Nicolet Bankshares (NIC) 10-K 28 Feb 24 2023 FY Annual report Financial data

Cover

Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Feb. 27, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-37700
Entity Registrant Name	NICOLET BANKSHARES, INC
Entity Incorporation, State or Country Code	WI
Entity Tax Identification Number	47-0871001
Entity Address, Address Line One	111 North Washington Street
Entity Address, City or Town	Green Bay
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	54301
City Area Code	920
Local Phone Number	430-1400
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	NIC
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 873
Entity Common Stock, Shares Outstanding		14,904,370
Entity Central Index Key	0001174850
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Documents Incorporated by Reference	Portions of the Proxy Statement (the “2024 Proxy Statement”) for the 2024 Annual Meeting of Shareholders to be held on May 20, 2024, are incorporated by reference into Part III of this Annual Report on Form 10-K.

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	FORVIS, LLP
Auditor Location	Springfield, Missouri
Auditor Firm ID	686

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)		Dec. 31, 2023	Dec. 31, 2022
Assets
Cash and due from banks		$ 129,898,000	$ 121,211,000
Interest-earning deposits		361,533,000	33,512,000
Cash and cash equivalents	[1]	491,431,000	154,723,000
Certificates of deposit in other banks		6,374,000	12,518,000
Securities available for sale (“AFS”), at fair value		802,573,000	917,618,000
Securities held to maturity (“HTM”), at amortized cost		0	679,128,000
Other investments		57,560,000	65,286,000
Loans held for sale		4,160,000	1,482,000
Loans		6,353,942,000	6,180,499,000
Allowance for credit losses - loans (“ACL-Loans”)		(63,610,000)	(61,829,000)
Loans, net		6,290,332,000	6,118,670,000
Premises and equipment, net		118,756,000	108,956,000
Bank owned life insurance (“BOLI”)		169,392,000	165,137,000
Goodwill and other intangibles, net		394,366,000	402,438,000
Accrued interest receivable and other assets		133,734,000	138,013,000
Total assets		8,468,678,000	8,763,969,000
Liabilities:
Noninterest-bearing demand deposits		1,958,709,000	2,361,816,000
Interest-bearing deposits		5,239,091,000	4,817,105,000
Total deposits		7,197,800,000	7,178,921,000
Short-term borrowings		0	317,000,000
Long-term borrowings		166,930,000	225,342,000
Accrued interest payable and other liabilities		64,941,000	70,177,000
Total liabilities		7,429,671,000	7,791,440,000
Stockholders’ Equity:
Common stock		149,000	147,000
Additional paid-in capital		633,770,000	621,988,000
Retained earnings		458,261,000	407,864,000
Accumulated other comprehensive income (loss)		(53,173,000)	(57,470,000)
Total stockholders’ equity		1,039,007,000	972,529,000
Total liabilities and stockholders’ equity		$ 8,468,678,000	$ 8,763,969,000
Preferred shares authorized (no par value) (in shares)		10,000,000	10,000,000
Preferred shares outstanding (in shares)		0	0
Preferred shares issued (in shares)		0	0
Common shares authorized (par value $0.01 per share) (in shares)		30,000,000	30,000,000
Common shares outstanding (in shares)		14,894,209	14,690,614
Common shares issued (in shares)		14,951,367	14,764,104
[1]Cash and cash equivalents at both December 31, 2023 and December 31, 2022 did not include any restricted cash. At December 31, 2021, cash and cash equivalents included restricted cash of $1.9 million pledged as collateral on interest rate swaps and no reserve balance was required with the Federal Reserve.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest income:
Loans, including loan fees	$ 341,155	$ 243,680	$ 156,559
Investment securities:
Taxable	18,182	21,383	9,934
Tax-exempt	6,031	4,418	2,157
Other interest income	17,494	4,437	2,909
Total interest income	382,862	273,918	171,559
Interest expense:
Deposits	125,824	21,752	10,448
Short-term borrowings	4,794	3,246	1
Long-term borrowings	10,728	8,959	3,155
Total interest expense	141,346	33,957	13,604
Net interest income	241,516	239,961	157,955
Provision for credit losses	4,990	11,500	14,900
Net interest income after provision for credit losses	236,526	228,461	143,055
Noninterest income:
Mortgage income, net	7,164	8,497	22,155
BOLI income	4,524	3,818	2,380
Deferred compensation plan asset market valuations	1,937	(2,040)	609
LSR income, net	4,425	(1,366)	0
Asset gains (losses), net	(32,808)	3,130	4,181
Other income	8,016	7,264	3,936
Total noninterest income	35,972	57,920	67,364
Noninterest expense:
Personnel	99,109	88,713	70,618
Occupancy, equipment and office	36,222	29,722	21,058
Business development and marketing	7,790	8,472	5,403
Data processing	19,892	14,518	11,990
Intangibles amortization	8,072	6,616	3,494
FDIC assessments	3,999	1,920	2,035
Merger-related expense	189	1,664	5,651
Other expense	10,593	9,019	9,048
Total noninterest expense	185,866	160,644	129,297
Income before income tax expense	86,632	125,737	81,122
Income tax expense	25,116	31,477	20,470
Net income	$ 61,516	$ 94,260	$ 60,652
Earnings per common share:
Basic (in dollars per share)	$ 4.17	$ 6.78	$ 5.65
Diluted (in dollars per share)	$ 4.08	$ 6.56	$ 5.44
Weighted average common shares outstanding:
Basic (in shares)	14,742,675	13,909,299	10,735,605
Diluted (in shares)	15,070,579	14,374,931	11,144,866
Wealth management fee income
Noninterest income:
Fees and commissions	$ 23,747	$ 20,870	$ 19,917
Service charges on deposit accounts
Noninterest income:
Fees and commissions	5,976	6,104	5,023
Card interchange income
Noninterest income:
Fees and commissions	$ 12,991	$ 11,643	$ 9,163

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 61,516	$ 94,260	$ 60,652
Unrealized gains (losses) on securities AFS:
Net unrealized holding gains (losses)	23,233	(83,219)	(13,495)
Net realized (gains) losses included in income	3,313	244	283
Reclassification adjustment for securities transferred from held to maturity to available for sale	(20,434)	0	0
Income tax (expense) benefit	(1,815)	22,403	3,567
Total other comprehensive income (loss), net of tax	4,297	(60,572)	(9,645)
Comprehensive income (loss)	$ 65,813	$ 33,688	$ 51,007

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	County Bancorp, Inc.	Mackinac Financial Corporation	Common Stock	Common Stock County Bancorp, Inc.	Common Stock Mackinac Financial Corporation	Additional Paid-In Capital	Additional Paid-In Capital County Bancorp, Inc.	Additional Paid-In Capital Mackinac Financial Corporation	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders’ equity	$ 539,189			$ 100			$ 273,390			$ 252,952	$ 12,747
Comprehensive income:
Net income	60,652									60,652
Other comprehensive income (loss)	(9,645)										(9,645)
Stock-based compensation expense	7,307						7,307
Exercise of stock options, net	1,837			1			1,836
Issuance of common stock in acquisitions, net of capitalized issuance costs		$ 175,155	$ 179,434		$ 24	$ 23		$ 175,131	$ 179,411
Issuance of common stock	545						545
Purchase and retirement of common stock	(62,583)			(8)			(62,575)
Stockholders’ equity	891,891			140			575,045			313,604	3,102
Net income	94,260									94,260
Other comprehensive income (loss)	(60,572)										(60,572)
Stock-based compensation expense	7,016						7,016
Exercise of stock options, net	2,531			1			2,530
Common stock issued in acquisitions	98,149			13			98,136
Issuance of common stock	751						751
Purchase and retirement of common stock	(61,497)			(7)			(61,490)
Stockholders’ equity	972,529			147			621,988			407,864	(57,470)
Net income	61,516									61,516
Other comprehensive income (loss)	4,297										4,297
Stock-based compensation expense	6,438						6,438
Cash dividends on common stock	(11,119)									(11,119)
Exercise of stock options, net	6,023			3			6,020
Issuance of common stock	844						844
Purchase and retirement of common stock	(1,521)			(1)			(1,520)
Stockholders’ equity	$ 1,039,007			$ 149			$ 633,770			$ 458,261	$ (53,173)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parentheticals) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2021
Cash dividends on common stock (in dollars per share)	$ 0.75
County Bancorp, Inc.
Common stock issued, capitalized Issuance costs		$ 397
Mackinac Financial Corporation
Common stock issued, capitalized Issuance costs		$ 392

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Cash Flows From Operating Activities:
Net income		$ 61,516		$ 94,260		$ 60,652
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion		18,403		21,930		13,857
Provision for credit losses		4,990		11,500		14,900
Provision for deferred taxes		3,027		(12,907)		6,332
Increase in cash surrender value of life insurance		(4,411)		(3,701)		(2,380)
Stock-based compensation expense		6,438		7,016		7,307
Assets (gains) losses, net		32,808		(3,130)		(4,181)
Gain on sale of loans held for sale, net		(4,546)		(4,888)		(20,468)
Proceeds from sale of loans held for sale		147,906		208,296		650,573
Origination of loans held for sale		(147,578)		(200,770)		(619,431)
Net change in accrued interest receivable and other assets		(5,343)		73		(10,531)
Net change in accrued interest payable and other liabilities		(5,236)		(283)		1,024
Net cash provided by (used in) operating activities		107,974		117,396		97,654
Cash Flows From Investing Activities:
Net (increase) decrease in certificates of deposit in other banks		6,144		9,411		10,968
Purchases of securities AFS		(59,734)		(8,623)		(299,746)
Purchases of securities HTM		0		(56,479)		(569,910)
Proceeds from sales of securities AFS		65,749		28,438		42,973
Proceeds from sales of securities HTM		460,051		0		0
Proceeds from calls, paydowns, and maturities of securities AFS		285,407		104,063		167,024
Proceeds from calls, paydowns, and maturities of securities HTM		2,915		28,306		0
Net (increase) decrease in loans		(168,801)		(731,904)		(76,427)
Purchases of other investments		(13,465)		(24,999)		(13,432)
Proceeds from sales of other investments		18,941		13,138		10,203
Net (increase) decrease in premises and equipment		(18,202)		(12,234)		(12,791)
Net (increase) decrease in other real estate		12,151		13,150		2,743
Proceeds from redemption of BOLI		306		1,757		0
Net cash (paid) received in branch sale		0		147,833		0
Net cash (paid) received in business combination		0		(28,221)
Net cash (paid) received in business combination						367,797
Net cash provided by (used in) investing activities		591,462		(516,364)		(370,598)
Cash Flows From Financing Activities:
Net increase (decrease) in deposits		19,045		(147,520)		210,375
Net increase (decrease) in short-term borrowings		(317,000)		184,134		0
Proceeds from long-term borrowings		0		0		103,953
Repayments of long-term borrowings		(59,000)		(20,000)		(187,961)
Capitalized issuance costs, net		0		0		(789)
Purchase and retirement of common stock		(1,521)		(61,497)		(62,583)
Cash dividends paid on common stock		(11,119)		0		0
Proceeds from issuance of common stock, net		6,867		3,282		2,382
Net cash provided by (used in) financing activities		(362,728)		(41,601)		65,377
Net increase (decrease) in cash and cash equivalents		336,708		(440,569)		(207,567)
Cash and cash equivalents:
Beginning cash and cash equivalents		154,723	[1]	595,292	[1]	802,859
Ending cash and cash equivalents	[1]	491,431		154,723		595,292
Supplemental Disclosures of Cash Flow Information:
Cash paid for interest		138,012		37,433		10,882
Cash paid for taxes		23,015		33,560		24,341
Transfer of securities from HTM to AFS		178,391		0		0
Transfer of loans and bank premises to other real estate owned		985		612		8,177
Capitalized mortgage servicing rights		1,540		2,327		0
Acquisitions:
Fair value of assets acquired		0		1,121,000		2,968,000
Fair value of liabilities assumed		0		1,034,000		2,666,000
Net assets acquired		0		87,000		302,000
Common stock issued in acquisitions		$ 0		$ 98,149		$ 355,378
[1]Cash and cash equivalents at both December 31, 2023 and December 31, 2022 did not include any restricted cash. At December 31, 2021, cash and cash equivalents included restricted cash of $1.9 million pledged as collateral on interest rate swaps and no reserve balance was required with the Federal Reserve.

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Cash Flows [Abstract]
Restricted cash pledged as collateral	$ 0	$ 0	$ 1,900,000

