using models to evaluate the changes to our net interest income under different interest rate scenarios.

Finally, we seek to maintain adequate capital levels to absorb unforeseen operating losses and to help support the growth of our balance sheet. We evaluate our capital adequacy using the regulatory and financial capital ratios including leverage capital ratio, tier 1 risk-based capital ratio, total risk-based capital ratio, tangible common equity to tangible assets, and tier 1 common capital to total risk-weighted assets.

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, 2018.

Our critical accounting estimates are summarized below. Management considers an accounting estimate to be critical if: (1) the accounting estimate requires management to make particularly difficult, subjective, and/or complex judgments about matters that are inherently uncertain and (2) changes in the estimate that are reasonably likely to occur from period to period, or the use of different estimates that management could have reasonably used in the current period, would have a material impact on our consolidated financial statements, results of operations, or liquidity.

Allowance for Loan Losses

The provision for loan losses creates an allowance for loan losses known and inherent in the loan portfolio at each balance sheet date. The allowance for loan losses represents management’s estimate of probable credit losses inherent in the loan portfolio.

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We perform a quarterly assessment of the risks inherent in our loan portfolio, as well as a detailed review of each significant loan we have assessed to have weaknesses. Based on this analysis, we record a provision for loan losses in order to maintain the allowance for loan losses at appropriate levels. In determining the allowance for loan losses, we estimate losses on specific loans, or groups of loans, where the probable loss can be identified and reasonably determined. Loans acquired in business combinations are recorded at their estimated fair values on the date of acquisition. Accordingly, no allowance for loan losses related to these loans is recorded at the date of transfer. An allowance for loan losses is recorded for credit deterioration occurring subsequent to the transfer date. Determining the amount of the allowance for loan losses is considered a critical accounting estimate because it requires significant judgment and the use of subjective measurements, including management’s assessment of the internal risk classifications of loans, historical loan loss rates, changes in the nature of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends and the impact of current local, regional, and national economic factors on the quality of the loan portfolio. Changes in these estimates and assumptions are possible and may have a material impact on our allowance, and as a result, on our consolidated financial statements or results of operations. The allowance for loan losses is maintained at an amount we believe is sufficient to provide for estimated losses inherent in our loan portfolio at each balance sheet date, and fluctuations in the provision for loan losses result from management’s assessment of the adequacy of the allowance for loan losses. The loan loss rates for 2018 and 2019 incorporate the available loss history data from Bank of the Cascades prior to the merger date to represent a consolidated institutional loss rate for both originated and acquired portfolios. Management monitors qualitative and quantitative trends in the loan portfolio, including changes in the levels of past due, internally classified, and non-performing loans. Note 1 of the Notes to Consolidated Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2018 describes the methodology used to determine the allowance for loan losses. A discussion of the factors driving changes in the amount of the allowance for loan losses is included herein under the heading “Financial Condition - Allowance for Loan Losses.”

Goodwill

The excess purchase price over the fair value of net assets from acquisitions, or goodwill, is evaluated for impairment at least annually and on an interim basis if an event or circumstance indicates that it is likely impairment has occurred. Goodwill impairment is determined by comparing the fair value of a reporting unit to its carrying amount. In any given year the Company may elect to perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is in excess of its carrying value. If it is not more likely than not that the fair value of the reporting unit is in excess of the carrying value, or if the Company elects to bypass the qualitative assessment, a quantitative impairment test is performed. In performing a quantitative test for impairment, the fair value of net assets is estimated based on analyses of the Company’s market value, discounted cash flows and peer values. The determination of goodwill impairment is sensitive to market-based economics and other key assumptions used in determining or allocating fair value. Variability in the market and changes in assumptions or subjective measurements used to estimate fair value are reasonably possible and may have a material impact on our consolidated financial statements or results of operations. Note 1 of the Notes to the Consolidated Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2018 describes our accounting policy with regard to goodwill.

Our annual goodwill impairment test is performed each year as of July 1^st. The Company performed its most recent goodwill impairment qualitative assessment as of July 1, 2018 and determined the Company’s goodwill was not considered impaired. We will continue to monitor our performance and evaluate our goodwill for impairment annually or more frequently as needed.

Fair Values of Loans Acquired in Business Combinations

Loans acquired in business combinations are initially recorded at fair value with no carryover of the related allowance for credit losses. Credit risks are included in the determination of fair value. Determining the fair value of the loans involves 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.

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. Loans acquired with evidence of deterioration in credit quality since origination are accounted for in accordance with Accounting Standards Codification (“ASC”) Topic 310-30 “Loans and Debt Securities Acquired with Deteriorated Credit Quality.” For loans that meet the criteria stipulated in ASC Topic 310-30, the excess of all cash flows expected at acquisition over the initial fair value of the loans acquired (“accretable yield”) is amortized to interest income over the expected remaining contractual lives of the underlying loans using the effective interest method. The Company continues to evaluate the reasonableness of expectations for the timing and amount of cash to be collected. Increases in expected cash flows subsequent to the initial measurement are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Note 1 of the Notes to the Consolidated Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2018 further describes our accounting policy with regard to acquired loans.

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Results of Operations

The following discussion and analysis is intended to provide greater details of the results of our operations and financial condition. The financial statements as of March 31, 2019 are inclusive of the effects of the combined results of operations of the INB acquisition, which closed in August 2018. Due to the timing of the acquisition, certain comparisons between periods are significantly affected by the transactions.

Net Interest Income

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.

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

Average Balance Sheets, Yields and Rates
(Dollars in millions)	Three Months Ended
	March 31, 2019							March 31, 2018
	Average Balance		Interest			Average Rate		Average Balance		Interest			Average Rate
Interest earning assets:
Loans (1) (2)	$	8,467.9	$	111.7		5.35	%	$	7,590.6	$	92.0		4.92	%
Investment securities (2)	2,630.2		15.8			2.44		2,695.6		14.0			2.11
Interest bearing deposits in banks	598.6		3.6			2.44		553.2		2.1			1.55
Federal funds sold	0.6		—			—		0.2		—			—
Total interest earnings assets	$	11,697.3	$	131.1		4.55	%	$	10,839.6	$	108.1		4.05	%
Non-earning assets	1,542.9							1,319.6
Total assets	$	13,240.2						$	12,159.2
Interest bearing liabilities:
Demand deposits	$	2,922.7	$	2.4		0.33	%	$	2,797.8	$	1.6		0.23	%
Savings deposits	3,262.3		5.1			0.63		3,134.2		2.3			0.30
Time deposits	1,356.5		4.6			1.38		1,142.0		2.3			0.82
Repurchase agreements	675.5		1.0			0.60		635.2		0.4			0.27
Other borrowed funds	—		—			—		3.1		0.1			18.36
Long-term debt	15.6		0.3			7.80		14.2		0.2			5.64
Subordinated debentures held by subsidiary trusts	86.9		1.2			5.60		82.5		0.9			4.37
Total interest bearing liabilities	$	8,319.5	$	14.6		0.71	%	$	7,809.0	$	7.8		0.41	%
Non-interest bearing deposits	3,048.9							2,819.8
Other non-interest bearing liabilities	160.6							92.2
Stockholders’ equity	1,711.2							1,438.2
Total liabilities and stockholders’ equity	$	13,240.2						$	12,159.2
Net FTE interest income			$	116.5						$	100.3
Less FTE adjustments (2)			(0.5		)					(0.5		)
Net interest income from consolidated statements of income			$	116.0						$	99.8
Interest rate spread						3.84	%						3.64	%
Net FTE interest margin (3)						4.04	%						3.75	%
Cost of funds, including non-interest bearing demand deposits (4)						0.52	%						0.30	%

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⁽¹⁾  Average loan balances include non-accrual loans. Interest income on loans includes amortization of deferred loan fees net of deferred loan costs, which is not material.

⁽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.

Our net interest income increased $16.2 million, or 16.2%, to $116.0 million during the three months ended March 31, 2019, as compared to $99.8 million for the same period in 2018, primarily as a result of higher levels of earning assets and an expansion in our net interest margin.

Net interest income included interest accretion related to the fair valuation of acquired loans of $3.9 million during the three months ended March 31, 2019, of which $1.7 million was the result of early loan payoffs. This compares to interest accretion of $3.1 million during the three months ended March 31, 2018, of which $1.1 million was the result of early loan payoffs.

Recoveries of charged-off interest also impact net interest income. Charged-off interest recoveries were $0.9 million during the three months ended March 31, 2019, as compared to $0.7 million during the same period in 2018.

Our net FTE interest margin ratio increased 29 basis points to 4.04% for the three months ended March 31, 2019, as compared to 3.75% for the same period in 2018. The increase in net FTE interest margin ratio during the three months ended March 31, 2019, as compared to the same period in 2018, were primarily due to increases in average outstanding loans and higher yields on interest earning assets, which were offset by increases in funding costs.

Exclusive of the impact of the recovery of charged-off interest and the impact of interest accretion on acquired loans, our net FTE interest margin ratio was 3.87% during the three months ended March 31, 2019, as compared to 3.61% for the same period in 2018, or a 26 basis point increase.

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 (rate) for the three month periods ended March 31, 2019 and 2018. 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 March 31, 2019 compared with Three Months Ended March 31, 2018
	Volume			Rate		Net
Interest earning assets:
Loans (1)	$	10.6		$	9.1	$	19.7
Investment securities (1)	(0.3		)	2.1		1.8
Interest bearing deposits in banks	0.2			1.3		1.5
Total change	10.5			12.5		23.0
Interest bearing liabilities:
Demand deposits	0.1			0.7		0.8
Savings deposits	0.1			2.7		2.8
Time deposits	0.4			1.9		2.3
Repurchase agreements	—			0.6		0.6
Other borrowed funds	(0.1		)	—		(0.1		)
Long-term debt	—			0.1		0.1
Subordinated debentures held by subsidiary trusts	—			0.3		0.3
Total change	0.5			6.3		6.8
Increase in FTE net interest income (1)	$	10.0		$	6.2	$	16.2

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

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Provision for Loan Losses

Fluctuations in the provision for loan losses reflect management’s estimate of possible loan losses based upon the composition of our loan portfolio, evaluation of the borrowers’ ability to repay, collateral value underlying loans, loan loss trends and estimated effects of current economic conditions on our loan portfolio. The Company recorded a provision for loan losses of $3.7 million during the three months ended March 31, 2019, as compared to $2.1 million during same period in 2018, as a result of higher net charge-offs in the current period. Changes in the provision for loan loss between quarters are reflective of management’s assessment of the adequacy of our allowance for loan losses.

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

Non-interest Income

Our principal sources of non-interest income primarily include 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. The following table presents the composition of our non-interest income as of the dates indicated:

Non-interest income
(Dollars in millions)	Three Months Ended March 31,				$ Change			% Change
	2019		2018
Payment services revenues	$	9.4	$	10.5	$	(1.1	)	(10.5	)%
Mortgage banking revenues	5.4		5.4		—			—
Wealth management revenues	6.1		5.9		0.2			3.4
Service charges on deposit accounts	5.0		5.6		(0.6		)	(10.7	)
Other service charges, commissions and fees	4.3		3.9		0.4			10.3
Other income	4.3		3.9		0.4			10.3
Total non-interest income	$	34.5	$	35.2	$	(0.7	)	(2.0	)%

Total non-interest income decreased $0.7 million, or 2.0%, to $34.5 million for the three months ended March 31, 2019, as compared to $35.2 million for the same period in 2018. 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 decreased $1.1 million, or 10.5%, to $9.4 million during the three months ended March 31, 2019, as compared to $10.5 million during the same period in 2018, primarily due to the impact of the Durbin Amendment rule (which limits the amount of interchange fees certain banks may charge), which impacted our Company beginning July 1, 2018. A decrease in payment services revenues of $3.1 million during the three months ended March 31, 2019 was attributable to the Durbin Amendment. This decrease was offset by increases in debit card and credit card volume resulting in higher interchange revenues during the three months ended March 31, 2019.

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Non-interest Expense

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

Non-interest expense
(Dollars in millions)	Three Months Ended March 31,				$ Change			% Change
	2019		2018
Salaries and wages	$	36.1	$	34.6	$	1.5		4.3	%
Employee benefits	14.4		11.3		3.1			27.4
Outsourced technology services	7.9		7.0		0.9			12.9
Occupancy, net	7.0		6.3		0.7			11.1
Furniture and equipment	3.5		3.1		0.4			12.9
OREO expense, net of income	0.1		0.2		(0.1		)	(50.0	)
Professional fees	1.9		1.2		0.7			58.3
FDIC insurance premiums	1.5		1.5		—			—
Mortgage servicing rights amortization	0.9		0.8		0.1			12.5
Core deposit intangibles amortization	2.3		1.8		0.5			27.8
Other expenses	15.9		15.8		0.1			0.6
Acquisition related expenses	2.3		2.3		—			—
Total non-interest expense	$	93.8	$	85.9	$	7.9		9.2	%

Non-interest expense increased $7.9 million, or 9.2%, to $93.8 million during the three months ended March 31, 2019 as compared to the same period in 2018. Included in non-interest expenses for the three months ended March 31, 2019 and 2018 are $2.3 million and $2.3 million, respectively, of expenses related to acquisitions, including 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.

Salaries and wages expense increased $1.5 million, or 4.3%, to $36.1 million during the three months ended March 31, 2019, as compared to $34.6 million during the same period in 2018. The increase reflects higher levels of wages and incentive compensation for INB employees who joined the Company in August 2018.

Employee benefits expense increased $3.1 million, or 27.4%, to $14.4 million during the three months ended March 31, 2019, as compared to $11.3 million during the same period in 2018. The increase in employee benefits expense in 2019, as compared to 2018, is primarily due to additional benefits costs resulting from the INB acquisition.

Income Tax Expense

Our effective tax rate decreased to 21.5% for the three months ended March 31, 2019 compared to 22.1% for the three months ended March 31, 2018.

Financial Condition

Total Assets

Total assets increased$198.0 million, or 1.5%, to $13,498.2 million as of March 31, 2019, from $13,300.2 million as of December 31, 2018, primarily due to an increase in cash and cash equivalents and recording right-of-use assets and related lease liabilities in conjunction with the adoption of the new leasing accounting standard. Significant fluctuations in balance sheet accounts are discussed below.

Total Loans

Total loans decreased to $8,493.2 million as of March 31, 2019, compared to $8,503.7 million as of December 31, 2018.

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Loans Held for Investment

Loans held for investment decreased to $8,459.2 million as of March 31, 2019, as compared to $8,470.4 million as of December 31, 2018. The loans held for investment portfolios are discussed in greater detail below:

Total real estate loans increased slightly to $5,833.6 million as of March 31, 2019, as compared to $5,833.5 million as of December 31, 2018. Within the portfolio, commercial loans increased$20.4 million, or 0.6%, to $3,255.8 million, construction loans decreased$0.8 million, or 0.1%, to $837.9 million, residential loans decreased$12.5 million, or 0.8%, and agricultural loans decreased$7.0 million, or 3.2% as of March 31, 2019.

Total consumer loans decreased$23.2 million, or 2.2%, to $1,047.0 million as of March 31, 2019, from $1,070.2 million as of December 31, 2018, primarily due to the seasonal decline typically experienced across the indirect portfolio and increased credit standards centered in the direct portfolio.

Commercial loans increased$31.8 million, or 2.4%, to $1,342.1 million as of March 31, 2019, from $1,310.3 million as of December 31, 2018. This growth primarily occurred in Western Montana and Oregon.

Agricultural loans decreased$20.1 million, or 7.9%, to $234.7 million as of March 31, 2019, from $254.8 million as of December 31, 2018, as a result of $2.0 million in payoffs of non-accruing loans and seasonal paydowns.

Loans Held for Sale

Loans held for sale consist of residential mortgage loans pending sale to investors in the secondary market. Loans held for sale increased to $34.0 million as of March 31, 2019, compared to $33.3 million as of December 31, 2018.

Non-performing Assets

Non-performing assets include non-accrual loans, loans contractually past due by 90 days or more and still accruing interest, and OREO. The following table sets forth information regarding non-performing assets as of the dates indicated.    

Non-Performing Assets and Troubled Debt Restructurings
(Dollars in millions)	March 31, 2019			December 31, 2018			September 30, 2018			June 30, 2018			March 31, 2018
Non-performing loans:
Non-accrual loans	$	45.1		$	54.3		$	61.2		$	69.3		$	63.1
Accruing loans past due 90 days or more	7.1			3.8			5.2			6.1			3.7
Total non-performing loans	52.2			58.1			66.4			75.4			66.8
OREO	21.1			14.4			17.3			14.9			11.0
Total non-performing assets	$	73.3		$	72.5		$	83.7		$	90.3		$	77.8
Troubled debt restructurings not included above	$	5.8		$	5.6		$	5.9		$	7.2		$	6.9
Non-performing loans to total loans	0.61		%	0.68		%	0.78		%	0.97		%	0.87		%
Non-performing assets to total loans and OREO	0.86			0.85			0.98			1.16			1.02
Non-performing assets to total assets	0.54			0.55			0.63			0.74			0.63

Non-performing loans. Non-performing loans include non-accrual loans and loans contractually past due 90 days or more and still accruing interest. Impaired loans include all loans risk rated doubtful, loans placed on non-accrual status and loans renegotiated in troubled debt restructurings, with the exception of consumer loans. We monitor and evaluate collateral values on impaired loans quarterly. Appraisals are required on all impaired loans every 18-24 months, or sooner as conditions necessitate. We update valuations on collateral underlying oil and gas credits based on recent market-based oil price forecasts provided by an independent third party. We also monitor real estate values by market for our larger market areas. Based on trends in real estate values, adjustments may be made to the appraised value based on time elapsed between the appraisal date and the impairment analysis or a new appraisal may be ordered. Appraised values in our smaller market areas may be adjusted based on trends identified through discussions with local realtors and appraisers. Appraisals are also adjusted for selling costs. The collateral valuation is then compared to the loan balance and any resulting shortfall is recorded in the allowance for loan losses as a specific valuation allowance. Provisions for loan losses are impacted by changes in the specific valuation allowances and historical or general valuation elements of the allowance for loan losses.    

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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)	March 31, 2019		Percent of Total		December 31, 2018		Percent of Total
Real estate:
Commercial	$	13.6	26.1	%	$	10.0	17.2	%
Construction:
Land acquisition and development	4.2		8.0		3.9		6.7
Residential	1.3		2.5		1.0		1.7
Commercial	0.2		0.4		0.2		0.3
Total construction	5.7		10.9		5.1		8.7
Residential	6.1		11.7		6.8		11.8
Agricultural	2.7		5.2		12.6		21.7
Total real estate	28.1		53.9		34.5		59.4
Consumer	4.0		7.6		3.5		6.0
Commercial	17.0		32.6		17.1		29.4
Agricultural	3.1		5.9		3.0		5.2
Total non-performing loans	$	52.2	100.0	%	$	58.1	100.0	%

Non-accrual loans. We generally place loans, excluding acquired credit impaired 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. If all loans on non-accrual status had been current in accordance with their original terms, gross income of approximately $0.6 million and $0.8 million would have been accrued for the three months ended March 31, 2019 and 2018, respectively. Non-accrual loans decreased approximately $9.2 million, to $45.1 million as of March 31, 2019, from $54.3 million as of December 31, 2018. The decrease in non-accrual loans was driven by an agricultural real estate loan moved into OREO. Accruing loans past due 90 days or more increased $3.3 million, or 86.8%, primarily due to an increase in commercial real estate loans. Other real estate owned increased$6.7 million, or 46.5%, from December 31, 2018. The increase in other real estate owned was driven by $8.4 million in foreclosures, consisting primarily of one agricultural real estate asset, offset by $1.4 million in dispositions.

Allowance for Loan Losses

The Company performs a quarterly assessment of the adequacy of its allowance for loan losses in accordance with GAAP. The methodology used to assess the adequacy is consistently applied to the Company’s loan portfolio. The allowance for loan losses is established through a provision for loan losses based on our evaluation of known and inherent risk in our loan portfolio at each balance sheet date. In determining the allowance for loan losses, we estimate losses on specific loans, or groups of loans, where the probable loss can be identified and reasonably determined. The balance of the allowance for loan losses is based on internally assigned risk classifications of loans, historical loan loss rates, changes in the nature of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends, current economic factors and the estimated impact of current economic conditions on certain historical loan loss rates. See the discussion under “Critical Accounting Estimates and Significant Accounting Policies - Allowance for Loan Losses.”

The allowance for loan 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 loan losses consists of three elements:

(1) Specific valuation allowances associated with impaired loans. Specific valuation allowances are determined based on assessment of the fair value of the collateral underlying the loans as determined through independent appraisals, the present value of future cash flows, observable market prices and any relevant qualitative or environmental factors impacting loans. No specific valuation allowances are recorded for impaired loans that are adequately secured.

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(2) Historical valuation allowances based on loan loss experience for similar loans with similar characteristics and trends. Historical valuation allowances are determined by applying percentage loss factors to the credit exposures from outstanding loans. For commercial, agricultural and real estate loans, loss factors are applied based on the internal risk classifications of these loans. For consumer loans, loss factors are applied on a portfolio basis. For commercial, agriculture and real estate loans, loss factor percentages are based on a migration analysis of our historical loss experience, designed to account for credit deterioration. For consumer loans, loss factor percentages are based on a three-year loss history.

(3) General valuation allowances determined based on changes in the nature of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends, general economic conditions and other qualitative risk factors both internal and external to us.

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

Loans acquired in business combinations are recorded at fair value with no allowance for loan losses on the date of acquisition. Subsequent to the acquisition date, an allowance for loan loss is recorded for the emergence of new probable and estimable losses on loans acquired without evidence of credit impairment. Loans acquired with evidence of credit impairment are regularly monitored and to the extent that the performance has deteriorated from the Company’s expectations at the date of acquisition, an allowance for loan losses is established. As of March 31, 2019, the Company determined that an allowance of $0.9 million related to loans acquired in prior year acquisitions with evidence of credit impairment was required under GAAP.

Loans, or portions thereof, are charged-off against the allowance for loan losses when management believes that 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 the impaired loan is adequately collateralized, a specific valuation allowance is not recorded. As such, significant changes in impaired and non-performing loans do not necessarily correspond proportionally with changes in the specific valuation component of the allowance for loan 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 loan losses or changes in non-performing or impaired loans due to timing differences among the initial identification of an impaired loan, recording of a specific valuation allowance for the impaired loan and any resulting charge-off of uncollectible principal.

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

Allowance for Loan Losses
(Dollars in millions)	Three Months Ended
	Mar 31, 2019			Dec 31, 2018			Sep 30, 2018			Jun 30, 2018			Mar 31, 2018
Balance at beginning of period	$	73.0		$	73.6		$	74.1		$	73.5		$	72.1
Provision charged to operating expense	3.7			1.6			2.0			2.9			2.1
Charge offs:
Real estate
Commercial	0.2			0.5			0.3			0.6			0.5
Construction	1.3			0.4			0.3			—			—
Residential	0.6			—			0.1			0.7			0.3
Consumer	3.0			2.8			3.0			2.8			2.7
Commercial	0.8			1.0			1.1			0.9			1.7
Agricultural	0.1			—			—			—			—
Total charge-offs	6.0			4.7			4.8			5.0			5.2
Recoveries:
Real estate
Commercial	0.2			0.4			—			0.5			1.0
Construction	—			0.2			0.5			0.1			0.1
Residential	—			0.5			0.1			0.2			0.1
Consumer	1.1			0.9			1.2			1.3			1.1
Commercial	0.4			0.5			0.5			0.6			2.0
Agricultural	—			—			—			—			0.2
Total recoveries	1.7			2.5			2.3			2.7			4.5
Net charge-offs	4.3			2.2			2.5			2.3			0.7
Balance at end of period	$	72.4		$	73.0		$	73.6		$	74.1		$	73.5
Period end loans	$	8,493.2		$	8,503.7		$	8,518.0		$	7,758.7		$	7,646.8
Average loans	8,467.9			8,520.7			8,128.9			7,688.0			7,590.6
Net loans charged-off to average loans, annualized	0.21		%	0.10		%	0.12		%	0.12		%	0.04		%
Allowance to period end loans	0.85			0.86			0.86			0.96			0.96

Our allowance for loan losses was $72.4 million, or 0.85% of period end loans, as of March 31, 2019, as compared to $73.0 million, or 0.86% of period end loans, as of December 31, 2018. Although we have established our allowance for loan losses in accordance with GAAP and we believe that our allowance for loan 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.

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. Investment securities increased$11.5 million, or 0.4%, to $2,689.0 million, or 19.9% of total assets, as of March 31, 2019, from $2,677.5 million, or 20.1% of total assets, as of December 31, 2018. As of March 31, 2019, the estimated duration of our investment portfolio was 2.2 years, as compared to 2.5 years as of December 31, 2018.

We evaluate our investment portfolio quarterly for other-than-temporary declines in the market value of individual investment securities. This evaluation includes monitoring credit ratings; market, industry and corporate news; volatility in market prices; and, determining whether the market value of a security has been below its cost for an extended period of time. As of March 31, 2019, we had investment securities with fair values aggregating $742.2 million that had been in a continuous loss position more than twelve months. Gross unrealized losses on these securities of $8.2 million as of March 31, 2019 were attributable to changes in interest rates. No impairment losses were recorded during the three months ended March 31, 2019 or 2018.

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At December 31, 2018, we had $406.8 million of investment securities classified as held to maturity. As a result of the adoption of ASU 2017-12 discussed in “Note 16 – Recent Authoritative Accounting Guidance” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report, the Company transferred investment securities classified as held-to-maturity to investment securities available-for-sale. At the time of transfer, the amortized cost and fair value of these securities totaled $281.1 million and $275.0 million, respectively. In addition, the unrealized loss of $6.0 million was recorded in the consolidated statement of comprehensive income.

Premises and equipment. 