NATURE OF BUSINESS AND SIGNIFIC

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES	NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES Nature of Banking Activities and Subsidiaries : Nicolet Bankshares, Inc. (the “Company” or “Nicolet”) was incorporated on April 5, 2000, to serve as the holding company and sole shareholder of Nicolet National Bank (the “Bank”). The Bank opened for business on November 1, 2000. Since its opening in late 2000, Nicolet has supplemented its organic growth with branch purchase and acquisition transactions. At December 31, 2023, the Company had three wholly owned subsidiaries, the Bank, Nicolet Advisory Services, LLC (“Nicolet Advisory”), and Nicolet Insurance Services, LLC (“Nicolet Insurance”). The consolidated income of the Company is derived principally from the Bank, which conducts lending (primarily commercial and agricultural-based loans, as well as residential and consumer loans) and deposit gathering (including other banking- and deposit-related products and services, such as ATMs, safe deposit boxes, check cashing, wires, and debit cards) to businesses, consumers and governmental units principally in its trade area of Wisconsin, Michigan and Minnesota, trust services, brokerage services (delivered through the Bank and Nicolet Advisory), and the support to deliver, fund and manage all such banking and wealth management services to its customer base. At December 31, 2023, the Bank wholly owns an investment subsidiary based in Nevada, a subsidiary that provides a web-based investment management platform for financial advisor trades and related activity, and an entity that owns the building in which Nicolet is headquartered, Nicolet Joint Ventures, LLC (the “JV”). Nicolet Advisory is a registered investment advisor subsidiary that provides brokerage and investment advisory services to customers. Nicolet Insurance, acquired in 2021, was formed to facilitate the delivery of a crop insurance product associated with Nicolet’s agricultural lending. Principles of Consolidation : The consolidated financial statements of the Company include the accounts of its subsidiaries. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and conform to general practices within the banking industry. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements. Results of operations of companies purchased, if any, are included from the date of acquisition. Because the Company is not the primary beneficiary, the consolidated financial statements exclude the following wholly-owned variable interest entities: Mid-Wisconsin Statutory Trust, Baylake Capital Trust II, First Menasha Bancshares Statutory Trust I, First Menasha Bancshares Statutory Trust II, County Bancorp Statutory Trust II, County Bancorp Statutory Trust III, and Fox River Valley Trust I. Operating Segment : The Bank represents the primary operating segment (as discussed above). While the chief operating decision makers monitor the revenue streams of the various products and services, and evaluate costs, balance sheet positions and quality, all such products, services and activities are directly or indirectly related to the business of community banking, with no regular, formal or material segment delineations. Operations are managed and financial performance is evaluated on a company-wide basis, and accordingly, all the financial service operations are considered by management to be aggregated in one reportable operating segment. Use of Estimates : In preparing the accompanying consolidated financial statements in conformity with U.S. GAAP, the Company’s management is required to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and the disclosures provided. Actual results may differ from these estimates. Material estimates that are particularly susceptible to significant change in the near-term include the fair value of securities available for sale, the determination of the allowance for credit losses, acquisitions accounting, goodwill, and income taxes. Business Combinations : The Company accounts for business combinations under the acquisition method of accounting in accordance with Accounting Standards Codification (“ASC”) 805, Business Combinations (“ASC 805”). The Company recognizes the full fair value of the assets acquired and liabilities assumed and immediately expenses transaction costs. If the amount of consideration exceeds the fair value of assets purchased less the fair value of liabilities assumed, goodwill is recorded. Alternatively, if the amount by which the fair value of assets purchased exceeds the fair value of liabilities assumed and consideration paid, a gain (“bargain purchase gain”) is recorded. Fair values are subject to refinement for up to one year after the closing date of an acquisition as information relative to closing date fair values becomes available. Results of operations of the acquired business are included in the statements of income from the effective date of the acquisition. Cash and Cash Equivalents : For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash and due from banks, interest-earning deposits in other banks with original maturities of less than 90 days, and federal funds sold. The Bank maintains amounts in due from banks which, at times, may exceed federally insured limits. Management monitors these correspondent relationships, and the Bank has not experienced any losses in such accounts. Securities Available for Sale : Securities are classified as AFS on the consolidated balance sheets at the time of purchase and include those securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity. Any decision to sell a security classified as AFS would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Company’s assets and liabilities, liquidity needs, regulatory capital considerations, and other similar factors. Securities classified as AFS are carried at fair value, with unrealized gains or losses, net of related deferred income taxes, reported as increases or decreases in accumulated other comprehensive income (loss). Realized gains or losses on sales of securities AFS (using the specific identification method) are included in the consolidated statements of income under asset gains (losses), net. Premiums and discounts are amortized or accreted into interest income over the estimated life of the related securities using the effective interest method. Management evaluates securities AFS in unrealized loss positions on a quarterly basis to determine whether the decline in fair value below the amortized cost basis (impairment) is due to credit-related factors or noncredit-related factors. In making this evaluation, management considers the extent to which the fair value has been less than cost, the financial condition and near-term prospects of the issuer, and the intent and ability of the Company to hold the security for a period of time sufficient to allow for any anticipated recovery in fair value. Any impairment that is not credit-related is recognized in other comprehensive income (loss), net of related deferred income taxes. Credit-related impairment is recognized as an allowance for credit losses (“ACL”) on the balance sheet based on the amount by which the amortized cost basis exceeds the fair value, with a corresponding charge to net income. Both the ACL and charge to net income may be reversed if conditions change. However, if the Company intends to sell an impaired AFS security or more likely than not will be required to sell such a security before recovering its amortized cost basis, the entire impairment must be recognized in net income with a corresponding adjustment to the security’s amortized cost basis rather than through the establishment of an ACL. Securities Held to Maturity : Securities are classified as HTM on the consolidated balance sheets at the time of purchase and include those securities that the Company has both the positive intent and ability to hold to maturity. HTM securities are carried at amortized cost on the consolidated balance sheets. Premiums and discounts are amortized or accreted into interest income over the estimated life of the related securities using the effective interest method. Management evaluates securities HTM on a quarterly basis to determine whether an ACL is necessary. In making this determination, management considers the facts and circumstances of the underlying investment securities. The ACL for HTM securities, if deemed necessary, evaluates expected credit losses on HTM securities by security type, aggregated by similar risk characteristics, and considers historical credit loss information as adjusted for current conditions and supportable forecasts. Other Investments : Other investments include equity securities with readily determinable fair values, “restricted” equity securities, and private company securities. As a member of the Federal Reserve Bank System and the Federal Home Loan Bank (“FHLB”) System, the Bank is required to maintain an investment in the capital stock of these entities. These equity securities are “restricted” in that they can only be sold back to the respective institutions or another member institution at par. Therefore, they are less liquid than other exchange traded equity securities. As no ready market exists for these stocks, and they have no quoted market value, these investments are carried at cost. Also included are investments in other private companies that do not have quoted market prices, which are carried at cost less impairment charges, if any. Management’s evaluation of these other investments for impairment includes consideration of the financial condition and other available relevant information of the issuer. Loans Held for Sale : Loans originated and intended for sale in the secondary market are carried at the lower of cost or estimated fair value as determined on an aggregate basis and generally consist of current production of certain fixed-rate residential first lien mortgages. The amount by which cost exceeds fair value is recorded as a valuation allowance and charged to earnings. Changes, if any, in the valuation allowance are included in earnings in the period in which the change occurs. As of December 31, 2023 and 2022, no valuation allowance was necessary. Loans held for sale may be sold servicing retained or servicing released, and are generally sold without recourse. The carrying value of mortgage loans sold with servicing retained is reduced by the amount allocated to the servicing right at the time of sale. Gains and losses on sales of mortgage loans held for sale are included in earnings in mortgage income, net. Loans – Originated : Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are carried at their amortized cost basis, which is the unpaid principal amount outstanding, net of deferred loan fees and costs, and any direct principal charge-off. The Company made an accounting policy election to exclude accrued interest from the amortized cost basis of loans and report such accrued interest as part of accrued interest receivable and other assets on the consolidated balance sheets. Interest income is accrued on the unpaid principal balance using the simple interest method. The accrual of interest income on loans is discontinued when, in the opinion of management, there is reasonable doubt as to the borrower’s ability to meet payment of interest or principal when due. Loans are generally placed on nonaccrual status when contractually past due 90 days or more as to interest or principal, though may be placed in such status earlier based on the circumstances. Loans past due 90 days or more may continue on accrual only when they are well secured and / or in process of collection or renewal. When interest accrual is discontinued, all previously accrued but uncollected interest is reversed against current period interest income. Except in very limited circumstances, cash collections on nonaccrual loans are credited to the loan receivable balance and no interest income is recognized on those loans until the principal balance is paid in full. Accrual of interest may be resumed when the customer is current on all principal and interest payments and has been paying on a timely basis for a sustained period of time. A description of each segment of the loan portfolio, including the corresponding credit risk, is included below. Commercial and industrial loans consist primarily of commercial loans to small and mid-sized businesses within a diverse range of industries (manufacturing, wholesaling, paper, packaging, food production and processing, retail, service, and businesses supporting the general building industry). These loans are made for a wide variety of general corporate purposes, including working capital, equipment, and business expansion loans, with varying terms based upon the underlying purpose of the loan. Commercial and industrial loans are based primarily on the historical and projected cash flow of the underlying borrower, and secondarily on any underlying assets pledged by the borrower. The credit risk related to commercial and industrial loans is largely influenced by general economic conditions and the resulting impact on a borrower’s operations, or on the value of underlying collateral, if any. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, formally reviewing the borrower’s financial condition on an ongoing basis, and generally require a guarantee (in full or part) from the primary business owners. Commercial bankers utilize SBA programs, where appropriate, as Nicolet is a preferred SBA lender. Owner-occupied CRE loans primarily consist of loans within a diverse range of industries secured by business real estate that is occupied by borrowers who operate their businesses out of the underlying collateral and who may also have commercial and industrial loans. The credit risk related to owner-occupied CRE loans is largely influenced by general economic conditions and the resulting impact on a borrower’s operations, or on the value of underlying collateral. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, periodically evaluating the underlying collateral, formally reviewing the borrower’s financial performance on an ongoing basis, and generally require a guarantee (in full or part) from the primary business owners. Agricultural loans consist of loans secured by farmland and the related farming operations, primarily within the dairy industry. These loans support short-term needs (planting crops or buying feed), as well as longer term needs (fund cattle, equipment or real estate purchases and improvements) of our agricultural customers. The credit risk related to agricultural loans is largely influenced by the agricultural economy, including market prices for the cost of feed and the price of milk, and / or the underlying value of the farmland. Credit risk is managed by employing sound underwriting guidelines, regular personal contact with our agricultural customers, formally reviewing the borrower’s financial condition on an ongoing basis, and generally require a guarantee (in full or part) from the primary business owners. Agricultural bankers utilize FSA programs, where appropriate, as Nicolet is a preferred FSA lender. The CRE investment loan classification primarily includes commercial-based mortgage loans that are secured by non-owner occupied, nonfarm / nonresidential real estate properties, and multi-family residential properties. Lending in this segment is focused on loans that are secured by commercial income-producing properties as opposed to speculative real estate development. The credit risk related to CRE investment loans is influenced by the cash flows of the properties, including vacancy experience, credit capacity of the tenants occupying the real estate, and general economic conditions, all of which may impact the borrower’s operations or the value of underlying collateral. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, periodically evaluating the underlying collateral, regularly reviewing the borrower’s financial condition, and generally require a guarantee (in full or part) from the principals. Construction and land development loans provide financing for the development of commercial income properties, multi-family residential development, and land designated for future development. The credit risk on construction loans depends largely upon the accuracy of the initial estimate of the property’s value at completion of construction and the estimated cost of construction. Nicolet controls the credit risk on these types of loans by making loans in familiar markets, reviewing the merits of individual projects, controlling loan structure, and monitoring the progress of projects through the analysis of construction advances. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, periodically evaluating the underlying collateral, formally reviewing the borrower’s financial soundness and relationships on an ongoing basis, and generally require a guarantee (in full or part) from the principals. Residential real estate includes residential first mortgage loans and residential junior mortgage loans (home equity lines and term loans secured by junior mortgage liens). Residential real estate also includes residential construction loans. As part of its management of originating residential mortgage loans, Nicolet generally sells the majority of its long-term, fixed-rate residential first mortgage loans in the secondary market with the servicing rights retained, and retains the adjustable-rate mortgage loans in its loan portfolio. The Company may also retain a portion of the long-term, fixed rate residential mortgage loans that do not conform with secondary market standards, but do meet other specific underwriting guidelines. Credit risk for residential real estate loans largely depends upon factors affecting the borrower’s ability to repay as well as general economic trends. Residential real estate loan underwriting is subject to specific regulations, and Nicolet typically underwrites these loans to conform with those widely accepted standards. Residential real estate loans typically have longer terms and higher balances with lower yields, but generally carry lower risks of default. Retail loans include predominantly credit cards and other personal installment loans to individuals within Nicolet’s market areas. Retail loans are centrally underwritten utilizing the borrower’s financial history and information on the underlying collateral. Retail loans typically have shorter terms and lower balances with higher yields, but generally carry higher risks of default. Collection of these loans depends on the borrower’s financial stability, and is more likely to be affected by adverse personal circumstances. Loans – Acquired : Loans purchased in acquisition transactions are acquired loans, and are recorded at their estimated fair value on the acquisition date. Acquired loans that have evidence of more-than-insignificant deterioration in credit quality since origination are considered purchased credit deteriorated (“PCD”) loans. At acquisition, an estimate of expected credit losses is made for PCD loans. This initial allowance for credit losses is allocated to individual PCD loans and added to the purchase price or acquisition date fair value to establish the initial amortized cost basis of the PCD loans. Any difference between the unpaid principal balance of PCD loans and the amortized cost basis is considered to relate to noncredit factors, resulting in a discount or premium that is amortized to interest income. For acquired loans not deemed PCD loans at acquisition, the difference between the initial fair value mark and the unpaid principal balance are recognized in interest income over the estimated life of the loans. In addition, an initial allowance for expected credit losses is estimated and recorded as provision expense at the acquisition date. The subsequent measurement of expected credit losses for all acquired loans is the same as the subsequent measurement of expected credit losses for originated loans. Allowance for Credit Losses - Loans : The ACL-Loans represents management’s estimate of expected credit losses over the lifetime of the loan based on loans in the Company’s loan portfolio at the balance sheet date. The Company estimates the ACL-Loans based on the amortized cost basis of the underlying loan and has made an accounting policy election to exclude accrued interest from the loan’s amortized cost basis and the related measurement of the ACL-Loans. Estimating the amount of the ACL-Loans is a function of a number of factors, including but not limited to changes in the loan portfolio, net charge-offs, trends in past due and nonaccrual loans, and the level of potential problem loans, all of which may be susceptible to significant change. Actual credit losses, net of recoveries, are deducted from the ACL-Loans. Loans are charged-off when management believes that the collectability of the principal is unlikely. Subsequent recoveries, if any, are credited to the ACL-Loans. A provision for credit losses, which is a charge against income, is recorded to bring the ACL-Loans to a level that, in management’s judgment, is appropriate to absorb expected credit losses in the loan portfolio. The Company uses the current expected credit loss model (“CECL”) to estimate the ACL-Loans. This model considers historical loss rates and other qualitative adjustments, as well as a forward-looking component that considers reasonable and supportable forecasts over the expected life of each loan. To develop the ACL-Loans estimate under the CECL model, the Company segments the loan portfolio into loan pools based on loan type and similar credit risk elements; performs an individual evaluation of PCD and other credit-deteriorated loans; calculates the historical loss rates for the segmented loan pools; applies the loss rates over the calculated life of the pooled loans; adjusts for forecasted macro-level economic conditions; and determines qualitative adjustments based on factors and conditions unique to Nicolet’s portfolio. To assess the overall appropriateness of the ACL-Loans, management applies an allocation methodology which focuses on evaluation of qualitative and environmental factors, including but not limited to: evaluation of facts and issues related to specific loans; management’s ongoing review and grading of the loan portfolio; consideration of historical loan loss and delinquency experience on each portfolio segment; trends in past due and nonaccrual loans; the risk characteristics of the various loan segments; changes in the size and character of the loan portfolio; concentrations of loans to specific borrowers or industries; existing economic conditions; the fair value of underlying collateral; and other qualitative and quantitative factors which could affect expected credit losses. Assessing these numerous factors involves significant judgment. Management allocates the ACL-Loans by pools of risk within each loan portfolio segment. The allocation methodology consists of the following components. First, a specific reserve is established for individually evaluated PCD and other credit-deteriorated loans, which management defines as nonaccrual credit relationships over $250,000, collateral dependent loans, and other loans with evidence of credit deterioration. The specific reserve in the ACL-Loans for these credit deteriorated loans is equal to the aggregate collateral or discounted cash flow shortfall. Next, management allocates the ACL-Loans with historical loss rates by loan segment. The loss factors are measured on a quarterly basis and applied to each loan segment based on current loan balances and projected for their expected remaining life. Management also allocates the ACL-Loans using the qualitative and environmental factors mentioned above. Consideration is given to those current qualitative or environmental factors that are likely to cause estimated credit losses at the evaluation date to differ from the historical loss experience of each loan segment. Lastly, management considers reasonable and supportable forecasts to assess the collectability of future cash flows. Allocations to the ACL-Loans may be made for specific loans but the entire ACL-Loans is available for any loan that, in management’s judgment, should be charged-off or for which an actual loss is realized. The allowance analysis is reviewed by the Board on a quarterly basis in compliance with internal and regulatory requirements. Credit-Related Financial Instruments : In the ordinary course of business, the Company has entered into financial instruments consisting of commitments to extend credit, financial standby letters of credit, and performance standby letters of credit. Financial standby letters of credit are issued specifically to facilitate commerce and typically result in the commitment being drawn on when the underlying transaction is consummated between the customer and the third party, while performance standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party. Such financial instruments are recorded in the consolidated financial statements when they are funded. Allowance for Credit Losses - Unfunded Commitments : In addition to the ACL-Loans, the Company has established an allowance for unfunded commitments, included in accrued interest payable and other liabilities on the consolidated balance sheets, representing expected credit losses over the contractual period for which the Company is exposed to credit risk resulting from a contractual obligation to extend credit. The ACL-Unfunded Commitments is maintained at a level that management believes is sufficient to absorb losses arising from unfunded loan commitments, and is determined quarterly based on methodology similar to the methodology for determining the ACL-Loans. Transfers of Financial Assets : Transfers of financial assets, primarily in loan participation activities, are accounted for as sales only when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of the right) to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity or the ability to unilaterally cause the holder to return assets. Premises and Equipment : Premises and equipment are stated at cost less accumulated depreciation and amortization. Premises and equipment from acquisitions were recorded at estimated fair value on the respective dates of acquisition. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets. Leasehold improvements are amortized on a straight-line basis over the shorter of the estimated useful lives of the improvements or the terms of the related leases. Maintenance and repairs are expensed as incurred. Estimated useful lives of new premises and equipment generally range as follows: Building and improvements 25 – 40 years Leasehold improvements 5 – 15 years Furniture and equipment 3 – 10 years Operating Leases : The Company accounts for its operating leases in accordance with ASC 842, Leases , which requires lessees to record almost all leases on the balance sheet as a right-of-use (“ROU”) asset and lease liability. The operating lease ROU asset represents the right to use an underlying asset during the lease term (included in accrued interest receivable and other assets accrued interest payable and other liabilities Other Real Estate Owned (“OREO”) : OREO acquired through partial or total satisfaction of loans or bank facilities no longer in use are carried at fair value less estimated costs to sell. Any write-down in the carrying value of loans or vacated bank premises at the time of transfer to OREO is charged to the ACL-Loans or to write-down of assets, respectively. OREO properties acquired in conjunction with acquisition transactions were recorded at fair value on the date of acquisition. Any subsequent write-downs to reflect current fair value, as well as gains or losses on disposition and revenues and expenses incurred to hold and maintain such properties, are treated as period costs. Goodwill and Other Intangibles : Goodwill represents the excess of the purchase price over the fair value of the net identifiable assets acquired. Goodwill is not amortized but, instead, is subject to impairment tests on at least an annual basis or more frequently if certain events or circumstances occur. Other intangibles include core deposit intangibles (which represent the value of acquired customer core deposit bases) and customer list intangibles. The core deposit intangibles have an estimated finite life, are amortized on an accelerated basis over a 10-year period, and are subject to periodic impairment evaluation. The customer list intangibles have finite lives, are amortized on a straight-line basis to expense over their initial weighted average life of approximately 12 years as of acquisition, and are subject to periodic impairment evaluation. Management periodically reviews the carrying value of its intangible assets to determine if any impairment has occurred, in which case an impairment charge would be recorded as an expense in the period of impairment, or whether changes in circumstances have occurred that would require a revision to the remaining useful life which would impact expense prospectively. In making such determination, management evaluates whether there are any adverse qualitative factors indicating that an impairment may exist, as well as the performance, on an undiscounted basis, of the underlying operations or assets which give rise to the intangible. Mortgage Servicing Rights (“MSRs”) : The Company sells originated residential mortgages into the secondary market and retains the right to service the loans sold. A mortgage servicing right asset (liability) is capitalized upon sale of such loans with the offsetting effect recorded as a gain (loss) on sale of loans in earnings (included in mortgage income, net), representing the then-current estimated fair value of future net cash flows expected to be realized for performing the servicing activities. MSRs when purchased (including MSRs purchased in acquisitions) are initially recorded at their then-estimated fair value. As the Company has not elected to measure any class of servicing assets under the fair value method, the Company utilizes the amortization method. MSRs are amortized in proportion to and over the period of estimated net servicing income, with the amortization charged to earnings (included in mortgage income, net). MSRs are carried at the lower of initial capitalized amount, net of accumulated amortization, or estimated fair value, and are included in other assets in the consolidated balance sheets. Mortgage loan servicing fee income is typically based on a contractual percentage of the outstanding principal and is recorded as income when earned (included in mortgage income, net with less material late fees and ancillary fees related to loan servicing). At each reporting date, the MSR asset is assessed for impairment based on the estimated fair value, which considers the estimated prepayment speeds and stratifications based on the risk characteristics of the underlying loans serviced (predominantly loan type and note interest rate). The value of MSRs is adversely affected when mortgage interest rates decline and mortgage loan prepayments increase. A valuation allowance is established through a charge to earnings (included in mortgage income, net) to the extent the amortized cost of the MSRs exceeds the estimated fair value by stratification. If it is later determined that all or a portion of the tempo

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2023
Business Combination and Asset Acquisition [Abstract]
ACQUISITIONS	ACQUISITIONS Completed Acquisitions: Charter Bankshares, Inc. (“Charter”): On August 26, 2022, Nicolet completed its merger with Charter, pursuant to the Agreement and Plan of Merger dated March 29, 2022, at which time Charter merged with and into Nicolet, and Charter Bank, the wholly owned bank subsidiary of Charter, was merged with and into the Bank. In the merger, Nicolet issued approximately 1.26 million shares of common stock for stock consideration of $98 million and cash consideration of $39 million, or a total purchase price of $137 million. With the Charter merger, Nicolet expanded into Western Wisconsin and Minnesota. A summary of the assets acquired and liabilities assumed in the Charter transaction, as of the acquisition date, including the purchase price allocation was as follows. (In millions, except share data) Acquired from Charter Fair Value Adjustments Estimated Fair Value Assets Acquired: Cash and cash equivalents $ 10 $ — $ 10 Investment securities 218 — 218 Loans 848 (21) 827 ACL-Loans (9) 7 (2) Premises and equipment 9 1 10 BOLI 29 — 29 Core deposit intangible — 19 19 Other assets 5 5 10 Total assets $ 1,110 $ 11 $ 1,121 Liabilities Assumed: Deposits $ 869 $ 1 $ 870 Borrowings 161 — 161 Other liabilities 3 — 3 Total liabilities $ 1,033 $ 1 $ 1,034 Net assets acquired $ 87 Purchase Price: Nicolet common stock issued (in shares) 1,262,360 Value of Nicolet common stock consideration $ 98 Cash consideration paid 39 Total purchase price $ 137 Goodwill $ 50 The Company purchased loans through the acquisition of Charter for which there was, at the date of acquisition, more than insignificant deterioration of credit quality since origination (purchased credit deteriorated loans or “PCD” loans). The carrying amount of these loans at acquisition was as follows. (In thousands) August 26, 2022 Purchase price of PCD loans at acquisition $ 24,031 Allowance for credit losses on PCD loans at acquisition 1,709 Par value of PCD acquired loans at acquisition $ 25,740 The Company accounted for the Charter acquisition under the acquisition method of accounting, and thus, the financial position and results of operations of Charter prior to the consummation date were not included in the accompanying consolidated financial statements. The accounting required assets purchased and liabilities assumed to be recorded at their respective estimated fair values at the date of acquisition. The estimated fair value was determined with the assistance of third party valuations, appraisals, and third party advisors. Goodwill arising as a result of the Charter acquisition is not deductible for tax purposes. County Bancorp, Inc. (“County”): On December 3, 2021, Nicolet completed its merger with County, pursuant to the terms of the Agreement and Plan of Merger dated June 22, 2021, at which time County merged with and into Nicolet, and Investors Community Bank, the wholly owned bank subsidiary of County, was merged with and into the Bank. In the merger, Nicolet issued approximately 2.4 million shares of common stock for stock consideration of $176 million and cash consideration of $48 million, or a total purchase price of $224 million. With the County merger, Nicolet became the premier agriculture lender throughout Wisconsin. A summary of the assets acquired and liabilities assumed in the County transaction, as of the acquisition date, including the purchase price allocation was as follows. (In millions, except share data) Acquired from County Fair Value Adjustments Estimated Fair Value Assets Acquired: Cash and cash equivalents $ 20 $ — $ 20 Investment securities 301 (1) 300 Loans 1,015 (1) 1,014 ACL-Loans (11) 8 (3) Premises and equipment 21 (4) 17 BOLI 33 — 33 Core deposit intangible — 7 7 Loan servicing rights 20 — 20 Other assets 6 (2) 4 Total assets $ 1,405 $ 7 $ 1,412 Liabilities Assumed: Deposits $ 1,027 $ 3 $ 1,030 Borrowings 218 1 219 Other liabilities 8 — 8 Total liabilities $ 1,253 $ 4 $ 1,257 Net assets acquired $ 155 Purchase Price: Nicolet common stock issued (in shares) 2,366,243 Value of Nicolet common stock consideration $ 176 Cash consideration paid 48 Total purchase price $ 224 Write-off prior investment in County (1) Goodwill $ 70 The Company purchased loans through the acquisition of County for which there was, at the date of acquisition, more than insignificant deterioration of credit quality since origination (PCD loans). The carrying amount of these loans at acquisition was as follows. (In thousands) December 3, 2021 Purchase price of PCD loans at acquisition $ 64,720 Allowance for credit losses on PCD loans at acquisition 3,490 Par value of PCD acquired loans at acquisition $ 68,210 The Company accounted for the County acquisition under the acquisition method of accounting, and thus, the financial position and results of operations of County prior to the consummation date were not included in the accompanying consolidated financial statements. The accounting required assets purchased and liabilities assumed to be recorded at their respective estimated fair values at the date of acquisition. The estimated fair value was determined with the assistance of third party valuations, appraisals, and third party advisors. Goodwill arising as a result of the County acquisition is not deductible for tax purposes. Mackinac Financial Corporation (“Mackinac”): On September 3, 2021, Nicolet completed its merger with Mackinac, pursuant to the terms of the Agreement and Plan of Merger dated April 12, 2021, at which time Mackinac merged with and into Nicolet, and mBank, the wholly owned bank subsidiary of Mackinac, was merged with and into the Bank. In the merger, Nicolet issued approximately 2.3 million shares of common stock for stock consideration of $180 million and cash consideration of $49 million, for a total purchase price of $229 million. With the Mackinac merger, Nicolet expanded into Northern Michigan and the Upper Peninsula of Michigan, and added to Nicolet’s presence in upper northeastern Wisconsin. A summary of the assets acquired and liabilities assumed in the Mackinac transaction, as of the acquisition date, including the purchase price allocation was as follows. (In millions, except share data) Acquired from Mackinac Fair Value Adjustments Estimated Fair Value Assets Acquired: Cash and cash equivalents $ 448 $ — $ 448 Investment securities 104 — 104 Loans 930 10 940 ACL-Loans (6) 4 (2) Premises and equipment 24 (3) 21 BOLI 16 — 16 Goodwill 20 (20) — Other intangibles 4 3 7 Other assets 25 (3) 22 Total assets $ 1,565 $ (9) $ 1,556 Liabilities Assumed: Deposits $ 1,365 $ 1 $ 1,366 Borrowings 28 1 29 Other liabilities 13 1 14 Total liabilities $ 1,406 $ 3 $ 1,409 Net assets acquired $ 147 Purchase Price: Nicolet common stock issued (in shares) 2,337,230 Value of Nicolet common stock consideration $ 180 Cash consideration paid 49 Total purchase price $ 229 Write-off prior investment in Mackinac (2) Goodwill $ 84 The Company purchased loans through the acquisition of Mackinac for which there was, at the date of acquisition, more than insignificant deterioration of credit quality since origination (PCD loans). The carrying amount of these loans at acquisition was as follows. (In thousands) September 3, 2021 Purchase price of PCD loans at acquisition $ 10,605 Allowance for credit losses on PCD loans at acquisition 1,896 Par value of PCD acquired loans at acquisition $ 12,501 The Company accounted for the Mackinac acquisition under the acquisition method of accounting, and thus, the financial position and results of operations of Mackinac prior to the consummation date were not included in the accompanying consolidated financial statements. The accounting required assets purchased and liabilities assumed to be recorded at their respective estimated fair values at the date of acquisition. The estimated fair value was determined with the assistance of third party valuations, appraisals, and third party advisors. Goodwill arising as a result of the Mackinac acquisition is not deductible for tax purposes. Summary Unaudited Pro Forma Information: The following unaudited pro forma information is presented for illustrative purposes only, and gives effect to the acquisitions of County and Mackinac as if the acquisitions had occurred on January 1, 2021, the beginning of the earliest period presented. The pro forma information should not be relied upon as being indicative of the historical results of operations the companies would have had if the acquisitions had occurred before such periods or the future results of operations that the companies will experience as a result of the mergers. The pro forma information, although helpful in illustrating the financial characteristics of the combined company under one set of assumptions, does not reflect the benefits of expected cost savings, opportunities to earn additional revenue, the impact of restructuring and merger-related expenses, or other factors that may result as a consequence of the mergers and, accordingly, does not attempt to predict or suggest future results. Years Ended (In thousands, except per share data) December 31, 2021 Total revenue, net of interest expense $ 320,307 Net income $ 87,860 Diluted earnings per common share $ 5.91

SECURITIES AND OTHER INVESTMENT

SECURITIES AND OTHER INVESTMENTS	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
SECURITIES AND OTHER INVESTMENTS	SECURITIES AND OTHER INVESTMENTS Securities Securities are classified as AFS or HTM on the consolidated balance sheets at the time of purchase. AFS securities include those securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity, and are carried at fair value on the consolidated balance sheets. HTM securities include those securities which the Company has both the positive intent and ability to hold to maturity, and are carried at amortized cost on the consolidated balance sheets. The amortized cost and fair value of securities available for sale and held to maturity are summarized as follows. December 31, 2023 (in thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Fair Securities AFS: U.S. Treasury securities $ 15,988 $ — $ 1,865 $ 14,123 U.S. government agency securities 7,430 — 46 7,384 State, county and municipals 360,496 651 26,325 334,822 Mortgage-backed securities 388,378 1,437 37,193 352,622 Corporate debt securities 102,895 26 9,299 93,622 Total securities AFS $ 875,187 $ 2,114 $ 74,728 $ 802,573 December 31, 2022 (in thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Fair Securities AFS: U.S. Treasury securities $ 192,116 $ — $ 8,286 $ 183,830 U.S. government agency securities 2,133 — 33 2,100 State, county and municipals 433,733 123 35,668 398,188 Mortgage-backed securities 227,650 10 26,728 200,932 Corporate debt securities 140,712 3 8,147 132,568 Total securities AFS $ 996,344 $ 136 $ 78,862 $ 917,618 Securities HTM: U.S. Treasury securities $ 497,648 $ — $ 35,722 $ 461,926 U.S. government agency securities 8,744 46 — 8,790 State, county and municipals 34,874 — 3,349 31,525 Mortgage-backed securities 137,862 — 16,751 121,111 Total securities HTM $ 679,128 $ 46 $ 55,822 $ 623,352 On March 7, 2023, Nicolet executed the sale of $500 million (par value) U.S. Treasury held to maturity securities for a pre-tax loss of $37.7 million or an after-tax loss of $28 million. Proceeds from the sale were used to reduce existing FHLB borrowings with the remainder held in investable cash. As a result of the sale of securities previously classified as held to maturity, the remaining unsold portfolio of held to maturity securities was reclassified to available for sale with a carrying value of approximately $157 million (at the time of reclassification). The unrealized loss on this portfolio of $20 million (at the time of reclassification) increased the balance of accumulated other comprehensive loss $15 million, net of the deferred tax effect, and is subject to future market changes. Proceeds and realized gains / losses from the sale of securities AFS were as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Securities AFS: Gross gains $ 268 $ 28 $ 5 Gross losses (3,581) (272) (288) Gains (losses) on sales of securities AFS, net $ (3,313) $ (244) $ (283) Proceeds from sales of securities AFS * $ 65,749 $ 28,438 $ 42,973 Securities HTM: Gross gains $ — $ — $ — Gross losses (37,723) — — Gains (losses) on sales of securities HTM, net $ (37,723) $ — $ — Proceeds from sales of securities HTM $ 460,051 $ — $ — * Includes proceeds of $21 million recognized on the sale of securities AFS upon acquisition of Charter in August 2022 for which no gain or loss was recognized in the income statement as the investment securities were marked to fair value through purchase accounting. All mortgage-backed securities included in the securities portfolio were issued by U.S. government agencies and corporations. Securities with a fair value of $364 million and $883 million as of December 31, 2023 and 2022, respectively, were pledged as collateral to secure public deposits and borrowings, as applicable, and for liquidity or other purposes as required by regulation. Accrued interest on securities totaled $5 million and $6 million at December 31, 2023 and 2022, respectively, and is included in accrued interest receivable and other assets on the consolidated balance sheets. The following tables present gross unrealized losses and the related estimated fair value of investment securities for which an allowance for credit losses has not been recorded, aggregated by investment category and the length of time the individual securities have been in a continuous unrealized loss position. December 31, 2023 Less than 12 months 12 months or more Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized Number of Securities Securities AFS: U.S. Treasury securities $ — $ — $ 14,123 $ 1,865 $ 14,123 $ 1,865 1 U.S. government agency securities 4,621 31 1,793 15 6,414 46 10 State, county and municipals 29,336 330 257,916 25,995 287,252 26,325 528 Mortgage-backed securities 6 — 291,124 37,193 291,130 37,193 433 Corporate debt securities — — 85,265 9,299 85,265 9,299 59 Total $ 33,963 $ 361 $ 650,221 $ 74,367 $ 684,184 $ 74,728 1,031 December 31, 2022 Less than 12 months 12 months or more Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized Number of Securities Securities AFS: U.S. Treasury securities $ 448 $ 14 $ 183,382 $ 8,272 $ 183,830 $ 8,286 9 U.S. government agency securities 2,083 32 17 1 2,100 33 9 State, county and municipals 277,546 18,041 86,569 17,627 364,115 35,668 812 Mortgage-backed securities 102,108 11,320 95,614 15,408 197,722 26,728 376 Corporate debt securities 114,887 6,186 12,938 1,961 127,825 8,147 90 Total $ 497,072 $ 35,593 $ 378,520 $ 43,269 $ 875,592 $ 78,862 1,296 Securities HTM: U.S. Treasury securities $ — $ — $ 461,926 $ 35,722 $ 461,926 $ 35,722 6 State, county and municipals 17,591 1,594 11,654 1,755 29,245 3,349 58 Mortgage-backed securities 68,108 8,029 53,003 8,722 121,111 16,751 106 Total $ 85,699 $ 9,623 $ 526,583 $ 46,199 $ 612,282 $ 55,822 170 During first quarter 2023, the Company recognized provision expense of $2.3 million related to the expected credit loss on a bank subordinated debt investment (acquired in an acquisition), and immediately charged-off the full investment. The Company does not consider its remaining securities AFS with unrealized losses to be attributable to credit-related factors, as the unrealized losses in each category have occurred as a result of changes in noncredit-related factors such as changes in interest rates, market spreads and market conditions subsequent to purchase, not credit deterioration. Furthermore, the Company does not have the intent to sell any of these securities AFS and believes that it is more likely than not that we will not have to sell any such securities before a recovery of cost. As of December 31, 2023, 2022, and 2021, no allowance for credit losses on securities AFS was recognized. The Company evaluated the securities HTM and determined no allowance for credit losses was necessary at December 31, 2022. The U.S. Treasury and U.S. government agency securities are guaranteed by the U.S. government. For the state, county and municipal securities, management considered issuer bond ratings, historical loss rates by bond ratings, whether issuers continue to make timely principal and interest payments per the contractual terms of the investment securities, internal forecasts, and whether or not such investment securities provide insurance, other credit enhancement, or are pre-refunded by the issuers. For the mortgage-backed securities, all such securities were issued by U.S. government agencies and corporations, which are currently explicitly or implicitly guaranteed by the U.S. government and have a long history of no credit losses. The amortized cost and fair value of investment securities by contractual maturity are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties; as this is particularly inherent in mortgage-backed securities, these securities are not included in the maturity categories below. As of December 31, 2023 Securities AFS (in thousands) Amortized Cost Fair Value Due in less than one year $ 55,132 $ 54,675 Due in one year through five years 117,392 109,079 Due after five years through ten years 208,859 186,493 Due after ten years 105,426 99,704 486,809 449,951 Mortgage-backed securities 388,378 352,622 Total $ 875,187 $ 802,573 Other Investments Other investments include “restricted” equity securities, equity securities with readily determinable fair values, and private company securities. The carrying value of other investments are summarized as follows. (in thousands) December 31, 2023 December 31, 2022 Federal Reserve Bank stock $ 33,087 $ 32,219 FHLB stock 9,674 18,625 Equity securities with readily determinable fair values 4,240 4,376 Other investments 10,559 10,066 Total other investments $ 57,560 $ 65,286