Premises and equipment, net of accumulated depreciation increased$53.0 million, or 21.6%, to $298.2 million as of March 31, 2019, from $245.2 million as of December 31, 2018, primarily due to the Company recognizing $54.6 million in right-of-use assets related to leases, as a result of the adoption of ASU 2016-02 discussed in “Note 1 – Basis of Accounting” and “Note 16 – Recent Authoritative Accounting Guidance” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report.

Other real estate owned. 

Other real estate owned increased$6.7 million, or 46.5%, to $21.1 million as of March 31, 2019, from $14.4 million as of December 31, 2018, primarily attributable to the addition of one agricultural real estate loan offset by dispositions.

Deposits

Our deposits consist of non-interest bearing and interest bearing demand, savings, individual retirement and time deposit accounts. Total deposits increased$134.0 million, or 1.3%, to $10,814.7 million as of March 31, 2019, from $10,680.7 million as of December 31, 2018, as a result of increases in total interest bearing deposits. The following table summarizes our deposits as of the dates indicated:

Deposits
(Dollars in millions)	March 31, 2019		Percent of Total		December 31, 2018		Percent of Total
Non-interest bearing demand	$	3,158.7	29.2	%	$	3,158.3	29.6	%
Interest bearing:
Demand	2,979.6		27.6		2,957.5		27.7
Savings	3,270.0		30.2		3,247.9		30.4
Time, $100 and over	629.6		5.8		547.6		5.1
Time, other (1)	776.8		7.2		769.4		7.2
Total interest bearing	$	7,656.0	70.8	%	$	7,522.4	70.4	%
Total deposits	$	10,814.7	100.0	%	$	10,680.7	100.0	%

⁽¹⁾  Included in Time, other are Certificate of Deposit Account Registry Service, or CDARS, deposits of $79.1 million and brokered deposits of $11.8 million as of March 31, 2019, compared to $87.1 million and $24.1 million as of December 31, 2018, 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 decreased $39.8 million, or 5.6%, to $672.6 million as of March 31, 2019, from $712.4 million as of December 31, 2018.

Accounts Payable and Accrued Expenses. 

Accounts payable and accrued expenses increased$48.5 million, or 51.5%, to $142.6 million as of March 31, 2019, from $94.1 million as of December 31, 2018, primarily due to the Company recognizing $54.6 million in liabilities related to leases, as a result of the adoption of ASU 2016-02 discussed in “Note 1 – Basis of Accounting” and “Note 16 – Recent Authoritative Accounting Guidance” in the accompanying “Notes to Unaudited Consolidated Financial Statements” included in this report.

Deferred Tax Asset / Liability

Our deferred tax liability, net increased$10.1 million, or 117.4%, to $18.7 million as of March 31, 2019, from $8.6 million as of December 31, 2018, primarily as a result of mark-to-market unrealized gains and stock compensation.

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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$43.0 million, or 2.5%, to $1,736.9 million as of March 31, 2019, from $1,693.9 million as of December 31, 2018, due to the retention of earnings, other comprehensive income, stock-based compensation, and proceeds from stock option exercises. This increase was offset by stock repurchases of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants, and cash dividends paid.

On May 3, 2019, the Company’s board of directors declared a dividend of $0.31 per common share, payable on May 23, 2019, to common stockholders of record as of May 13, 2019. The dividend equates to a 3.1% annual yield based on the $39.98 average closing pricing of the Company’s common stock during the first quarter of 2019.

On July 2, 2013, the Board of Governors of the Federal Reserve Bank issued a final rule implementing a revised regulatory capital framework for U.S. banks in accordance with the Basel III international accord and satisfying related mandates under the Dodd-Frank Wall Street Reform and Consumer Protection Act. The revised regulatory capital framework (the “Basel III Capital Rules”) substantially revised the risk-based capital requirements applicable to bank holding companies and depository institutions by defining the components of capital and addressing other issues affecting the numerator in banking institutions’ regulatory capital ratios, addressing risk weights and other issues affecting the denominator in banking institutions’ regulatory capital ratios and replacing the existing risk-weighting approach with a more risk-sensitive approach. The Basel III Capital Rules became effective for the Company on January 1, 2015, subject to a phase-in period for certain provisions. The capital conservation buffer required under Basel III began to phase in starting January 1, 2016 and became fully implemented on January 1, 2019.

As of March 31, 2019 and December 31, 2018, 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 11 – 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 customers, 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.

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 customer 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 16 – 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.    

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Item 3.

QUANTITATIVE AND QUALITATIVE DISCLOSURES

ABOUT MARKET RISK

As of March 31, 2019, there have been no material changes in the quantitative and qualitative information about market risk provided pursuant to Item 305 of Regulation S-K as presented in our Annual Report on Form 10-K for the year ended December 31, 2018.

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 March 31, 2019, 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 March 31, 2019 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 March 31, 2019 that have materially affected, or are reasonably likely to materially affect, such control.

Limitations on Controls and Procedures

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

PART II.

OTHER INFORMATION

Item 1. Legal Proceedings

There have been no material changes in legal proceedings as described in our Annual Report on Form 10-K for the year ended December 31, 2018.

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, 2018.

54

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 March 31, 2019.

(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 March 31, 2019. 

				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
January 2019	—	$	—	—	24,123
February 2019	29,993	41.11		—	24,123
March 2019	27,095	41.97		—	24,123
Total	57,088	$	41.52	—	24,123

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

Item 3. Defaults upon Senior Securities

None.

Item 4. Mine Safety Disclosures

Not applicable.

Item 5. Other Information

None.

55

Item 6.    Exhibits

Exhibit Number		Description
10.1*†		First Interstate BancSystem, Inc. 2015 Equity and Incentive Plan, amended and restated as of January 1, 2019 (incorporated herein by reference to Exhibit 10.8 to the Company’s Annual Report on Form 10-K, File No. 001-34653, filed for the year ended December 31, 2018)
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
†	Management contract or compensatory plan or arrangement.
*	Filed herewith.
**	Furnished herewith.

56

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:	May 8, 2019	By:	/S/  KEVIN P. RILEY
			Kevin P. Riley President and Chief Executive Officer
Date:	May 8, 2019	By:	/S/  MARCY D. MUTCH
			Marcy D. Mutch Executive Vice President and Chief Financial Officer

57

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: May 8, 2019

/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: May 8, 2019

/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 March 31, 2019.

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 May 8, 2019.

/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

Document and Entity Information	3 Months Ended
	Mar. 31, 2019 shares
Entity Registrant Name	FIRST INTERSTATE BANCSYSTEM INC
Trading Symbol	FIBK
Entity Central Index Key	0000860413
Document Fiscal Year Focus	2019
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Fiscal Period Focus	Q1
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Class A Common Stock
Entity Common Stock, Shares Outstanding	38,461,948
Class B Common Stock
Entity Common Stock, Shares Outstanding	22,374,171

XML

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 213.6	$ 244.1
Interest bearing deposits in banks	0.1	0.1
Federal Funds Sold	741.5	577.8
Total cash and cash equivalents	955.2	822.0
Investment securities:
Available-for-sale	2,572.0	2,270.7
Held-to-maturity (estimated fair values of $118.0 and $400.7 at March 31, 2019 and December 31, 2018, respectively)	117.0	406.8
Debt Securities	2,689.0	2,677.5
Loans held for investment	8,459.2	8,470.4
Mortgage loans held for sale	34.0	33.3
Total loans	8,493.2	8,503.7
Less allowance for loan losses	72.4	73.0
Net loans	8,420.8	8,430.7
Goodwill	546.3	546.7
Life Insurance, Corporate or Bank Owned, Amount	275.8	275.1
Premises and equipment, net of accumulated depreciation	298.2	245.2
Indefinite-lived Intangible Assets (Excluding Goodwill)	54.6	56.9
Accrued interest receivable	46.5	44.9
Mortgage servicing rights, net of accumulated amortization and impairment reserve	27.9	27.7
Other real estate owned (“OREO”)	21.1	14.4
Other assets	162.8	159.1
Total assets	13,498.2	13,300.2
Deposits:
Non-interest bearing	3,158.7	3,158.3
Interest bearing	7,656.0	7,522.4
Total deposits	10,814.7	10,680.7
Securities sold under repurchase agreements	672.6	712.4
Accounts payable and accrued expenses	142.6	94.1
Accrued interest payable	10.0	7.8
Deferred tax liability, net	18.7	8.6
Long-term debt	15.8	15.8
Subordinated debentures held by subsidiary trusts	86.9	86.9
Total liabilities	11,761.3	11,606.3
Stockholders’ equity:
Nonvoting noncumulative preferred stock without par value; authorized 100,000 shares; no shares issued and outstanding as of March 31, 2019 or December 31, 2018	0.0	0.0
Common stock	866.6	866.7
Retained earnings	874.7	851.8
Accumulated other comprehensive loss, net	(4.4)	(24.6)
Total stockholders’ equity	1,736.9	1,693.9
Total liabilities and stockholders’ equity	$ 13,498.2	$ 13,300.2

XML

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Investment securities:
Estimated fair value	$ 118,000	$ 400,700
Stockholders' equity:
Nonvoting, noncumulative preferred stock, shares authorized	100,000	100,000
Nonvoting, noncumulative preferred stock, shares issued	0	0
Nonvoting, noncumulative preferred stock, shares outstanding	0	0

XML

Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Interest income:
Interest and fees on loans	$ 111.4	$ 91.7
Interest and dividends on investment securities:
Taxable	15.1	13.2
Exempt from federal taxes	0.5	0.6
Interest on deposits in banks	3.6	2.1
Total interest income	130.6	107.6
Interest expense:
Interest on deposits	12.1	6.2
Interest on securities sold under repurchase agreements	1.0	0.4
Interest on other borrowed funds	0.0	0.1
Interest on other debt	0.3	0.2
Interest on subordinated debentures held by subsidiary trusts	1.2	0.9
Total interest expense	14.6	7.8
Net interest income	116.0	99.8
Provision for loan losses	3.7	2.1
Net interest income after provision for loan losses	112.3	97.7
Non-interest income:
Mortgage banking revenues	5.4	5.4
Investment securities gains (losses), net	0.0	0.0
Other income	4.3	3.9
Total non-interest income	34.5	35.2
Non-interest expense:
Salaries and wages	36.1	34.6
Employee benefits	14.4	11.3
Outsourced technology services	7.9	7.0
Occupancy, net	7.0	6.3
Furniture and equipment	3.5	3.1
OREO expense, net of income	0.1	0.2
Professional fees	1.9	1.2
FDIC insurance premiums	1.5	1.5
Mortgage servicing rights amortization	0.9	0.8
Core deposit intangibles amortization	2.3	1.8
Other expenses	15.9	15.8
Acquisition related expenses	2.3	2.3
Total non-interest expense	93.8	85.9
Income before income tax expense	53.0	47.0
Income tax expense	11.4	10.3
Net income	$ 41.6	$ 36.7
Basic earnings per common share (in dollars per share)	$ 0.69	$ 0.65
Diluted earnings per common share (in dollars per share)	$ 0.69	$ 0.65
Weighted average common shares outstanding for basic earnings per share computation	60,311,171	56,241,201
Weighted Average Number of Shares Outstanding, Diluted	60,598,070	56,652,178
Credit and Debit Card [Member]
Non-interest income:
Payment services revenues	$ 9.4	$ 10.5
Investment Advisory, Management and Administrative Service [Member]
Non-interest income:
Wealth management revenues	6.1	5.9
Deposit Account [Member]
Non-interest income:
Payment services revenues	5.0	5.6
Financial Service, Other [Member]
Non-interest income:
Payment services revenues	$ 4.3	$ 3.9

XML

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 41.6	$ 36.7
Other comprehensive income (loss), before tax:
Change in net unrealized gains (losses) during period	33.6	(23.7)
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	(6.0)	0.0
Other Comprehensive Income (Loss), Transfers from Available-for-Sale to Held-to-Maturity Securities, before Tax	0.0	0.5
Defined benefit post-retirement benefits plans:
Change in net actuarial gain	(0.2)	(0.1)
Other comprehensive income (loss), before tax	27.4	(23.3)
Deferred tax (expense) benefit related to other comprehensive income	(7.2)	6.1
Other comprehensive income (loss), net of tax	20.2	(17.2)
Comprehensive income, net of tax	$ 61.8	$ 19.5

XML

Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Retained earnings	Accumulated other comprehensive income (loss)
Beginning Balance at Dec. 31, 2017	$ 1,427.6	$ 687.0	$ 752.6	$ (12.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	36.7		36.7
Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings			3.1	(3.1)
Other comprehensive income, net of tax expense	(17.2)			(17.2)
Common stock transactions:
Common shares purchased and retired	(0.9)	(0.9)
Stock options exercised, net of shares tendered in payment of option price and income tax withholding amounts	0.8	0.8
Stock-based compensation expense	1.1	1.1
Common cash dividend declared	(15.7)		(15.7)
Ending Balance at Mar. 31, 2018	1,432.4	688.0	776.7	(32.3)
Beginning Balance at Dec. 31, 2018	1,693.9	866.7	851.8	(24.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	41.6		41.6
Other comprehensive income, net of tax expense	20.2			20.2
Common stock transactions:
Common shares purchased and retired	(2.4)	(2.4)
Stock options exercised, net of shares tendered in payment of option price and income tax withholding amounts	0.4	0.4
Stock-based compensation expense	1.9	1.9
Common cash dividend declared	(18.7)		(18.7)
Ending Balance at Mar. 31, 2019	$ 1,736.9	$ 866.6	$ 874.7	$ (4.4)

XML

Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Common stock
Common stock transactions:
Common shares purchased and retired	38,753	24,271
Common shares issued	0	3,848,929
Non-vested common shares issued	200,028	214,892
Non-vested common shares forfeited	5,385	43,079
stock options exercised	56,982	161,217
net of shares tendered	19,004	38,450
Retained earnings
Common stock transactions:
Common dividends (in dollars per share)	$ 0.31	$ 1.12

XML

Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 41.6	$ 36.7
Adjustments to reconcile net income to net cash provided by operating activities:
Increase (Decrease) in Mortgage Loans Held-for-sale	129.8	204.1
Provision for Loan and Lease Losses	3.7	2.1
Depreciation and amortization	7.5	6.6
Net premium amortization on investment securities	2.0	2.8
Realized and unrealized net gains on mortgage banking activities	(4.7)	(1.6)
Impairment of Real Estate and Other Assets Pending Disposal	0.3	0.0
Net loss (gain) on sale of OREO	(0.4)	0.0
Deferred income tax expense	2.7	10.1
Net increase in cash surrender value of company-owned life insurance	(0.7)	(1.3)
Stock-based compensation expense	1.9	1.1
Proceeds from sales of mortgage loans held for sale	132.7	218.8
Changes in operating assets and liabilities, net of effects of acquisition:
Increase in interest receivable	(1.6)	(0.9)
(Increase) decrease in other assets	(3.7)	3.9
Increase in accrued interest payable	2.2	0.1
Decrease in accounts payable and accrued expenses	(6.1)	(10.9)
Net cash provided by operating activities	47.6	63.4
Cash flows from investing activities:
Purchase of investment securities, Available-for-sale	(161.3)	(212.9)
Proceeds from maturities and paydowns of held-to-maturity investment securities	11.3	22.2
Proceeds from maturities and paydowns of available-for-sale investment securities	164.0	114.9
Extensions of credit to customers, net of repayments	(3.2)	(53.3)
Recoveries of loans charged-off	1.7	4.5
Proceeds from sale of OREO	1.8	0.3
Capital expenditures, net of sales	(2.2)	(2.4)
Net cash provided by (used in) investing activities	12.1	(126.7)
Cash flows from financing activities:
Proceeds from Issuance of Unsecured Debt	0.0	2.6
Net increase (decrease) in deposits	134.0	91.0
Net (decrease) increase in securities sold under repurchase agreements	(39.8)	(9.2)
Net decrease in other borrowed funds	0.0	(20.0)
Proceeds from issuance of common stock	0.4	0.8
Purchase and retirement of common stock	(2.4)	(0.9)
Dividends paid to common stockholders	(18.7)	(15.7)
Net cash provided by financing activities	73.5	48.6
Net increase (decrease) in cash and cash equivalents	133.2	(14.7)
Cash and cash equivalents at beginning of period	822.0	758.9
Cash and cash equivalents at end of period	955.2	744.2
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	0.0	4.6
Cash paid during the period for interest expense	12.4	7.7
Noncash or Part Noncash Acquisition, Value of Assets Acquired [Abstract]
Amortization of unrealized gains and losses on transfers of securities	0.0	0.5
Right-of-use assets obtained in exchange for operating lease liabilities	54.6	0.0
Transfer of loans to other real estate owned	8.4	1.2
Capitalization of internally originated mortgage servicing rights	$ 1.1	$ 1.3

XML

Basis of Presentation

3 Months Ended

Mar. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

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 (together, 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 March 31, 2019 and December 31, 2018, the results of operations for each of the three month periods ended March 31, 2019 and 2018, and cash flows and changes in stockholders’ equity for each of the three month periods ended March 31, 2019 and 2018, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2018 is derived from audited consolidated financial statements. Certain reclassifications, none of which were material, have been made to conform prior year financial statements to the March 31, 2019 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, 2018. Operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019.

Leases

We have leased branches and office space and have entered into various other agreements in conducting our business. At inception, we determine whether an agreement represents a lease and at commencement we evaluate each lease agreement to determine whether the lease is an operating or financing lease. Some of our lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses. As discussed in “Note 16 – Recent Authoritative Accounting Guidance” included in this report, we adopted ASU 2016-02, as of January 1, 2019.

Pursuant to ASU 2016-02, all of our long-term operating leases outstanding on December 31, 2018 continued to be classified as operating leases. Our capital lease outstanding at December 31, 2018 is classified as a financing lease. With the adoption of ASU 2016-02, we recorded an operating lease right-of-use asset, within the Premises and Equipment line item, and an operating lease liability, within the Other Liabilities line item, on our balance sheet. Right-of-use lease assets represent our right to use the underlying asset for the lease term and the lease obligation represents our commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit rate, we have used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as property taxes are expensed as incurred. Leases with an initial term of 12 months or less are not recorded on the balance sheet.

Prior to our adoption of ASU 2016-02, when our lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, we recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the statements of operations over the term of each lease. In cases where the lessor granted us leasehold improvement allowances that reduced our lease expense, we capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements.

XML

Acquisitions

3 Months Ended

Mar. 31, 2019

Business Combinations [Abstract]

Acquisitions

Acquisitions

Idaho Independent Bank. On October 11, 2018, the Company entered into a definitive agreement to acquire all of the outstanding stock of Idaho Independent Bank (“IIBK”), a community bank headquartered in Coeur d' Alene, Idaho with 11 banking offices across Idaho. The acquisition was completed on April 8, 2019, and conversion of the data processing systems will occur in June 2019. Consideration for the acquisition was $157.3 million, consisting of the issuance of 3.871 million shares of the Company's Class A common stock valued at $40.64 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. Holders of each share of IIBK common stock received 0.50 shares of First Interstate Class A common stock for each share of IIBK common stock. Previously unvested IIBK restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close and included in the consideration.

Community 1^st Bank. On October 11, 2018, the Company also entered into a definitive agreement to acquire all of the outstanding stock of Community 1st Bank (“CMYF”), a community bank headquartered in Post Falls, Idaho with three banking offices in North Idaho. The acquisition was completed on April 8, 2019, and conversion of the data processing systems will occur in June 2019. Consideration for the acquisition was $18.8 million, consisting of the issuance of 0.463 million shares of the Company's Class A common stock valued at $40.64 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. Holders of each share of CMYF common stock received 0.3784 shares of First Interstate Class A common stock for each share of CMYF common stock. Previously unvested CMYF restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close and included in consideration.

Northwest Bancorporation, Inc. On April 25, 2018, the Company entered into a definitive agreement to acquire all of the outstanding stock of Northwest Bancorporation, Inc. (“Northwest”), the parent company of Inland Northwest Bank (“INB”), a Spokane, Washington based community bank with 20 banking offices across Idaho, Oregon and Washington. The acquisition was completed on August 16, 2018, and the Company merged INB with its existing bank subsidiary, First Interstate Bank, on November 9, 2018.

Consideration for the acquisition was $176.3 million, consisting of the issuance of 3.84 million shares of the Company's Class A common stock valued at $45.15 per share, the closing price of the Company's Class A common stock as quoted on the NASDAQ stock market on the acquisition date. The Company paid approximately $3.0 million in cash related to Northwest warrants, which were included in the consideration paid. Holders of each share of Northwest common stock received 0.516 shares of First Interstate Class A common stock for each share of Northwest common stock. Additionally, all Northwest stock purchase warrants outstanding immediately prior to the close of the transaction were canceled in exchange for the right to receive a cash payment as provided in the Agreement. Previously unvested Northwest restricted stock awards outstanding immediately prior to the close of the transaction vested and were considered issued and outstanding at acquisition close.

The assets and liabilities of Northwest were provisionally recorded in the Company’s consolidated financial statements at their estimated fair values as of the acquisition date and will be finalized in the coming months. The excess value of the consideration paid over the fair value of assets acquired and liabilities assumed is recorded as provisional goodwill. The preliminary purchase price allocation resulted in provisional goodwill of $100.7 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 Northwest and the Company.

The following table summarizes the consideration paid, fair values of the Northwest assets acquired and liabilities assumed, and the resulting goodwill. The amounts reported for net deferred tax assets and goodwill are provisional pending completion of the Company's review of tax items.

	As Recorded			Fair Value				As Recorded
As of August 16, 2018	by Northwest			Adjustments				by the Company
Assets acquired:
Cash and cash equivalents	$	31.2		$	—			$	31.2
Investment securities	3.1			—				3.1
Loans held for investment	727.9			(14.8		)	(1)	713.1
Allowance for loan loss	(8.0		)	8.0			(2)	—
Premises and equipment	14.5			—				14.5
Other real estate owned (“OREO”)	0.3			0.3				0.6
Core deposit intangible assets	2.4			13.3			(3)	15.7
Other assets	29.3			(10.0		)	(4)	19.3
Total assets acquired	800.7			(3.2		)		797.5
Liabilities assumed:
Deposits	696.1			0.2			(5)	696.3
Accounts payable and accrued expense	8.1			(0.4		)	(6)	7.7
Long term debt	13.0			0.1				13.1
Trust preferred securities	5.2			(0.8		)	(7)	4.4
Deferred tax liability, net	(1.2		)	1.6			(8)	0.4
Total liabilities assumed	721.2			0.7				721.9
Net assets acquired	$	79.5		$	(3.9	)		$	75.6
Consideration paid:
Cash								$	3.0
Class A common stock								173.3
Total consideration paid								176.3
Goodwill								$	100.7

Explanation of fair value adjustments and the removal of previously recorded fair value marks recorded by Northwest. Note adjustments to the marks for deferred tax assets and premises and equipment were made since the prior quarter, none of which were material. The adjustments had no impact on 2018 earnings and a net decrease to goodwill of $0.4 million from the December 31, 2018 reported balances.
(1)	Write down of the book value of loans to their estimated fair values. The fair value of the loans was estimated using cash flow projections based on the remaining maturity and repricing terms, adjusted for estimated future credit losses and prepayments and discounted to present value using a risk-adjusted market rate for similar loans. The fair value of collateral dependent loans acquired with deteriorated credit quality was estimated based on the Company’s analysis of the fair value of each loan’s underlying collateral, discounted using market-derived rates of return with consideration given to the period of time and costs associated with foreclosure and disposition of the collateral.
(2)	Adjustment to remove the Northwest allowance for loan losses at acquisition date, as the credit risk is included in the fair value adjustment for loans receivable described in (1) above.
(3)	Adjustment represents the value of the core deposit base assumed in the acquisition based upon valuation from an independent accounting and advisory firm.
(4)	Adjustment consists of reductions to the fair value of other items, including the removal of Northwest previously recorded goodwill.
(5)	Increase in book value of time deposits to their estimated fair values based upon interest rates of similar time deposits with similar terms on the date of acquisition based upon valuation from an independent accounting and advisory firm.
(6)	Decrease due to the write-off of off balance sheet reserves.
(7)	Write down of the book value of debt to the estimated fair values on the date of acquisition based upon favorable interest rates in the market.
(8)	Adjustment consists of the write-off of pre-existing deferred tax assets and purchase accounting adjustments as a result of the acquisition.

Core deposit intangible assets of $15.7 million are being amortized using an accelerated method over the estimated useful lives of the related deposits of 10 years.

The Company acquired certain loans that are subject to Accounting Standards Codification ("ASC") Topic 310-30 "Loans and Debt Securities Acquired with Deteriorated Credit Quality." ASC Topic 310-30 provides recognition, measurement and disclosure guidance for acquired loans that have evidence of deterioration in credit quality since origination for which it is probable, at acquisition, the Company will be unable to collect all contractual amounts owed. For loans that meet the criteria stipulated in ASC Topic 310-30, the excess of all cash flows expected at acquisition over the initial fair value of the loans acquired ("accretable yield") is amortized to interest income over the expected remaining lives of the underlying loans using the effective interest method. The accretable yield will fluctuate due to changes in (i) estimated lives of underling credit-impaired loans, (ii) assumptions regarding future principal and interest amounts collected, and (iii) indices used to fair value variable rate loans.

Information regarding Northwest loans acquired deemed credit-impaired as of the August 16, 2018 acquisition date are as follows:

Contractually required principal and interest payments	$	27.5
Contractual cash flows not expected to be collected (“non-accretable discount”)	4.4
Cash flows expected to be collected	23.1
Interest component of cash flows expected to be collected (“accretable discount”)	3.2
Fair value of acquired credit-impaired loans	$	19.9

Information regarding Northwest acquired loans not deemed credit-impaired at the August 16, 2018 acquisition date are as follows:

Contractually required principal and interest payments	$	894.8
Contractual cash flows not expected to be collected	26.1
Fair value at acquisition	$	693.2

Unaudited pro forma consolidated revenues and net income as if the Northwest acquisition had occurred as of January 1, 2018, are not presented because the effect of this acquisition was not considered significant.

The accompanying consolidated statements of income for the three months ended March 31, 2019, include the results of operations of the acquired entity from the August 16, 2018 acquisition date. The acquired entity continued to operate as INB until November 9, 2018 at which point INB’s operations were integrated with the Company’s operations, and INB merged with FIB.

The Company recorded $2.3 million and $2.3 million in pre-tax acquisition related expenses for the three months ended March 31, 2019 and 2018. These costs are incorporated in non-interest expenses in the Company’s consolidated statements of income.

	Three Months Ended March 31, 2019		Three Months Ended March 31, 2018
Legal and Professional Fees	$	0.3	$	0.5
Employee Expenses	0.6		0.1
Technology Conversion and Contract Termination	0.8		1.5
Other	0.6		0.2
Total Acquisition Related Expenses	$	2.3	$	2.3

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Goodwill and Intangibles

3 Months Ended

Mar. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangibles

Goodwill and Core Deposit Intangibles

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, 2018 and 2017 and concluded that there was no impairment to goodwill.

Goodwill

	As of March 31,
	2019			2018
Net carrying value at beginning of three month period	$	546.7		$	444.7
Measurement period adjustment to previously recorded goodwill	(0.4		)	0.9
Net carrying value at end of period	$	546.3		$	445.6

Core deposit intangibles (“CDI”)

	As of March 31,
	2019			2018
Gross CDI, beginning of period	$	89.7		$	74.0
Accumulated amortization	(35.1		)	(26.7		)
Net CDI, end of period	$	54.6		$	47.3

The Company recorded $2.3 million and $1.8 million of CDI amortization expense for the three months ended March 31, 2019 and 2018.

CDI are evaluated for impairment if events and circumstances indicate a possible impairment and are amortized using an accelerated method based on the estimated weighted average useful lives of the related deposits, which is generally ten years.

The following table provides the estimated future CDI amortization expense:

Years Ending December 31,
2019 remaining	$	6.6
2020	8.1
2021	7.5
2022	6.9
2023	6.3
Thereafter	19.2
Total	$	54.6

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Investment Securities

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Investment Securities

Investment Securities

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

March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	4.0	$	—	$	—		$	4.0
State, county and municipal securities	77.7		0.8		(0.1		)	78.4
Obligations of U.S. government agencies	601.4		0.3		(4.0		)	597.7
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	1,735.9		9.4		(12.4		)	1,732.9
Private mortgage-backed securities	66.2		—		(0.9		)	65.3
Corporate securities	92.1		0.2		(0.3		)	92.0
Other investments	1.7		—		—			1.7
Total	$	2,579.0	$	10.7	$	(17.7	)	$	2,572.0

March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held-to-Maturity:
State, county and municipal securities	$	67.6	$	1.5	$	(0.2	)	$	68.9
Obligations of U.S. government agencies	19.8		—		(0.2		)	19.6
U.S agency residential mortgage-backed securities & collateralized mortgage obligations	1.3		—		—			1.3
Corporate securities	28.2		—		(0.1		)	28.1
Other investments	0.1		—		—			0.1
Total	$	117.0	$	1.5	$	(0.5	)	$	118.0

December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	2.6	$	—	$	—		$	2.6
Obligations of U.S. government agencies	569.3		0.1		(10.2		)	559.2
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	1,566.4		2.5		(24.1		)	1,544.8
Private mortgage-backed securities	72.0		—		(1.8		)	70.2
Corporate securities	92.9		—		(1.0		)	91.9
Other investments	2.0		—		—			2.0
Total	$	2,305.2	$	2.6	$	(37.1	)	$	2,270.7

December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held-to-Maturity:
State, county and municipal securities	$	150.9	$	1.8	$	(0.9	)	$	151.8
Obligations of U.S. government agencies	19.8		—		(0.3		)	19.5
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	189.7		0.3		(6.5		)	183.5
Corporate securities	46.3		0.1		(0.6		)	45.8
Other investments	0.1		—		—			0.1
Total	$	406.8	$	2.2	$	(8.3	)	$	400.7

At December 31, 2018, we had $406.8 million of investment securities classified as held to maturity. As a result of the adoption of ASU 2017-12 discussed in “Note 16 – Recent Authoritative Accounting Guidance” included in this report, the Company transferred investment securities classified as held-to-maturity to investment securities available-for-sale. At the time of transfer, the amortized cost and fair value of these securities totaled $281.1 million and $275.0 million, respectively. In addition, the unrealized loss of $6.0 million was recorded in the consolidated statement of comprehensive income.

There were no material gross realized gains and losses from the disposition of available-for-sale investment securities for the three month periods ended March 31, 2019 and 2018.

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 a continuous unrealized loss position, as of March 31, 2019 and December 31, 2018:

	Less than 12 Months					12 Months or More					Total
March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Available-for-Sale:
State, county and municipal securities	$	—	$	—		$	16.2	$	(0.1	)	$	16.2	$	(0.1	)
Obligations of U.S. government agencies	336.8		(2.8		)	129.7		(1.2		)	466.5		(4.0		)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	535.9		(6.9		)	450.3		(5.5		)	986.2		(12.4		)
Private mortgage-backed securities	—		—			64.5		(0.9		)	64.5		(0.9		)
Corporate securities	—		—			36.9		(0.3		)	36.9		(0.3		)
Total	$	872.7	$	(9.7	)	$	697.6	$	(8.0	)	$	1,570.3	$	(17.7	)

	Less than 12 Months					12 Months or More					Total
March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Held-to-Maturity:
State, county and municipal securities	$	9.0	$	(0.1	)	$	16.6	$	(0.1	)	$	25.6	$	(0.2	)
Obligations of U.S. government agencies	19.6		(0.2		)	—		—			19.6		(0.2		)
Corporate securities	—		—			28.0		(0.1		)	28.0		(0.1		)
Total	$	28.6	$	(0.3	)	$	44.6	$	(0.2	)	$	73.2	$	(0.5	)

	Less than 12 Months					12 Months or More					Total
December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Available-for-Sale:
Obligations of U.S. government agencies	$	363.1	$	(7.9	)	$	154.5	$	(2.3	)	$	517.6	$	(10.2	)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	735.2		(14.5		)	503.7		(9.6		)	1,238.9		(24.1		)
Private mortgage-backed securities	—		—			69.4		(1.8		)	69.4		(1.8		)
Corporate securities	24.9		(0.2		)	51.4		(0.8		)	76.3		(1.0		)
Total	$	1,123.2	$	(22.6	)	$	779.0	$	(14.5	)	$	1,902.2	$	(37.1	)

	Less than 12 Months					12 Months or More					Total
December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Held-to-Maturity:
State, county and municipal securities	$	25.9	$	(0.3	)	$	57.1	$	(0.6	)	$	83.0	$	(0.9	)
Obligations of U.S. government agencies	19.5		(0.3		)	—		—			19.5		(0.3		)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	45.0		(2.2		)	120.2		(4.3		)	165.2		(6.5		)
Corporate securities	—		—			39.6		(0.6		)	39.6		(0.6		)
Total	$	90.4	$	(2.8	)	$	216.9	$	(5.5	)	$	307.3	$	(8.3	)

The investment portfolio is evaluated quarterly for other-than-temporary declines in the market value of each individual investment security. The Company had 551 and 760 individual investment securities that were in an unrealized loss position as of March 31, 2019 and December 31, 2018, respectively, related primarily to fluctuations in the current interest rates. As of March 31, 2019, the Company had the intent and ability to hold these investment securities for a period of time sufficient to allow for an anticipated recovery. Furthermore, the Company does not have the intent to sell any of the available-for-sale securities in the above table and it is more likely than not that the Company will not have to sell any securities before a recovery in cost. No impairment losses were recorded during the three month periods ended March 31, 2019 or 2018.

Maturities of investment securities at March 31, 2019 are shown below. 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
March 31, 2019	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	497.2	$	496.0	$	44.9	$	44.8
After one year but within five years	1,509.8		1,504.9		44.2		44.1
After five years but within ten years	395.3		395.5		24.3		25.5
After ten years	176.7		175.6		3.6		3.6
Total	$	2,579.0	$	2,572.0	$	117.0	$	118.0

As of March 31, 2019, the Company had investment securities callable within one year with amortized costs and estimated fair values of $121.3 million and $121.5 million, respectively. These investment securities are primarily included in the after one year but within five years category in the table above. As of March 31, 2019, the Company had callable structured notes with amortized costs and estimated fair values of $2.0 million and $2.0 million, respectively. These callable structured notes, which are classified as available-for-sale, are included in the after one year but within five years category in the table above.

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Loans

3 Months Ended

Mar. 31, 2019

Receivables [Abstract]

Loans

Loans

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

	March 31, 2019		December 31, 2018
Real estate loans:
Commercial	$	3,255.8	$	3,235.4
Construction:
Land acquisition & development	292.7		321.6
Residential	233.1		242.8
Commercial	312.1		274.3
Total construction loans	837.9		838.7
Residential	1,529.5		1,542.0
Agricultural	210.4		217.4
Total real estate loans	5,833.6		5,833.5
Consumer:
Indirect consumer	775.7		787.8
Other consumer	194.1		200.6
Credit card	77.2		81.8
Total consumer loans	1,047.0		1,070.2
Commercial	1,342.1		1,310.3
Agricultural	234.7		254.8
Other, including overdrafts	1.8		1.6
Loans held for investment	8,459.2		8,470.4
Mortgage loans held for sale	34.0		33.3
Total loans	$	8,493.2	$	8,503.7

The following tables present the Company’s recorded investment and contractual aging of the Company’s recorded investment in loans by class as of the dates indicated. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due.

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of March 31, 2019	Past Due		Past Due		Past Due		Past Due		Loans		Loans		Loans
Real estate
Commercial	$	12.6	$	7.2	$	2.5	$	22.3	$	3,222.4	$	11.1	$	3,255.8
Construction:
Land acquisition & development	1.2		0.7		0.4		2.3		286.6		3.8		292.7
Residential	2.2		—		—		2.2		229.6		1.3		233.1
Commercial	—		—		—		—		311.9		0.2		312.1
Total construction loans	3.4		0.7		0.4		4.5		828.1		5.3		837.9
Residential	4.6		1.6		0.2		6.4		1,517.2		5.9		1,529.5
Agricultural	4.0		0.9		0.3		5.2		202.8		2.4		210.4
Total real estate loans	24.6		10.4		3.4		38.4		5,770.5		24.7		5,833.6
Consumer:
Indirect consumer	6.5		1.1		0.5		8.1		765.6		2.0		775.7
Other consumer	1.4		0.7		0.3		2.4		191.2		0.5		194.1
Credit card	0.6		0.5		0.7		1.8		75.4		—		77.2
Total consumer loans	8.5		2.3		1.5		12.3		1,032.2		2.5		1,047.0
Commercial	4.0		4.1		1.7		9.8		1,317.0		15.3		1,342.1
Agricultural	1.3		1.3		0.5		3.1		229.0		2.6		234.7
Other, including overdrafts	—		—		—		—		1.8		—		1.8
Loans held for investment	38.4		18.1		7.1		63.6		8,350.5		45.1		8,459.2
Mortgage loans originated for sale	—		—		—		—		34.0		—		34.0
Total loans	$	38.4	$	18.1	$	7.1	$	63.6	$	8,384.5	$	45.1	$	8,493.2

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2018	Past Due		Past Due		Past Due		Past Due		Loans		Loans		Loans
Real estate
Commercial	$	10.4	$	1.0	$	0.8	$	12.2	$	3,214.0	$	9.2	$	3,235.4
Construction:
Land acquisition & development	1.6		0.1		0.2		1.9		316.0		3.7		321.6
Residential	1.0		0.4		—		1.4		240.4		1.0		242.8
Commercial	0.4		—		—		0.4		273.7		0.2		274.3
Total construction loans	3.0		0.5		0.2		3.7		830.1		4.9		838.7
Residential	8.8		1.1		0.2		10.1		1,525.3		6.6		1,542.0
Agricultural	2.2		—		—		2.2		202.6		12.6		217.4
Total real estate loans	24.4		2.6		1.2		28.2		5,772.0		33.3		5,833.5
Consumer:
Indirect consumer	6.8		2.1		0.4		9.3		776.8		1.7		787.8
Other consumer	1.4		0.5		0.1		2.0		198.1		0.5		200.6
Credit card	0.9		0.4		0.8		2.1		79.7		—		81.8
Total consumer loans	9.1		3.0		1.3		13.4		1,054.6		2.2		1,070.2
Commercial	8.3		1.2		1.3		10.8		1,283.7		15.8		1,310.3
Agricultural	2.1		0.3		—		2.4		249.4		3.0		254.8
Other, including overdrafts	—		—		—		—		1.6		—		1.6
Loans held for investment	43.9		7.1		3.8		54.8		8,361.3		54.3		8,470.4
Mortgage loans originated for sale	—		—		—		—		33.3		—		33.3
Total loans	$	43.9	$	7.1	$	3.8	$	54.8	$	8,394.6	$	54.3	$	8,503.7

Loans from business combinations included in the tables above include certain loans that had evidence of deterioration in credit quality since origination and for which it was probable, at acquisition, that all contractually required payments would not be collected.

The following table displays the outstanding unpaid balances and accrual status of loans acquired with credit impairment as of the dates indicated:    

	March 31, 2019		December 31, 2018
Outstanding balance	$	40.9	$	43.4
Carrying value
Loans on accrual status	28.0		30.2
Total carrying value	$	28.0	$	30.2

The following table summarizes changes in the accretable yield for loans acquired deemed credit impaired for the three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	8.9		$	7.3
Accretion income	(0.7		)	(0.7		)
Reductions due to exit events	(0.3		)	(0.2		)
Reclassifications from non-accretable differences	0.5			0.8
Ending balance	$	8.4		$	7.2

Acquired loans that met the criteria for non-accrual of interest prior to acquisition were considered performing upon acquisition. If interest on non-accrual loans had been accrued, such income would have been approximately $0.6 million and $0.8 million for the three months ended March 31, 2019 and 2018, respectively.

The Company considers impaired loans to include all originated loans, except consumer loans, that are risk rated as doubtful, or have been placed on non-accrual status or renegotiated in troubled debt restructurings, and all loans acquired with evidence of deterioration in credit quality and for which it was probable, at acquisition, that the Company would be unable to collect all contractual amounts owed. The following tables present information on the Company’s recorded investment in impaired loans as of the dates indicated:

As of March 31, 2019	Unpaid Total Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
Real estate:
Commercial	$	27.0	$	10.7	$	10.6	$	21.3	$	0.7
Construction:
Land acquisition & development	10.0		0.4		3.4		3.8		0.3
Residential	1.5		0.9		0.4		1.3		—
Commercial	0.6		0.1		—		0.1		—
Total construction loans	12.1		1.4		3.8		5.2		0.3
Residential	8.9		4.2		3.3		7.5		0.5
Agricultural	2.7		2.4		0.2		2.6		—
Total real estate loans	50.7		18.7		17.9		36.6		1.5
Commercial	24.3		5.8		14.0		19.8		5.1
Agricultural	5.0		1.6		3.2		4.8		0.5
Total	$	80.0	$	26.1	$	35.1	$	61.2	$	7.1

As of December 31, 2018	Unpaid Total Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
Real estate:
Commercial	$	22.2	$	8.6	$	7.7	$	16.3	$	0.7
Construction:
Land acquisition & development	10.0		0.4		3.5		3.9		0.2
Residential	1.1		0.6		0.4		1.0		0.1
Commercial	0.7		0.2		—		0.2		—
Total construction loans	11.8		1.2		3.9		5.1		0.3
Residential	8.8		5.7		2.0		7.7		0.3
Agricultural	12.9		12.5		0.2		12.7		—
Total real estate loans	55.7		28.0		13.8		41.8		1.3
Commercial	24.1		5.5		14.4		19.9		5.2
Agricultural	3.2		2.5		0.6		3.1		0.3
Total	$	83.0	$	36.0	$	28.8	$	64.8	$	6.8

The following table presents the average recorded investment in and income recognized on impaired loans for the periods indicated:

	Three Months Ended March 31,
	2019				2018
	Average Recorded Investment		Income Recognized		Average Recorded Investment		Income Recognized
Real estate	$	39.3	$	—	$	56.1	$	—
Commercial	19.9		—		22.1		—
Agricultural	3.9		—		1.5		—
Total	$	63.1	$	—	$	79.7	$	—

Interest payments received on non-accrual impaired loans are applied to principal. Interest income is subsequently recognized only to the extent cash payments are received in excess of principal due. If interest on impaired loans had been accrued, interest income on impaired loans would have been approximately $0.6 million and $0.8 million for the three months ended March 31, 2019 and 2018, respectively.

Collateralized impaired loans are generally recorded at the fair value of the underlying collateral using discounted cash flows, independent appraisals and management estimates based upon current market conditions. For loans measured under the present value of cash flows method, the change in present value attributable to the passage of time, if applicable, is recognized in the provision for loan losses and thus no interest income is recognized.

Modifications of performing loans are made in the ordinary course of business and are completed on a case-by-case basis as negotiated with the borrower. Loan modifications typically include interest rate changes, interest only periods of less than twelve months, short-term payment deferrals and extension of amortization periods to provide payment relief. 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 otherwise consider. Certain troubled debt restructurings are on non-accrual status at the time of restructuring and may be returned to accrual status after considering the borrower’s sustained repayment performance in accordance with the restructuring agreement for a period of at least six months and management is reasonably assured of future performance. If the troubled debt restructuring meets these performance criteria and the interest rate granted at the modification is equal to or greater than the rate that the Company was willing to accept at the time of the restructuring for a new loan with comparable risk, then the loan will return to performing status and the accrual of interest will resume, although they continue to be individually evaluated for impairment and disclosed as impaired loans.

The Company had loans renegotiated in troubled debt restructurings of $22.7 million as of March 31, 2019, of which $16.9 million were included in non-accrual loans and $5.8 million were on accrual status. The Company had loans renegotiated in troubled debt restructurings of $23.4 million as of December 31, 2018, of which $17.8 million were included in non-accrual loans and $5.6 million were on accrual status.

The Company had no material troubled debt restructurings that occurred during the three months ended March 31, 2019.

For troubled debt restructurings that were on non-accrual status or otherwise deemed impaired before the modification, a specific reserve may already be recorded. In periods subsequent to modification, the Company continues to evaluate all troubled debt restructurings for possible impairment and recognizes impairment through the allowance. Additionally these loans continue to work their way 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 no charge-offs directly related to modifying troubled debt restructurings during the three months ended March 31, 2019 or 2018.

The Company had no material troubled debt restructurings during the previous 12 months for which there was a payment default during the three months ended March 31, 2019. The Company considers a payment default to occur on troubled debt restructurings when the loan is 90 days or more past due or was placed on non-accrual status after the modification.

At March 31, 2019, there were no material commitments to lend additional funds to borrowers whose existing loans have been renegotiated or are classified as non-accrual.

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. The Company adheres to a Uniform Classification System developed jointly by the various bank regulatory agencies to internally risk rate loans. The Uniform Classification System defines three broad categories of criticized assets, which the Company uses as credit quality indicators:

Other Assets Especially Mentioned — includes loans that exhibit weaknesses in financial condition, loan structure or documentation, which if not promptly corrected, may lead to the development of abnormal risk elements.

Substandard — includes loans that are inadequately protected by the current sound worth and paying capacity of the borrower. Although the primary source of repayment for a substandard loan is not currently 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 to a point where collection or liquidation in full, on the basis of currently existing facts, conditions and values, is highly questionable and improbable. Doubtful loans are required to be placed on non-accrual status and are assigned specific loss exposure.

Company management undertakes the same process for assigning risk ratings to acquired loans as it does for originated loans. Acquired loans rated as substandard or lower or that were on non-accrual status or designated as troubled debt restructurings at the time of acquisition are deemed to be acquired credit impaired loans accounted for under ASC Topic 310-30, regardless of whether they are classified as performing or non-performing loans.

The following tables present the Company’s recorded investment in criticized loans by class and credit quality indicator based on the most recent analysis performed as of the dates indicated:

As of March 31, 2019	Other Assets Especially Mentioned		Substandard		Doubtful		Total Criticized Loans
Real estate:
Commercial	$	100.4	$	90.9	$	2.8	$	194.1
Construction:
Land acquisition & development	5.1		2.2		3.4		10.7
Residential	0.9		2.2		0.9		4.0
Commercial	1.8		4.1		—		5.9
Total construction loans	7.8		8.5		4.3		20.6
Residential	2.6		8.9		1.9		13.4
Agricultural	15.7		18.0		0.1		33.8
Total real estate loans	126.5		126.3		9.1		261.9
Consumer:
Indirect consumer	0.3		2.7		0.1		3.1
Direct consumer	0.3		0.8		0.1		1.2
Total consumer loans	0.6		3.5		0.2		4.3
Commercial	42.3		46.5		11.3		100.1
Agricultural	16.8		18.3		1.1		36.2
Total	$	186.2	$	194.6	$	21.7	$	402.5

As of December 31, 2018	Other Assets Especially Mentioned		Substandard		Doubtful		Total Criticized Loans
Real estate:
Commercial	$	102.5	$	87.4	$	2.9	$	192.8
Construction:
Land acquisition & development	5.0		7.0		3.3		15.3
Residential	2.8		2.0		0.4		5.2
Commercial	1.7		3.9		—		5.6
Total construction loans	9.5		12.9		3.7		26.1
Residential	3.0		10.8		0.7		14.5
Agricultural	9.0		24.0		0.1		33.1
Total real estate loans	124.0		135.1		7.4		266.5
Consumer:
Indirect consumer	0.7		2.1		0.1		2.9
Direct consumer	0.3		0.8		0.1		1.2
Total consumer loans	1.0		2.9		0.2		4.1
Commercial	39.4		45.8		11.8		97.0
Agricultural	14.4		17.8		1.5		33.7
Total	$	178.8	$	201.6	$	20.9	$	401.3

The Company maintains a credit review function, which is independent of the credit approval process, to assess assigned internal risk classifications and monitor compliance with internal lending policies and procedures.

Written action plans with firm target dates for resolution of identified problems are maintained and reviewed on a quarterly basis for all categories of criticized loans.

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Allowance for Loan Losses

3 Months Ended

Mar. 31, 2019

Receivables [Abstract]

Allowance for Loan Losses

Allowance for Loan Losses

The following tables present a summary of changes in the allowance for loan losses by portfolio segment for the periods indicated:

Three Months Ended March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Allowance for loan losses:
Beginning balance	$	31.0		$	8.7		$	31.3		$	2.0		$	—	$	73.0
Provision charged to operating expense	(1.7		)	2.0			3.6			(0.2		)	—		3.7
Less loans charged-off	(2.1		)	(3.0		)	(0.8		)	(0.1		)	—		(6.0		)
Add back recoveries of loans previously    charged-off	0.2			1.1			0.4			—			—		1.7
Ending balance	$	27.4		$	8.8		$	34.5		$	1.7		$	—	$	72.4
As of March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Allowance for loan losses:
Loans individually evaluated for impairment	$	1.5		$	—		$	5.1		$	0.5		$	—	$	7.1
Loans collectively evaluated for impairment	25.9			8.8			29.4			1.2			—		65.3
Allowance for loan losses	$	27.4		$	8.8		$	34.5		$	1.7		$	—	$	72.4
As of March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Loans held for investment:
Individually evaluated for impairment	$	36.6		$	—		$	19.8		$	4.8		$	—	$	61.2
Collectively evaluated for impairment	5,797.0			1,047.0			1,322.3			229.9			1.8		8,398.0
Total loans held for investment	$	5,833.6		$	1,047.0		$	1,342.1		$	234.7		$	1.8	$	8,459.2

Three Months Ended March 31, 2018	Real Estate			Consumer			Commercial			Agriculture		Other		Total
Allowance for loan losses:
Beginning balance	$	31.7		$	8.7		$	30.5		$	1.2	$	—	$	72.1
Provision charged to operating expense	1.8			0.7			(0.7		)	0.3		—		2.1
Less loans charged-off	(0.8		)	(2.7		)	(1.7		)	—		—		(5.2		)
Add back recoveries of loans previously    charged-off	1.2			1.1			2.0			0.2		—		4.5
Ending balance	$	33.9		$	7.8		$	30.1		$	1.7	$	—	$	73.5

As of December 31, 2018	Real Estate		Consumer		Commercial		Agriculture		Other		Total
Allowance for loan losses:
Loans individually evaluated for impairment	$	1.3	$	—	$	5.2	$	0.3	$	—	$	6.8
Loans collectively evaluated for impairment	29.7		8.7		26.1		1.7		—		66.2
Allowance for loan losses	$	31.0	$	8.7	$	31.3	$	2.0	$	—	$	73.0
As of December 31, 2018	Real Estate		Consumer		Commercial		Agriculture		Other		Total
Loans held for investment:
Individually evaluated for impairment	$	41.8	$	—	$	19.9	$	3.1	$	—	$	64.8
Collectively evaluated for impairment	5,791.7		1,070.2		1,290.4		251.7		1.6		8,405.6
Total loans held for investment	$	5,833.5	$	1,070.2	$	1,310.3	$	254.8	$	1.6	$	8,470.4

The Company performs a quarterly assessment of the adequacy of its allowance for loan losses in accordance with GAAP. The methodology used to assess the adequacy is consistently applied to the Company’s loan portfolio and consists of three elements: (1) specific valuation allowances based on probable losses on impaired loans; (2) historical valuation allowances based on loan loss experience for similar loans with similar characteristics and trends; and (3) general valuation allowances determined based on changes in the nature of the loan portfolio, overall portfolio quality, industry concentrations, delinquency trends, general economic conditions and other qualitative risk factors both internal and external to the Company.