LOANS, ALLOWANCE FOR LOAN LOSSE

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY	12 Months Ended
	Dec. 31, 2023
Receivables [Abstract]
LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY	LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY Loans : The loan composition was as follows. December 31, 2023 December 31, 2022 (in thousands) Amount % of Total Amount % of Total Commercial & industrial $ 1,284,009 20 % $ 1,304,819 21 % Owner-occupied commercial real estate (“CRE”) 956,594 15 954,599 15 Agricultural 1,161,531 18 1,088,607 18 Commercial 3,402,134 53 3,348,025 54 CRE investment 1,142,251 18 1,149,949 19 Construction & land development 310,110 5 318,600 5 Commercial real estate 1,452,361 23 1,468,549 24 Commercial-based loans 4,854,495 76 4,816,574 78 Residential construction 75,726 1 114,392 2 Residential first mortgage 1,167,109 19 1,016,935 16 Residential junior mortgage 200,884 3 177,332 3 Residential real estate 1,443,719 23 1,308,659 21 Retail & other 55,728 1 55,266 1 Retail-based loans 1,499,447 24 1,363,925 22 Loans 6,353,942 100 % 6,180,499 100 % Less ACL-Loans 63,610 61,829 Loans, net $ 6,290,332 $ 6,118,670 ACL-Loans to loans 1.00 % 1.00 % Accrued interest on loans totaled $19 million and $15 million at December 31, 2023 and December 31, 2022, respectively, and is included in accrued interest receivable and other assets Allowance for Credit Losses-Loans : The majority of the Company’s loans, commitments, and letters of credit have been granted to customers in the Company’s market area. Although the Company has a diversified loan portfolio, the credit risk in the loan portfolio is largely influenced by general economic conditions and trends of the counties and markets in which the debtors operate, and the resulting impact on the operations of borrowers or on the value of underlying collateral, if any. A roll forward of the allowance for credit losses - loans was as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Beginning balance $ 61,829 $ 49,672 $ 32,173 ACL on PCD loans acquired — 1,937 5,159 Provision for credit losses 2,650 10,950 12,500 Charge-offs (1,653) (1,033) (513) Recoveries 784 303 353 Net (charge-offs) recoveries (869) (730) (160) Ending balance $ 63,610 $ 61,829 $ 49,672 The following table presents the balance and activity in the ACL-Loans by portfolio segment. Year Ended December 31, 2023 (in thousands) Commercial Owner- Agricultural CRE Construction & land Residential Residential Residential Retail Total ACL-Loans Beginning balance $ 16,350 $ 9,138 $ 9,762 $ 12,744 $ 2,572 $ 1,412 $ 6,976 $ 1,846 $ 1,029 $ 61,829 Provision (1,205) 470 2,930 (51) (132) (496) 346 347 441 2,650 Charge-offs (440) (773) (66) — — — (5) (96) (273) (1,653) Recoveries 520 247 3 — — — 3 1 10 784 Net (charge-offs) recoveries 80 (526) (63) — — — (2) (95) (263) (869) Ending balance $ 15,225 $ 9,082 $ 12,629 $ 12,693 $ 2,440 $ 916 $ 7,320 $ 2,098 $ 1,207 $ 63,610 As % of ACL-Loans 24 % 14 % 20 % 20 % 4 % — % 12 % 4 % 2 % 100 % For comparison purposes, the following table presents the balance and activity in the ACL-Loans by portfolio segment for the prior year-end period. Year Ended December 31, 2022 (in thousands) Commercial Owner- Agricultural CRE Construction & land Residential Residential Residential Retail Total ACL-Loans Beginning balance $ 12,613 $ 7,222 $ 9,547 $ 8,462 $ 1,812 $ 900 $ 6,844 $ 1,340 $ 932 $ 49,672 ACL on PCD loans 1,408 384 — 38 2 — 93 12 — 1,937 Provision 2,415 2,087 215 4,075 758 512 96 493 299 10,950 Charge-offs (190) (555) — — — — (65) — (223) (1,033) Recoveries 104 — — 169 — — 8 1 21 303 Net (charge-offs) recoveries (86) (555) — 169 — — (57) 1 (202) (730) Ending balance $ 16,350 $ 9,138 $ 9,762 $ 12,744 $ 2,572 $ 1,412 $ 6,976 $ 1,846 $ 1,029 $ 61,829 As % of ACL-Loans 26 % 15 % 16 % 21 % 4 % 2 % 11 % 3 % 2 % 100 % Allowance for Credit Losses-Unfunded Commitments : In addition to the ACL-Loans, the Company has established an ACL-Unfunded Commitments of $3.0 million at both December 31, 2023 and December 31, 2022, classified in accrued interest payable and other liabilities on the consolidated balance sheets. Provision for Credit Losses : The provision for credit losses is determined by the Company as the amount to be added to the ACL loss accounts for various types of financial instruments (including loans, investment securities, and off-balance sheet credit exposures) after net charge-offs have been deducted to bring the ACL to a level that, in management’s judgment, is necessary to absorb expected credit losses over the lives of the respective financial instruments. The following table presents the components of the provision for credit losses. Years Ended December 31, (in thousands) 2023 2022 2021 Provision for credit losses on: Loans $ 2,650 $ 10,950 $ 12,500 Unfunded commitments — 550 2,400 Investment securities 2,340 — — Total provision for credit losses $ 4,990 $ 11,500 $ 14,900 Collateral Dependent Loans : A loan is considered to be collateral dependent when, based upon management’s assessment, the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the operation or sale of the collateral. For collateral dependent loans, expected credit losses are based on the fair value of the collateral at the balance sheet date, with consideration for estimated selling costs if satisfaction of the loan depends on the sale of the collateral. The following table presents collateral dependent loans by portfolio segment and collateral type, including those loans with and without a related allowance allocation. December 31, 2023 Collateral Type (in thousands) Real Estate Other Business Assets Total Without an Allowance With an Allowance Allowance Allocation Commercial & industrial $ — $ 2,576 $ 2,576 $ 2,164 $ 412 $ 196 Owner-occupied CRE 3,614 — 3,614 3,465 149 24 Agricultural 6,931 5,219 12,150 7,261 4,889 117 CRE investment 1,261 — 1,261 871 390 18 Construction & land development — — — — — — Residential construction — — — — — — Residential first mortgage 674 — 674 674 — — Residential junior mortgage — — — — — — Retail & other — — — — — — Total loans $ 12,480 $ 7,795 $ 20,275 $ 14,435 $ 5,840 $ 355 December 31, 2022 Collateral Type (in thousands) Real Estate Other Business Assets Total Without an Allowance With an Allowance Allowance Allocation Commercial & industrial $ — $ 3,475 $ 3,475 $ 1,927 $ 1,548 $ 595 Owner-occupied CRE 4,907 — 4,907 4,699 208 53 Agricultural 13,758 6,458 20,216 14,358 5,858 261 CRE investment 2,713 — 2,713 979 1,734 212 Construction & land development 670 — 670 670 — — Residential construction — — — — — — Residential first mortgage 91 — 91 91 — — Residential junior mortgage — — — — — — Retail & other — — — — — — Total loans $ 22,139 $ 9,933 $ 32,072 $ 22,724 $ 9,348 $ 1,121 Past Due and Nonaccrual Loans : The following tables present past due loans by portfolio segment. December 31, 2023 (in thousands) 30-89 Days Past 90 Days & Over Current Total Commercial & industrial $ 540 $ 4,046 $ 1,279,423 $ 1,284,009 Owner-occupied CRE 2,123 4,399 950,072 956,594 Agricultural 12 12,185 1,149,334 1,161,531 CRE investment 3,060 1,453 1,137,738 1,142,251 Construction & land development 171 161 309,778 310,110 Residential construction — — 75,726 75,726 Residential first mortgage 2,663 4,059 1,160,387 1,167,109 Residential junior mortgage 547 150 200,187 200,884 Retail & other 327 172 55,229 55,728 Total loans $ 9,443 $ 26,625 $ 6,317,874 $ 6,353,942 Percent of total loans 0.1 % 0.4 % 99.5 % 100.0 % December 31, 2022 (in thousands) 30-89 Days Past 90 Days & Over Current Total Commercial & industrial $ 210 $ 3,328 $ 1,301,281 $ 1,304,819 Owner-occupied CRE 833 5,647 948,119 954,599 Agricultural 20 20,416 1,068,171 1,088,607 CRE investment — 3,832 1,146,117 1,149,949 Construction & land development — 771 317,829 318,600 Residential construction — — 114,392 114,392 Residential first mortgage 3,628 3,780 1,009,527 1,016,935 Residential junior mortgage 236 224 176,872 177,332 Retail & other 261 82 54,923 55,266 Total loans $ 5,188 $ 38,080 $ 6,137,231 $ 6,180,499 Percent of total loans 0.1 % 0.6 % 99.3 % 100.0 % The following table presents nonaccrual loans by portfolio segment. The nonaccrual loans without a related allowance for credit losses have been reflected in the collateral dependent loans table above. Total Nonaccrual Loans (in thousands) December 31, 2023 % to Total December 31, 2022 % to Total Commercial & industrial $ 4,046 15 % $ 3,328 9 % Owner-occupied CRE 4,399 16 5,647 15 Agricultural 12,185 46 20,416 53 CRE investment 1,453 5 3,832 10 Construction & land development 161 1 771 2 Residential construction — — — — Residential first mortgage 4,059 15 3,780 10 Residential junior mortgage 150 1 224 1 Retail & other 172 1 82 — Nonaccrual loans $ 26,625 100 % $ 38,080 100 % Percent of total loans 0.4 % 0.6 % Credit Quality Information : The following tables present total loans by risk categories and year of origination. Acquired loans have been included based upon the actual origination date. December 31, 2023 Amortized Cost Basis by Origination Year (in thousands) 2023 2022 2021 2020 2019 Prior Revolving Revolving to Term TOTAL Commercial & industrial Grades 1-4 $ 223,515 $ 234,193 $ 171,555 $ 66,026 $ 49,054 $ 81,272 $ 359,284 $ — $ 1,184,899 Grade 5 3,252 13,656 7,516 3,388 5,074 7,020 18,753 — 58,659 Grade 6 — 562 502 187 3 1,009 10,974 — 13,237 Grade 7 5,742 3,702 2,655 2,409 1,769 9,244 1,693 — 27,214 Total $ 232,509 $ 252,113 $ 182,228 $ 72,010 $ 55,900 $ 98,545 $ 390,704 $ — $ 1,284,009 Current period gross charge-offs $ — $ (89) $ (114) $ — $ — $ (222) $ (15) $ — $ (440) Owner-occupied CRE Grades 1-4 $ 114,704 $ 156,723 $ 181,128 $ 91,038 $ 85,430 $ 247,730 $ 4,181 $ — $ 880,934 Grade 5 5,416 4,024 7,858 5,092 3,994 27,585 52 — 54,021 Grade 6 — — 3,905 — 1,531 12 — — 5,448 Grade 7 — 1,304 1,071 6,988 338 6,340 150 — 16,191 Total $ 120,120 $ 162,051 $ 193,962 $ 103,118 $ 91,293 $ 281,667 $ 4,383 $ — $ 956,594 Current period gross charge-offs $ — $ — $ — $ — $ — $ (773) $ — $ — $ (773) Agricultural Grades 1-4 $ 120,200 $ 274,491 $ 134,706 $ 78,944 $ 22,985 $ 139,212 $ 277,170 $ — $ 1,047,708 Grade 5 6,345 11,975 5,718 703 394 33,658 15,522 — 74,315 Grade 6 — 130 1,017 — 51 2,256 194 — 3,648 Grade 7 2,519 6,691 5,360 428 1,679 12,098 7,085 — 35,860 Total $ 129,064 $ 293,287 $ 146,801 $ 80,075 $ 25,109 $ 187,224 $ 299,971 $ — $ 1,161,531 Current period gross charge-offs $ — $ — $ — $ — $ — $ (66) $ — $ — $ (66) CRE investment Grades 1-4 $ 30,720 $ 194,442 $ 256,765 $ 169,078 $ 113,510 $ 283,339 $ 11,146 $ — $ 1,059,000 Grade 5 2,790 7,746 17,899 9,857 11,232 23,108 49 — 72,681 Grade 6 — — — — — 1,340 65 — 1,405 Grade 7 — 51 21 — 1,034 8,059 — — 9,165 Total $ 33,510 $ 202,239 $ 274,685 $ 178,935 $ 125,776 $ 315,846 $ 11,260 $ — $ 1,142,251 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Construction & land development Grades 1-4 $ 51,253 $ 149,155 $ 64,761 $ 9,441 $ 4,939 $ 22,548 $ 2,883 $ — $ 304,980 Grade 5 — 23 3,044 1,264 504 88 — — 4,923 Grade 7 46 — — — — 86 75 — 207 Total $ 51,299 $ 149,178 $ 67,805 $ 10,705 $ 5,443 $ 22,722 $ 2,958 $ — $ 310,110 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential construction Grades 1-4 $ 57,033 $ 13,035 $ 3,316 $ 1,118 $ 130 $ 1,094 $ — $ — $ 75,726 Total $ 57,033 $ 13,035 $ 3,316 $ 1,118 $ 130 $ 1,094 $ — $ — $ 75,726 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential first mortgage Grades 1-4 $ 164,917 $ 389,246 $ 247,957 $ 130,857 $ 56,223 $ 162,424 $ 887 $ 2 $ 1,152,513 Grade 5 — 1,286 1,088 1,250 2,239 2,913 — — 8,776 Grade 7 28 392 616 388 1,117 3,279 — — 5,820 Total $ 164,945 $ 390,924 $ 249,661 $ 132,495 $ 59,579 $ 168,616 $ 887 $ 2 $ 1,167,109 Current period gross charge-offs $ — $ — $ — $ — $ — $ (5) $ — $ — $ (5) Residential junior mortgage Grades 1-4 $ 14,020 $ 7,277 $ 4,053 $ 4,187 $ 2,753 $ 3,909 $ 157,960 $ 6,342 $ 200,501 Grade 7 31 31 202 — — 27 92 — 383 Total $ 14,051 $ 7,308 $ 4,255 $ 4,187 $ 2,753 $ 3,936 $ 158,052 $ 6,342 $ 200,884 Current period gross charge-offs $ — $ — $ — $ — $ — $ (96) $ — $ — $ (96) Retail & other Grades 1-4 $ 8,207 $ 8,107 $ 5,345 $ 2,434 $ 1,689 $ 3,869 $ 25,891 $ — $ 55,542 Grade 5 — — 38 — — — — — 38 Grade 7 31 — 25 8 19 65 — — 148 Total $ 8,238 $ 8,107 $ 5,408 $ 2,442 $ 1,708 $ 3,934 $ 25,891 $ — $ 55,728 Current period gross charge-offs $ (7) $ (1) $ — $ (1) $ — $ (52) $ (212) $ — $ (273) Total loans $ 810,769 $ 1,478,242 $ 1,128,121 $ 585,085 $ 367,691 $ 1,083,584 $ 894,106 $ 6,344 $ 6,353,942 December 31, 2022 Amortized Cost Basis by Origination Year (in thousands) 2022 2021 2020 2019 2018 Prior Revolving Revolving to Term TOTAL Commercial & industrial Grades 1-4 $ 317,394 $ 226,065 $ 101,374 $ 68,884 $ 50,189 $ 77,589 $ 360,978 $ — $ 1,202,473 Grade 5 9,938 5,902 10,811 1,530 3,986 4,562 20,617 — 57,346 Grade 6 1,459 2,283 629 511 402 11,653 14,047 — 30,984 Grade 7 556 293 3,211 2,990 775 1,070 5,121 — 14,016 Total $ 329,347 $ 234,543 $ 116,025 $ 73,915 $ 55,352 $ 94,874 $ 400,763 $ — $ 1,304,819 Current period gross charge-offs $ (38) $ (41) $ (2) $ — $ (109) $ — $ — $ — $ (190) Owner-occupied CRE Grades 1-4 $ 151,391 $ 190,313 $ 105,156 $ 100,606 $ 91,479 $ 252,574 $ 6,734 $ — $ 898,253 Grade 5 5,241 3,192 4,287 2,163 4,791 14,632 348 — 34,654 Grade 6 — — 763 2,361 — 877 — — 4,001 Grade 7 227 706 6,344 616 — 9,798 — — 17,691 Total $ 156,859 $ 194,211 $ 116,550 $ 105,746 $ 96,270 $ 277,881 $ 7,082 $ — $ 954,599 Current period gross charge-offs $ — $ — $ — $ — $ — $ (555) $ — $ — $ (555) Agricultural Grades 1-4 $ 275,208 $ 145,272 $ 85,413 $ 25,463 $ 19,687 $ 130,849 $ 249,033 $ — $ 930,925 Grade 5 13,295 18,178 2,694 1,992 517 43,927 21,199 — 101,802 Grade 6 115 1,457 28 33 — 5,258 429 — 7,320 Grade 7 7,165 2,632 720 1,977 4,611 19,948 11,507 — 48,560 Total $ 295,783 $ 167,539 $ 88,855 $ 29,465 $ 24,815 $ 199,982 $ 282,168 $ — $ 1,088,607 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — CRE investment Grades 1-4 $ 205,930 $ 229,252 $ 192,527 $ 134,301 $ 79,649 $ 248,595 $ 11,383 $ — $ 1,101,637 Grade 5 567 1,649 3,578 4,266 3,086 24,897 — — 38,043 Grade 6 — — — 1,170 2,396 2,483 206 — 6,255 Grade 7 — — 121 299 245 3,140 209 — 4,014 Total $ 206,497 $ 230,901 $ 196,226 $ 140,036 $ 85,376 $ 279,115 $ 11,798 $ — $ 1,149,949 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Construction & land development Grades 1-4 $ 104,804 $ 140,727 $ 12,188 $ 9,747 $ 23,811 $ 13,138 $ 13,235 $ — $ 317,650 Grade 5 37 — — 14 — 95 — — 146 Grade 7 33 — — — — 771 — — 804 Total $ 104,874 $ 140,727 $ 12,188 $ 9,761 $ 23,811 $ 14,004 $ 13,235 $ — $ 318,600 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential construction Grades 1-4 $ 92,417 $ 16,774 $ 966 $ 123 $ 336 $ 229 $ 3,547 $ — $ 114,392 Total $ 92,417 $ 16,774 $ 966 $ 123 $ 336 $ 229 $ 3,547 $ — $ 114,392 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential first mortgage Grades 1-4 $ 318,628 $ 272,011 $ 147,857 $ 68,975 $ 31,208 $ 162,153 $ 2,080 $ 3 $ 1,002,915 Grade 5 1,494 758 997 1,803 2,272 465 — — 7,789 Grade 6 — — — 711 — — — — 711 Grade 7 154 329 188 349 197 4,303 — — 5,520 Total $ 320,276 $ 273,098 $ 149,042 $ 71,838 $ 33,677 $ 166,921 $ 2,080 $ 3 $ 1,016,935 Current period gross charge-offs $ — $ — $ — $ — $ — $ (65) $ — $ — $ (65) Residential junior mortgage Grades 1-4 $ 10,119 $ 4,580 $ 5,207 $ 3,151 $ 1,573 $ 3,409 $ 142,784 $ 5,762 $ 176,585 Grade 5 — — — — — 143 165 — 308 Grade 7 — 206 — — — 24 209 — 439 Total $ 10,119 $ 4,786 $ 5,207 $ 3,151 $ 1,573 $ 3,576 $ 143,158 $ 5,762 $ 177,332 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Retail & other Grades 1-4 $ 12,318 $ 8,957 $ 4,221 $ 3,188 $ 1,035 $ 24,950 $ 492 $ — $ 55,161 Grade 5 — 23 — — — — — — 23 Grade 7 — 23 22 2 30 5 — — 82 Total $ 12,318 $ 9,003 $ 4,243 $ 3,190 $ 1,065 $ 24,955 $ 492 $ — $ 55,266 Current period gross charge-offs $ — $ (1) $ (6) $ (1) $ — $ — $ (215) $ — $ (223) Total loans $ 1,528,490 $ 1,271,582 $ 689,302 $ 437,225 $ 322,275 $ 1,061,537 $ 864,323 $ 5,765 $ 6,180,499 An internal loan review function rates loans using a grading system based on different risk categories. Loans with a Substandard grade are considered to have a greater risk of loss and may be assigned allocations for loss based on specific review of the weaknesses observed in the individual credits. Such loans are monitored by the loan review function to help ensure early identification of any deterioration. A description of the loan risk categories used by the Company follows. Grades 1-4, Pass : Credits exhibit adequate cash flows, appropriate management and financial ratios within industry norms and/or are supported by sufficient collateral. Some credits in these rating categories may require a need for monitoring but elements of concern are not severe enough to warrant an elevated rating. Grade 5, Watch : Credits with this rating are adequately secured and performing but are being monitored due to the presence of various short-term weaknesses which may include unexpected, short-term adverse financial performance, managerial problems, potential impact of a decline in the entire industry or local economy and delinquency issues. Loans to individuals or loans supported by guarantors with marginal net worth or collateral may be included in this rating category. Grade 6, Special Mention : Credits with this rating have potential weaknesses that, without the Company’s attention and correction may result in deterioration of repayment prospects. These assets are considered Criticized Assets. Potential weaknesses may include adverse financial trends for the borrower or industry, repeated lack of compliance with Company requests, increasing debt to net worth, serious management conditions and decreasing cash flow. Grade 7, Substandard : Assets with this rating are characterized by the distinct possibility the Company will sustain some loss if deficiencies are not corrected. All foreclosures, liquidations, and nonaccrual loans are considered to be categorized in this rating, regardless of collateral sufficiency. Modifications to Borrowers Experiencing Financial Difficulty: On January 1, 2023, the Company adopted ASU 2022-02, which eliminated the accounting guidance for TDRs by creditors and enhanced the disclosure requirements for certain loan modifications to borrowers experiencing financial difficulty. The following table presents the amortized cost of loans that were both experiencing financial difficulty and were modified during the year ended December 31, 2023, aggregated by portfolio segment and type of modification. (in thousands) Payment Delay Term Extension Interest Rate Reduction Term Extension & Interest Rate Reduction Total % of Total Loans Commercial & industrial $ 412 $ — $ 85 $ — $ 497 0.04 % Owner-occupied CRE — — — — — — % Agricultural 105 — — — 105 0.01 % CRE investment — — — — — — % Construction & land development — — — — — — % Residential first mortgage — — — — — — % Total $ 517 $ — $ 85 $ — $ 602 0.01 % The loans presented in the table above have had more than insignificant payment delays (which the Company has defined as payment delays in excess of three months). These modified loans are closely monitored by the Company to understand the effectiveness of its modification efforts, and such loans generally remain in nonaccrual status pending a sustained period of performance in accordance with the modified terms. As of December 31, 2023, there were no loans made to borrowers experiencing financial difficulty that were modified during the current period and subsequently defaulted, and there were no commitments to lend additional funds to such debtors. Troubled Debt Restructuring Disclosures Prior to Adoption of ASU 2022-02 : As of December 31, 2022, the Company had restructured loans totaling $18 million, with a pre-modification balance of $24 million, all of which were also reflected as nonaccrual loans. There were no restructured loans modified during 2022 that subsequently defaulted, and there were no commitments to lend additional funds to such debtors.