Specific allowances are established for loans where management has determined that probability of a loss exists by analyzing the borrower’s ability to repay amounts owed, collateral deficiencies and any relevant qualitative or economic factors impacting the loan. Historical valuation allowances are determined by applying percentage loss factors to the credit exposures from outstanding loans. For commercial, agricultural and real estate loans, loss factors are applied based on the internal risk classifications of these loans. For consumer loans, loss factors are applied on a portfolio basis. For commercial, agriculture and real estate loans, loss factor percentages are based on a migration analysis of our historical loss experience, designed to account for credit deterioration. For consumer loans, the loss factor percentages are based on a three-year loss history for the 2018 period and on a one-year loss history for the comparable periods. The loan loss rates for 2018 also incorporate the available loss history data from Bank of the Cascades prior to the merger date to represent a consolidated institutional loss rate for both originated and acquired portfolios. General valuation allowances are determined by evaluating, on a quarterly basis, changes in the nature and volume of the loan portfolio, overall portfolio quality, industry concentrations, current economic and regulatory conditions and the estimated impact of these factors on historical loss rates.

An allowance for loan losses is established for loans acquired deemed credit impaired and for which the Company projects a decrease in the expected cash flows in periods subsequent to the acquisition of such loans. As of March 31, 2019 and December 31, 2018, the Company’s allowance for loan losses included $0.9 million and $0.8 million related to loans acquired credit impaired.

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Other Real Estate Owned

3 Months Ended

Mar. 31, 2019

Repossessed Assets [Abstract]

Other Real Estate Owned

Other Real Estate Owned

Information with respect to the Company’s other real estate owned follows:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	14.4		$	10.1
Additions	8.4			1.2
Valuation adjustments	(0.3		)	—
Dispositions	(1.4		)	(0.3		)
Ending balance	$	21.1		$	11.0

The carrying values of foreclosed residential real estate properties included in other real estate owned were $1.7 million and $2.0 million as of March 31, 2019 and December 31, 2018, respectively. The Company had $0.5 million of consumer mortgage loans collateralized by residential real estate property that were in the process of foreclosure as of March 31, 2019 and $0.4 million as of December 31, 2018.

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Derivatives and Hedging Activities

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative and Hedging Activities

Derivatives and Hedging Activities

The Company 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 customer 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 customer, 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.

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

The notional amounts and estimated fair values of the Company’s derivatives are presented in the following table. Fair value estimates are obtained from third parties and are based on pricing models.

	March 31, 2019				December 31, 2018
	Notional Amount		Estimated Fair Value		Notional Amount		Estimated Fair Value
Derivative Assets (included in other assets on the consolidated balance sheets):
Non-hedging interest rate derivatives:
Interest rate swap contracts	$	449.2	$	12.7	$	403.3	$	8.8
Interest rate lock commitments	76.9		1.9		51.0		1.3
Total derivative assets	$	526.1	$	14.6	$	454.3	$	10.1
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Non-hedging interest rate derivatives:
Interest rate swap contracts	$	449.2	$	12.7	$	403.3	$	8.8
Forward loan sales contracts	90.4		0.8		64.6		0.6
Total derivative liabilities	$	539.6	$	13.5	$	467.9	$	9.4

Derivative assets and liabilities are recorded at fair value on the balance sheet and do not take into account the effects of master netting arrangements. Master netting arrangements allow the Company to settle all contracts held with a single counterparty on a net basis and to offset net contract position with related collateral where applicable.

The following table illustrates the potential effect of the Company’s master netting arrangements, by type of financial instrument, on the Company’s consolidated balance sheets as of March 31, 2019 and December 31, 2018:

	March 31, 2019
	Gross Amounts Recognized		Gross Amounts Offset in the Balance Sheet		Net Amounts in the Balance Sheet		Financial Instruments		Fair Value of Financial Collateral in the Balance Sheet		Net Amount
Financial Assets
Interest rate swap contracts	$	12.7	$	—	$	12.7	$	2.0	$	7.5	$	3.2
Mortgage related derivatives	1.9		—		1.9		—		—		1.9
Total derivatives	14.6		—		14.6		2.0		7.5		5.1
Total assets	$	14.6	$	—	$	14.6	$	2.0	$	7.5	$	5.1
Financial Liabilities
Interest rate swap contracts	$	12.7	$	—	$	12.7	$	2.0	$	0.2	$	10.5
Mortgage related derivatives	0.8		—		0.8		—		—		0.8
Total derivatives	13.5		—		13.5		2.0		0.2		11.3
Repurchase agreements	672.6		—		672.6		—		672.6		—
Total liabilities	$	686.1	$	—	$	686.1	$	2.0	$	672.8	$	11.3

	December 31, 2018
	Gross Amounts Recognized		Gross Amounts Offset in the Balance Sheet		Net Amounts in the Balance Sheet		Financial Instruments		Fair Value of Financial Collateral in the Balance Sheet		Net Amount
Financial Assets
Interest rate swap contracts	$	8.8	$	—	$	8.8	$	2.7	$	2.4	$	3.7
Mortgage related derivatives	1.3		—		1.3		—		—		1.3
Total derivatives	10.1		—		10.1		2.7		2.4		5.0
Total assets	$	10.1	$	—	$	10.1	$	2.7	$	2.4	$	5.0
Financial Liabilities
Interest rate swap contracts	$	8.8	$	—	$	8.8	$	2.7	$	4.1	$	2.0
Mortgage related derivatives	0.6		—		0.6		—		—		0.6
Total derivatives	9.4		—		9.4		2.7		4.1		2.6
Repurchase agreements	712.4		—		712.4		—		712.4		—
Total liabilities	$	721.8	$	—	$	721.8	$	2.7	$	716.5	$	2.6

The following table presents the pre-tax gains or losses related to derivative contracts that were recorded in other non-interest income in the Company’s statements of income for the periods indicated:

	Three Months Ended March 31,
	2019		2018
Non-hedging interest rate derivatives:
Amount of gain recognized in other non-interest income	$	—	$	0.3
Amount of net fee income recognized in other non-interest income	0.8		0.5
Amount of net gains recognized in mortgage banking revenues	0.4		(0.1		)

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Capital Stock

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Capital Stock

Capital Stock

The Company had 38,461,948 shares of Class A common stock and 22,374,171 shares of Class B common stock outstanding as of March 31, 2019. The Company had 38,169,575 shares of Class A common stock and 22,453,672 shares of Class B common stock outstanding as of December 31, 2018.

During the three months ended March 31, 2019 and 2018, the Company did not repurchase any shares of its Class A common stock other than stock repurchases which 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.

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Earnings per Common Share

3 Months Ended

Mar. 31, 2019

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 three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019		2018
Net income	$	41.6	$	36.7
Weighted average common shares outstanding for basic earnings per share computation	60,311,171		56,241,201
Dilutive effects of stock-based compensation	286,899		410,977
Weighted average common shares outstanding for diluted earnings per common share computation	60,598,070		56,652,178
Basic earnings per common share	$	0.69	$	0.65
Diluted earnings per common share	$	0.69	$	0.65
Anti-dilutive unvested time restricted stock	121,452		139,943

The Company had 154,387 and 164,019 shares of unvested restricted stock as of March 31, 2019 and 2018, 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

3 Months Ended

Mar. 31, 2019

Banking and Thrift [Abstract]

Regulatory Capital

Regulatory Capital

On July 2, 2013, the Board of Governors of the Federal Reserve Bank issued a final rule implementing a revised regulatory capital framework for U.S. banks in accordance with the Basel III international accord and satisfying related mandates under the Dodd-Frank Wall Street Reform and Consumer Protection Act. The revised regulatory capital framework (the “Basel III Capital Rules”) substantially revised the risk-based capital requirements applicable to bank holding companies and depository institutions by defining the components of capital and addressing other issues affecting the numerator in banking institutions’ regulatory capital ratios, addressing risk weights and other issues affecting the denominator in banking institutions’ regulatory capital ratios and replacing the existing risk-weighting approach with a more risk-sensitive approach. The Basel III Capital Rules became effective for the Company on January 1, 2015, subject to a phase-in period for certain provisions. The capital conservation buffer required under Basel III began to phase in starting January 1, 2016 and became fully implemented on January 1, 2019.

As of March 31, 2019 and December 31, 2018, 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 March 31, 2019 and December 31, 2018 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)
March 31, 2019	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,310.3	13.23	%	$	792.4	8.000	%	$	1,040.0	10.50	%	$	990.5	10.00	%
FIB	1,201.4		12.16		790.2		8.000		1,037.1		10.50		987.8		10.00
Tier 1 risk-based capital:
Consolidated	1,237.9		12.50		594.3		6.000		841.9		8.50		792.4		8.00
FIB	1,129.0		11.43		592.7		6.000		839.6		8.50		790.2		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,153.7		11.65		445.7		4.500		693.4		7.00		643.8		6.50
FIB	1,129.0		11.43		444.5		4.500		691.4		7.00		642.0		6.50
Leverage capital ratio:
Consolidated	1,237.9		9.76		507.5		4.000		507.5		4.00		634.4		5.00
FIB	1,129.0		8.92		506.3		4.000		506.3		4.00		632.8		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, 2018	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,285.0	12.99	%	$	791.2	8.00	%	$	976.6	9.875	%	$	989.0	10.00	%
FIB	1,184.5		12.01		788.8		8.00		973.7		9.875		986.0		10.00
Tier 1 risk-based capital:
Consolidated	1,212.0		12.26		593.4		6.00		778.8		7.875		791.2		8.00
FIB	1,111.6		11.27		591.6		6.00		776.5		7.875		788.8		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,127.8		11.40		445.0		4.50		630.5		6.375		642.8		6.50
FIB	1,111.6		11.27		443.7		4.50		628.6		6.375		640.9		6.50
Leverage capital ratio:
Consolidated	1,212.0		9.47		511.9		4.00		511.9		4.000		639.9		5.00
FIB	1,111.6		8.97		495.9		4.00		495.9		4.000		619.8		5.00

(1) The ratios for 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 entity and has presented the ratios as if they also applied on a consolidated basis.

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Commitments and Contingencies

In the normal course of business, the Company is involved in various other claims and litigation. In the opinion of management, following consultation with legal counsel, the ultimate liability or disposition thereof of all other 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 March 31, 2019, the Company had commitments under construction contracts of $1.5 million.

Residential mortgage loans sold to investors in the secondary market are sold with varying recourse provisions. Essentially all of 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; unmarketability; etc. 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 $1.5 million of sold residential mortgage loans with recourse provisions still in effect as of March 31, 2019.

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Financial Instruments with Off-Balance Sheet Risk

3 Months Ended

Mar. 31, 2019

Financial Instruments with Off-Balance Sheet Risk [Abstract]

Financial Instruments with Off-Balance Sheet Risk

Financial Instruments with Off-Balance Sheet Risk

The Company is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and standby letters of credit. Commitments to extend credit are agreements to lend to a customer as 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. At March 31, 2019, commitments to extend credit to existing and new borrowers approximated $2,637.1 million, which included $720.7 million on unused credit card lines and $1,058.9 million with commitment maturities beyond one year.

Standby letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. At March 31, 2019, the Company had outstanding standby letters of credit of $47.6 million. The estimated fair value of the obligation undertaken by the Company in issuing the standby letters of credit is included in other liabilities in the Company’s consolidated balance sheet.

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Other Comprehensive Income/Loss

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Other Comprehensive Income/Loss

Other Comprehensive Income/Loss

The gross amounts of each component of other comprehensive income and the related tax effects are as follows:

	Pre-tax						Tax Expense (Benefit)						Net of Tax
Three Months Ended March 31,	2019			2018			2019			2018			2019			2018
Investment securities available-for sale:
Change in net unrealized gains during period	$	33.6		$	(23.7	)	$	8.8		$	(6.2	)	$	24.8		$	(17.5	)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(6.0		)	—			(1.6		)	—			(4.4		)	—
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	—			0.5			—			0.2			—			0.3
Defined benefits post-retirement benefit plan:
Change in net actuarial (gain) loss	(0.2		)	(0.1		)	—			(0.1		)	(0.2		)	—
Total other comprehensive income (loss)	$	27.4		$	(23.3	)	$	7.2		$	(6.1	)	$	20.2		$	(17.2	)

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

	March 31, 2019			December 31, 2018
Net unrealized gain (loss) on investment securities available-for-sale	$	(5.1	)	$	(25.5	)
Net actuarial gain (loss) on defined benefit post-retirement benefit plans	0.7			0.9
Net accumulated other comprehensive gain (loss)	$	(4.4	)	$	(24.6	)

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Fair Value Measurements

3 Months Ended

Mar. 31, 2019

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 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 that may be used 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 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, and therefore are classified within Level 2 of the valuation hierarchy. The Company’s policy is to recognize transfers between levels as of the end of the reporting period. There were no transfers between Level 1 and Level 2 during the three months ended March 31, 2019 and 2018.

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 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.

Interest Rate Swap Contracts. Fair values for derivative interest rate swap contracts 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 3 month LIBOR forward curve to estimate variable rate cash inflows and the federal funds effective swap 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 from each other, was not significant in the reported periods. The Company also obtains and compares the reasonableness of the pricing from an independent third party.

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 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 liabilities measured at fair value on a recurring basis are as follows:

			Fair Value Measurements at Reporting Date Using
As of March 31, 2019	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	$	4.0	$	—	$	4.0	$	—
State, county and municipal securities	78.4			—	78.4			—
Obligations of U.S. government agencies	597.7			—	597.7			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	1,732.9			—	1,732.9			—
Private mortgage-backed securities	65.3			—	65.3			—
Corporate securities	92.0			—	92.0			—
Other investments	1.7			—	1.7			—
Loans held for sale	34.0			—	34.0			—
Derivative assets:
Interest rate swap contracts	12.7			—	12.7			—
Interest rate lock commitments	1.9			—	1.9			—
Derivative liabilities:
Interest rate swap contracts	12.7			—	12.7			—
Forward loan sale contracts	0.8			—	0.8			—
Deferred compensation plan assets	12.4			—	12.4			—
Deferred compensation plan liabilities	$	12.4	$	—	$	12.4	$	—

			Fair Value Measurements at Reporting Date Using
As of December 31, 2018	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	$	2.6	$	—	$	2.6	$	—
Obligations of U.S. government agencies	559.2			—	559.2			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	1,544.8			—	1,544.8			—
Private mortgage-backed securities	70.2			—	70.2			—
Corporate securities	91.9			—	91.9			—
Other investments	2.0			—	2.0			—
Loans held for sale	33.3			—	33.3			—
Derivative assets:
Interest rate swap contracts	8.8			—	8.8			—
Interest rate lock commitments	1.3			—	1.3			—
Derivative liabilities
Interest rate swap contracts	8.8			—	8.8			—
Forward loan sales contracts	0.6			—	0.6			—
Deferred compensation plan assets	12.1			—	12.1			—
Deferred compensation plan liabilities	$	12.1	$	—	$	12.1	$	—

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 impairment. 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 March 31, 2019	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Impaired loans	$	30.9	$	—	$	—	$	30.9
Other real estate owned	2.0			—		—	2.0
Long-lived assets to be disposed of by sale	$	5.5	$	—	$	—	$	5.5
				Fair Value Measurements at Reporting Date Using
As of December 31, 2018	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Impaired loans	$	24.1	$	—	$	—	$	24.1
Other real estate owned	0.6			—		—	0.6
Long-lived assets to be disposed of by sale	$	4.9	$	—	$	—	$	4.9

Impaired Loans. Collateralized impaired loans are reported at the fair value of the underlying collateral if repayment is expected solely from collateral. The impaired loans are reported at fair value through specific valuation allowance allocations. In addition, when it is determined that the fair value of an impaired 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 loan losses. Collateral values are estimated using independent appraisals and management estimates of current market conditions. As of March 31, 2019, certain impaired loans with a carrying value of $44.2 million were reduced by specific valuation allowance allocations of $7.1 million and partial loan charge-offs of $6.2 million resulting in a reported fair value of $30.9 million. As of December 31, 2018, certain impaired loans with a carrying value of $36.3 million were reduced by specific valuation allowance allocations of $6.8 million and partial loan charge-offs of $5.4 million resulting in a reported fair value of $24.1 million.

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 loan 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 $0.3 million and zero write downs on OREO properties during the three months ended March 31, 2019 and 2018, 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 March 31, 2019, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $6.0 million, which was reduced by write-downs of $0.5 million, resulting in a fair value of $5.5 million. As of December 31, 2018, the Company had long-lived assets to be disposed of by sale with carrying values aggregating $5.4 million, reduced by write-downs of $0.5 million, resulting in a fair value of $4.9 million.         

The following table presents additional quantitative information about assets measured at fair value on a non-recurring basis and for which the Company has utilized Level 3 inputs to determine fair values:

	Fair Value As of
	March 31, 2019		December 31, 2018		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Impaired loans	$	30.9	$	24.1	Appraisal	Appraisal adjustment	0%	-	26%	(13%)
Other real estate owned	2.0		0.6		Appraisal	Appraisal adjustment	8%	-	96%	(39%)
Long-lived assets to be disposed of by sale	$	5.5	$	4.9	Appraisal	Appraisal adjustment	0%	-	43%	(10%)

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 payable on demand at the reporting date. The fair values of fixed-maturity certificates of deposit are estimated using external market rates currently offered for deposits with 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 with 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, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, are as follows:

					Fair Value Measurements at Reporting Date Using
As of March 31, 2019	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	$	955.2	$	955.2	$	955.2	$	—	$	—
Investment debt securities available-for-sale	2,572.0		2,572.0		—		2,572.0		—
Investment debt securities held-to-maturity	117.0		118.0		—		118.0		—
Accrued interest receivable	46.5		46.5		—		46.5		—
Mortgage servicing rights, net	27.9		40.5		—		40.5		—
Loans held for sale	34.0		34.0		—		34.0		—
Net loans held for investment	8,386.8		8,408.6		—		8,377.7		30.9
Derivative assets	14.6		14.6		—		14.6		—
Deferred compensation plan assets	12.4		12.4		—		12.4		—
Total financial assets	$	12,166.4	$	12,201.8	$	955.2	$	11,215.7	$	30.9
Financial liabilities:
Total deposits, excluding time deposits	$	9,408.3	$	9,408.3	$	9,408.3	$	—	$	—
Time deposits	1,406.4		1,393.2		—		1,393.2		—
Securities sold under repurchase agreements	672.6		672.6		—		672.6		—
Accrued interest payable	10.0		10.0		—		10.0		—
Long-term debt	15.8		13.9		—		13.9		—
Subordinated debentures held by subsidiary trusts	86.9		85.1		—		85.1		—
Derivative liabilities	13.5		13.5		—		13.5		—
Deferred compensation plan liabilities	12.4		12.4		—		12.4		—
Total financial liabilities	$	11,625.9	$	11,609.0	$	9,408.3	$	2,200.7	$	—

					Fair Value Measurements at Reporting Date Using
As of December 31, 2018	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	$	822.0	$	822.0	$	822.0	$	—	$	—
Investment debt securities available-for-sale	2,270.7		2,270.7		—		2,270.7		—
Investment debt securities held-to-maturity	406.8		400.7		—		400.7		—
Accrued interest receivable	44.9		44.9		—		44.9		—
Mortgage servicing rights, net	27.7		42.4		—		42.4		—
Loans held for sale	33.3		33.3		—		33.3		—
Net loans held for investment	8,397.4		8,439.7		—		8,415.6		24.1
Derivative assets	10.1		10.1		—		10.1		—
Deferred compensation plan assets	12.1		12.1		—		12.1		—
Total financial assets	$	12,025.0	$	12,075.9	$	822.0	$	11,229.8	$	24.1
Financial liabilities:
Total deposits, excluding time deposits	$	9,363.7	$	9,363.7	$	9,363.7	$	—	$	—
Time deposits	1,317.0		1,299.0		—		1,299.0		—
Securities sold under repurchase agreements	712.4		712.4		—		712.4		—
Accrued interest payable	7.8		7.8		—		7.8		—
Long-term debt	15.8		13.0		—		13.0		—
Subordinated debentures held by subsidiary trusts	86.9		84.9		—		84.9		—
Derivative liabilities	9.4		9.4		—		9.4		—
Deferred compensation plan liabilities	12.1		12.1		—		12.1		—
Total financial liabilities	$	11,525.1	$	11,502.3	$	9,363.7	$	2,138.6	$	—

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Recent Authoritative Accounting Guidance

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Recent Authoritative Accounting Guidance

Recent Authoritative Accounting Guidance

ASU 2016-02, “Leases (Topic 842).” In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” Under the new guidance, lessees will be required to recognize a lease liability and a right of use asset for all leases (with the exception of short-term leases) at the commencement date of the lease and disclose key information about leasing arrangements.  Accounting by lessors is largely unchanged. In July 2018, the FASB issued ASU 2018-11 to provide entities with an additional (and optional) transition method to adopt the new leases standard. Under this new transition method, an entity initially applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Additionally, in December 2018, the FASB issued ASU 2018-20, “Leases (Topic 842) - Narrow-Scope Improvements for Lessors,” which provides for certain policy elections and changes lessor accounting for sales and similar taxes and certain lessor costs. Upon adoption of ASU 2016-02, ASU 2018-11 and ASU 2018-20 on January 1, 2019, the Company recognized right-of-use assets and related lease liabilities totaling $54.6 million and $54.6 million, respectively, with an immaterial impact on its consolidated results of operations and liquidity. The Company elected to apply certain practical expedients provided under ASU 2016-02 whereby we did not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases and (iii) initial direct costs for any existing leases. The Company elected the hindsight practical expedient to determine the lease term for existing leases. We also did not apply the recognition requirements of ASU 2016-02 to any short-term leases (as defined by related accounting guidance). Lease and non-lease components are accounted for separately as the amounts are readily determinable under our lease contracts.

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendments in ASU 2016-13 require a financial asset or group of financial assets measured at amortized cost basis to be presented on a company’s financial statements at the net amount expected to be collected based on historical experience, current conditions and reasonable and supportable forecasts. ASU 2016-13 requires a company’s income statement to reflect the measurement of credit losses for newly recognized financial assets as well as the expected increases or decreases of expected credit losses that have taken place during the period. The amendments in ASU 2016-13 require that the allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination be measured at amortized cost basis with the initial allowance for credit losses added to the purchase price rather than being reported as a credit loss expense. ASU 2016-13 also requires that credit losses relating to available-for-sale debt securities be recorded through an allowance for credit losses. The amendments in ASU 2016-13 are effective for the Company for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The amendments will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period. A prospective transition approach is required for debt securities for which other-than-temporary impairment was recognized before the effective date. Amounts previously recognized in accumulated other comprehensive income as of the date of adoption that relate to improvement in cash flows expected to be collected will continue to be accreted into income over the remaining life of the asset. Recoveries of amounts previously written off relating to improvements in cash flows after the date of adoption will be recorded in earnings when received. We are currently evaluating the potential impact of ASU 2016-13 on our financial statements, which will be effective on January 1, 2020. We have formed a cross-functional working group comprised of individuals from various functional areas including credit, risk management, finance and information technology, among others. We are currently working through our implementation plan which includes assessment and documentation of processes, internal controls and data sources; model development and documentation; and system configuration, among other things. We are in the process of implementing a third-party vendor solution. The adoption of ASU 2016-13 could result in an increase in the allowance for loan losses as a result of changing from an “incurred loss” model, which encompasses allowances for current known and inherent losses within the portfolio, to an “expected loss” model, which encompasses allowances for losses expected to be incurred over the life of the portfolio. The adoption will also necessitate that we establish an allowance for expected credit losses for certain debt securities and other financial assets. While we are currently unable to reasonably estimate the impact of adopting ASU 2016-13, we expect that the impact of adoption will be significantly influenced by the composition, characteristics and quality of our loan and securities portfolios as well as the prevailing economic conditions and forecasts as of the adoption date.

ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” The amendments in ASU 2017-08 shorten the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The new guidance does not change the accounting for purchased callable debt securities held at a discount; the discount continues to be amortized to maturity. ASU No. 2017-08 is effective for interim and annual reporting periods beginning after December 15, 2018. As the Company amortized premiums on callable debt securities to the earliest call date, the amendments in ASU 2017-08 became effective for the Company on January 1, 2019, and did not have a significant impact on the Company’s consolidated financial statements, results of operations or liquidity.

ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12). The purpose of this updated guidance is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. In addition, this ASU makes certain targeted improvements to simplify the application of the hedge accounting, including to derivative instruments as well as allow a one-time election to reclassify fixed-rate, prepayable debt securities from a held-to-maturity classification to an available-for-sale classification. ASU 2017-12 is effective for public business entities for fiscal years beginning after December 15, 2018. Guidance related to existing cash flow hedges and, if elected, fair value hedges is to be applied under a modified retrospective approach and guidance related to amended presentation and disclosures is to be applied under a prospective approach. Upon adoption of ASU 2017-12 on January 1, 2019, the guidance did not have an impact on the Company's derivatives and, thus, no adjustments were made related to derivatives. In conjunction with the adoption of ASU 2017-12, the Company made the transition election to reclassify $281.1 million in book value of securities, that qualified, from held-to-maturity to available-for-sale.

ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement.” In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement: Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (ASU 2018-13). The amendments in this Update removes, modifies, and adds to the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in the Concepts Statement, including the consideration of costs and benefits. The amendments in this Update are effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. An entity is permitted to early adopt any removed or modified disclosures upon issuance of this Update and delay adoption of the additional disclosures until their effective date. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements disclosures.

ASU 2018-14, “Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans.” In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General: Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans (ASU 2018-14). The amendments in this Update remove disclosures that no longer are considered cost beneficial, clarify the specific requirements of disclosures, and add disclosure requirements identified as relevant. Although narrow in scope, the amendments are considered an important part of the Board’s efforts to improve the effectiveness of disclosures in the notes to financial statements by applying concepts in the Concepts Statement. The amendments in this Update are effective for fiscal years ending after December 15, 2020, for public business entities. Early adoption is permitted. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements disclosures.

ASU 2018-15, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other- Internal-Use Software (Subtopic 350-40). The amendments in this Update clarifies certain aspects of ASU 2015-05, “Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement,” which was issued in April 2015. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the Update. The amendments in this Update are effective for fiscal years beginning after December 15, 2019, for public business entities. Early adoption is permitted. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements disclosures.

ASU 2018-16, “Derivatives and Hedging (Topic 815) - Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes.” In October 2018, the FASB issued ASU 2018-16, Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes. The amendments in this Update permit use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes under Topic 815 in addition to the interest rates on direct U.S. Treasury obligations, the LIBOR swap rate, the OIS rate based on the Fed Funds Effective Rate and the Securities Industry and Financial Markets Association (SIFMA) Municipal Swap Rate. The amendments in ASU 2018-16 became effective for the Company in conjunction with the adoption of ASU 2017-12 on January 1, 2019, and did not have a significant impact on the Company’s consolidated financial statements, results of operations or liquidity.

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Subsequent Events

3 Months Ended

Mar. 31, 2019

Subsequent Events [Abstract]

Subsequent Events

Subsequent Events

Subsequent events have been evaluated for potential recognition and disclosure through the date financial statements were filed with the SEC. On May 3, 2019, the Company declared a quarterly dividend to common shareholders of $0.31 per share, to be paid on May 23, 2019 to shareholders of record as of May 13, 2019.

No other undisclosed events requiring recognition or disclosure were identified.

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Basis of Presentation Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Revenue Recognition, Policy [Policy Text Block]

Leases

We have leased branches and office space and have entered into various other agreements in conducting our business. At inception, we determine whether an agreement represents a lease and at commencement we evaluate each lease agreement to determine whether the lease is an operating or financing lease. Some of our lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses. As discussed in “Note 16 – Recent Authoritative Accounting Guidance” included in this report, we adopted ASU 2016-02, as of January 1, 2019.

Pursuant to ASU 2016-02, all of our long-term operating leases outstanding on December 31, 2018 continued to be classified as operating leases. Our capital lease outstanding at December 31, 2018 is classified as a financing lease. With the adoption of ASU 2016-02, we recorded an operating lease right-of-use asset, within the Premises and Equipment line item, and an operating lease liability, within the Other Liabilities line item, on our balance sheet. Right-of-use lease assets represent our right to use the underlying asset for the lease term and the lease obligation represents our commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit rate, we have used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as property taxes are expensed as incurred. Leases with an initial term of 12 months or less are not recorded on the balance sheet.

Prior to our adoption of ASU 2016-02, when our lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, we recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the statements of operations over the term of each lease. In cases where the lessor granted us leasehold improvement allowances that reduced our lease expense, we capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements.

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Acquisitions (Tables)

3 Months Ended

Mar. 31, 2019

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table summarizes the consideration paid, fair values of the Northwest assets acquired and liabilities assumed, and the resulting goodwill. The amounts reported for net deferred tax assets and goodwill are provisional pending completion of the Company's review of tax items.

	As Recorded			Fair Value				As Recorded
As of August 16, 2018	by Northwest			Adjustments				by the Company
Assets acquired:
Cash and cash equivalents	$	31.2		$	—			$	31.2
Investment securities	3.1			—				3.1
Loans held for investment	727.9			(14.8		)	(1)	713.1
Allowance for loan loss	(8.0		)	8.0			(2)	—
Premises and equipment	14.5			—				14.5
Other real estate owned (“OREO”)	0.3			0.3				0.6
Core deposit intangible assets	2.4			13.3			(3)	15.7
Other assets	29.3			(10.0		)	(4)	19.3
Total assets acquired	800.7			(3.2		)		797.5
Liabilities assumed:
Deposits	696.1			0.2			(5)	696.3
Accounts payable and accrued expense	8.1			(0.4		)	(6)	7.7
Long term debt	13.0			0.1				13.1
Trust preferred securities	5.2			(0.8		)	(7)	4.4
Deferred tax liability, net	(1.2		)	1.6			(8)	0.4
Total liabilities assumed	721.2			0.7				721.9
Net assets acquired	$	79.5		$	(3.9	)		$	75.6
Consideration paid:
Cash								$	3.0
Class A common stock								173.3
Total consideration paid								176.3
Goodwill								$	100.7

Explanation of fair value adjustments and the removal of previously recorded fair value marks recorded by Northwest. Note adjustments to the marks for deferred tax assets and premises and equipment were made since the prior quarter, none of which were material. The adjustments had no impact on 2018 earnings and a net decrease to goodwill of $0.4 million from the December 31, 2018 reported balances.
(1)	Write down of the book value of loans to their estimated fair values. The fair value of the loans was estimated using cash flow projections based on the remaining maturity and repricing terms, adjusted for estimated future credit losses and prepayments and discounted to present value using a risk-adjusted market rate for similar loans. The fair value of collateral dependent loans acquired with deteriorated credit quality was estimated based on the Company’s analysis of the fair value of each loan’s underlying collateral, discounted using market-derived rates of return with consideration given to the period of time and costs associated with foreclosure and disposition of the collateral.
(2)	Adjustment to remove the Northwest allowance for loan losses at acquisition date, as the credit risk is included in the fair value adjustment for loans receivable described in (1) above.
(3)	Adjustment represents the value of the core deposit base assumed in the acquisition based upon valuation from an independent accounting and advisory firm.
(4)	Adjustment consists of reductions to the fair value of other items, including the removal of Northwest previously recorded goodwill.
(5)	Increase in book value of time deposits to their estimated fair values based upon interest rates of similar time deposits with similar terms on the date of acquisition based upon valuation from an independent accounting and advisory firm.
(6)	Decrease due to the write-off of off balance sheet reserves.
(7)	Write down of the book value of debt to the estimated fair values on the date of acquisition based upon favorable interest rates in the market.
(8)	Adjustment consists of the write-off of pre-existing deferred tax assets and purchase accounting adjustments as a result of the acquisition.

Schedule of Acquired Loans with Credit Impairment

Contractually required principal and interest payments	$	27.5
Contractual cash flows not expected to be collected (“non-accretable discount”)	4.4
Cash flows expected to be collected	23.1
Interest component of cash flows expected to be collected (“accretable discount”)	3.2
Fair value of acquired credit-impaired loans	$	19.9

The following table displays the outstanding unpaid balances and accrual status of loans acquired with credit impairment as of the dates indicated:    

	March 31, 2019		December 31, 2018
Outstanding balance	$	40.9	$	43.4
Carrying value
Loans on accrual status	28.0		30.2
Total carrying value	$	28.0	$	30.2

The following table summarizes changes in the accretable yield for loans acquired deemed credit impaired for the three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	8.9		$	7.3
Accretion income	(0.7		)	(0.7		)
Reductions due to exit events	(0.3		)	(0.2		)
Reclassifications from non-accretable differences	0.5			0.8
Ending balance	$	8.4		$	7.2

Schedule of Acquired Loans not Deemed to Have Credit Impairment

Information regarding Northwest acquired loans not deemed credit-impaired at the August 16, 2018 acquisition date are as follows:

Contractually required principal and interest payments	$	894.8
Contractual cash flows not expected to be collected	26.1
Fair value at acquisition	$	693.2

Summary of Pre-tax Merger Related Expenses

The Company recorded $2.3 million and $2.3 million in pre-tax acquisition related expenses for the three months ended March 31, 2019 and 2018. These costs are incorporated in non-interest expenses in the Company’s consolidated statements of income.

	Three Months Ended March 31, 2019		Three Months Ended March 31, 2018
Legal and Professional Fees	$	0.3	$	0.5
Employee Expenses	0.6		0.1
Technology Conversion and Contract Termination	0.8		1.5
Other	0.6		0.2
Total Acquisition Related Expenses	$	2.3	$	2.3

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Goodwill and Intangibles (Tables)

3 Months Ended

Mar. 31, 2019

Goodwill [Line Items]

Schedule of Goodwill [Table Text Block]

	As of March 31,
	2019			2018
Net carrying value at beginning of three month period	$	546.7		$	444.7
Measurement period adjustment to previously recorded goodwill	(0.4		)	0.9
Net carrying value at end of period	$	546.3		$	445.6

Schedule of Finite-Lived Intangible Assets

	As of March 31,
	2019			2018
Gross CDI, beginning of period	$	89.7		$	74.0
Accumulated amortization	(35.1		)	(26.7		)
Net CDI, end of period	$	54.6		$	47.3

Schedule of Future Amortization Expense

The following table provides the estimated future CDI amortization expense:

Years Ending December 31,
2019 remaining	$	6.6
2020	8.1
2021	7.5
2022	6.9
2023	6.3
Thereafter	19.2
Total	$	54.6

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Investment Securities (Tables)

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Amortized Cost and Approximate Fair Values of Investment Securities

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

March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	4.0	$	—	$	—		$	4.0
State, county and municipal securities	77.7		0.8		(0.1		)	78.4
Obligations of U.S. government agencies	601.4		0.3		(4.0		)	597.7
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	1,735.9		9.4		(12.4		)	1,732.9
Private mortgage-backed securities	66.2		—		(0.9		)	65.3
Corporate securities	92.1		0.2		(0.3		)	92.0
Other investments	1.7		—		—			1.7
Total	$	2,579.0	$	10.7	$	(17.7	)	$	2,572.0

March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held-to-Maturity:
State, county and municipal securities	$	67.6	$	1.5	$	(0.2	)	$	68.9
Obligations of U.S. government agencies	19.8		—		(0.2		)	19.6
U.S agency residential mortgage-backed securities & collateralized mortgage obligations	1.3		—		—			1.3
Corporate securities	28.2		—		(0.1		)	28.1
Other investments	0.1		—		—			0.1
Total	$	117.0	$	1.5	$	(0.5	)	$	118.0

December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	2.6	$	—	$	—		$	2.6
Obligations of U.S. government agencies	569.3		0.1		(10.2		)	559.2
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	1,566.4		2.5		(24.1		)	1,544.8
Private mortgage-backed securities	72.0		—		(1.8		)	70.2
Corporate securities	92.9		—		(1.0		)	91.9
Other investments	2.0		—		—			2.0
Total	$	2,305.2	$	2.6	$	(37.1	)	$	2,270.7

December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Held-to-Maturity:
State, county and municipal securities	$	150.9	$	1.8	$	(0.9	)	$	151.8
Obligations of U.S. government agencies	19.8		—		(0.3		)	19.5
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	189.7		0.3		(6.5		)	183.5
Corporate securities	46.3		0.1		(0.6		)	45.8
Other investments	0.1		—		—			0.1
Total	$	406.8	$	2.2	$	(8.3	)	$	400.7

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 a continuous unrealized loss position, as of March 31, 2019 and December 31, 2018:

	Less than 12 Months					12 Months or More					Total
March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Available-for-Sale:
State, county and municipal securities	$	—	$	—		$	16.2	$	(0.1	)	$	16.2	$	(0.1	)
Obligations of U.S. government agencies	336.8		(2.8		)	129.7		(1.2		)	466.5		(4.0		)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	535.9		(6.9		)	450.3		(5.5		)	986.2		(12.4		)
Private mortgage-backed securities	—		—			64.5		(0.9		)	64.5		(0.9		)
Corporate securities	—		—			36.9		(0.3		)	36.9		(0.3		)
Total	$	872.7	$	(9.7	)	$	697.6	$	(8.0	)	$	1,570.3	$	(17.7	)

	Less than 12 Months					12 Months or More					Total
March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Held-to-Maturity:
State, county and municipal securities	$	9.0	$	(0.1	)	$	16.6	$	(0.1	)	$	25.6	$	(0.2	)
Obligations of U.S. government agencies	19.6		(0.2		)	—		—			19.6		(0.2		)
Corporate securities	—		—			28.0		(0.1		)	28.0		(0.1		)
Total	$	28.6	$	(0.3	)	$	44.6	$	(0.2	)	$	73.2	$	(0.5	)

	Less than 12 Months					12 Months or More					Total
December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Available-for-Sale:
Obligations of U.S. government agencies	$	363.1	$	(7.9	)	$	154.5	$	(2.3	)	$	517.6	$	(10.2	)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	735.2		(14.5		)	503.7		(9.6		)	1,238.9		(24.1		)
Private mortgage-backed securities	—		—			69.4		(1.8		)	69.4		(1.8		)
Corporate securities	24.9		(0.2		)	51.4		(0.8		)	76.3		(1.0		)
Total	$	1,123.2	$	(22.6	)	$	779.0	$	(14.5	)	$	1,902.2	$	(37.1	)

	Less than 12 Months					12 Months or More					Total
December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Held-to-Maturity:
State, county and municipal securities	$	25.9	$	(0.3	)	$	57.1	$	(0.6	)	$	83.0	$	(0.9	)
Obligations of U.S. government agencies	19.5		(0.3		)	—		—			19.5		(0.3		)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations	45.0		(2.2		)	120.2		(4.3		)	165.2		(6.5		)
Corporate securities	—		—			39.6		(0.6		)	39.6		(0.6		)
Total	$	90.4	$	(2.8	)	$	216.9	$	(5.5	)	$	307.3	$	(8.3	)

Maturities of Investment Securities

Maturities of investment securities at March 31, 2019 are shown below. 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
March 31, 2019	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	497.2	$	496.0	$	44.9	$	44.8
After one year but within five years	1,509.8		1,504.9		44.2		44.1
After five years but within ten years	395.3		395.5		24.3		25.5
After ten years	176.7		175.6		3.6		3.6
Total	$	2,579.0	$	2,572.0	$	117.0	$	118.0

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Loans (Tables)

3 Months Ended

Mar. 31, 2019

Receivables [Abstract]

Schedule of Loans by Class

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

	March 31, 2019		December 31, 2018
Real estate loans:
Commercial	$	3,255.8	$	3,235.4
Construction:
Land acquisition & development	292.7		321.6
Residential	233.1		242.8
Commercial	312.1		274.3
Total construction loans	837.9		838.7
Residential	1,529.5		1,542.0
Agricultural	210.4		217.4
Total real estate loans	5,833.6		5,833.5
Consumer:
Indirect consumer	775.7		787.8
Other consumer	194.1		200.6
Credit card	77.2		81.8
Total consumer loans	1,047.0		1,070.2
Commercial	1,342.1		1,310.3
Agricultural	234.7		254.8
Other, including overdrafts	1.8		1.6
Loans held for investment	8,459.2		8,470.4
Mortgage loans held for sale	34.0		33.3
Total loans	$	8,493.2	$	8,503.7

Schedule of Recorded Investment in Past Due Loans by Class

The following tables present the Company’s recorded investment and contractual aging of the Company’s recorded investment in loans by class as of the dates indicated. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due.

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of March 31, 2019	Past Due		Past Due		Past Due		Past Due		Loans		Loans		Loans
Real estate
Commercial	$	12.6	$	7.2	$	2.5	$	22.3	$	3,222.4	$	11.1	$	3,255.8
Construction:
Land acquisition & development	1.2		0.7		0.4		2.3		286.6		3.8		292.7
Residential	2.2		—		—		2.2		229.6		1.3		233.1
Commercial	—		—		—		—		311.9		0.2		312.1
Total construction loans	3.4		0.7		0.4		4.5		828.1		5.3		837.9
Residential	4.6		1.6		0.2		6.4		1,517.2		5.9		1,529.5
Agricultural	4.0		0.9		0.3		5.2		202.8		2.4		210.4
Total real estate loans	24.6		10.4		3.4		38.4		5,770.5		24.7		5,833.6
Consumer:
Indirect consumer	6.5		1.1		0.5		8.1		765.6		2.0		775.7
Other consumer	1.4		0.7		0.3		2.4		191.2		0.5		194.1
Credit card	0.6		0.5		0.7		1.8		75.4		—		77.2
Total consumer loans	8.5		2.3		1.5		12.3		1,032.2		2.5		1,047.0
Commercial	4.0		4.1		1.7		9.8		1,317.0		15.3		1,342.1
Agricultural	1.3		1.3		0.5		3.1		229.0		2.6		234.7
Other, including overdrafts	—		—		—		—		1.8		—		1.8
Loans held for investment	38.4		18.1		7.1		63.6		8,350.5		45.1		8,459.2
Mortgage loans originated for sale	—		—		—		—		34.0		—		34.0
Total loans	$	38.4	$	18.1	$	7.1	$	63.6	$	8,384.5	$	45.1	$	8,493.2

							Total Loans
	30 - 59		60 - 89		> 90		30 or More
	Days		Days		Days		Days		Current		Non-accrual		Total
As of December 31, 2018	Past Due		Past Due		Past Due		Past Due		Loans		Loans		Loans
Real estate
Commercial	$	10.4	$	1.0	$	0.8	$	12.2	$	3,214.0	$	9.2	$	3,235.4
Construction:
Land acquisition & development	1.6		0.1		0.2		1.9		316.0		3.7		321.6
Residential	1.0		0.4		—		1.4		240.4		1.0		242.8
Commercial	0.4		—		—		0.4		273.7		0.2		274.3
Total construction loans	3.0		0.5		0.2		3.7		830.1		4.9		838.7
Residential	8.8		1.1		0.2		10.1		1,525.3		6.6		1,542.0
Agricultural	2.2		—		—		2.2		202.6		12.6		217.4
Total real estate loans	24.4		2.6		1.2		28.2		5,772.0		33.3		5,833.5
Consumer:
Indirect consumer	6.8		2.1		0.4		9.3		776.8		1.7		787.8
Other consumer	1.4		0.5		0.1		2.0		198.1		0.5		200.6
Credit card	0.9		0.4		0.8		2.1		79.7		—		81.8
Total consumer loans	9.1		3.0		1.3		13.4		1,054.6		2.2		1,070.2
Commercial	8.3		1.2		1.3		10.8		1,283.7		15.8		1,310.3
Agricultural	2.1		0.3		—		2.4		249.4		3.0		254.8
Other, including overdrafts	—		—		—		—		1.6		—		1.6
Loans held for investment	43.9		7.1		3.8		54.8		8,361.3		54.3		8,470.4
Mortgage loans originated for sale	—		—		—		—		33.3		—		33.3
Total loans	$	43.9	$	7.1	$	3.8	$	54.8	$	8,394.6	$	54.3	$	8,503.7

Schedule of Acquired Loans with Credit Impairment

Contractually required principal and interest payments	$	27.5
Contractual cash flows not expected to be collected (“non-accretable discount”)	4.4
Cash flows expected to be collected	23.1
Interest component of cash flows expected to be collected (“accretable discount”)	3.2
Fair value of acquired credit-impaired loans	$	19.9

The following table displays the outstanding unpaid balances and accrual status of loans acquired with credit impairment as of the dates indicated:    

	March 31, 2019		December 31, 2018
Outstanding balance	$	40.9	$	43.4
Carrying value
Loans on accrual status	28.0		30.2
Total carrying value	$	28.0	$	30.2

The following table summarizes changes in the accretable yield for loans acquired deemed credit impaired for the three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	8.9		$	7.3
Accretion income	(0.7		)	(0.7		)
Reductions due to exit events	(0.3		)	(0.2		)
Reclassifications from non-accretable differences	0.5			0.8
Ending balance	$	8.4		$	7.2

Schedule of Recorded Investment in Impaired Loans

The following tables present information on the Company’s recorded investment in impaired loans as of the dates indicated:

As of March 31, 2019	Unpaid Total Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
Real estate:
Commercial	$	27.0	$	10.7	$	10.6	$	21.3	$	0.7
Construction:
Land acquisition & development	10.0		0.4		3.4		3.8		0.3
Residential	1.5		0.9		0.4		1.3		—
Commercial	0.6		0.1		—		0.1		—
Total construction loans	12.1		1.4		3.8		5.2		0.3
Residential	8.9		4.2		3.3		7.5		0.5
Agricultural	2.7		2.4		0.2		2.6		—
Total real estate loans	50.7		18.7		17.9		36.6		1.5
Commercial	24.3		5.8		14.0		19.8		5.1
Agricultural	5.0		1.6		3.2		4.8		0.5
Total	$	80.0	$	26.1	$	35.1	$	61.2	$	7.1

As of December 31, 2018	Unpaid Total Principal Balance		Recorded Investment With No Allowance		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance
Real estate:
Commercial	$	22.2	$	8.6	$	7.7	$	16.3	$	0.7
Construction:
Land acquisition & development	10.0		0.4		3.5		3.9		0.2
Residential	1.1		0.6		0.4		1.0		0.1
Commercial	0.7		0.2		—		0.2		—
Total construction loans	11.8		1.2		3.9		5.1		0.3
Residential	8.8		5.7		2.0		7.7		0.3
Agricultural	12.9		12.5		0.2		12.7		—
Total real estate loans	55.7		28.0		13.8		41.8		1.3
Commercial	24.1		5.5		14.4		19.9		5.2
Agricultural	3.2		2.5		0.6		3.1		0.3
Total	$	83.0	$	36.0	$	28.8	$	64.8	$	6.8

The following table presents the average recorded investment in and income recognized on impaired loans for the periods indicated:

	Three Months Ended March 31,
	2019				2018
	Average Recorded Investment		Income Recognized		Average Recorded Investment		Income Recognized
Real estate	$	39.3	$	—	$	56.1	$	—
Commercial	19.9		—		22.1		—
Agricultural	3.9		—		1.5		—
Total	$	63.1	$	—	$	79.7	$	—

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

The following tables present the Company’s recorded investment in criticized loans by class and credit quality indicator based on the most recent analysis performed as of the dates indicated:

As of March 31, 2019	Other Assets Especially Mentioned		Substandard		Doubtful		Total Criticized Loans
Real estate:
Commercial	$	100.4	$	90.9	$	2.8	$	194.1
Construction:
Land acquisition & development	5.1		2.2		3.4		10.7
Residential	0.9		2.2		0.9		4.0
Commercial	1.8		4.1		—		5.9
Total construction loans	7.8		8.5		4.3		20.6
Residential	2.6		8.9		1.9		13.4
Agricultural	15.7		18.0		0.1		33.8
Total real estate loans	126.5		126.3		9.1		261.9
Consumer:
Indirect consumer	0.3		2.7		0.1		3.1
Direct consumer	0.3		0.8		0.1		1.2
Total consumer loans	0.6		3.5		0.2		4.3
Commercial	42.3		46.5		11.3		100.1
Agricultural	16.8		18.3		1.1		36.2
Total	$	186.2	$	194.6	$	21.7	$	402.5

As of December 31, 2018	Other Assets Especially Mentioned		Substandard		Doubtful		Total Criticized Loans
Real estate:
Commercial	$	102.5	$	87.4	$	2.9	$	192.8
Construction:
Land acquisition & development	5.0		7.0		3.3		15.3
Residential	2.8		2.0		0.4		5.2
Commercial	1.7		3.9		—		5.6
Total construction loans	9.5		12.9		3.7		26.1
Residential	3.0		10.8		0.7		14.5
Agricultural	9.0		24.0		0.1		33.1
Total real estate loans	124.0		135.1		7.4		266.5
Consumer:
Indirect consumer	0.7		2.1		0.1		2.9
Direct consumer	0.3		0.8		0.1		1.2
Total consumer loans	1.0		2.9		0.2		4.1
Commercial	39.4		45.8		11.8		97.0
Agricultural	14.4		17.8		1.5		33.7
Total	$	178.8	$	201.6	$	20.9	$	401.3

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Allowance for Loan Losses (Tables)

3 Months Ended

Mar. 31, 2019

Receivables [Abstract]

Schedule of Allowance for Loan Losses by Portfolio Segment

The following tables present a summary of changes in the allowance for loan losses by portfolio segment for the periods indicated:

Three Months Ended March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Allowance for loan losses:
Beginning balance	$	31.0		$	8.7		$	31.3		$	2.0		$	—	$	73.0
Provision charged to operating expense	(1.7		)	2.0			3.6			(0.2		)	—		3.7
Less loans charged-off	(2.1		)	(3.0		)	(0.8		)	(0.1		)	—		(6.0		)
Add back recoveries of loans previously    charged-off	0.2			1.1			0.4			—			—		1.7
Ending balance	$	27.4		$	8.8		$	34.5		$	1.7		$	—	$	72.4
As of March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Allowance for loan losses:
Loans individually evaluated for impairment	$	1.5		$	—		$	5.1		$	0.5		$	—	$	7.1
Loans collectively evaluated for impairment	25.9			8.8			29.4			1.2			—		65.3
Allowance for loan losses	$	27.4		$	8.8		$	34.5		$	1.7		$	—	$	72.4
As of March 31, 2019	Real Estate			Consumer			Commercial			Agriculture			Other		Total
Loans held for investment:
Individually evaluated for impairment	$	36.6		$	—		$	19.8		$	4.8		$	—	$	61.2
Collectively evaluated for impairment	5,797.0			1,047.0			1,322.3			229.9			1.8		8,398.0
Total loans held for investment	$	5,833.6		$	1,047.0		$	1,342.1		$	234.7		$	1.8	$	8,459.2

Three Months Ended March 31, 2018	Real Estate			Consumer			Commercial			Agriculture		Other		Total
Allowance for loan losses:
Beginning balance	$	31.7		$	8.7		$	30.5		$	1.2	$	—	$	72.1
Provision charged to operating expense	1.8			0.7			(0.7		)	0.3		—		2.1
Less loans charged-off	(0.8		)	(2.7		)	(1.7		)	—		—		(5.2		)
Add back recoveries of loans previously    charged-off	1.2			1.1			2.0			0.2		—		4.5
Ending balance	$	33.9		$	7.8		$	30.1		$	1.7	$	—	$	73.5

As of December 31, 2018	Real Estate		Consumer		Commercial		Agriculture		Other		Total
Allowance for loan losses:
Loans individually evaluated for impairment	$	1.3	$	—	$	5.2	$	0.3	$	—	$	6.8
Loans collectively evaluated for impairment	29.7		8.7		26.1		1.7		—		66.2
Allowance for loan losses	$	31.0	$	8.7	$	31.3	$	2.0	$	—	$	73.0
As of December 31, 2018	Real Estate		Consumer		Commercial		Agriculture		Other		Total
Loans held for investment:
Individually evaluated for impairment	$	41.8	$	—	$	19.9	$	3.1	$	—	$	64.8
Collectively evaluated for impairment	5,791.7		1,070.2		1,290.4		251.7		1.6		8,405.6
Total loans held for investment	$	5,833.5	$	1,070.2	$	1,310.3	$	254.8	$	1.6	$	8,470.4

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Other Real Estate Owned (Tables)

3 Months Ended

Mar. 31, 2019

Repossessed Assets [Abstract]

Other Real Estate Owned Roll Forward

Information with respect to the Company’s other real estate owned follows:

	Three Months Ended March 31,
	2019			2018
Beginning balance	$	14.4		$	10.1
Additions	8.4			1.2
Valuation adjustments	(0.3		)	—
Dispositions	(1.4		)	(0.3		)
Ending balance	$	21.1		$	11.0

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Derivatives and Hedging Activities (Tables)

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts and Estimated Fair Values of Derivatives

The notional amounts and estimated fair values of the Company’s derivatives are presented in the following table. Fair value estimates are obtained from third parties and are based on pricing models.