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
PREMISES AND EQUIPMENT	PREMISES AND EQUIPMENT Premises and equipment, less accumulated depreciation and amortization, is summarized as follows. (in thousands) December 31, 2023 December 31, 2022 Land $ 18,015 $ 14,841 Land improvements 5,461 5,361 Building and improvements 99,664 89,630 Leasehold improvements 7,228 7,079 Furniture and equipment 38,838 35,717 169,206 152,628 Less accumulated depreciation and amortization 50,450 43,672 Premises and equipment, net $ 118,756 $ 108,956 Depreciation and amortization expense was $8.2 million in 2023, $7.6 million in 2022, and $5.0 million in 2021. The Company and certain of its subsidiaries are obligated under non-cancelable operating leases for facilities, certain of which provide for rental adjustments based upon increases in cost of living adjustments and other indices. Rent expense under leases totaled $2.6 million in 2023, $2.2 million in 2022, and $1.3 million in 2021. Nicolet leases space under non-cancelable operating lease agreements for certain bank branch facilities with remaining lease terms of 1 to 10 years. Certain lease arrangements contain extension options which typically range from 5 to 10 years at the then fair market rental rates. The lease asset and liability considers renewal options when they are reasonably certain of being exercised. A summary of net lease cost and selected other information related to operating leases was as follows. Years Ended ($ in thousands) December 31, 2023 December 31, 2022 December 31, 2021 Net lease cost: Operating lease cost $ 2,004 $ 1,778 $ 1,018 Variable lease cost 631 448 234 Net lease cost $ 2,635 $ 2,226 $ 1,252 Selected other operating lease information: Weighted average remaining lease term (years) 5.8 5.4 6.3 Weighted average discount rate 2.7 % 2.3 % 1.5 % The following table summarizes the maturity of remaining lease liabilities. Years Ending December 31, (in thousands) 2024 $ 2,486 2025 2,176 2026 1,994 2027 1,831 2028 1,312 Thereafter 1,842 Total future minimum lease payments 11,641 Less: amount representing interest (315) Present value of net future minimum lease payments $ 11,326

GOODWILL AND OTHER INTANGIBLES

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS	GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS Management periodically reviews the carrying value of its goodwill and other intangibles for potential impairment. In making such determination, management evaluates whether there are any adverse qualitative factors indicating that an impairment may exist, as well as the overall financial performance of the Company and the performance of the underlying operations or assets which give rise to the intangible. Management also regularly monitors economic factors for potential impairment indications on the value of our franchise, stability of deposits, and wealth client base, underlying our goodwill and other intangibles. Management concluded no impairment was indicated for 2023 or 2022. A summary of goodwill and other intangibles was as follows. (in thousands) December 31, 2023 December 31, 2022 Goodwill $ 367,387 $ 367,387 Core deposit intangibles 25,112 32,701 Customer list intangibles 1,867 2,350 Other intangibles 26,979 35,051 Goodwill and other intangibles, net $ 394,366 $ 402,438 Goodwill : Goodwill is not amortized but, instead, is subject to impairment tests on at least an annual basis or more frequently if certain events or circumstances occur. During 2022, goodwill increased due to the acquisition of Charter. (in thousands) December 31, 2023 December 31, 2022 Goodwill: Goodwill at beginning of year $ 367,387 $ 317,189 Acquisitions — 49,970 Purchase accounting adjustment — 228 Goodwill at end of year $ 367,387 $ 367,387 Other intangibles : Other intangible assets, consisting of core deposit intangibles and customer list intangibles, are amortized over their estimated finite lives. During 2022, core deposit intangibles increased due to the acquisition of Charter. (in thousands) December 31, 2023 December 31, 2022 Core deposit intangibles: Gross carrying amount $ 60,724 $ 60,724 Accumulated amortization (35,612) (28,023) Net book value $ 25,112 $ 32,701 Additions during the period $ — $ 19,364 Amortization during the period $ 7,589 $ 6,108 Customer list intangibles: Gross carrying amount $ 5,523 $ 5,523 Accumulated amortization (3,656) (3,173) Net book value $ 1,867 $ 2,350 Amortization during the period $ 483 $ 508 Mortgage servicing rights : A summary of the changes in the MSR asset was as follows. (in thousands) December 31, 2023 December 31, 2022 MSR asset: MSR asset at beginning of year $ 13,080 $ 13,636 Capitalized MSR 1,540 2,327 Amortization during the period (2,965) (2,883) MSR asset at end of year $ 11,655 $ 13,080 Valuation allowance at beginning of year $ (500) $ (1,200) Reversals 500 700 Valuation allowance at end of year $ — $ (500) MSR asset, net $ 11,655 $ 12,580 Fair value of MSR asset at end of period $ 16,810 $ 17,215 Residential mortgage loans serviced for others $ 1,609,395 $ 1,637,109 Net book value of MSR asset to loans serviced for others 0.72 % 0.77 % The Company periodically evaluates its mortgage servicing rights asset for impairment. At each reporting date, impairment is assessed based on estimated fair value using estimated prepayment speeds of the underlying mortgage loans serviced and stratification based on the risk characteristics of the underlying loans (predominantly loan type and note interest rate). Loan servicing rights : The Company acquired an agricultural LSR asset in December 2021 which will be amortized over the estimated remaining loan service period. The Company does not expect to add new loans to this servicing portfolio. A summary of the changes in the LSR asset was as follows. (in thousands) December 31, 2023 December 31, 2022 LSR asset: LSR asset at beginning of year $ 11,039 $ 20,055 Amortization during the period (2,208) (9,016) LSR asset at end of year $ 8,831 $ 11,039 Agricultural loans serviced for others $ 492,137 $ 538,392 The following table shows the estimated future amortization expense for amortizing intangible assets and servicing assets. The projections are based on existing asset balances, the current interest rate environment and prepayment speeds as of December 31, 2023. The actual amortization expense the Company recognizes in any given period may be significantly different depending upon acquisition or sale activities, changes in interest rates, prepayment speeds, market conditions, regulatory requirements and events or circumstances that indicate the carrying amount of an asset may not be recoverable. (in thousands) Core deposit Customer list MSR asset LSR asset Years Ending December 31, 2024 $ 6,298 $ 449 $ 2,704 $ 1,962 2025 5,161 449 2,037 1,717 2026 3,983 249 1,495 1,472 2027 3,218 166 1,495 1,227 2028 2,622 166 1,494 981 Thereafter 3,830 388 2,430 1,472 Total $ 25,112 $ 1,867 $ 11,655 $ 8,831

OTHER REAL ESTATE OWNED

OTHER REAL ESTATE OWNED	12 Months Ended
	Dec. 31, 2023
Real Estate [Abstract]
OTHER REAL ESTATE OWNED	OTHER REAL ESTATE OWNED A summary of OREO, which is included in other assets in the consolidated balance sheets, for the periods indicated was as follows. Years Ended December 31, (in thousands) 2023 2022 Balance at beginning of period $ 1,975 $ 11,955 Transfer in loans at net realizable value 985 183 Transfer in former bank branch properties at net realizable value — 25 Sales proceeds (1,933) (13,150) Net gain from sales 421 3,206 Write-downs (181) (244) Balance at end of period $ 1,267 $ 1,975

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2023
Deposits [Abstract]
DEPOSITS	DEPOSITS The deposit composition was as follows. December 31, 2023 December 31, 2022 (in thousands) Amount % of Total Amount % of Total Noninterest-bearing demand $ 1,958,709 27 % $ 2,361,816 33 % Interest-bearing demand 1,055,520 15 % 1,279,850 18 % Money market 1,891,287 26 % 1,707,619 24 % Savings 768,401 11 % 931,417 13 % Time 1,523,883 21 % 898,219 12 % Total deposits $ 7,197,800 100 % $ 7,178,921 100 % At December 31, 2023, the scheduled maturities of time deposits were as follows. Years Ending December 31, (in thousands) 2024 $ 1,171,328 2025 311,446 2026 19,455 2027 14,860 2028 6,684 Thereafter 110 Total time deposits $ 1,523,883

SHORT AND LONG-TERM BORROWINGS

SHORT AND LONG-TERM BORROWINGS	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
SHORT AND LONG-TERM BORROWINGS	SHORT AND LONG-TERM BORROWINGS Short-Term Borrowings: Short-term borrowings include any borrowing with an original contractual maturity of one year or less. The Company did not have any short-term borrowings outstanding at December 31, 2023, while at December 31, 2022, short-term borrowings included $317 million of short-term FHLB advances, comprised of $117 million due in January 2023 at a weighted average rate of 4.29% and $200 million due in September 2023 at a weighted average rate of 4.30%. Long-Term Borrowings: Long-term borrowings include any borrowing with an original contractual maturity greater than one year. The components of long-term borrowings were as follows. (in thousands) December 31, 2023 December 31, 2022 FHLB advances $ 5,000 $ 33,000 Junior subordinated debentures 40,552 39,720 Subordinated notes 121,378 152,622 Total long-term borrowings $ 166,930 $ 225,342 FHLB Advances : The FHLB advances bear fixed rates, require interest-only monthly payments, and have maturity dates through March 2025. The weighted average rate of the FHLB advances was 1.55% and 1.09% at December 31, 2023 and 2022, respectively. The FHLB advances are collateralized by a blanket lien on qualifying residential first and junior mortgage loans which had a pledged balance of $807 million and $665 million at December 31, 2023 and 2022, respectively. In addition, $34 million of investments (municipal securities) were pledged to the FHLB at December 31, 2023, compared to $500 million of investments (U.S. Treasury securities) at December 31, 2022. The following table shows the maturity schedule of the FHLB advances as of December 31, 2023. Maturing in: (in thousands) 2024 $ — 2025 5,000 2026 — 2027 — 2028 — Thereafter — $ 5,000 Junior Subordinated Debentures : Each of the junior subordinated debentures was issued to an underlying statutory trust (the “statutory trusts”), which issued trust preferred securities and common securities and used the proceeds from the issuance of the common and the trust preferred securities to purchase the junior subordinated debentures of the Company. The debentures represent the sole asset of the statutory trusts. All of the common securities of the statutory trusts are owned by the Company. The statutory trusts are not included in the consolidated financial statements. The net effect of all the documents entered into with respect to the trust preferred securities is that the Company, through payments on its debentures, is liable for the distributions and other payments required on the trust preferred securities. Interest on all debentures is current. Any applicable discounts (initially recorded to carry an acquired debenture at its then estimated fair value) are being accreted to interest expense over the remaining life of the debenture. All the junior subordinated debentures are currently callable and may be redeemed in part or in full, at par, plus any accrued but unpaid interest. At December 31, 2023 and 2022, $39 million and $38 million, respectively, of trust preferred securities qualify as Tier 1 capital. Subordinated Notes (the “Notes”) : In July 2021, the Company completed the private placement of $100 million in fixed-to-floating rate subordinated notes due in 2031, with a fixed annual rate of 3.125% for the first five years, and will reset quarterly thereafter to the then current three-month Secured Overnight Financing Rate (“SOFR”) plus 237.5 basis points. The Notes due in 2031 are redeemable beginning July 15, 2026 and quarterly thereafter on any interest payment date. In December 2021, Nicolet assumed two subordinated note issuances at a premium as the result of an acquisition. One issuance was $30 million in fixed-to-floating rate subordinated notes due in 2028, with a fixed annual interest rate of 5.875% for the first five years, and will reset quarterly thereafter to the then current three-month SOFR, as adjusted for the LIBOR to SOFR spread adjustment, plus 2.88%. The Company redeemed these notes on December 1, 2023. The second issuance was $22 million in fixed-to-floating rate subordinated notes due in 2030, with a fixed annual interest rate of 7.00% for the first five years, and will reset quarterly thereafter to the then current SOFR plus 687.5 basis points. The Notes due in 2030 are redeemable beginning June 30, 2025, and quarterly thereafter on any interest payment date. All Notes qualify as Tier 2 capital for regulatory purposes, and are discounted in accordance with regulations when the debt has five years or less remaining to maturity. The following table shows the breakdown of junior subordinated debentures and subordinated notes. As of 12/31/2023 As of 12/31/2022 (in thousands) Maturity Interest Par Unamortized Premium /(Discount) / Debt Issue Costs (1) Carrying Interest Carrying Junior Subordinated Debentures: Mid-Wisconsin Statutory Trust I (2) 12/15/2035 7.08 % $ 10,310 $ (2,380) $ 7,930 6.20 % $ 7,734 Baylake Capital Trust II (3) 9/30/2036 6.94 % 16,598 (2,938) 13,660 6.08 % 13,424 First Menasha Statutory Trust (4) 3/17/2034 8.43 % 5,155 (443) 4,712 7.53 % 4,668 County Bancorp Statutory Trust II (5) 9/15/2035 7.18 % 6,186 (753) 5,433 6.30 % 5,277 County Bancorp Statutory Trust III (6) 6/15/2036 7.34 % 6,186 (811) 5,375 6.46 % 5,219 Fox River Valley Capital Trust (7) 5/30/2033 7.89 % 3,610 (168) 3,442 6.40 % 3,398 Total $ 48,045 $ (7,493) $ 40,552 $ 39,720 Subordinated Notes: Subordinated Notes due 2031 7/15/2031 3.13 % $ 99,000 $ (524) $ 98,476 3.13 % $ 99,267 County Subordinated Notes due 2028 6/1/2028 — % — — — 5.88 % 30,119 County Subordinated Notes due 2030 6/30/2030 7.00 % 22,400 502 22,902 7.00 % 23,236 Total $ 121,400 $ (22) $ 121,378 $ 152,622 1. Represents the remaining unamortized premium or discount on debt issuances assumed in acquisitions, and represents the unamortized debt issue costs for the debt issued directly by Nicolet. 2. The debentures, assumed in April 2013 as the result of an acquisition, have a floating rate of three-month SOFR plus 1.43%, adjusted quarterly. * 3. The debentures, assumed in April 2016 as a result of an acquisition, have a floating rate of three-month SOFR plus 1.35%, adjusted quarterly. * 4. The debentures, assumed in April 2017 as the result of an acquisition, have a floating rate of three-month SOFR plus 2.79%, adjusted quarterly. * 5. The debentures, assumed in December 2021 as the result of an acquisition, have a floating rate of three-month SOFR plus 1.53%, adjusted quarterly. * 6. The debentures, assumed in December 2021 as the result of an acquisition, have a floating rate of three-month SOFR plus 1.69%, adjusted quarterly. * 7. The debentures, assumed in December 2021 as the result of an acquisition, have a floating rate of 5-year swap rate plus 3.40%, which resets every five years.

EMPLOYEE AND DIRECTOR BENEFIT P

EMPLOYEE AND DIRECTOR BENEFIT PLANS	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
EMPLOYEE AND DIRECTOR BENEFIT PLANS	EMPLOYEE AND DIRECTOR BENEFIT PLANS Nonqualified deferred compensation plans : The Company sponsors two deferred compensation plans, one for certain key management employees and another for directors. Under the management plan, employees designated by the Board of Directors may elect to defer compensation and the Company may at its discretion make nonelective contributions on behalf of one or more eligible plan participants. Upon retirement, termination of employment or at their election, the employee shall become entitled to receive the deferred amounts plus earnings thereon. The liability for the cumulative employee and employer contributions, including earnings thereon, at December 31, 2023 and 2022 totaled approximately $15.9 million and $12.1 million, respectively, and is included in other liabilities on the consolidated balance sheets. The Company recorded discretionary contributions of $1.3 million and $2.4 million to selected participants during 2023 and 2022, respectively, with approximately half vesting over a two year period (of which, one-third vested immediately and one-third vests on each of the first and second anniversaries of the initial grant) and the remainder vested immediately. The expense related to these discretionary contributions is recognized over the vesting period of the related grant. Under the director plan, participating directors may defer up to 100% of their Board compensation towards the purchase of Company common stock at market prices on a quarterly basis that is held in a Rabbi Trust and distributed when each such participating director ends his or her board service. During 2023 and 2022, the director plan purchased 2,542 and 1,898 shares of Company common stock valued at approximately $178,000 and $154,000, respectively. Common stock valued at approximately $138,000 (and representing 1,721 shares) was distributed to past directors during 2023, while no common stock was distributed during 2022. The common stock outstanding and the related director deferred compensation liability are offsetting components of the Company’s equity in the amount of $1.3 million at December 31, 2023 and $1.2 million at December 31, 2022 representing 30,481 shares and 29,660 shares, respectively. Nicolet 401(k) plan: The Company sponsors a 401(k) savings plan under which eligible employees may choose to save up to 100% of salary compensation on either a pre-tax or after-tax basis, subject to certain IRS limits. Under the plan, the Company matches 100% of participating employee contributions up to 6% of the participant’s eligible compensation. The Company contribution vests over five years. The Company can make additional annual discretionary profit sharing contributions, as determined by the Board of Directors. During 2023, 2022 and 2021, the Company’s 401(k) expense was approximately $4.1 million (including a $0.6 million profit sharing contribution), $4.0 million (including a $1.0 million profit sharing contribution), and $2.5 million (including a $0.5 million profit sharing contribution), respectively. Employee stock purchase plan: The Company sponsors an employee stock purchase plan under which eligible employees may purchase Nicolet common stock at a 10% discount, utilizing payroll deductions that range from a minimum of $20 to a maximum of $400 per payroll, during offering periods (currently quarterly).