	March 31, 2019				December 31, 2018
	Notional Amount		Estimated Fair Value		Notional Amount		Estimated Fair Value
Derivative Assets (included in other assets on the consolidated balance sheets):
Non-hedging interest rate derivatives:
Interest rate swap contracts	$	449.2	$	12.7	$	403.3	$	8.8
Interest rate lock commitments	76.9		1.9		51.0		1.3
Total derivative assets	$	526.1	$	14.6	$	454.3	$	10.1
Derivative Liabilities (included in accounts payable and accrued expenses on the consolidated balance sheets):
Non-hedging interest rate derivatives:
Interest rate swap contracts	$	449.2	$	12.7	$	403.3	$	8.8
Forward loan sales contracts	90.4		0.8		64.6		0.6
Total derivative liabilities	$	539.6	$	13.5	$	467.9	$	9.4

Offsetting Assets and Liabilities

The following table illustrates the potential effect of the Company’s master netting arrangements, by type of financial instrument, on the Company’s consolidated balance sheets as of March 31, 2019 and December 31, 2018:

	March 31, 2019
	Gross Amounts Recognized		Gross Amounts Offset in the Balance Sheet		Net Amounts in the Balance Sheet		Financial Instruments		Fair Value of Financial Collateral in the Balance Sheet		Net Amount
Financial Assets
Interest rate swap contracts	$	12.7	$	—	$	12.7	$	2.0	$	7.5	$	3.2
Mortgage related derivatives	1.9		—		1.9		—		—		1.9
Total derivatives	14.6		—		14.6		2.0		7.5		5.1
Total assets	$	14.6	$	—	$	14.6	$	2.0	$	7.5	$	5.1
Financial Liabilities
Interest rate swap contracts	$	12.7	$	—	$	12.7	$	2.0	$	0.2	$	10.5
Mortgage related derivatives	0.8		—		0.8		—		—		0.8
Total derivatives	13.5		—		13.5		2.0		0.2		11.3
Repurchase agreements	672.6		—		672.6		—		672.6		—
Total liabilities	$	686.1	$	—	$	686.1	$	2.0	$	672.8	$	11.3

	December 31, 2018
	Gross Amounts Recognized		Gross Amounts Offset in the Balance Sheet		Net Amounts in the Balance Sheet		Financial Instruments		Fair Value of Financial Collateral in the Balance Sheet		Net Amount
Financial Assets
Interest rate swap contracts	$	8.8	$	—	$	8.8	$	2.7	$	2.4	$	3.7
Mortgage related derivatives	1.3		—		1.3		—		—		1.3
Total derivatives	10.1		—		10.1		2.7		2.4		5.0
Total assets	$	10.1	$	—	$	10.1	$	2.7	$	2.4	$	5.0
Financial Liabilities
Interest rate swap contracts	$	8.8	$	—	$	8.8	$	2.7	$	4.1	$	2.0
Mortgage related derivatives	0.6		—		0.6		—		—		0.6
Total derivatives	9.4		—		9.4		2.7		4.1		2.6
Repurchase agreements	712.4		—		712.4		—		712.4		—
Total liabilities	$	721.8	$	—	$	721.8	$	2.7	$	716.5	$	2.6

Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss)

The following table presents the pre-tax gains or losses related to derivative contracts that were recorded in other non-interest income in the Company’s statements of income for the periods indicated:

	Three Months Ended March 31,
	2019		2018
Non-hedging interest rate derivatives:
Amount of gain recognized in other non-interest income	$	—	$	0.3
Amount of net fee income recognized in other non-interest income	0.8		0.5
Amount of net gains recognized in mortgage banking revenues	0.4		(0.1		)

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Earnings per Common Share (Tables)

3 Months Ended

Mar. 31, 2019

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 three month periods ended March 31, 2019 and 2018:

	Three Months Ended March 31,
	2019		2018
Net income	$	41.6	$	36.7
Weighted average common shares outstanding for basic earnings per share computation	60,311,171		56,241,201
Dilutive effects of stock-based compensation	286,899		410,977
Weighted average common shares outstanding for diluted earnings per common share computation	60,598,070		56,652,178
Basic earnings per common share	$	0.69	$	0.65
Diluted earnings per common share	$	0.69	$	0.65
Anti-dilutive unvested time restricted stock	121,452		139,943

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Regulatory Capital (Tables)

3 Months Ended

Mar. 31, 2019

Banking and Thrift [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 March 31, 2019 and December 31, 2018 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)
March 31, 2019	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,310.3	13.23	%	$	792.4	8.000	%	$	1,040.0	10.50	%	$	990.5	10.00	%
FIB	1,201.4		12.16		790.2		8.000		1,037.1		10.50		987.8		10.00
Tier 1 risk-based capital:
Consolidated	1,237.9		12.50		594.3		6.000		841.9		8.50		792.4		8.00
FIB	1,129.0		11.43		592.7		6.000		839.6		8.50		790.2		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,153.7		11.65		445.7		4.500		693.4		7.00		643.8		6.50
FIB	1,129.0		11.43		444.5		4.500		691.4		7.00		642.0		6.50
Leverage capital ratio:
Consolidated	1,237.9		9.76		507.5		4.000		507.5		4.00		634.4		5.00
FIB	1,129.0		8.92		506.3		4.000		506.3		4.00		632.8		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, 2018	Amount		Ratio		Amount		Ratio		Amount		Ratio		Amount		Ratio
Total risk-based capital:
Consolidated	$	1,285.0	12.99	%	$	791.2	8.00	%	$	976.6	9.875	%	$	989.0	10.00	%
FIB	1,184.5		12.01		788.8		8.00		973.7		9.875		986.0		10.00
Tier 1 risk-based capital:
Consolidated	1,212.0		12.26		593.4		6.00		778.8		7.875		791.2		8.00
FIB	1,111.6		11.27		591.6		6.00		776.5		7.875		788.8		8.00
Common equity tier 1 risk-based capital:
Consolidated	1,127.8		11.40		445.0		4.50		630.5		6.375		642.8		6.50
FIB	1,111.6		11.27		443.7		4.50		628.6		6.375		640.9		6.50
Leverage capital ratio:
Consolidated	1,212.0		9.47		511.9		4.00		511.9		4.000		639.9		5.00
FIB	1,111.6		8.97		495.9		4.00		495.9		4.000		619.8		5.00

(1) The ratios for 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 entity and has presented the ratios as if they also applied on a consolidated basis.

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Other Comprehensive Income/Loss (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Schedule of Comprehensive Income (Loss)

The gross amounts of each component of other comprehensive income and the related tax effects are as follows:

	Pre-tax						Tax Expense (Benefit)						Net of Tax
Three Months Ended March 31,	2019			2018			2019			2018			2019			2018
Investment securities available-for sale:
Change in net unrealized gains during period	$	33.6		$	(23.7	)	$	8.8		$	(6.2	)	$	24.8		$	(17.5	)
Reclassification adjustment for securities transferred from held-to-maturity to available-for-sale	(6.0		)	—			(1.6		)	—			(4.4		)	—
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity	—			0.5			—			0.2			—			0.3
Defined benefits post-retirement benefit plan:
Change in net actuarial (gain) loss	(0.2		)	(0.1		)	—			(0.1		)	(0.2		)	—
Total other comprehensive income (loss)	$	27.4		$	(23.3	)	$	7.2		$	(6.1	)	$	20.2		$	(17.2	)

Schedule of Accumulated Other Comprehensive Income (Loss)

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

	March 31, 2019			December 31, 2018
Net unrealized gain (loss) on investment securities available-for-sale	$	(5.1	)	$	(25.5	)
Net actuarial gain (loss) on defined benefit post-retirement benefit plans	0.7			0.9
Net accumulated other comprehensive gain (loss)	$	(4.4	)	$	(24.6	)

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Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis

Financial assets and liabilities measured at fair value on a recurring basis are as follows:

			Fair Value Measurements at Reporting Date Using
As of March 31, 2019	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	$	4.0	$	—	$	4.0	$	—
State, county and municipal securities	78.4			—	78.4			—
Obligations of U.S. government agencies	597.7			—	597.7			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	1,732.9			—	1,732.9			—
Private mortgage-backed securities	65.3			—	65.3			—
Corporate securities	92.0			—	92.0			—
Other investments	1.7			—	1.7			—
Loans held for sale	34.0			—	34.0			—
Derivative assets:
Interest rate swap contracts	12.7			—	12.7			—
Interest rate lock commitments	1.9			—	1.9			—
Derivative liabilities:
Interest rate swap contracts	12.7			—	12.7			—
Forward loan sale contracts	0.8			—	0.8			—
Deferred compensation plan assets	12.4			—	12.4			—
Deferred compensation plan liabilities	$	12.4	$	—	$	12.4	$	—

			Fair Value Measurements at Reporting Date Using
As of December 31, 2018	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	$	2.6	$	—	$	2.6	$	—
Obligations of U.S. government agencies	559.2			—	559.2			—
U.S. agencies mortgage-backed securities & collateralized mortgage obligations	1,544.8			—	1,544.8			—
Private mortgage-backed securities	70.2			—	70.2			—
Corporate securities	91.9			—	91.9			—
Other investments	2.0			—	2.0			—
Loans held for sale	33.3			—	33.3			—
Derivative assets:
Interest rate swap contracts	8.8			—	8.8			—
Interest rate lock commitments	1.3			—	1.3			—
Derivative liabilities
Interest rate swap contracts	8.8			—	8.8			—
Forward loan sales contracts	0.6			—	0.6			—
Deferred compensation plan assets	12.1			—	12.1			—
Deferred compensation plan liabilities	$	12.1	$	—	$	12.1	$	—

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 March 31, 2019	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Impaired loans	$	30.9	$	—	$	—	$	30.9
Other real estate owned	2.0			—		—	2.0
Long-lived assets to be disposed of by sale	$	5.5	$	—	$	—	$	5.5
				Fair Value Measurements at Reporting Date Using
As of December 31, 2018	Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Impaired loans	$	24.1	$	—	$	—	$	24.1
Other real estate owned	0.6			—		—	0.6
Long-lived assets to be disposed of by sale	$	4.9	$	—	$	—	$	4.9

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
	March 31, 2019		December 31, 2018		Valuation Technique	Unobservable Inputs	Range (Weighted Average)
Impaired loans	$	30.9	$	24.1	Appraisal	Appraisal adjustment	0%	-	26%	(13%)
Other real estate owned	2.0		0.6		Appraisal	Appraisal adjustment	8%	-	96%	(39%)
Long-lived assets to be disposed of by sale	$	5.5	$	4.9	Appraisal	Appraisal adjustment	0%	-	43%	(10%)

Fair Value, by Balance Sheet Grouping

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

					Fair Value Measurements at Reporting Date Using
As of March 31, 2019	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	$	955.2	$	955.2	$	955.2	$	—	$	—
Investment debt securities available-for-sale	2,572.0		2,572.0		—		2,572.0		—
Investment debt securities held-to-maturity	117.0		118.0		—		118.0		—
Accrued interest receivable	46.5		46.5		—		46.5		—
Mortgage servicing rights, net	27.9		40.5		—		40.5		—
Loans held for sale	34.0		34.0		—		34.0		—
Net loans held for investment	8,386.8		8,408.6		—		8,377.7		30.9
Derivative assets	14.6		14.6		—		14.6		—
Deferred compensation plan assets	12.4		12.4		—		12.4		—
Total financial assets	$	12,166.4	$	12,201.8	$	955.2	$	11,215.7	$	30.9
Financial liabilities:
Total deposits, excluding time deposits	$	9,408.3	$	9,408.3	$	9,408.3	$	—	$	—
Time deposits	1,406.4		1,393.2		—		1,393.2		—
Securities sold under repurchase agreements	672.6		672.6		—		672.6		—
Accrued interest payable	10.0		10.0		—		10.0		—
Long-term debt	15.8		13.9		—		13.9		—
Subordinated debentures held by subsidiary trusts	86.9		85.1		—		85.1		—
Derivative liabilities	13.5		13.5		—		13.5		—
Deferred compensation plan liabilities	12.4		12.4		—		12.4		—
Total financial liabilities	$	11,625.9	$	11,609.0	$	9,408.3	$	2,200.7	$	—

					Fair Value Measurements at Reporting Date Using
As of December 31, 2018	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	$	822.0	$	822.0	$	822.0	$	—	$	—
Investment debt securities available-for-sale	2,270.7		2,270.7		—		2,270.7		—
Investment debt securities held-to-maturity	406.8		400.7		—		400.7		—
Accrued interest receivable	44.9		44.9		—		44.9		—
Mortgage servicing rights, net	27.7		42.4		—		42.4		—
Loans held for sale	33.3		33.3		—		33.3		—
Net loans held for investment	8,397.4		8,439.7		—		8,415.6		24.1
Derivative assets	10.1		10.1		—		10.1		—
Deferred compensation plan assets	12.1		12.1		—		12.1		—
Total financial assets	$	12,025.0	$	12,075.9	$	822.0	$	11,229.8	$	24.1
Financial liabilities:
Total deposits, excluding time deposits	$	9,363.7	$	9,363.7	$	9,363.7	$	—	$	—
Time deposits	1,317.0		1,299.0		—		1,299.0		—
Securities sold under repurchase agreements	712.4		712.4		—		712.4		—
Accrued interest payable	7.8		7.8		—		7.8		—
Long-term debt	15.8		13.0		—		13.0		—
Subordinated debentures held by subsidiary trusts	86.9		84.9		—		84.9		—
Derivative liabilities	9.4		9.4		—		9.4		—
Deferred compensation plan liabilities	12.1		12.1		—		12.1		—
Total financial liabilities	$	11,525.1	$	11,502.3	$	9,363.7	$	2,138.6	$	—

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Acquisitions - Business Combination (Narrative) (Details) $ / shares in Units, $ in Millions			3 Months Ended		12 Months Ended
	Apr. 08, 2019 USD ($) $ / shares shares	Aug. 16, 2018 USD ($) $ / shares shares	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill			$ 546.3	$ 445.6	$ 546.7	$ 444.7
Acquisition related expenses			2.3	2.3	$ 2.3
Net income			$ 41.6	$ 36.7
Core Deposits
Business Acquisition [Line Items]
Estimated useful lives of related deposits			10 years
Northwest Bank Acquisition, as Recorded by the Company [Member]
Business Acquisition [Line Items]
Core deposit intangible assets		$ 15.7
Cash paid by First Interstate in connection with merger		$ 3.0
Inland Northwest Bank
Business Acquisition [Line Items]
Number of banking offices acquired		20
Total consideration exchanged in connection with the merger		$ 176.3
Goodwill		$ 100.7
Number of Operating Segments | segment					1
Inland Northwest Bank | Class A Common Stock
Business Acquisition [Line Items]
Business acquisition conversion share rate | shares		0.516
Number of shares issued in connection with Cascade merger | shares		3,840,000
Price per share of First Interstate Class A common stock (in dollars per share) | $ / shares		$ 45.15
Inland Northwest Bank | Core Deposits
Business Acquisition [Line Items]
Estimated useful lives of related deposits		10 years
Subsequent Event | Idaho Independent Bank [Member]
Business Acquisition [Line Items]
Number of banking offices acquired	11
Cash paid by First Interstate in connection with merger	$ 157.3
Subsequent Event | Idaho Independent Bank [Member] | Class A Common Stock
Business Acquisition [Line Items]
Business acquisition conversion share rate | shares	0.5
Number of shares issued in connection with Cascade merger | shares	3,871,000
Price per share of First Interstate Class A common stock (in dollars per share) | $ / shares	$ 40.64
Subsequent Event | Community 1st Bank [Member]
Business Acquisition [Line Items]
Number of banking offices acquired	3
Cash paid by First Interstate in connection with merger	$ 18.8
Subsequent Event | Community 1st Bank [Member] | Class A Common Stock
Business Acquisition [Line Items]
Business acquisition conversion share rate | shares	0.3784
Number of shares issued in connection with Cascade merger | shares	463,000
Price per share of First Interstate Class A common stock (in dollars per share) | $ / shares	$ 40.64

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Acquisitions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions			3 Months Ended		12 Months Ended
		Aug. 16, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs			$ 2.3	$ 2.3	$ 2.3
Goodwill			546.3	445.6	$ 546.7	$ 444.7
Net increase to goodwill			(0.4)	$ 0.9
Northwest Bank Acquisition, As Recorded By Inland Northwest Bank [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		$ 31.2
Investment securities		3.1
Loans held for investment		727.9
Allowance for loan loss		(8.0)
Premises and equipment		14.5
Other real estate owned (“OREO”)		0.3
Core deposit intangible assets		2.4
Other assets		29.3
Total assets acquired		800.7
Deposits		696.1
Accounts Payable and Accrued Expense		8.1
Long term debt		13.0
Trust preferred securities		5.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Deferred Tax Liability		(1.2)
Total liabilities assumed		721.2
Net assets acquired		79.5
Northwest Bank Acquisition, Fair Value Adjustments [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		0.0
Investment securities		0.0
Loans held for investment	[1]	(14.8)
Allowance for loan loss	[2]	8.0
Premises and equipment		0.0
Other real estate owned (“OREO”)		0.3
Core deposit intangible assets	[3]	13.3
Other assets	[4]	(10.0)
Total assets acquired		(3.2)
Deposits	[5]	0.2
Accounts Payable and Accrued Expense	[6]	(0.4)
Long term debt		0.1
Trust preferred securities		(0.8)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Deferred Tax Liability	[7]	1.6
Total liabilities assumed		0.7
Net assets acquired		(3.9)
Northwest Bank Acquisition, as Recorded by the Company [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		31.2
Investment securities		3.1
Loans held for investment		713.1
Allowance for loan loss		0.0
Premises and equipment		14.5
Other real estate owned (“OREO”)		0.6
Core deposit intangible assets		15.7
Other assets		19.3
Total assets acquired		797.5
Deposits		696.3
Accounts Payable and Accrued Expense		7.7
Long term debt		13.1
Trust preferred securities		4.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Deferred Tax Liability		0.4
Total liabilities assumed		721.9
Net assets acquired		75.6
Cash		3.0
Class A common stock		173.3
Inland Northwest Bank
Business Acquisition [Line Items]
Total consideration paid		176.3
Goodwill		$ 100.7
Cascade Bank Acquisition, as Recorded by the Company [Member]
Business Acquisition [Line Items]
Net increase to goodwill			$ 0.9

[1] (1) Write down of the book value of loans to their estimated fair values. The fair value of the loans was estimated using cash flow projections based on the remaining maturity and repricing terms, adjusted for estimated future credit losses and prepayments and discounted to present value using a risk-adjusted market rate for similar loans. The fair value of collateral dependent loans acquired with deteriorated credit quality was estimated based on the Company’s analysis of the fair value of each loan’s underlying collateral, discounted using market-derived rates of return with consideration given to the period of time and costs associated with foreclosure and disposition of the collateral.

[2] (2) Adjustment to remove the Northwest allowance for loan losses at acquisition date, as the credit risk is included in the fair value adjustment for loans receivable described in (1) above.

[3] (3) Write down of the book value of premises and equipment to their estimated fair values on the date of acquisition based upon broker’s opinion of value.

[4] (4) Adjustment represents the value of the core deposit base assumed in the acquisition based upon valuation from an independent accounting and advisory firm.

[5] (6) Adjustment consists of reductions to the fair value of other items, including the removal of Northwest previously recorded goodwill.

[6] (7) Increase in book value of time deposits to their estimated fair values based upon interest rates of similar time deposits with similar terms on the date of acquisition based upon valuation from an independent accounting and advisory firm.

[7] (9) Write down of the book value of debt to the estimated fair values on the date of acquisition based upon favorable interest rates in the market.

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Acquisitions - Schedule of Acquired loans with credit impairment (Details) - Inland Northwest Bank $ in Millions	Aug. 16, 2018 USD ($)
Business Acquisition [Line Items]
Contractually required principal and interest payments	$ 27.5
Contractual cash flows not expected to be collected (“non-accretable discount”)	4.4
Cash flows expected to be collected	23.1
Interest component of cash flows expected to be collected (“accretable discount”)	3.2
Fair value of acquired credit-impaired loans	$ 19.9

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Acquisitions - Schedule of Acquired Loans not Deemed to Have Credit Impairment (Details) - Inland Northwest Bank $ in Millions	Aug. 16, 2018 USD ($)
Business Acquisition [Line Items]
Contractually required principal and interest payments	$ 894.8
Contractual cash flows not expected to be collected	26.1
Fair value at acquisition	$ 693.2

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Acquisitions - Summary of Pre-tax Merger Related Costs (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs, Legal Fees	$ 0.3	$ 0.5
Business Combination, Acquisition Related Costs, Employee Expense	0.6	0.1
Business Combination, Acquisition Related Costs, Technology and Contract Termination	0.8	1.5
Business Combination, Acquisition Related Costs, Other Expenses	0.6	0.2
Acquisition related expenses	$ 2.3	$ 2.3	$ 2.3

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Goodwill and Intangibles - Narrative (Details) $ in Millions		3 Months Ended		12 Months Ended
	Aug. 16, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Goodwill [Line Items]
Goodwill		$ 546.3	$ 445.6	$ 546.7	$ 444.7
Measurement period adjustment to previously recorded goodwill		$ (0.4)	$ 0.9
Inland Northwest Bank
Goodwill [Line Items]
Goodwill	$ 100.7
Number of Operating Segments | segment				1
Core Deposits
Goodwill [Line Items]
Weighted average useful lives of related deposits		10 years
Core Deposits | Inland Northwest Bank
Goodwill [Line Items]
Weighted average useful lives of related deposits	10 years

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Goodwill and Intangibles - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Gross CDI, beginning of period	$ 89.7	$ 74.0
Accumulated amortization	(35.1)	(26.7)
Net CDI, end of period	54.6	47.3
Goodwill [Roll Forward]
Net carrying value at beginning of three month period	546.7	444.7
Net increase to goodwill	(0.4)	0.9
Net carrying value at end of period	$ 546.3	$ 445.6

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Goodwill and Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Total	$ 54.6	$ 47.3
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2019 remaining	6.6
2018	8.1
2019	7.5
2020	6.9
2021	6.3
Thereafter	19.2
Total	$ 54.6

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Investment Securities - Amortized Cost and Approximate Fair Values of Investment Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Schedule of Available for Sale and Held-to-Maturity Securities [Line Items]
Debt Securities, Held-to-maturity, Transfer, Amount	$ 281,100
Debt Securities, Held-to-maturity, transfer, Fair value amount	275,000
Available-for-Sale:
Amortized Cost	2,579,000	$ 2,305,200
Gross Unrealized Gains	10,700	2,600
Gross Unrealized Losses	(17,700)	(37,100)
Estimated Fair Value	2,572,000	2,270,700
Held-to-Maturity:
Amortized Cost	117,000	406,800
Gross Unrealized Gains	1,500	2,200
Gross Unrealized Losses	(500)	(8,300)
Estimated Fair Value	118,000	400,700
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)	6,000
U.S. Treasury notes
Available-for-Sale:
Amortized Cost	4,000	2,600
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	4,000	2,600
Obligations of U.S. government agencies
Available-for-Sale:
Amortized Cost	601,400	569,300
Gross Unrealized Gains	300	100
Gross Unrealized Losses	(4,000)	(10,200)
Estimated Fair Value	597,700	559,200
Held-to-Maturity:
Amortized Cost	19,800	19,800
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(200)	(300)
Estimated Fair Value	19,600	19,500
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations
Available-for-Sale:
Amortized Cost	1,735,900	1,566,400
Gross Unrealized Gains	9,400	2,500
Gross Unrealized Losses	(12,400)	(24,100)
Estimated Fair Value	1,732,900	1,544,800
Held-to-Maturity:
Amortized Cost	1,300	189,700
Gross Unrealized Gains	0	300
Gross Unrealized Losses	0	(6,500)
Estimated Fair Value	1,300	183,500
Private mortgage-backed securities
Available-for-Sale:
Amortized Cost	66,200	72,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(900)	(1,800)
Estimated Fair Value	65,300	70,200
State, county and municipal securities
Available-for-Sale:
Amortized Cost	77,700
Gross Unrealized Gains	800
Gross Unrealized Losses	(100)
Estimated Fair Value	78,400
Held-to-Maturity:
Amortized Cost	67,600	150,900
Gross Unrealized Gains	1,500	1,800
Gross Unrealized Losses	(200)	(900)
Estimated Fair Value	68,900	151,800
Corporate securities
Available-for-Sale:
Amortized Cost	92,100	92,900
Gross Unrealized Gains	200	0
Gross Unrealized Losses	(300)	(1,000)
Estimated Fair Value	92,000	91,900
Held-to-Maturity:
Amortized Cost	28,200	46,300
Gross Unrealized Gains	0	100
Gross Unrealized Losses	(100)	(600)
Estimated Fair Value	28,100	45,800
Other investments
Available-for-Sale:
Amortized Cost	1,700	2,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	1,700	2,000
Other Investments
Held-to-Maturity:
Amortized Cost	100	100
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 100	$ 100