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The Company may grant stock options and restricted stock under its stock-based compensation plan to certain officers, employees and directors. The plan is administered by a committee of the Board of Directors. The Company’s stock-based compensation plan at December 31, 2023 is described below. 2011 Long-Term Incentive Plan (“2011 LTIP”) : The Company’s 2011 LTIP, as subsequently amended with shareholder approval, has reserved 3,000,000 shares of the Company’s common stock for potential stock-based awards. This plan provides for certain stock-based awards such as, but not limited to, stock options, stock appreciation rights and restricted common stock, as well as cash performance awards. As of December 31, 2023, approximately 0.7 million shares were available for grant under this plan. Stock option grants generally will expire ten years after the date of grant, have an exercise price equal to the Company’s closing stock price on the date of grant, and will become exercisable based upon vesting terms determined by the committee. Restricted stock grants generally are issued at the Company’s closing stock price on the date of grant, are restricted as to transfer, but are not restricted as to dividend payments or voting rights, and the transfer restrictions lapse over time, depending upon vesting terms provided for in the grant and contingent upon continued employment. A Black-Scholes model is utilized to estimate the fair value of stock option grants. The weighted average assumptions used in the model for valuing stock option grants were as follows. 2023 2022 2021 Dividend yield 1.55 % — % — % Expected volatility 30 % 30 % 30 % Risk-free interest rate 4.22 % 3.03 % 1.19 % Expected average life 7 years 7 years 7 years Weighted average per share fair value of options $ 24.24 $ 30.99 $ 26.33 A summary of the Company’s stock option activity is summarized below. Stock Options Option Shares Weighted Average Weighted Average Remaining Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding – December 31, 2020 1,437,460 $ 50.47 Granted 450,000 77.99 Exercise of stock options * (53,214) 34.40 Forfeited (1,000) 48.85 Outstanding – December 31, 2021 1,833,246 $ 57.69 6.6 $ 51,426 Granted 132,929 81.04 Exercise of stock options * (82,611) 41.84 Forfeited (30,500) 75.08 Outstanding – December 31, 2022 1,853,064 $ 59.79 5.9 $ 37,526 Granted 39,000 71.99 Exercise of stock options * (241,876) 43.54 Forfeited (27,100) 84.37 Outstanding – December 31, 2023 1,623,088 $ 62.09 5.3 $ 30,126 Exercisable – December 31, 2023 1,184,045 $ 56.63 4.4 $ 28,297 *The terms of the stock option agreements permit having a number of shares of stock withheld, the fair market value of which as of the date of exercise is sufficient to satisfy the exercise price and/or tax withholding requirements, and accordingly 55,467 shares, 7,957 shares, and 10,354 shares were surrendered during 2023, 2022, and 2021, respectively. Intrinsic value represents the amount by which the fair value of the underlying stock exceeds the exercise price of the stock options. The intrinsic value of options exercised in 2023, 2022, and 2021 was approximately $7.7 million, $3.9 million, and $2.2 million, respectively. The following options were outstanding at December 31, 2023. Number of Shares Weighted Average Weighted Average Outstanding Exercisable Outstanding Exercisable Outstanding Exercisable $23.80 – $40.00 76,659 76,659 $ 32.45 $ 32.45 2.0 2.0 $40.01 – $50.00 589,250 589,250 48.85 48.85 3.4 3.4 $50.01 – $65.00 169,850 157,850 56.77 56.39 4.3 4.0 $65.01 – $75.00 307,400 191,300 71.28 70.77 6.6 6.1 $75.01 – $93.09 479,929 168,986 79.08 78.95 7.7 7.5 1,623,088 1,184,045 $ 62.09 $ 56.63 5.3 4.4 A summary of the Company’s restricted stock activity is summarized below. Restricted Stock Restricted Shares Weighted Average Grant Outstanding – December 31, 2020 18,925 $ 53.57 Granted 33,153 75.83 Vested * (25,831) 64.53 Forfeited (446) 41.44 Outstanding – December 31, 2021 25,801 $ 71.42 Granted 72,948 76.81 Vested * (24,659) 72.64 Forfeited (600) 56.01 Outstanding – December 31, 2022 73,490 $ 76.49 Granted 19,213 64.28 Vested * (35,545) 69.69 Forfeited — — Outstanding – December 31, 2023 57,158 $ 76.61 *The terms of the restricted stock agreements permit the surrender of shares to the Company upon vesting in order to satisfy applicable tax withholding at the minimum statutory withholding rate, and accordingly 3,637 shares, 2,249 shares, and 3,215 shares were surrendered during 2023, 2022, and 2021, respectively.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2023
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY The Board of Directors has authorized the repurchase of Nicolet’s outstanding common stock through its common stock repurchase program. During 2023, $2 million was utilized to repurchase and cancel approximately 27,000 common shares at a weighted average price of $56.57, while during 2022, $61 million was utilized to repurchase and cancel approximately 672,000 common shares at a weighted average price of $91.54. As of December 31, 2023, there remained $46 million authorized under the repurchase program to be utilized from time-to-time to repurchase common shares in the open market, through block transactions or in private transactions. On August 26, 2022, in connection with its acquisition of Charter, the Company issued 1,262,360 shares of its common stock for stock consideration valued at $98 million plus cash consideration of $39 million. On September 3, 2021, in connection with its acquisition of Mackinac, the Company issued 2,337,230 shares of its common stock for stock consideration valued at $180 million plus cash consideration of $49 million. Approximately $0.4 million in direct stock issuance costs for the merger were incurred and charged against additional paid-in capital.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The current and deferred amounts of income tax expense were as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Current $ 17,898 $ 44,384 $ 14,138 Deferred 3,027 (12,907) 6,332 Valuation allowance for securities AFS, net 4,191 — — Income tax expense $ 25,116 $ 31,477 $ 20,470 The differences between the income tax expense recognized and the amount computed by applying the statutory federal income tax rate of 21% to the income before income tax expense for the years ended as indicated are included in the following table. Years Ended December 31, (in thousands) 2023 2022 2021 Tax on pretax income, at statutory rates $ 18,193 $ 26,405 $ 17,023 State income taxes, net of federal effect — 7,847 5,064 Tax-exempt interest income (1,072) (1,037) (517) Increase in cash surrender value life insurance (950) (1,040) (570) Stock-based employee compensation (811) (1,101) (618) Executive compensation 1,094 82 163 Valuation allowance, net 8,677 — — Other, net (15) 321 (75) Income tax expense $ 25,116 $ 31,477 $ 20,470 The net deferred tax asset includes the following amounts of deferred tax assets and liabilities. (in thousands) December 31, 2023 December 31, 2022 Deferred tax assets: ACL-Loans $ 16,937 $ 16,315 Net operating loss carryforwards 2,142 2,721 Compensation 10,971 10,274 Purchase accounting adjustments 1,963 9,400 Other real estate 132 672 Unrealized loss on securities AFS 19,196 21,011 Valuation allowance - securities AFS (4,191) — Valuation allowance - other timing differences (4,486) — Total deferred tax assets 42,664 60,393 Deferred tax liabilities: Premises and equipment (3,138) (3,000) Prepaid expenses (662) (801) Core deposit and other intangibles (5,917) (8,817) MSR and LSR assets (5,455) (6,570) Other (319) (513) Total deferred tax liabilities (15,491) (19,701) Net deferred tax assets $ 27,173 $ 40,692 For the year ended December 31, 2023, income tax expense was impacted by a change in Wisconsin state income taxes. The Wisconsin State Budget, signed in July 2023 and retroactive to January 1, 2023, included language that provides financial institutions with an exemption from state taxable income for interest, fees, and penalties earned on loans to existing Wisconsin-based business or agriculture purpose loans that are $5 million or less in balance on January 1, 2023, and to new loans that meet the criteria. The impact of this tax law change to Nicolet moving forward will be a reduction / elimination of State income taxes being recognized. However, the elimination of State income tax expense also required a valuation allowance to be established for the State-related deferred tax asset as of the effective date of the legislation, resulting in a one-time $9.1 million charge to state income tax expense being recognized in the third quarter of 2023 to establish this valuation allowance. A valuation allowance is required if it is more likely than not that some portion of the deferred tax asset will not be realized. At December 31, 2022, no valuation allowance was determined to be necessary. The remaining valuation allowance as of December 31, 2023, of $8.7 million is the result of the initial valuation allowance for state related attributes, net of subsequent changes to those attributes along with the state related impact of changes to the unrealized losses on securities AFS disposed. At December 31, 2023, the Company had a federal and state net operating loss carryforward of $5.9 million and $15.9 million, respectively. The entire federal and state net operating loss carryforwards were the result of the Company’s acquisitions. The federal and state net operating loss carryovers resulting from the acquisitions have been included in the IRC section 382 limitation calculation and are being limited to the overall amount expected to be realized.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES The Company is 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, financial guarantees, and standby letters of credit. Such commitments may involve, to varying degrees, elements of credit risk in excess of amounts recognized on the consolidated balance sheets. The Company’s exposure to credit loss in the event of nonperformance by the other party to the financial instruments for commitments to extend credit and standby letters of credit is represented by the contractual amount of those instruments. The Company uses the same credit policies in making commitments and issuing letters of credit as they do for on-balance sheet instruments. See Note 1 for the Company’s accounting policy on commitments, contingencies, and the allowance for credit losses-unfunded commitments and see Note 4 for information on the allowance for credit losses-unfunded commitments. A summary of the contract or notional amount of the Company’s exposure to off-balance sheet risk was as follows. (in thousands) December 31, 2023 December 31, 2022 Commitments to extend credit $ 1,877,327 $ 1,850,601 Financial standby letters of credit 17,500 26,530 Performance standby letters of credit 11,381 9,375 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commercial-related commitments to extend credit represented 79% of the total year-end commitments for 2023, compared to 80% for 2022, and were predominantly commercial lines of credit that carry a term of one year or less. The commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Financial and performance standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Financial standby letters of credit are issued specifically to facilitate commerce and typically result in the commitment being drawn on when the underlying transaction is consummated between the customer and the third party, while performance standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party. Both of these guarantees are primarily issued to support public and private borrowing arrangements and, generally, have terms of one year or less. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. The Company holds collateral, which may include accounts receivable, inventory, property, equipment, and income-producing properties, supporting those commitments if deemed necessary. In the event the customer does not perform in accordance with the terms of the agreement with the third-party, the Company would be required to fund the commitment. The maximum potential amount of future payments the Company could be required to make is represented by the contractual amount. If the commitment is funded, the Company would be entitled to seek recovery from the customer. Interest rate lock commitments to originate residential mortgage loans held for sale and forward commitments to sell residential mortgage loans held for sale are considered derivative instruments (“mortgage derivatives”) and the contractual amounts of each was $13 million at December 31, 2023. In comparison, interest rate lock commitments to originate residential mortgage loans held for sale and forward commitments to sell residential mortgage loans held for sale each totaled $9 million at December 31, 2022. The net fair value of these mortgage derivatives combined was a net gain of $0.1 million at both December 31, 2023 and December 31, 2022. The Company has federal funds lines available with other financial institutions where funds may be borrowed on a short-term basis at the market rate in effect at the time of the borrowing. Federal funds lines of $195 million were available at both December 31, 2023 and December 31, 2022. Nicolet is party to various pending and threatened claims and legal proceedings arising in the normal course of business activities, some of which may involve claims for substantial amounts. Although Nicolet has developed policies and procedures to minimize legal noncompliance and the impact of claims and other proceedings and endeavored to procure reasonable amounts of insurance coverage, litigation and regulatory actions present an ongoing risk. With respect to all such claims, Nicolet continuously assesses its potential liability based on the allegations and evidence available. If the facts indicate that it is probable that Nicolet will incur a loss and the amount of such loss can be reasonably estimated, Nicolet will establish an accrual for the probable loss. For matters where a loss is not probable, or the amount of the loss cannot be reasonably estimated, Nicolet does not establish an accrual.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS The Company conducts transactions, in the normal course of business, with its directors and executive officers, including companies in which they have a beneficial interest. The Company is required to disclose material related party transactions, other than certain compensation arrangements, entered into in the normal course of business. The Company has granted loans to its directors, executive officers, and their related interests. These loans were made on substantially the same terms, including rates and collateral, as those prevailing at the time made for comparable transactions with other unrelated persons. A summary of the loans to related parties was as follows. (in thousands) December 31, 2023 Balance at beginning of year $ 110,707 New loans 15,265 Repayments (10,962) Changes due to status of executive officers and directors (3,308) Balance at end of year $ 111,702 In October 2013, the Company entered into a lease for a branch location in a facility owned by a member of the Company’s Board and incurred annual rent expense of $228,000, $153,000, and $124,000, on this facility during 2023, 2022, and 2021, respectively. This same Board member participated in a competitive bid process for and was awarded the contract as general contractor for the construction of two new branch locations (one during 2023 and one during 2022). The 2023 new branch construction is estimated to total $11.5 million, of which, approximately $2.0 million was paid during 2023 as progress was made on the construction. The 2022 new branch construction is estimated to total $2.3 million, of which, approximately $1.2 million was paid during 2023 and $1.1 million was paid during 2022 as progress was made on the construction. In addition, payments of $199,000 and $154,000 were made during 2023 and 2022, respectively, for two small branch construction projects at two other branch locations. At least 75% of all branch construction payments were passed through to various subcontractors. In August 2022, the Company assumed a lease for a Charter administrative location in a facility owned by an entity for which another Board member has the controlling ownership interest. Rent expense of $149,000 and $49,000 was paid during 2023 and 2022 (from the acquisition of Charter), respectively, on this location.

ASSET GAINS (LOSSES), NET

ASSET GAINS (LOSSES), NET	12 Months Ended
	Dec. 31, 2023
Assets Gains (Losses), Net [Abstract]
ASSET GAINS (LOSSES), NET	ASSET GAINS (LOSSES), NET Components of the net gains (losses) on assets are as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Gains (losses) on sales of securities AFS, net $ (3,313) $ (244) $ (283) Gains (losses) on sales of securities HTM, net (37,723) — — Gains (losses) on equity securities, net (252) (127) 3,445 Gains (losses) on sales of OREO, net 421 3,206 597 Write-downs of OREO (181) (244) (28) Write-down of other investment (954) — — Gains (losses) on sales of other investments, net 9,372 531 550 Gains (losses) on sales or dispositions of other assets, net (178) 8 (100) Asset gains (losses), net $ (32,808) $ 3,130 $ 4,181

REGULATORY CAPITAL REQUIREMENTS

REGULATORY CAPITAL REQUIREMENTS	12 Months Ended
	Dec. 31, 2023
Regulatory Capital Requirements Under Banking Regulations [Abstract]
REGULATORY CAPITAL REQUIREMENTS	REGULATORY CAPITAL REQUIREMENTS The Company (on a consolidated basis) and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company’s and Bank’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and Bank must meet specific capital guidelines that involve quantitative measures of their assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk-weightings, and other factors. Prompt corrective action provisions are not applicable to bank holding companies. The Company and Bank must also maintain a “capital conservation buffer” consisting of common equity Tier 1 (“CET1”) in an amount equal to 2.5% of risk-weighted assets in order to avoid certain restrictions. The capital conservation buffer effectively increases the minimum well-capitalized CET1 capital, Tier 1 capital, and total capital ratios for U.S. banking organizations to 7.0%, 8.5%, and 10.5%, respectively. Failure to meet this capital conservation buffer would result in limitations on dividends, other distributions, and discretionary bonuses. Quantitative measures established by regulation to ensure capital adequacy require the Company and Bank to maintain minimum amounts and ratios (set forth in the table below) of Total, Tier 1 and CET1 capital (as defined in the regulations) to risk-weighted assets (as defined), and Tier 1 capital (as defined) to average assets (as defined). Management believes the Company and the Bank met all capital adequacy requirements to which they are subject as of December 31, 2023 and 2022. As of December 31, 2023 and 2022, the most recent notifications from the regulatory agencies categorized the Bank as well-capitalized under the regulatory framework for prompt corrective action. To be categorized as well-capitalized, an institution must maintain minimum Total risk-based, Tier 1 risk-based, CET1 risk-based, and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since these notifications that management believes have changed the Bank’s category. The Bank is also subject to legal limitations on dividends that can be paid to the parent company without prior approval of the applicable regulatory agencies. Dividends declared by the Bank that exceed the retained net income for the most current year plus retained net income for the preceding two years must be approved by Federal regulatory agencies. At December 31, 2023, the Bank could pay dividends of approximately $18 million to the Company without seeking regulatory approval. The Company’s and the Bank’s actual regulatory capital amounts and ratios are presented in the following table. Actual For Capital Adequacy To Be Well Capitalized Under Prompt Corrective Action Provisions (2) (in thousands) Amount Ratio (1) Amount Ratio (1) Amount Ratio (1) December 31, 2023 Company Total risk-based capital $ 930,804 13.0 % $ 574,231 8.0 % Tier 1 risk-based capital 750,811 10.5 430,673 6.0 Common equity Tier 1 capital 712,040 9.9 323,005 4.5 Leverage 750,811 9.2 326,483 4.0 Bank Total risk-based capital $ 827,341 11.5 % $ 573,221 8.0 % $ 716,527 10.0 % Tier 1 risk-based capital 768,726 10.7 429,916 6.0 573,221 8.0 Common equity Tier 1 capital 768,726 10.7 322,437 4.5 465,742 6.5 Leverage 768,726 9.4 325,868 4.0 407,334 5.0 December 31, 2022 Company Total risk-based capital $ 889,763 12.3 % $ 577,138 8.0 % Tier 1 risk-based capital 684,280 9.5 432,853 6.0 Common equity Tier 1 capital 646,341 9.0 324,640 4.5 Leverage 684,280 8.2 335,621 4.0 Bank Total risk-based capital $ 816,951 11.3 % $ 576,241 8.0 % $ 720,301 10.0 % Tier 1 risk-based capital 764,090 10.6 432,181 6.0 576,241 8.0 Common equity Tier 1 capital 764,090 10.6 324,135 4.5 468,196 6.5 Leverage 764,090 9.1 334,916 4.0 418,645 5.0 (1) The Total risk-based capital ratio is defined as Tier 1 capital plus tier 2 capital divided by total risk-weighted assets. The Tier 1 risk-based capital ratio is defined as Tier 1 capital divided by total risk-weighted assets. CET1 risk-based capital ratio is defined as Tier 1 capital, with deductions for goodwill and other intangible assets (other than mortgage servicing assets), net of associated deferred tax liabilities, and limitations on the inclusion of deferred tax assets, mortgage servicing assets and investments in other financial institutions, in each case as provided further in the rules, divided by total risk-weighted assets. The Leverage ratio is defined as Tier 1 capital divided by the most recent quarter’s average total assets as adjusted. (2) Prompt corrective action provisions are not applicable at the bank holding company level.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Fair value represents the estimated price at which an orderly transaction to sell an asset or transfer a liability would take place between market participants at the measurement date under current market conditions (i.e., an exit price concept), and is a market-based measurement versus an entity-specific measurement. The Company records and/or discloses certain financial instruments on a fair value basis. These financial assets and financial liabilities are measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the observability of the assumptions used to determine fair value. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from independent sources. Unobservable inputs are inputs that reflect assumptions of the reporting entity about how market participants would price the asset or liability based on the best information available under the circumstances. The three fair value levels are: • Level 1 – quoted market prices in active markets for identical assets or liabilities that a company has the ability to access at the measurement date • Level 2 – inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly • Level 3 – significant unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity In instances where the fair value measurement is based on inputs from different levels, the level within which the entire fair value measurement will be categorized is based on the lowest level input that is significant to the fair value measurement in its entirety. This assessment of the significance of an input requires management judgment. Recurring basis fair value measurements: The following table presents the balances of assets and liabilities measured at fair value on a recurring basis. (in thousands) Fair Value Measurements Using Measured at Fair Value on a Recurring Basis: Total Level 1 Level 2 Level 3 December 31, 2023 U.S. Treasury securities $ 14,123 $ — $ 14,123 $ — U.S. government agency securities 7,384 — 7,384 — State, county and municipals 334,822 — 333,401 1,421 Mortgage-backed securities 352,622 — 351,658 964 Corporate debt securities 93,622 — 89,944 3,678 Securities AFS $ 802,573 $ — $ 796,510 $ 6,063 Other investments (equity securities) $ 4,240 $ 4,240 $ — $ — Derivative assets 152 — — 152 Derivative liabilities 79 — — 79 December 31, 2022 U.S. Treasury securities $ 183,830 $ — $ 183,830 $ — U.S. government agency securities 2,100 — 2,100 — State, county and municipals 398,188 — 396,315 1,873 Mortgage-backed securities 200,932 — 199,951 981 Corporate debt securities 132,568 — 127,269 5,299 Securities AFS $ 917,618 $ — $ 909,465 $ 8,153 Other investments (equity securities) $ 4,376 $ 4,376 $ — $ — Derivative assets 60 — — 60 Derivative liabilities 10 — — 10 The following is a description of the valuation methodologies used by the Company for the assets and liabilities measured at fair value on a recurring basis, noted in the table above. Securities: Where quoted market prices on securities exchanges are available, the investments are classified as Level 1. Level 1 investments primarily include exchange-traded equity securities. If quoted market prices are not available, fair value is generally determined using prices obtained from independent pricing vendors who use pricing models (with typical inputs including benchmark yields, reported trades for similar securities, issuer spreads or relationship to other benchmark quoted securities), or discounted cash flows, and are classified as Level 2. Examples of these investments include U.S. Treasury securities, U.S. government agency securities, mortgage-backed securities, obligations of state, county and municipals, and certain corporate debt securities. Finally, in certain cases where there is limited activity or less transparency around inputs to the estimated fair value, investments are classified within Level 3 of the hierarchy. Examples of these include private corporate debt securities, which are primarily trust preferred security investments, as well as certain municipal bonds and mortgage-backed securities. At December 31, 2023 and 2022, it was determined that carrying value was the best approximation of fair value for these Level 3 securities, based primarily on the internal analysis performed on these securities. Derivatives: The derivative assets and liabilities include interest rate lock commitments to originate residential mortgage loans held for sale and forward commitments to sell residential mortgage loans held for sale, which are considered derivative instruments (“mortgage derivatives”). The fair value of interest rate lock commitments are determined using the projected sale price of individual loans based on changes in the market interest rates, projected pull-through rates (the probability that an interest rate lock commitment will ultimately result in an originated loan), the reduction in the value of the applicant’s option due to the passage of time, and the remaining origination costs to be incurred based on management’s estimate of market costs. The fair value of forward commitments are determined using quoted prices of to-be-announced securities in active markets, or benchmarked to such securities. The derivative assets and liabilities are classified within Level 3 of the hierarchy. The following table presents the changes in Level 3 securities AFS measured at fair value on a recurring basis. (in thousands) Years Ended Level 3 Fair Value Measurements: December 31, 2023 December 31, 2022 Balance at beginning of year $ 8,153 $ 8,065 Acquired balances — 750 Paydowns/Sales/Settlements (2,425) (451) Unrealized gains / (losses) 335 (211) Balance at end of year $ 6,063 $ 8,153 Nonrecurring basis fair value measurements: The following table presents the Company’s assets measured at fair value on a nonrecurring basis, aggregated by the level in the fair value hierarchy within which those measurements fall. (in thousands) Fair Value Measurements Using Measured at Fair Value on a Nonrecurring Basis: Total Level 1 Level 2 Level 3 December 31, 2023 Collateral dependent loans $ 19,920 $ — $ — $ 19,920 OREO 1,267 — — 1,267 MSR asset 11,655 — — 11,655 December 31, 2022 Collateral dependent loans $ 30,951 $ — $ — $ 30,951 OREO 1,975 — — 1,975 MSR asset 12,580 — — 12,580 The following is a description of the valuation methodologies used by the Company for the assets and liabilities measured at fair value on a nonrecurring basis, noted in the table above. Collateral dependent loans : For individually evaluated collateral dependent loans, the estimated fair value is based upon the present value of expected future cash flows discounted at the loan’s effective interest rate, the estimated fair value of the underlying collateral with consideration for estimated selling costs if satisfaction of the loan depends upon the sale of the collateral, or the estimated liquidity of the note. OREO : For OREO, the fair value is based upon the estimated fair value of the underlying collateral adjusted for the expected costs to sell. MSR asset : To estimate the fair value of the MSR asset, the underlying serviced loan pools are stratified by interest rate tranche and term of the loan, and a valuation model is used to calculate the present value of the expected future cash flows for each stratum. The servicing valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as costs to service, a discount rate, ancillary income, default rates and losses, and prepayment speeds. Although some of these assumptions are based on observable market data, other assumptions are based on unobservable estimates of what market participants would use to measure fair value. Financial instruments: The carrying amounts and estimated fair values of the Company’s financial instruments are shown below. December 31, 2023 (in thousands) Carrying Estimated Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 491,431 $ 491,431 $ 491,431 $ — $ — Certificates of deposit in other banks 6,374 6,293 — 6,293 — Securities AFS 802,573 802,573 — 796,510 6,063 Other investments 57,560 57,560 4,240 44,010 9,310 Loans held for sale 4,160 4,276 — 4,276 — Loans, net 6,290,332 6,083,942 — — 6,083,942 MSR asset 11,655 16,810 — — 16,810 LSR asset 8,831 8,831 — — 8,831 Accrued interest receivable 24,237 24,237 24,237 — — Financial liabilities: Deposits $ 7,197,800 $ 7,184,712 $ — $ — $ 7,184,712 Short-term borrowings — — — — — Long-term borrowings 166,930 155,179 — 4,820 150,359 Accrued interest payable 7,765 7,765 7,765 — — December 31, 2022 (in thousands) Carrying Estimated Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 154,723 $ 154,723 $ 154,723 $ — $ — Certificates of deposit in other banks 12,518 12,407 — 12,407 — Securities AFS 917,618 917,618 — 909,465 8,153 Securities HTM 679,128 623,352 — 623,352 — Other investments 65,286 65,286 4,376 52,093 8,817 Loans held for sale 1,482 1,529 — 1,529 — Loans, net 6,118,670 5,863,570 — — 5,863,570 MSR asset 12,580 17,215 — — 17,215 LSR asset 11,039 11,039 — — 11,039 Accrued interest receivable 21,275 21,275 21,275 — — Financial liabilities: Deposits $ 7,178,921 $ 7,172,779 $ — $ — $ 7,172,779 Short-term borrowings 317,000 317,000 317,000 — — Long-term borrowings 225,342 220,513 — 33,001 187,512 Accrued interest payable 4,265 4,265 4,265 — — The carrying value of certain assets and liabilities such as cash and cash equivalents, accrued interest receivable, nonmaturing deposits, short-term borrowings, and accrued interest payable approximate their estimated fair value due to their immediate and shorter term maturities. For those financial instruments not previously disclosed, the following is a description of the valuation methodologies used. Certificates of deposit in other banks: Fair values are estimated using discounted cash flow analysis based on current interest rates being offered by instruments with similar terms and represents a Level 2 measurement. Securities HTM: The valuation methodologies for Securities HTM are consistent with the valuation methodologies used for Securities, as discussed under “Recurring basis fair value measurements” above. Other investments : The valuation methodologies utilized for the exchange-traded equity securities are discussed under “Recurring basis fair value measurements” above. The carrying amount of Federal Reserve Bank and FHLB stock is a reasonably accepted fair value estimate given their restricted nature. Fair value is the redeemable (carrying) value based on the redemption provisions of the instruments which is considered a Level 2 measurement. The carrying amount of the remaining other investments (particularly common stocks of companies or other banks that are not publicly traded) approximates their fair value, determined primarily by analysis of company financial statements and recent capital issuances of the respective companies or banks, if any, and represents a Level 3 measurement. Loans held for sale: The fair value estimation process for the loans held for sale portfolio is segregated by loan type. The estimated fair value was based on what secondary markets are currently offering for portfolios with similar characteristics and represents a Level 2 measurement. Loans, net : For variable-rate loans that reprice frequently and with no significant change in credit risk or other optionality, fair values are based on carrying values. Fair values for all other loans are estimated by discounting contractual cash flows using estimated market discount rates, which reflect the credit and interest rate risk inherent in the loan based on market participants. Collateral-dependent loans are included in loans, net. The fair value of loans is considered to be a Level 3 measurement due to internally developed discounted cash flow measurements. Deposits : The fair value of deposits with no stated maturity (such as demand deposits, savings, interest and noninterest checking, and money market accounts) is equal to the amount payable on demand at the reporting date. Fair values for fixed-rate certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered in the market place on certificates of similar remaining maturities. Use of internal discounted cash flows provides a Level 3 fair value measurement. Long-term borrowings : The fair value of the FHLB advances is obtained from the FHLB which uses a discounted cash flow analysis based on current market rates of similar maturity debt securities and represents a Level 2 measurement. The fair values of the junior subordinated debentures and subordinated notes utilize a discounted cash flow analysis based on an estimate of current interest rates being offered by instruments with similar terms and credit quality. Since the market for these instruments is limited, the internal valuation represents a Level 3 measurement. Lending-related commitments : The estimated fair value of lending-related commitments (letters of credit, interest rate lock commitments on residential mortgage loans and outstanding mandatory commitments to sell residential mortgage loans into the secondary market) were not significant. Limitations : Fair value estimates are made at a specific point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the Company’s entire holdings of a particular financial instrument. Fair value estimates may not be realizable in an immediate settlement of the instrument. In some instances, there are no quoted market prices for the Company’s various financial instruments, in which case fair values may be based on estimates using present value or other valuation techniques, or based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of the financial instruments, or other factors. Those techniques are significantly affected by the assumptions used, including the discount rate and estimate of future cash flows. Subsequent changes in assumptions could significantly affect the estimates.

PARENT COMPANY ONLY FINANCIAL I

PARENT COMPANY ONLY FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2023
Condensed Financial Information Disclosure [Abstract]
PARENT COMPANY ONLY FINANCIAL INFORMATION	PARENT COMPANY ONLY FINANCIAL INFORMATION Condensed Parent Company only financial statements of Nicolet Bankshares, Inc. follow. Balance Sheets December 31, (in thousands) 2023 2022 Assets Cash and due from subsidiary $ 88,365 $ 63,927 Investments 10,535 10,313 Investments in subsidiaries 1,104,356 1,094,063 Other assets 680 392 Total assets $ 1,203,936 $ 1,168,695 Liabilities and Stockholders’ Equity Junior subordinated debentures $ 40,552 $ 39,720 Subordinated notes 121,378 152,622 Other liabilities 2,999 3,824 Stockholders’ equity 1,039,007 972,529 Total liabilities and stockholders’ equity $ 1,203,936 $ 1,168,695 Statements of Income Years Ended December 31, (in thousands) 2023 2022 2021 Interest income $ 126 $ 81 $ 18 Interest expense 10,633 8,687 2,959 Net interest expense (10,507) (8,606) (2,941) Dividend income from subsidiaries 70,000 77,775 65,000 Operating expense (107) (457) (2,562) Gain (loss) on investments, net (1,164) 395 3,995 Income tax benefit 3,803 2,373 437 Earnings before equity in undistributed income (loss) of subsidiaries 62,025 71,480 63,929 Equity in undistributed income (loss) of subsidiaries (509) 22,780 (3,277) Net income $ 61,516 $ 94,260 $ 60,652 Statements of Cash Flows Years Ended December 31, (in thousands) 2023 2022 2021 Cash Flows From Operating Activities: Net income $ 61,516 $ 94,260 $ 60,652 Adjustments to reconcile net income to net cash provided by operating activities: Accretion of discounts on borrowings 588 427 584 (Gain) loss on investments, net 1,164 (395) (3,995) Change in other assets and liabilities, net (1,190) (1,775) 1,013 Equity in undistributed (income) loss of subsidiaries, net of dividends 509 (22,780) 3,277 Net cash provided by operating activities 62,587 69,737 61,531 Cash Flows from Investing Activities: Proceeds from sale of investments 75 1,835 4,105 Purchases of investments (1,451) (2,116) (5,049) Net cash paid in business combinations — (31,970) (63,892) Net cash used in investing activities (1,376) (32,251) (64,836) Cash Flows From Financing Activities: Purchase and retirement of common stock (1,521) (61,497) (62,583) Proceeds from issuance of common stock, net 6,867 3,282 2,382 Cash dividends on common stock (11,119) — — Capitalized issuance costs, net — — (789) Repayment of long-term borrowings (31,000) — — Proceeds from issuance of subordinated notes, net — — 98,953 Net cash provided by (used in) financing activities (36,773) (58,215) 37,963 Net increase (decrease) in cash and due from subsidiary 24,438 (20,729) 34,658 Beginning cash and due from subsidiary 63,927 84,656 49,998 Ending cash and due from subsidiary $ 88,365 $ 63,927 $ 84,656

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE Presented below are the calculations for basic and diluted earnings per common share. Years Ended December 31, (in thousands, except per share data) 2023 2022 2021 Net income $ 61,516 $ 94,260 $ 60,652 Weighted average common shares outstanding 14,743 13,909 10,736 Effect of dilutive common stock awards 328 466 409 Diluted weighted average common shares outstanding 15,071 14,375 11,145 Basic earnings per common share $ 4.17 $ 6.78 $ 5.65 Diluted earnings per common share $ 4.08 $ 6.56 $ 5.44

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net income	$ 61,516	$ 94,260	$ 60,652