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Investment Securities - Gross Unrealized Losses and Fair Values of Investment Securities (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) Investments	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) Investments	Dec. 31, 2017 USD ($)
Available-for-Sale:
Available-for-Sale, Less than 12 Months, Fair Value	$ 872,700,000			$ 1,123,200,000
Available-for-sale, Less than 12 Months, Gross Unrealized Losses	(9,700,000)			(22,600,000)
Available-for-Sale, 12 Months or More, Fair Value	697,600,000			779,000,000
Available-for-Sale, 12 Months or More, Gross Unrealized Losses	(8,000,000)			(14,500,000)
Available-for-Sale, Total Fair Value	1,570,300,000			1,902,200,000
Available-for-Sale, Total Gross Unrealized Losses	$ (17,700,000)			(37,100,000)
Held-to-Maturity:
Held-to-Maturity, Less than 12 Months, Fair Value			$ 28,600,000	90,400,000
Held-to-Maturity, Less Than 12 Months, Gross Unrealized Losses			(300,000)	(2,800,000)
Held-to-Maturity, 12 Months or More, Fair Value			44,600,000	216,900,000
Held-to-Maturity, 12 Months or More, Gross Unrealized Losses			(200,000)	(5,500,000)
Held-to-Maturity, Total Fair Value			73,200,000	307,300,000
Held-to-Maturity, Total Gross Unrealized Losses			$ (500,000)	(8,300,000)
Investment securities in an unrealized loss position (securities) | Investments	551		760
Impairment loss	$ 0	$ 0
Available-for-sale Securities, Gross Realized Gain (Loss)	0	$ 0
Obligations of U.S. government agencies
Available-for-Sale:
Available-for-Sale, Less than 12 Months, Fair Value	336,800,000			363,100,000
Available-for-sale, Less than 12 Months, Gross Unrealized Losses	(2,800,000)			(7,900,000)
Available-for-Sale, 12 Months or More, Fair Value	129,700,000			154,500,000
Available-for-Sale, 12 Months or More, Gross Unrealized Losses	(1,200,000)			(2,300,000)
Available-for-Sale, Total Fair Value	466,500,000			517,600,000
Available-for-Sale, Total Gross Unrealized Losses	(4,000,000)			(10,200,000)
Held-to-Maturity:
Held-to-Maturity, Less than 12 Months, Fair Value			$ 0	19,500,000
Held-to-Maturity, Less Than 12 Months, Gross Unrealized Losses			0	(300,000)
Held-to-Maturity, 12 Months or More, Fair Value			28,000,000	0
Held-to-Maturity, 12 Months or More, Gross Unrealized Losses			(100,000)	0
Held-to-Maturity, Total Fair Value			28,000,000	19,500,000
Held-to-Maturity, Total Gross Unrealized Losses			(100,000)	(300,000)
U.S. agency residential mortgage-backed securities & collateralized mortgage obligations
Available-for-Sale:
Available-for-Sale, Less than 12 Months, Fair Value	535,900,000			735,200,000
Available-for-sale, Less than 12 Months, Gross Unrealized Losses	(6,900,000)			(14,500,000)
Available-for-Sale, 12 Months or More, Fair Value	450,300,000			503,700,000
Available-for-Sale, 12 Months or More, Gross Unrealized Losses	(5,500,000)			(9,600,000)
Available-for-Sale, Total Fair Value	986,200,000			1,238,900,000
Available-for-Sale, Total Gross Unrealized Losses	(12,400,000)			(24,100,000)
Held-to-Maturity:
Held-to-Maturity, Less than 12 Months, Fair Value				45,000,000
Held-to-Maturity, Less Than 12 Months, Gross Unrealized Losses				(2,200,000)
Held-to-Maturity, 12 Months or More, Fair Value				120,200,000
Held-to-Maturity, 12 Months or More, Gross Unrealized Losses				(4,300,000)
Held-to-Maturity, Total Fair Value				165,200,000
Held-to-Maturity, Total Gross Unrealized Losses				(6,500,000)
Private mortgage-backed securities
Available-for-Sale:
Available-for-Sale, Less than 12 Months, Fair Value	0			0
Available-for-sale, Less than 12 Months, Gross Unrealized Losses	0			0
Available-for-Sale, 12 Months or More, Fair Value	64,500,000			69,400,000
Available-for-Sale, 12 Months or More, Gross Unrealized Losses	(900,000)			(1,800,000)
Available-for-Sale, Total Fair Value	64,500,000			69,400,000
Available-for-Sale, Total Gross Unrealized Losses	(900,000)			(1,800,000)
State, county and municipal securities
Available-for-Sale:
Available-for-Sale, Less than 12 Months, Fair Value	0
Available-for-sale, Less than 12 Months, Gross Unrealized Losses	0
Available-for-Sale, 12 Months or More, Fair Value	16,200,000
Available-for-Sale, 12 Months or More, Gross Unrealized Losses	(100,000)
Available-for-Sale, Total Fair Value	16,200,000
Available-for-Sale, Total Gross Unrealized Losses	(100,000)
Held-to-Maturity:
Held-to-Maturity, Less than 12 Months, Fair Value			9,000,000	25,900,000
Held-to-Maturity, Less Than 12 Months, Gross Unrealized Losses			(100,000)	(300,000)
Held-to-Maturity, 12 Months or More, Fair Value			16,600,000	57,100,000
Held-to-Maturity, 12 Months or More, Gross Unrealized Losses			(100,000)	(600,000)
Held-to-Maturity, Total Fair Value			25,600,000	83,000,000
Held-to-Maturity, Total Gross Unrealized Losses			(200,000)	(900,000)
Corporate securities
Available-for-Sale:
Available-for-Sale, Less than 12 Months, Fair Value	0			24,900,000
Available-for-sale, Less than 12 Months, Gross Unrealized Losses	0			(200,000)
Available-for-Sale, 12 Months or More, Fair Value	36,900,000			51,400,000
Available-for-Sale, 12 Months or More, Gross Unrealized Losses	(300,000)			(800,000)
Available-for-Sale, Total Fair Value	36,900,000			76,300,000
Available-for-Sale, Total Gross Unrealized Losses	$ (300,000)			(1,000,000)
Held-to-Maturity:
Held-to-Maturity, Less than 12 Months, Fair Value			19,600,000	0
Held-to-Maturity, Less Than 12 Months, Gross Unrealized Losses			(200,000)	0
Held-to-Maturity, 12 Months or More, Fair Value			0	39,600,000
Held-to-Maturity, 12 Months or More, Gross Unrealized Losses			0	(600,000)
Held-to-Maturity, Total Fair Value			19,600,000	39,600,000
Held-to-Maturity, Total Gross Unrealized Losses			$ (200,000)	$ (600,000)

XML

Investment Securities - Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity
Available-for-Sale Amortized Cost, Within One Year	$ 497,200
Available-for-Sale Amortized Cost, After One Year but Within Five Years	1,509,800
Available-for-Sale Amortized Cost, After Five Years but Within Ten Years	395,300
Available-for-Sale Amortized Cost, After Ten Years	176,700
Amortized Cost	2,579,000	$ 2,305,200
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity
Available-for-Sale Estimated Fair Value, Within One Year	496,000
Available-for-Sale Estimated Fair Value, After One Year but Within Five Years	1,504,900
Available-for-Sale Estimated Fair Value, After Five Years but Within Ten Years	395,500
Available-for-Sale Estimated Fair Value, After Ten Years	175,600
Available-for-Sale, Estimated Fair Value	2,572,000	2,270,700
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount
Held-to-Maturity Amortized Cost, Within One Year	44,900
Held-to-Maturity Amortized Cost, After One Year but Within Five Years	44,200
Held-to-Maturity Amortized Cost, After Five Years but Within Ten Years	24,300
Held-to-Maturity Amortized Cost, After Ten Years	3,600
Amortized Cost	117,000	406,800
Held-to-maturity Securities, Debt Maturities, Fair Value, Rolling Maturity
Held-to-Maturity Estimated Fair Value, Within One Year	44,800
Held-to-Maturity Estimated Fair Value, After One Year but Within Five Years	44,100
Held-to-Maturity Estimated Fair Value, After Five Years but Within Ten Years	25,500
Held-to-Maturity Estimated Fair Value, After Ten Years	3,600
Held-to-Maturity, Estimated Fair Value	118,000	$ 400,700
Callable Within One Year
Available-for-sale Securities and Held-to-maturity Securities
Amortized cost of investment securities callable after one year but within five years	121,300
Fair value of investment securities callable after one year but within five years	121,500
Investment Securities,Callable Structured, Amortized Cost Basis	2,000
Investment Securities,Callable Structured, Fair Value	$ 2,000

XML

Loans - Schedule of Recorded Investment in Past Due Loans by Class (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans	$ 8,459.2	$ 8,470.4
Mortgage loans held for sale	34.0	33.3
Total loans	8,493.2	8,503.7
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	22.3	12.2
Current Loans	3,222.4	3,214.0
Non-accrual Loans	11.1	9.2
Total Loans	3,255.8	3,235.4
Land acquisition & development
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	2.3	1.9
Current Loans	286.6	316.0
Non-accrual Loans	3.8	3.7
Total Loans	292.7	321.6
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	2.2	1.4
Current Loans	229.6	240.4
Non-accrual Loans	1.3	1.0
Total Loans	233.1	242.8
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.4
Current Loans	311.9	273.7
Non-accrual Loans	0.2	0.2
Total Loans	312.1	274.3
Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	4.5	3.7
Current Loans	828.1	830.1
Non-accrual Loans	5.3	4.9
Total Loans	837.9	838.7
Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	6.4	10.1
Current Loans	1,517.2	1,525.3
Non-accrual Loans	5.9	6.6
Total Loans	1,529.5	1,542.0
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	5.2	2.2
Current Loans	202.8	202.6
Non-accrual Loans	2.4	12.6
Total Loans	210.4	217.4
Total real estate loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	38.4	28.2
Current Loans	5,770.5	5,772.0
Non-accrual Loans	24.7	33.3
Total Loans	5,833.6	5,833.5
Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	8.1	9.3
Current Loans	765.6	776.8
Non-accrual Loans	2.0	1.7
Total Loans	775.7	787.8
Direct consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	2.4	2.0
Current Loans	191.2	198.1
Non-accrual Loans	0.5	0.5
Total Loans	194.1	200.6
Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.8	2.1
Current Loans	75.4	79.7
Non-accrual Loans	0.0	0.0
Total Loans	77.2	81.8
Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	12.3	13.4
Current Loans	1,032.2	1,054.6
Non-accrual Loans	2.5	2.2
Total Loans	1,047.0	1,070.2
Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	9.8	10.8
Current Loans	1,317.0	1,283.7
Non-accrual Loans	15.3	15.8
Total Loans	1,342.1	1,310.3
Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	3.1	2.4
Current Loans	229.0	249.4
Non-accrual Loans	2.6	3.0
Total Loans	234.7	254.8
Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
Current Loans	1.8	1.6
Non-accrual Loans	0.0	0.0
Total Loans	1.8	1.6
Loans held for investment
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	63.6	54.8
Current Loans	8,350.5	8,361.3
Non-accrual Loans	45.1	54.3
Total Loans	8,459.2	8,470.4
Mortgage loans originated for sale
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
Current Loans	34.0	33.3
Non-accrual Loans	0.0	0.0
Mortgage loans held for sale	34.0
Total loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	63.6	54.8
Current Loans	8,384.5	8,394.6
Non-accrual Loans	45.1	54.3
Total loans	8,493.2	8,503.7
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	12.6	10.4
30 to 59 Days Past Due | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.2	1.6
30 to 59 Days Past Due | Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	2.2	1.0
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.4
30 to 59 Days Past Due | Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	3.4	3.0
30 to 59 Days Past Due | Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	4.6	8.8
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	4.0	2.2
30 to 59 Days Past Due | Total real estate loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	24.6	24.4
30 to 59 Days Past Due | Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	6.5	6.8
30 to 59 Days Past Due | Direct consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.4	1.4
30 to 59 Days Past Due | Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.6	0.9
30 to 59 Days Past Due | Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	8.5	9.1
30 to 59 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	4.0	8.3
30 to 59 Days Past Due | Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.3	2.1
30 to 59 Days Past Due | Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
30 to 59 Days Past Due | Loans held for investment
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	38.4	43.9
30 to 59 Days Past Due | Mortgage loans originated for sale
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
30 to 59 Days Past Due | Total loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	38.4	43.9
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	7.2	1.0
60 to 89 Days Past Due | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.7	0.1
60 to 89 Days Past Due | Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.4
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
60 to 89 Days Past Due | Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.7	0.5
60 to 89 Days Past Due | Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.6	1.1
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.9	0.0
60 to 89 Days Past Due | Total real estate loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	10.4	2.6
60 to 89 Days Past Due | Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.1	2.1
60 to 89 Days Past Due | Direct consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.7	0.5
60 to 89 Days Past Due | Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.5	0.4
60 to 89 Days Past Due | Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	2.3	3.0
60 to 89 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	4.1	1.2
60 to 89 Days Past Due | Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.3	0.3
60 to 89 Days Past Due | Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
60 to 89 Days Past Due | Loans held for investment
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	18.1	7.1
60 to 89 Days Past Due | Mortgage loans originated for sale
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
60 to 89 Days Past Due | Total loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	18.1	7.1
Equal to Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	2.5	0.8
Equal to Greater than 90 Days Past Due | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.4	0.2
Equal to Greater than 90 Days Past Due | Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
Equal to Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
Equal to Greater than 90 Days Past Due | Total construction loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.4	0.2
Equal to Greater than 90 Days Past Due | Residential
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.2	0.2
Equal to Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.3	0.0
Equal to Greater than 90 Days Past Due | Total real estate loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	3.4	1.2
Equal to Greater than 90 Days Past Due | Indirect consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.5	0.4
Equal to Greater than 90 Days Past Due | Direct consumer
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.3	0.1
Equal to Greater than 90 Days Past Due | Credit card
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.7	0.8
Equal to Greater than 90 Days Past Due | Total consumer loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.5	1.3
Equal to Greater than 90 Days Past Due | Commercial
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	1.7	1.3
Equal to Greater than 90 Days Past Due | Agricultural
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.5	0.0
Equal to Greater than 90 Days Past Due | Other, including overdrafts
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
Equal to Greater than 90 Days Past Due | Loans held for investment
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	7.1	3.8
Equal to Greater than 90 Days Past Due | Mortgage loans originated for sale
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	0.0	0.0
Equal to Greater than 90 Days Past Due | Total loans
Loans and Leases Receivable Recorded Investment, Past Due [Line Items]
Total Loans 30 or More Days Past Due	$ 7.1	$ 3.8

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Loans - Schedule of Outstanding Unpaid Balances and Accrual Status of Loans Acquired with Credit Impairment (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities [Abstract]
Outstanding balance	$ 40.9	$ 43.4
Total carrying value	28.0	30.2
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Value, Accrual Status	$ 28.0	$ 30.2

XML

Loans - Schedule of Changes in the Accretable Yield for Loans Acquired (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Beginning Balance	$ 8.9	$ 7.3
Accretion income	(0.7)	(0.7)
Reductions due to exit events	(0.3)	(0.2)
Reclassifications from non-accretable differences	0.5	0.8
Ending Balance	$ 8.4	$ 7.2

XML

Loans - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Receivables [Abstract]
Loans and Leases Receivable, Impaired, Troubled Debt, Interest Income	$ 600,000	$ 800,000
Loans renegotiated in troubled debt restructurings	22,700,000		$ 23,400,000
Charge-offs directly related to modifying troubled debt restructurings	0	$ 0
Balance of defaulted loans under trouble debt restructurings	$ 0

XML

Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	$ 80.0		$ 83.0
Recorded Investment With No Allowance	26.1		36.0
Recorded Investment With Allowance	35.1		28.8
Total Recorded Investment	61.2		64.8
Related Allowance	7.1		6.8
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	63.1	$ 79.7
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	0.0	0.0
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	27.0		22.2
Recorded Investment With No Allowance	10.7		8.6
Recorded Investment With Allowance	10.6		7.7
Total Recorded Investment	21.3		16.3
Related Allowance	0.7		0.7
Land acquisition & development
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	10.0		10.0
Recorded Investment With No Allowance	0.4		0.4
Recorded Investment With Allowance	3.4		3.5
Total Recorded Investment	3.8		3.9
Related Allowance	0.3		0.2
Residential
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	1.5		1.1
Recorded Investment With No Allowance	0.9		0.6
Recorded Investment With Allowance	0.4		0.4
Total Recorded Investment	1.3		1.0
Related Allowance	0.0		0.1
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	0.6		0.7
Recorded Investment With No Allowance	0.1		0.2
Recorded Investment With Allowance	0.0		0.0
Total Recorded Investment	0.1		0.2
Related Allowance	0.0		0.0
Total construction loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	12.1		11.8
Recorded Investment With No Allowance	1.4		1.2
Recorded Investment With Allowance	3.8		3.9
Total Recorded Investment	5.2		5.1
Related Allowance	0.3		0.3
Residential
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	8.9		8.8
Recorded Investment With No Allowance	4.2		5.7
Recorded Investment With Allowance	3.3		2.0
Total Recorded Investment	7.5		7.7
Related Allowance	0.5		0.3
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	2.7		12.9
Recorded Investment With No Allowance	2.4		12.5
Recorded Investment With Allowance	0.2		0.2
Total Recorded Investment	2.6		12.7
Related Allowance	0.0		0.0
Total real estate loans
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	50.7		55.7
Recorded Investment With No Allowance	18.7		28.0
Recorded Investment With Allowance	17.9		13.8
Total Recorded Investment	36.6		41.8
Related Allowance	1.5		1.3
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	39.3	56.1
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	0.0	0.0
Commercial
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	24.3		24.1
Recorded Investment With No Allowance	5.8		5.5
Recorded Investment With Allowance	14.0		14.4
Total Recorded Investment	19.8		19.9
Related Allowance	5.1		5.2
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	19.9	22.1
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	0.0	0.0
Agricultural
Impaired Financing Receivable, Unpaid Principal Balance
Unpaid Total Principal Balance	5.0		3.2
Recorded Investment With No Allowance	1.6		2.5
Recorded Investment With Allowance	3.2		0.6
Total Recorded Investment	4.8		3.1
Related Allowance	0.5		$ 0.3
Impaired Financing Receivable, Average Recorded Investment and Cash Basis Method Interest Income
Average Recorded Investment	3.9	1.5
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Income Recognized	$ 0.0	$ 0.0

XML

Loans - Schedule of Loans Renegotiated in Troubled Debt Restructurings (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0
Loans renegotiated in troubled debt restructurings	22,700,000		$ 23,400,000
Financing Receivable, Modifications, Recorded Investment, Non Accrual	16,900,000		17,800,000
Loans renegotiated in troubled debt restructurings, accrual loans	5,800,000		$ 5,600,000
Charge-offs directly related to modifying troubled debt restructurings	0	$ 0
Balance of defaulted loans under trouble debt restructurings	0
Commitments to lend additional funds	$ 0

XML

Loans - Schedule of Recorded Investment in Criticized Loans by Class and Credit Quality Indicator (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	$ 8,459.2	$ 8,470.4
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	3,255.8	3,235.4
Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	292.7	321.6
Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	233.1	242.8
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	312.1	274.3
Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	837.9	838.7
Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1,529.5	1,542.0
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	210.4	217.4
Total real estate loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	5,833.6	5,833.5
Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	775.7	787.8
Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	194.1	200.6
Credit card
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	77.2	81.8
Total consumer loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1,047.0	1,070.2
Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1,342.1	1,310.3
Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	234.7	254.8
Other Assets Especially Mentioned
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	186.2	178.8
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	100.4	102.5
Other Assets Especially Mentioned | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	5.1	5.0
Other Assets Especially Mentioned | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.9	2.8
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1.8	1.7
Other Assets Especially Mentioned | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	7.8	9.5
Other Assets Especially Mentioned | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	2.6	3.0
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	15.7	9.0
Other Assets Especially Mentioned | Total real estate loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	126.5	124.0
Other Assets Especially Mentioned | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.3	0.7
Other Assets Especially Mentioned | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.3	0.3
Other Assets Especially Mentioned | Total consumer loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.6	1.0
Other Assets Especially Mentioned | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	42.3	39.4
Other Assets Especially Mentioned | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	16.8	14.4
Substandard
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	194.6	201.6
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	90.9	87.4
Substandard | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	2.2	7.0
Substandard | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	2.2	2.0
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	4.1	3.9
Substandard | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	8.5	12.9
Substandard | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	8.9	10.8
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	18.0	24.0
Substandard | Total real estate loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	126.3	135.1
Substandard | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	2.7	2.1
Substandard | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.8	0.8
Substandard | Total consumer loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	3.5	2.9
Substandard | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	46.5	45.8
Substandard | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	18.3	17.8
Doubtful
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	21.7	20.9
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	2.8	2.9
Doubtful | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	3.4	3.3
Doubtful | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.9	0.4
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.0	0.0
Doubtful | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	4.3	3.7
Doubtful | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1.9	0.7
Doubtful | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.1	0.1
Doubtful | Total real estate loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	9.1	7.4
Doubtful | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.1	0.1
Doubtful | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.1	0.1
Doubtful | Total consumer loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	0.2	0.2
Doubtful | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	11.3	11.8
Doubtful | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1.1	1.5
Total Criticized Loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	402.5	401.3
Total Criticized Loans | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	194.1	192.8
Total Criticized Loans | Land acquisition & development
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	10.7	15.3
Total Criticized Loans | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	4.0	5.2
Total Criticized Loans | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	5.9	5.6
Total Criticized Loans | Total construction loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	20.6	26.1
Total Criticized Loans | Residential
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	13.4	14.5
Total Criticized Loans | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	33.8	33.1
Total Criticized Loans | Total real estate loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	261.9	266.5
Total Criticized Loans | Indirect consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	3.1	2.9
Total Criticized Loans | Direct consumer
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	1.2	1.2
Total Criticized Loans | Total consumer loans
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	4.3	4.1
Total Criticized Loans | Commercial
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	100.1	97.0
Total Criticized Loans | Agricultural
Loans and Leases Receivable Recorded Investment, Criticized Loans [Line Items]
Loans held for investment	$ 36.2	$ 33.7

XML

Loans Schedule of Loans by Class (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	$ 8,459.2	$ 8,470.4
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	34.0	33.3
Loans and Leases Receivable, Gross	8,493.2	8,503.7
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	3,255.8	3,235.4
Land acquisition & development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	292.7	321.6
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	233.1	242.8
Commercial Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	312.1	274.3
Total construction loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	837.9	838.7
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	1,529.5	1,542.0
Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	210.4	217.4
Total real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	5,833.6	5,833.5
Indirect consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	775.7	787.8
Direct consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	194.1	200.6
Credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	77.2	81.8
Total consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	1,047.0	1,070.2
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	1,342.1	1,310.3
Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	234.7	254.8
Other, including overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	1.8	1.6
Loans held for investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Held For Investment	8,459.2	8,470.4
Mortgage loans originated for sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	34.0
Total loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 8,493.2	$ 8,503.7

XML

Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses			$ 0.9	$ 0.8
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 73.0	$ 72.1
Provision for loan losses	3.7	2.1
Less loans charged-off	(6.0)	5.2
Add back recoveries of loans previously charged-off	1.7	4.5
Ending balance	72.4	73.5
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment			7.1	6.8
Loans collectively evaluated for impairment			65.3	66.2
Allowance for loan losses	73.0	72.1	72.4	73.0
Loans held for investment:
Individually evaluated for impairment			61.2	64.8
Individually evaluated for impairment			8,398.0	8,405.6
Total loans			8,459.2	8,470.4
Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	31.0	31.7
Provision for loan losses	(1.7)	1.8
Less loans charged-off	(2.1)	0.8
Add back recoveries of loans previously charged-off	0.2	1.2
Ending balance	27.4	33.9
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for loan losses	31.0	31.7	27.4	31.0
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	8.7	8.7
Provision for loan losses	2.0	0.7
Less loans charged-off	(3.0)	2.7
Add back recoveries of loans previously charged-off	1.1	1.1
Ending balance	8.8	7.8
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for loan losses	8.7	8.7	8.8	8.7
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	31.3	30.5
Provision for loan losses	3.6	(0.7)
Less loans charged-off	(0.8)	1.7
Add back recoveries of loans previously charged-off	0.4	2.0
Ending balance	34.5	30.1
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for loan losses	31.3	30.5	34.5	31.3
Agriculture
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2.0	1.2
Provision for loan losses	(0.2)	0.3
Less loans charged-off	(0.1)	0.0
Add back recoveries of loans previously charged-off	0.0	0.2
Ending balance	1.7	1.7
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for loan losses	2.0	1.2	1.7	2.0
Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0.0	0.0
Provision for loan losses	0.0	0.0
Less loans charged-off	0.0	0.0
Add back recoveries of loans previously charged-off	0.0	0.0
Ending balance	0.0	0.0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for loan losses	0.0	$ 0.0	0.0	0.0
Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0.0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment				0.0
Loans collectively evaluated for impairment				0.0
Allowance for loan losses	0.0			0.0
Loans held for investment:
Individually evaluated for impairment				0.0
Individually evaluated for impairment				1.6
Total loans				1.6
Other | Other
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance	0.0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment			0.0
Loans collectively evaluated for impairment			0.0
Allowance for loan losses	0.0		0.0
Loans held for investment:
Individually evaluated for impairment			0.0
Individually evaluated for impairment			1.8
Total loans			1.8
Agriculture
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2.0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment				0.3
Loans collectively evaluated for impairment				1.7
Allowance for loan losses	2.0			2.0
Loans held for investment:
Individually evaluated for impairment				3.1
Individually evaluated for impairment				251.7
Total loans				254.8
Agriculture | Agriculture
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance	1.7
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment			0.5
Loans collectively evaluated for impairment			1.2
Allowance for loan losses	1.7		1.7
Loans held for investment:
Individually evaluated for impairment			4.8
Individually evaluated for impairment			229.9
Total loans			234.7
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	31.3
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment				5.2
Loans collectively evaluated for impairment				26.1
Allowance for loan losses	31.3			31.3
Loans held for investment:
Individually evaluated for impairment				19.9
Individually evaluated for impairment				1,290.4
Total loans				1,310.3
Commercial | Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance	34.5
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment			5.1
Loans collectively evaluated for impairment			29.4
Allowance for loan losses	34.5		34.5
Loans held for investment:
Individually evaluated for impairment			19.8
Individually evaluated for impairment			1,322.3
Total loans			1,342.1
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	8.7
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment				0.0
Loans collectively evaluated for impairment				8.7
Allowance for loan losses	8.7			8.7
Loans held for investment:
Individually evaluated for impairment				0.0
Individually evaluated for impairment				1,070.2
Total loans				1,070.2
Consumer | Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance	8.8
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment			0.0
Loans collectively evaluated for impairment			8.8
Allowance for loan losses	8.8		8.8
Loans held for investment:
Individually evaluated for impairment			0.0
Individually evaluated for impairment			1,047.0
Total loans			1,047.0
Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	31.0
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment				1.3
Loans collectively evaluated for impairment				29.7
Allowance for loan losses	31.0			31.0
Loans held for investment:
Individually evaluated for impairment				41.8
Individually evaluated for impairment				5,791.7
Total loans				$ 5,833.5
Real Estate | Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Ending balance	27.4
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Loans individually evaluated for impairment			1.5
Loans collectively evaluated for impairment			25.9
Allowance for loan losses	$ 27.4		27.4
Loans held for investment:
Individually evaluated for impairment			36.6
Individually evaluated for impairment			5,797.0
Total loans			$ 5,833.6

XML

Other Real Estate Owned (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Loans and Leases Receivable, Troubled Debt Restructuring [Line Items]
Foreclosed Residential Real Estate included in Other Real Estate Owned	$ 1.7		$ 2.0
Real Estate Acquired Through Foreclosure [Roll Forward]
Beginning balance	14.4	$ 10.1
Additions	8.4	1.2
Valuation adjustments	0.3	0.0
Dispositions	1.4	0.3
Ending balance	21.1	$ 11.0
Consumer mortgage loans collateralized by residential real estate property in the process of foreclosure	$ 0.5		$ 0.4

XML

Derivatives and Hedging Activities - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Asset, Notional Amount	$ 526.1	$ 454.3
Derivative Asset, Estimated Fair Value	14.6	10.1
Notional amount of terminated commitment	539.6	467.9
Derivative Liabilities, Estimated Fair Value	13.5	9.4
Not Designated as Hedging Instrument | Interest rate swap contracts
Derivative [Line Items]
Derivative Asset, Notional Amount	449.2	403.3
Derivative Asset, Estimated Fair Value	12.7	8.8
Notional amount of terminated commitment	449.2	403.3
Derivative Liabilities, Estimated Fair Value	12.7	8.8
Not Designated as Hedging Instrument | Interest rate lock commitments
Derivative [Line Items]
Derivative Asset, Notional Amount	76.9	51.0
Derivative Asset, Estimated Fair Value	1.9	1.3
Not Designated as Hedging Instrument | Forward loan sales contracts
Derivative [Line Items]
Notional amount of terminated commitment	90.4	64.6
Derivative Liabilities, Estimated Fair Value	$ 0.8	$ 0.6

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Derivatives and Hedging Activities - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Financial Assets
Gross Amounts Recognized	$ 14.6	$ 10.1
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Derivative assets:	14.6	10.1
Financial Instruments	2.0	2.7
Fair Value of Financial Collateral in the Balance Sheet	7.5	2.4
Net Amount	5.1	5.0
Financial Liabilities
Gross Amounts Recognized	13.5	9.4
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Derivative liabilities:	13.5	9.4
Financial Instruments	2.0	2.7
Fair Value of Financial Collateral in the Balance Sheet	0.2	4.1
Net Amount	11.3	2.6
Repurchase agreements
Gross Amounts Recognized	672.6	712.4
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Net Amounts in the Balance Sheet	672.6	712.4
Financial Instruments	0.0	0.0
Fair Value of Financial Collateral in the Balance Sheet	672.6	712.4
Net Amount	0.0	0.0
Offsetting Derivative Liability, Securities Sold under Agreements to Repurchase, Securities Loaned
Gross Amounts Recognized	686.1	721.8
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Net Amounts in the Balance Sheet	686.1	721.8
Financial Instruments	2.0	2.7
Fair Value of Financial Collateral in the Balance Sheet	672.8	716.5
Net Amount	11.3	2.6
Interest Rate Swap
Financial Assets
Gross Amounts Recognized	12.7	8.8
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Derivative assets:	12.7	8.8
Financial Instruments	2.0	2.7
Fair Value of Financial Collateral in the Balance Sheet	7.5	2.4
Net Amount	3.2	3.7
Financial Liabilities
Gross Amounts Recognized	12.7	8.8
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Derivative liabilities:	12.7	8.8
Financial Instruments	2.0	2.7
Fair Value of Financial Collateral in the Balance Sheet	0.2	4.1
Net Amount	10.5	2.0
Mortgage Related Derivatives
Financial Assets
Gross Amounts Recognized	1.9	1.3
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Derivative assets:	1.9	1.3
Financial Instruments	0.0	0.0
Fair Value of Financial Collateral in the Balance Sheet	0.0	0.0
Net Amount	1.9	1.3
Financial Liabilities
Gross Amounts Recognized	0.8	0.6
Gross Amounts Offset in the Balance Sheet	0.0	0.0
Derivative liabilities:	0.8	0.6
Financial Instruments	0.0	0.0
Fair Value of Financial Collateral in the Balance Sheet	0.0	0.0
Net Amount	$ 0.8	$ 0.6

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Derivatives and Hedging Activities - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative [Line Items]
Amount of gain recognized in other non-interest income	$ 0.0	$ 0.3
Amount of net fee income recognized in other non-interest income	0.8	0.5
Amount of net gains recognized in mortgage banking revenues	$ 0.4	$ (0.1)

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Capital Stock (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class A Common Stock
Class of Stock [Line Items]
Common Stock, Shares, Outstanding	38,461,948		38,169,575
Stock repurchased and retired (in shares)	0	0
Class B Common Stock
Class of Stock [Line Items]
Common Stock, Shares, Outstanding	22,374,171		22,453,672

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Earnings per Common Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Earnings Per Share, Basic and Diluted [Line Items]
Net income	$ 41.6	$ 36.7
Weighted average common shares outstanding for basic earnings per share computation	60,311,171	56,241,201
Dilutive effects of stock-based compensation	286,899	410,977
Weighted average common shares outstanding for diluted earnings per common share computation	60,598,070	56,652,178
Basic earnings per common share (in dollars per share)	$ 0.69	$ 0.65
Diluted earnings per common share (in dollars per share)	$ 0.69	$ 0.65
Restricted Stock [Member]
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock	121,452	139,943
Restricted stock
Earnings Per Share, Basic and Diluted [Line Items]
Anti-dilutive unvested time restricted stock	154,387	164,019
Class A Common Stock
Earnings Per Share, Basic and Diluted [Line Items]
Common Stock, Shares, Outstanding	38,461,948		38,169,575
Class B Common Stock
Earnings Per Share, Basic and Diluted [Line Items]
Common Stock, Shares, Outstanding	22,374,171		22,453,672

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Regulatory Capital - Schedule of Actual Capital Amounts and Ratios and Selected Minimum Regulatory Thresholds (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Total risk-based capital:
Actual Amount	$ 1,310.3	$ 1,285.0
Actual Ratio	13.23%	12.99%
Capital Required for Capital Adequacy under Basel III Fully Phased-in	$ 1,040.0	$ 976.6
Capital Required for Capital Adequacy under Basel III Fully Phased-in to Risk Weighted Assets	10.50%	9.875%
Well Capitalized Amount	$ 990.5	$ 989.0
Well Capitalized Ratio	10.00%	10.00%
Tier 1 risk-based capital:
Actual Amount	$ 1,237.9	$ 1,212.0
Actual Ratio	12.50%	12.26%
Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in	$ 841.9	$ 778.8
Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in to Risk Weighted Assets	8.50%	7.875%
Well Capitalized Amount	$ 792.4	$ 791.2
Well Capitalized Ratio	8.00%	8.00%
Common equity tier one risk-based capital:
Actual Amount	$ 1,153.7	$ 1,127.8
Actual Ratio	11.65%	11.40%
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Phase-in Schedule	$ 445.7	$ 445.0
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Phase-in Schedule to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in	$ 693.4	$ 630.5
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in to Risk Weighted Assets	7.00%	6.375%
Well Capitalized Amount	$ 643.8	$ 642.8
Well Capitalized Ratio	6.50%	6.50%
Leverage capital ratio:
Actual Amount	$ 1,237.9	$ 1,212.0
Actual Ratio	9.76%	9.47%
Adequately Capitalized Amount	$ 507.5	$ 511.9
Adequately Capitalized Ratio	4.00%	4.00%
Well Capitalized Amount	$ 634.4	$ 639.9
Well Capitalized Ratio	5.00%	5.00%
Capital Required for Capital Adequacy	$ 792.4	$ 791.2
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital Required for Capital Adequacy	$ 594.3	$ 593.4
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
FIB
Total risk-based capital:
Actual Amount	$ 1,201.4	$ 1,184.5
Actual Ratio	12.16%	12.01%
Capital Required for Capital Adequacy under Basel III Fully Phased-in	$ 1,037.1	$ 973.7
Capital Required for Capital Adequacy under Basel III Fully Phased-in to Risk Weighted Assets	10.50%	9.875%
Well Capitalized Amount	$ 987.8	$ 986.0
Well Capitalized Ratio	10.00%	10.00%
Tier 1 risk-based capital:
Actual Amount	$ 1,129.0	$ 1,111.6
Actual Ratio	11.43%	11.27%
Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in	$ 839.6	$ 776.5
Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in to Risk Weighted Assets	8.50%	7.875%
Well Capitalized Amount	$ 790.2	$ 788.8
Well Capitalized Ratio	8.00%	8.00%
Common equity tier one risk-based capital:
Actual Amount	$ 1,129.0	$ 1,111.6
Actual Ratio	11.43%	11.27%
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Phase-in Schedule	$ 444.5	$ 443.7
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Phase-in Schedule to Risk Weighted Assets	4.50%	4.50%
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in	$ 691.4	$ 628.6
Common Equity Tier One Capital Required for Capital Adequacy under Basel III Fully Phased-in to Risk Weighted Assets	7.00%	6.375%
Well Capitalized Amount	$ 642.0	$ 640.9
Well Capitalized Ratio	6.50%	6.50%
Leverage capital ratio:
Actual Amount	$ 1,129.0	$ 1,111.6
Actual Ratio	8.92%	8.97%
Adequately Capitalized Amount	$ 506.3	$ 495.9
Adequately Capitalized Ratio	4.00%	4.00%
Well Capitalized Amount	$ 632.8	$ 619.8
Well Capitalized Ratio	5.00%	5.00%
Capital Required for Capital Adequacy	$ 790.2	$ 788.8
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital Required for Capital Adequacy	$ 592.7	$ 591.6
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%

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Commitments and Contingencies (Details) $ in Millions	Apr. 08, 2019	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Aug. 16, 2018
Loss Contingencies [Line Items]
Notional amount of terminated commitment		$ 539.6	$ 467.9
Mortgage Loans Held for Sale
Loss Contingencies [Line Items]
Mortgage loans with recourse provision in effect		$ 1.5
Inland Northwest Bank
Loss Contingencies [Line Items]
Number of banking offices acquired				20
Subsequent Event | Idaho Independent Bank [Member]
Loss Contingencies [Line Items]
Number of banking offices acquired	11
Subsequent Event | Community 1st Bank [Member]
Loss Contingencies [Line Items]
Number of banking offices acquired	3
Construction Contracts
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation			$ 1.5

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Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Entity Information [Line Items]
Credit extension commitments		$ 2,637.1
Unused Credit Card Lines
Entity Information [Line Items]
Credit extension commitments		720.7
Credit extension commitments beyond one year	$ 1,058.9
Standby Letters of Credit
Entity Information [Line Items]
Credit extension commitments		$ 47.6

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Other Comprehensive Income/Loss - Schedule of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	$ 1,736.9	$ 1,432.4	$ 1,693.9	$ 1,427.6
Investment securities available-for sale:
Change in net unrealized gain during period, pre-tax	33.6	(23.7)
Change in net unrealized gain during period, tax expense (benefit)	8.8	(6.2)
Change in net unrealized gain during period, net of tax	24.8	(17.5)
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity, pre-tax	6.0	0.0
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity, tax expense (benefit)	(1.6)
Change in unamortized loss on available-for-sale securities transferred into held-to-maturity, net of tax	(4.4)	0.0
Other Comprehensive Income (Loss), Transfers from Available-for-Sale to Held-to-Maturity Securities, before Tax	0.0	0.5
Other Comprehensive Income (Loss), Transfers from Available-for-Sale to Held-to-Maturity Securities, Tax	0.0	0.2
Other Comprehensive Income (Loss), Transfers from Available-for-Sale to Held-to-Maturity Securities, Net of Tax	0.0	0.3
Defined benefits post-retirement benefit plan:
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax	0.0	0.1
Other comprehensive income (loss), before tax	27.4	(23.3)
Total other comprehensive income, tax expense (benefit)	7.2	(6.1)
Total other comprehensive income, net of tax amount	20.2	(17.2)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	(0.2)	(0.1)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax	(0.2)	0.0
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	(5.1)		(25.5)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	(4.4)	$ (32.3)	(24.6)	$ (12.0)
Postretirement Health Coverage [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 0.7		$ 0.9

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Other Comprehensive Income/Loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	$ 1,736.9	$ 1,693.9	$ 1,432.4	$ 1,427.6
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	(5.1)	(25.5)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity Attributable to Parent	(4.4)	(24.6)	$ (32.3)	$ (12.0)
Postretirement Health Coverage [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 0.7	$ 0.9

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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
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	$ 14.6		$ 10.1
Derivative liabilities:	13.5		9.4
Real Estate Acquired Through Foreclosure, Valuation Adjustments	(0.3)	$ 0.0
Related allowance	7.1		6.8
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 Receivable Held-for-sale, Amount	0.0		0.0
Deferred Compensation Plan Assets	0.0		0.0
Deferred Compensation Liability, Current and Noncurrent	0.0		0.0
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]
Impaired loans	0.0		0.0
Other real estate owned	0.0		0.0
Long-lived assets to be disposed, fair value disclosure	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 Receivable Held-for-sale, Amount	34.0		33.3
Derivative assets:			8.8
Derivative liabilities:			8.8
Deferred Compensation Plan Assets	12.4		12.1
Deferred Compensation Liability, Current and Noncurrent	12.4		12.1
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]
Impaired loans	0.0		0.0
Other real estate owned	0.0		0.0
Long-lived assets to be disposed, fair value disclosure	0.0		0.0
Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Amount	0.0		0.0
Deferred Compensation Plan Assets	0.0		0.0
Deferred Compensation Liability, Current and Noncurrent	0.0		0.0
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]
Impaired loans			24.1
Other real estate owned	2.0		0.6
Long-lived assets to be disposed, fair value disclosure	5.5		4.9
Related allowance			7.1	$ 6.8
Partial loan charge-offs			6.2	5.4
US Treasury Notes Securities [Member] | 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
US Treasury Notes Securities [Member] | 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:			2.6
US Treasury Notes Securities [Member] | 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
U.S. Treasury notes | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale:	0.0
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:	4.0
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
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
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:	78.4
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
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
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:	597.7		559.2
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
U.S. agency residential 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
U.S. agency residential 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:	1,732.9		1,544.8
U.S. agency residential 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
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
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:	65.3		70.2
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
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
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:	92.0		91.9
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
Other investments | 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
Other investments | 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:	1.7
Other investments | 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
Other Investments | 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
Other Investments | 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:			2.0
Other Investments | 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
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale:	2,572.0		2,270.7
Loans held for sale	34.0		33.3
Derivative assets:	14.6		10.1
Derivative liabilities:	13.5		9.4
Deferred Compensation Plan Assets	12.4		12.1
Deferred Compensation Liability, Current and Noncurrent	12.4		12.1
Estimated Fair Value | Fair Value Measured on a Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Amount	34.0		33.3
Deferred Compensation Plan Assets	12.4		12.1
Deferred Compensation Liability, Current and Noncurrent	12.4		12.1
Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets to be disposed of by sale			5.5	4.9
Estimated Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale:	0.0		0.0
Loans held for sale	0.0		0.0
Derivative assets:	0.0		0.0
Derivative liabilities:	0.0		0.0
Deferred Compensation Plan Assets	0.0		0.0
Deferred Compensation Liability, Current and Noncurrent	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:	2,572.0		2,270.7
Loans held for sale	34.0		33.3
Derivative assets:	14.6		10.1
Derivative liabilities:	13.5		9.4
Deferred Compensation Plan Assets	12.4		12.1
Deferred Compensation Liability, Current and Noncurrent	12.4		12.1
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
Loans held for sale	0.0		0.0
Derivative assets:	0.0		0.0
Derivative liabilities:	0.0		0.0
Deferred Compensation Plan Assets	0.0		0.0
Deferred Compensation Liability, Current and Noncurrent	0.0		0.0
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]
Impaired loans	30.9		30.9	24.1
Other real estate owned	2.0
Long-lived assets to be disposed, fair value disclosure	5.5		4.9
Estimated Fair Value | US Treasury Notes Securities [Member] | 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:			2.6
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:	4.0
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:	78.4
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:	597.7		559.2
Estimated Fair Value | U.S. agency residential 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:	1,732.9		1,544.8
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:	65.3		70.2
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:	92.0		91.9
Estimated Fair Value | Other investments | 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:	1.7
Estimated Fair Value | Other Investments | 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:			2.0
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment debt securities available-for-sale:	2,572.0		2,270.7
Derivative assets:	14.6		10.1
Derivative liabilities:	13.5		9.4
Deferred Compensation Plan Assets	12.4		12.1
Deferred Compensation Liability, Current and Noncurrent	12.4		12.1
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]
Impaired loans			44.2	36.3
Long-lived assets to be disposed of by sale			6.0	5.4
Change During Period | Fair Value Measured on a Non-recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets to be disposed of by sale			0.5	$ 0.5
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets:	12.7		8.8
Derivative liabilities:	12.7		8.8
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
Derivative liabilities:	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:	12.7
Derivative liabilities:	12.7
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
Derivative liabilities:	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:	12.7		8.8
Derivative liabilities:	12.7		8.8
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		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:	1.9		1.3
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		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:	1.9		1.3
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 liabilities:	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 liabilities:	0.8		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 liabilities:	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 liabilities:	$ 0.8		$ 0.6

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Fair Value Measurements - Fair Value Inputs, Quantitative Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2017
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Write downs on OREO properties	$ 0
Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount Rate for Level 3 Fair Value Disclosure		0.00%
Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount Rate for Assets HFS Level 3 Fair Value		43.00%
Discount Rate for OREO Level 3 Fair Value		96.00%
Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount Rate for Assets HFS Level 3 Fair Value		10.00%
Discount Rate for OREO Level 3 Fair Value		39.00%
Discount Rate for Level 3 Fair Value Disclosure		13.00%
Carrying Amount
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Net loans held for investment		$ 8,397,400,000	$ 8,386,800,000
Change During Period | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value of long-lived assets to be disposed of by sale		500,000		$ 500,000
Estimated Fair Value
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Net loans held for investment		8,439,700,000	8,408,600,000
Estimated Fair Value | Fair Value Measured on a Non-recurring Basis
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value of long-lived assets to be disposed of by sale		5,500,000		4,900,000
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)
Partial loan charge-offs		6,200,000		5,400,000
Long-lived assets to be disposed, fair value disclosure		4,900,000	5,500,000
Impaired loans		24,100,000
Other real estate owned		600,000	2,000,000
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)
Impaired loans		44,200,000		36,300,000
Fair Value of long-lived assets to be disposed of by sale		6,000,000		5,400,000
Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Net loans held for investment		24,100,000	30,900,000
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, fair value disclosure		4,900,000	5,500,000
Impaired loans		$ 30,900,000	30,900,000	$ 24,100,000
Other real estate owned			$ 2,000,000
Measurement Input, Discount Rate [Member] | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount Rate for Assets HFS Level 3 Fair Value		0.00%
Discount Rate for OREO Level 3 Fair Value		8.00%
Measurement Input, Discount Rate [Member] | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Discount Rate for Level 3 Fair Value Disclosure		26.00%

XML

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Instruments by Level of Valuation Inputs (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financial assets:
Investment debt securities held-to-maturity	$ 118,000	$ 400,700
Derivative assets	14,600	10,100
Financial liabilities:
Derivative liabilities	13,500	9,400
Carrying Amount
Financial assets:
Cash and cash equivalents	955,200	822,000
Investment debt securities available-for-sale:	2,572,000	2,270,700
Investment debt securities held-to-maturity	117,000	406,800
Accrued interest receivable	46,500	44,900
Mortgage servicing rights, net	27,900	27,700
Loans Held-for-sale, Fair Value Disclosure	34,000	33,300
Net loans held for investment	8,386,800	8,397,400
Derivative assets	14,600	10,100
Deferred Compensation Plan Assets	12,400	12,100
Total financial assets	12,166,400	12,025,000
Financial liabilities:
Total deposits, excluding time deposits	9,408,300	9,363,700
Time deposits	1,406,400	1,317,000
Securities sold under repurchase agreements	672,600	712,400
Accrued interest payable	10,000	7,800
Long-term debt	15,800	15,800
Subordinated debentures held by subsidiary trusts	86,900	86,900
Derivative liabilities	13,500	9,400
Deferred Compensation Liability, Current and Noncurrent	12,400	12,100
Total financial liabilities	11,625,900	11,525,100
Estimated Fair Value
Financial assets:
Cash and cash equivalents	955,200	822,000
Investment debt securities available-for-sale:	2,572,000	2,270,700
Investment debt securities held-to-maturity	118,000	400,700
Accrued interest receivable	46,500	44,900
Mortgage servicing rights, net	40,500	42,400
Loans held for sale	34,000	33,300
Net loans held for investment	8,408,600	8,439,700
Derivative assets	14,600	10,100
Deferred Compensation Plan Assets	12,400	12,100
Total financial assets	12,201,800	12,075,900
Financial liabilities:
Total deposits, excluding time deposits	9,408,300	9,363,700
Time deposits	1,393,200	1,299,000
Securities sold under repurchase agreements	672,600	712,400
Accrued interest payable	10,000	7,800
Long-term debt	13,900	13,000
Subordinated debentures held by subsidiary trusts	85,100	84,900
Derivative liabilities	13,500	9,400
Deferred Compensation Liability, Current and Noncurrent	12,400	12,100
Total financial liabilities	11,609,000	11,502,300
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	955,200	822,000
Investment debt securities available-for-sale:	0	0
Investment debt securities held-to-maturity	0	0
Accrued interest receivable	0	0
Mortgage servicing rights, net	0	0
Loans held for sale	0	0
Net loans held for investment	0	0
Derivative assets	0	0
Deferred Compensation Plan Assets	0	0
Total financial assets	955,200	822,000
Financial liabilities:
Total deposits, excluding time deposits	9,408,300	9,363,700
Time deposits	0	0
Securities sold under repurchase agreements	0	0
Accrued interest payable	0	0
Long-term debt	0	0
Subordinated debentures held by subsidiary trusts	0	0
Derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total financial liabilities	9,408,300	9,363,700
Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Investment debt securities available-for-sale:	2,572,000	2,270,700
Investment debt securities held-to-maturity	118,000	400,700
Accrued interest receivable	46,500	44,900
Mortgage servicing rights, net	40,500	42,400
Loans held for sale	34,000	33,300
Net loans held for investment	8,377,700	8,415,600
Derivative assets	14,600	10,100
Deferred Compensation Plan Assets	12,400	12,100
Total financial assets	11,215,700	11,229,800
Financial liabilities:
Total deposits, excluding time deposits	0	0
Time deposits	1,393,200	1,299,000
Securities sold under repurchase agreements	672,600	712,400
Accrued interest payable	10,000	7,800
Long-term debt	13,900	13,000
Subordinated debentures held by subsidiary trusts	85,100	84,900
Derivative liabilities	13,500	9,400
Deferred Compensation Liability, Current and Noncurrent	12,400	12,100
Total financial liabilities	2,200,700	2,138,600
Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Investment debt securities available-for-sale:	0	0
Investment debt securities held-to-maturity	0	0
Accrued interest receivable	0	0
Mortgage servicing rights, net	0	0
Loans held for sale	0	0
Net loans held for investment	30,900	24,100
Derivative assets	0	0
Deferred Compensation Plan Assets	0	0
Total financial assets	30,900	24,100
Financial liabilities:
Total deposits, excluding time deposits	0	0
Time deposits	0	0
Securities sold under repurchase agreements	0	0
Accrued interest payable	0	0
Long-term debt	0	0
Subordinated debentures held by subsidiary trusts	0	0
Derivative liabilities	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Total financial liabilities	$ 0	$ 0

XML

Recent Authoritative Accounting Guidance (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets obtained in exchange for operating lease liabilities	$ 54.6	$ 0.0
Operating Lease, Payments	$ 54.6