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

NATURE OF BUSINESS AND SIGNIF_2

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation : The consolidated financial statements of the Company include the accounts of its subsidiaries. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and conform to general practices within the banking industry. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements. Results of operations of companies purchased, if any, are included from the date of acquisition. Because the Company is not the primary beneficiary, the consolidated financial statements exclude the following wholly-owned variable interest entities: Mid-Wisconsin Statutory Trust, Baylake Capital Trust II, First Menasha Bancshares Statutory Trust I, First Menasha Bancshares Statutory Trust II, County Bancorp Statutory Trust II, County Bancorp Statutory Trust III, and Fox River Valley Trust I.
Operating Segment	Operating Segment : The Bank represents the primary operating segment (as discussed above). While the chief operating decision makers monitor the revenue streams of the various products and services, and evaluate costs, balance sheet positions and quality, all such products, services and activities are directly or indirectly related to the business of community banking, with no regular, formal or material segment delineations. Operations are managed and financial performance is evaluated on a company-wide basis, and accordingly, all the financial service operations are considered by management to be aggregated in one reportable operating segment.
Use of Estimates	Use of Estimates
Business Combinations	Business Combinations : The Company accounts for business combinations under the acquisition method of accounting in accordance with Accounting Standards Codification (“ASC”) 805, Business Combinations
Cash and Cash Equivalents	Cash and Cash Equivalents
Securities Available for Sale and Securities Held to Maturity	Securities Available for Sale : Securities are classified as AFS on the consolidated balance sheets at the time of purchase and include those securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity. Any decision to sell a security classified as AFS would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Company’s assets and liabilities, liquidity needs, regulatory capital considerations, and other similar factors. Securities classified as AFS are carried at fair value, with unrealized gains or losses, net of related deferred income taxes, reported as increases or decreases in accumulated other comprehensive income (loss). Realized gains or losses on sales of securities AFS (using the specific identification method) are included in the consolidated statements of income under asset gains (losses), net. Premiums and discounts are amortized or accreted into interest income over the estimated life of the related securities using the effective interest method. Securities Held to Maturity : Securities are classified as HTM on the consolidated balance sheets at the time of purchase and include those securities that the Company has both the positive intent and ability to hold to maturity. HTM securities are carried at amortized cost on the consolidated balance sheets. Premiums and discounts are amortized or accreted into interest income over the estimated life of the related securities using the effective interest method.
Other Investments and Partnership Investments	Other Investments Partnership Investments
Loans Held for Sale	Loans Held for Sale : Loans originated and intended for sale in the secondary market are carried at the lower of cost or estimated fair value as determined on an aggregate basis and generally consist of current production of certain fixed-rate residential first lien mortgages. The amount by which cost exceeds fair value is recorded as a valuation allowance and charged to earnings. Changes, if any, in the valuation allowance are included in earnings in the period in which the change occurs. As of December 31, 2023 and 2022, no valuation allowance was necessary. Loans held for sale may be sold servicing retained or servicing released, and are generally sold without recourse. The carrying value of mortgage loans sold with servicing retained is reduced by the amount allocated to the servicing right at the time of sale. Gains and losses on sales of mortgage loans held for sale are included in earnings in mortgage income, net.
Loans - Originated and Acquired	Loans – Originated : Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are carried at their amortized cost basis, which is the unpaid principal amount outstanding, net of deferred loan fees and costs, and any direct principal charge-off. The Company made an accounting policy election to exclude accrued interest from the amortized cost basis of loans and report such accrued interest as part of accrued interest receivable and other assets on the consolidated balance sheets. Interest income is accrued on the unpaid principal balance using the simple interest method. The accrual of interest income on loans is discontinued when, in the opinion of management, there is reasonable doubt as to the borrower’s ability to meet payment of interest or principal when due. Loans are generally placed on nonaccrual status when contractually past due 90 days or more as to interest or principal, though may be placed in such status earlier based on the circumstances. Loans past due 90 days or more may continue on accrual only when they are well secured and / or in process of collection or renewal. When interest accrual is discontinued, all previously accrued but uncollected interest is reversed against current period interest income. Except in very limited circumstances, cash collections on nonaccrual loans are credited to the loan receivable balance and no interest income is recognized on those loans until the principal balance is paid in full. Accrual of interest may be resumed when the customer is current on all principal and interest payments and has been paying on a timely basis for a sustained period of time. A description of each segment of the loan portfolio, including the corresponding credit risk, is included below. Commercial and industrial loans consist primarily of commercial loans to small and mid-sized businesses within a diverse range of industries (manufacturing, wholesaling, paper, packaging, food production and processing, retail, service, and businesses supporting the general building industry). These loans are made for a wide variety of general corporate purposes, including working capital, equipment, and business expansion loans, with varying terms based upon the underlying purpose of the loan. Commercial and industrial loans are based primarily on the historical and projected cash flow of the underlying borrower, and secondarily on any underlying assets pledged by the borrower. The credit risk related to commercial and industrial loans is largely influenced by general economic conditions and the resulting impact on a borrower’s operations, or on the value of underlying collateral, if any. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, formally reviewing the borrower’s financial condition on an ongoing basis, and generally require a guarantee (in full or part) from the primary business owners. Commercial bankers utilize SBA programs, where appropriate, as Nicolet is a preferred SBA lender. Owner-occupied CRE loans primarily consist of loans within a diverse range of industries secured by business real estate that is occupied by borrowers who operate their businesses out of the underlying collateral and who may also have commercial and industrial loans. The credit risk related to owner-occupied CRE loans is largely influenced by general economic conditions and the resulting impact on a borrower’s operations, or on the value of underlying collateral. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, periodically evaluating the underlying collateral, formally reviewing the borrower’s financial performance on an ongoing basis, and generally require a guarantee (in full or part) from the primary business owners. Agricultural loans consist of loans secured by farmland and the related farming operations, primarily within the dairy industry. These loans support short-term needs (planting crops or buying feed), as well as longer term needs (fund cattle, equipment or real estate purchases and improvements) of our agricultural customers. The credit risk related to agricultural loans is largely influenced by the agricultural economy, including market prices for the cost of feed and the price of milk, and / or the underlying value of the farmland. Credit risk is managed by employing sound underwriting guidelines, regular personal contact with our agricultural customers, formally reviewing the borrower’s financial condition on an ongoing basis, and generally require a guarantee (in full or part) from the primary business owners. Agricultural bankers utilize FSA programs, where appropriate, as Nicolet is a preferred FSA lender. The CRE investment loan classification primarily includes commercial-based mortgage loans that are secured by non-owner occupied, nonfarm / nonresidential real estate properties, and multi-family residential properties. Lending in this segment is focused on loans that are secured by commercial income-producing properties as opposed to speculative real estate development. The credit risk related to CRE investment loans is influenced by the cash flows of the properties, including vacancy experience, credit capacity of the tenants occupying the real estate, and general economic conditions, all of which may impact the borrower’s operations or the value of underlying collateral. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, periodically evaluating the underlying collateral, regularly reviewing the borrower’s financial condition, and generally require a guarantee (in full or part) from the principals. Construction and land development loans provide financing for the development of commercial income properties, multi-family residential development, and land designated for future development. The credit risk on construction loans depends largely upon the accuracy of the initial estimate of the property’s value at completion of construction and the estimated cost of construction. Nicolet controls the credit risk on these types of loans by making loans in familiar markets, reviewing the merits of individual projects, controlling loan structure, and monitoring the progress of projects through the analysis of construction advances. Credit risk is managed by employing sound underwriting guidelines, lending primarily to borrowers in local markets, periodically evaluating the underlying collateral, formally reviewing the borrower’s financial soundness and relationships on an ongoing basis, and generally require a guarantee (in full or part) from the principals. Residential real estate includes residential first mortgage loans and residential junior mortgage loans (home equity lines and term loans secured by junior mortgage liens). Residential real estate also includes residential construction loans. As part of its management of originating residential mortgage loans, Nicolet generally sells the majority of its long-term, fixed-rate residential first mortgage loans in the secondary market with the servicing rights retained, and retains the adjustable-rate mortgage loans in its loan portfolio. The Company may also retain a portion of the long-term, fixed rate residential mortgage loans that do not conform with secondary market standards, but do meet other specific underwriting guidelines. Credit risk for residential real estate loans largely depends upon factors affecting the borrower’s ability to repay as well as general economic trends. Residential real estate loan underwriting is subject to specific regulations, and Nicolet typically underwrites these loans to conform with those widely accepted standards. Residential real estate loans typically have longer terms and higher balances with lower yields, but generally carry lower risks of default. Retail loans include predominantly credit cards and other personal installment loans to individuals within Nicolet’s market areas. Retail loans are centrally underwritten utilizing the borrower’s financial history and information on the underlying collateral. Retail loans typically have shorter terms and lower balances with higher yields, but generally carry higher risks of default. Collection of these loans depends on the borrower’s financial stability, and is more likely to be affected by adverse personal circumstances. Loans – Acquired : Loans purchased in acquisition transactions are acquired loans, and are recorded at their estimated fair value on the acquisition date.
Allowance for Credit Losses - Loans and Unfunded Commitments	Allowance for Credit Losses - Loans : The ACL-Loans represents management’s estimate of expected credit losses over the lifetime of the loan based on loans in the Company’s loan portfolio at the balance sheet date. The Company estimates the ACL-Loans based on the amortized cost basis of the underlying loan and has made an accounting policy election to exclude accrued interest from the loan’s amortized cost basis and the related measurement of the ACL-Loans. Estimating the amount of the ACL-Loans is a function of a number of factors, including but not limited to changes in the loan portfolio, net charge-offs, trends in past due and nonaccrual loans, and the level of potential problem loans, all of which may be susceptible to significant change. Actual credit losses, net of recoveries, are deducted from the ACL-Loans. Loans are charged-off when management believes that the collectability of the principal is unlikely. Subsequent recoveries, if any, are credited to the ACL-Loans. A provision for credit losses, which is a charge against income, is recorded to bring the ACL-Loans to a level that, in management’s judgment, is appropriate to absorb expected credit losses in the loan portfolio. The Company uses the current expected credit loss model (“CECL”) to estimate the ACL-Loans. This model considers historical loss rates and other qualitative adjustments, as well as a forward-looking component that considers reasonable and supportable forecasts over the expected life of each loan. To develop the ACL-Loans estimate under the CECL model, the Company segments the loan portfolio into loan pools based on loan type and similar credit risk elements; performs an individual evaluation of PCD and other credit-deteriorated loans; calculates the historical loss rates for the segmented loan pools; applies the loss rates over the calculated life of the pooled loans; adjusts for forecasted macro-level economic conditions; and determines qualitative adjustments based on factors and conditions unique to Nicolet’s portfolio. To assess the overall appropriateness of the ACL-Loans, management applies an allocation methodology which focuses on evaluation of qualitative and environmental factors, including but not limited to: evaluation of facts and issues related to specific loans; management’s ongoing review and grading of the loan portfolio; consideration of historical loan loss and delinquency experience on each portfolio segment; trends in past due and nonaccrual loans; the risk characteristics of the various loan segments; changes in the size and character of the loan portfolio; concentrations of loans to specific borrowers or industries; existing economic conditions; the fair value of underlying collateral; and other qualitative and quantitative factors which could affect expected credit losses. Assessing these numerous factors involves significant judgment. Management allocates the ACL-Loans by pools of risk within each loan portfolio segment. The allocation methodology consists of the following components. First, a specific reserve is established for individually evaluated PCD and other credit-deteriorated loans, which management defines as nonaccrual credit relationships over $250,000, collateral dependent loans, and other loans with evidence of credit deterioration. The specific reserve in the ACL-Loans for these credit deteriorated loans is equal to the aggregate collateral or discounted cash flow shortfall. Next, management allocates the ACL-Loans with historical loss rates by loan segment. The loss factors are measured on a quarterly basis and applied to each loan segment based on current loan balances and projected for their expected remaining life. Management also allocates the ACL-Loans using the qualitative and environmental factors mentioned above. Consideration is given to those current qualitative or environmental factors that are likely to cause estimated credit losses at the evaluation date to differ from the historical loss experience of each loan segment. Lastly, management considers reasonable and supportable forecasts to assess the collectability of future cash flows. Allocations to the ACL-Loans may be made for specific loans but the entire ACL-Loans is available for any loan that, in management’s judgment, should be charged-off or for which an actual loss is realized. The allowance analysis is reviewed by the Board on a quarterly basis in compliance with internal and regulatory requirements. Allowance for Credit Losses - Unfunded Commitments
Credit-Related Financial Instruments	Credit-Related Financial Instruments : In the ordinary course of business, the Company has entered into financial instruments consisting of commitments to extend credit, financial standby letters of credit, and performance standby letters of credit. Financial standby letters of credit are issued specifically to facilitate commerce and typically result in the commitment being drawn on when the underlying transaction is consummated between the customer and the third party, while performance standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party. Such financial instruments are recorded in the consolidated financial statements when they are funded.
Transfers of Financial Assets	Transfers of Financial Assets : Transfers of financial assets, primarily in loan participation activities, are accounted for as sales only when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of the right) to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity or the ability to unilaterally cause the holder to return assets.
Premises and Equipment	Premises and Equipment : Premises and equipment are stated at cost less accumulated depreciation and amortization. Premises and equipment from acquisitions were recorded at estimated fair value on the respective dates of acquisition. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets. Leasehold improvements are amortized on a straight-line basis over the shorter of the estimated useful lives of the improvements or the terms of the related leases. Maintenance and repairs are expensed as incurred. Estimated useful lives of new premises and equipment generally range as follows: Building and improvements 25 – 40 years Leasehold improvements 5 – 15 years Furniture and equipment 3 – 10 years
Operating Leases	Operating Leases : The Company accounts for its operating leases in accordance with ASC 842, Leases accrued interest receivable and other assets accrued interest payable and other liabilities
Other Real Estate Owned ("OREO")	Other Real Estate Owned (“OREO”)
Goodwill and Other Intangibles	Goodwill and Other Intangibles : Goodwill represents the excess of the purchase price over the fair value of the net identifiable assets acquired. Goodwill is not amortized but, instead, is subject to impairment tests on at least an annual basis or more frequently if certain events or circumstances occur. Other intangibles include core deposit intangibles (which represent the value of acquired customer core deposit bases) and customer list intangibles. The core deposit intangibles have an estimated finite life, are amortized on an accelerated basis over a 10-year period, and are subject to periodic impairment evaluation. The customer list intangibles have finite lives, are amortized on a straight-line basis to expense over their initial weighted average life of approximately 12 years as of acquisition, and are subject to periodic impairment evaluation.
Mortgage Servicing Rights ("MSRs") and Loan Servicing Rights ("LSRs")	Mortgage Servicing Rights (“MSRs”) : The Company sells originated residential mortgages into the secondary market and retains the right to service the loans sold. A mortgage servicing right asset (liability) is capitalized upon sale of such loans with the offsetting effect recorded as a gain (loss) on sale of loans in earnings (included in mortgage income, net), representing the then-current estimated fair value of future net cash flows expected to be realized for performing the servicing activities. MSRs when purchased (including MSRs purchased in acquisitions) are initially recorded at their then-estimated fair value. As the Company has not elected to measure any class of servicing assets under the fair value method, the Company utilizes the amortization method. MSRs are amortized in proportion to and over the period of estimated net servicing income, with the amortization charged to earnings (included in mortgage income, net). MSRs are carried at the lower of initial capitalized amount, net of accumulated amortization, or estimated fair value, and are included in other assets in the consolidated balance sheets. Mortgage loan servicing fee income is typically based on a contractual percentage of the outstanding principal and is recorded as income when earned (included in mortgage income, net with less material late fees and ancillary fees related to loan servicing). At each reporting date, the MSR asset is assessed for impairment based on the estimated fair value, which considers the estimated prepayment speeds and stratifications based on the risk characteristics of the underlying loans serviced (predominantly loan type and note interest rate). The value of MSRs is adversely affected when mortgage interest rates decline and mortgage loan prepayments increase. A valuation allowance is established through a charge to earnings (included in mortgage income, net) to the extent the amortized cost of the MSRs exceeds the estimated fair value by stratification. If it is later determined that all or a portion of the temporary impairment no longer exists for a stratification, the valuation is reduced through a recovery to earnings, though not beyond the net amortized cost. An other-than-temporary impairment (i.e., recoverability is considered remote when considering Loan Servicing Rights (“LSRs”) :
Bank-owned Life Insurance ("BOLI")	Bank-owned Life Insurance (“BOLI”) : The Company owns BOLI on certain executives and employees. BOLI balances are recorded at their cash surrender values. Changes in the cash surrender values and death proceeds exceeding carrying values are included in BOLI income.
Stock-based Compensation Plans	Stock-based Compensation :
Income Taxes	Income Taxes : The Company files a consolidated federal income tax return with its wholly owned subsidiaries and files state income tax returns with the various taxing jurisdictions based on its taxable presence. Amounts equal to tax benefits of those subsidiaries having taxable federal or state losses or credits are reimbursed by the entities that incur federal or state tax liabilities. Amounts provided for income tax expense are based on income reported for financial statement purposes and do not necessarily represent amounts currently payable under tax laws. Deferred income tax assets and liabilities are computed quarterly for differences between the financial statement and tax bases of assets and liabilities that will result in taxable or deductible amounts in the future based on enacted tax rates applicable to the periods in which the differences are expected to affect taxable income. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through income tax expense. Valuation allowances are established when it is more likely than not that a portion of the full amount of the deferred tax asset will not be realized. In assessing the ability to realize deferred tax assets, management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies. At acquisition, deferred taxes were evaluated in respect to the acquired assets and assumed liabilities (including the acquired net operating losses), and a net deferred tax asset was recorded. Certain limitations within the provisions of the tax code are placed on the amount of net operating losses which can be utilized as part of acquisition accounting rules and were incorporated into the calculation of the deferred tax asset. In addition, a portion of the fair value discounts on PCD loans which resolved in the first twelve months after the acquisition were disallowed under provisions of the tax code.
Earnings per Common Share	Earnings per Common Share
Treasury Stock	Treasury Stock : Treasury stock is accounted for at cost on a first-in-first-out basis. It is the Company’s general practice to cancel treasury stock shares in the same quarter as purchased, and thus, not carry a treasury stock balance.
Comprehensive Income	Comprehensive Income : Accounting principles generally require that recognized revenue, expenses, gains and losses be included in net income. Certain changes in assets and liabilities, such as unrealized gains and losses on securities AFS, are reported in accumulated other comprehensive income (loss), as a separate component of the equity section of the balance sheet. Realized gains or losses are reclassified to current period income. Changes in these items, along with net income, are components of comprehensive income (loss). The Company presents comprehensive income in a separate consolidated statement of comprehensive income.
Revenue Recognition	Revenue Recognition : Accounting principles (ASC 606, Revenue from Contracts with Customers) require that an entity recognize revenue to depict the transfer of promised goods and services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. The guidance includes a five-step model to apply to revenue recognition, consisting of the following: (1) identify the contract; (2) identify the performance obligation in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations; and (5) recognize revenue when or as the performance obligation is satisfied. ASC 606 does not apply to revenue associated with financial instruments, including revenue from loans and securities, as well as certain noninterest income categories, such as gains or losses associated with mortgage servicing rights and income from BOLI. Descriptions of the Company’s primary revenue contracts within the scope of this revenue recognition guidance are discussed in detail below. Trust services and brokerage fee income : A contract between the Company and its customers to provide fiduciary and / or investment administration services on trust accounts and brokerage accounts in exchange for a fee. Trust services and brokerage fee income is generally based upon the month-end market value of the assets under management and the applicable fee rate, which is recognized over the period the underlying trust or brokerage account is serviced (generally on a monthly basis). Such contracts are generally cancellable at any time, with the customer subject to a pro-rated fee in the month of termination. Service charges on deposit accounts : The deposit contract obligates the Company to serve as a custodian of the customer’s deposited funds and generally can be terminated at will by either party. This contract permits the customer to access the funds on deposit and request additional services related to the deposit account. Service charges on deposit accounts consist of account analysis fees (net fees earned on analyzed business and public checking accounts), monthly service charges, nonsufficient fund (“NSF”) charges, and other deposit account related charges. The Company’s performance obligation for account analysis fees and monthly service charges is generally satisfied, and the related revenue recognized, over the period in which the service is provided (typically on a monthly basis); while NSF charges and other deposit account related charges are largely transactional based and the related revenue is recognized at the time the service is provided. Card interchange income : A contract between the Company, as a card-issuing bank, and its customers whereby the Company receives a transaction fee from the merchant’s bank whenever a customer uses a debit or credit card to make a purchase. The performance obligation is completed and the fees are recognized as the service is provided (i.e., when the customer uses a debit or credit card).
Recent Accounting Pronouncements Adopted and Future Accounting Pronouncements	Recent Accounting Pronouncements Adopted : In March 2022, the FASB issued ASU 2022-02, Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings (“TDRs”) and Vintage Disclosures . This ASU eliminated the accounting guidance for TDRs by creditors and enhanced the disclosure requirements for loan modifications to borrowers experiencing financial difficulty. The ASU also requires public business entities to expand the vintage disclosures to include gross charge-offs by year of origination. The updated guidance is effective for fiscal years beginning after December 15, 2022. Adoption of this ASU did not have a material impact on the Company’s consolidated financial statements; however, it resulted in new disclosures. See Note 4 for the new disclosures. In March 2020, the FASB issued ASU 2023-02, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting . This ASU provides optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. It provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. In December 2022, the FASB issued ASU ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848, which defers the sunset date of the original guidance from December 31, 2022 to December 31, 2024. The Company expects to utilize the reference rate reform transition guidance, as applicable, and does not expect such adoption to have a material impact on its consolidated financial statements or financial disclosures. Future Accounting Pronouncements : In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . The amendments in this ASU improve the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the rate reconciliation table, as well as income taxes paid disaggregated by jurisdiction. These expanded disclosures will allow investors to better assess how an entity’s overall operations, including the related tax risks, tax planning, and operational opportunities, affect its income tax rate and prospects for future cash flows. The updated guidance is effective for annual periods beginning after December 15, 2024. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . This ASU expands segment disclosure requirements for public entities to include disclosure of significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit or loss. The updated guidance is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. In March 2023, the FASB issued ASU 2023-02, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method . This ASU permits reporting entities to elect to account for tax equity investments, regardless of the tax credit program for which the income tax credits are received, using the proportional amortization method if certain conditions are met. Under the proportional amortization method, an entity amortizes the initial cost of the investment in proportion to the income tax credits and other income tax benefits received and recognizes the net amortization and income tax credits and other income tax benefits in the income statement as a component of income tax expense. A reporting entity makes an accounting policy election to apply the proportional amortization method on a tax-credit-program-by-tax-credit-program basis rather than electing to apply the proportional amortization method at the reporting entity level or to individual investments. This ASU also requires specific disclosures of investments that generate income tax credits and other income tax benefits from a tax credit program for which the entity has elected to apply the proportional amortization method. The updated guidance is effective for fiscal years beginning after December 15, 2023.
Reclassifications	Reclassifications : Certain amounts in the 2022 and 2021 consolidated financial statements have been reclassified to conform to the 2023 presentation.
Fair Value Measurement	The carrying value of certain assets and liabilities such as cash and cash equivalents, accrued interest receivable, nonmaturing deposits, short-term borrowings, and accrued interest payable approximate their estimated fair value due to their immediate and shorter term maturities. For those financial instruments not previously disclosed, the following is a description of the valuation methodologies used. Certificates of deposit in other banks: Fair values are estimated using discounted cash flow analysis based on current interest rates being offered by instruments with similar terms and represents a Level 2 measurement. Securities HTM: The valuation methodologies for Securities HTM are consistent with the valuation methodologies used for Securities, as discussed under “Recurring basis fair value measurements” above. Other investments : The valuation methodologies utilized for the exchange-traded equity securities are discussed under “Recurring basis fair value measurements” above. The carrying amount of Federal Reserve Bank and FHLB stock is a reasonably accepted fair value estimate given their restricted nature. Fair value is the redeemable (carrying) value based on the redemption provisions of the instruments which is considered a Level 2 measurement. The carrying amount of the remaining other investments (particularly common stocks of companies or other banks that are not publicly traded) approximates their fair value, determined primarily by analysis of company financial statements and recent capital issuances of the respective companies or banks, if any, and represents a Level 3 measurement. Loans held for sale: The fair value estimation process for the loans held for sale portfolio is segregated by loan type. The estimated fair value was based on what secondary markets are currently offering for portfolios with similar characteristics and represents a Level 2 measurement. Loans, net : For variable-rate loans that reprice frequently and with no significant change in credit risk or other optionality, fair values are based on carrying values. Fair values for all other loans are estimated by discounting contractual cash flows using estimated market discount rates, which reflect the credit and interest rate risk inherent in the loan based on market participants. Collateral-dependent loans are included in loans, net. The fair value of loans is considered to be a Level 3 measurement due to internally developed discounted cash flow measurements. Deposits : The fair value of deposits with no stated maturity (such as demand deposits, savings, interest and noninterest checking, and money market accounts) is equal to the amount payable on demand at the reporting date. Fair values for fixed-rate certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered in the market place on certificates of similar remaining maturities. Use of internal discounted cash flows provides a Level 3 fair value measurement. Long-term borrowings : The fair value of the FHLB advances is obtained from the FHLB which uses a discounted cash flow analysis based on current market rates of similar maturity debt securities and represents a Level 2 measurement. The fair values of the junior subordinated debentures and subordinated notes utilize a discounted cash flow analysis based on an estimate of current interest rates being offered by instruments with similar terms and credit quality. Since the market for these instruments is limited, the internal valuation represents a Level 3 measurement. Lending-related commitments : The estimated fair value of lending-related commitments (letters of credit, interest rate lock commitments on residential mortgage loans and outstanding mandatory commitments to sell residential mortgage loans into the secondary market) were not significant. Limitations : Fair value estimates are made at a specific point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the Company’s entire holdings of a particular financial instrument. Fair value estimates may not be realizable in an immediate settlement of the instrument. In some instances, there are no quoted market prices for the Company’s various financial instruments, in which case fair values may be based on estimates using present value or other valuation techniques, or based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of the financial instruments, or other factors. Those techniques are significantly affected by the assumptions used, including the discount rate and estimate of future cash flows. Subsequent changes in assumptions could significantly affect the estimates.

NATURE OF BUSINESS AND SIGNIF_3

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of estimated useful lives of premises and equipment	Estimated useful lives of new premises and equipment generally range as follows: Building and improvements 25 – 40 years Leasehold improvements 5 – 15 years Furniture and equipment 3 – 10 years

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Business Combination and Asset Acquisition [Abstract]
Schedule of assets acquired and liabilities assumed and purchase price allocation	A summary of the assets acquired and liabilities assumed in the Charter transaction, as of the acquisition date, including the purchase price allocation was as follows. (In millions, except share data) Acquired from Charter Fair Value Adjustments Estimated Fair Value Assets Acquired: Cash and cash equivalents $ 10 $ — $ 10 Investment securities 218 — 218 Loans 848 (21) 827 ACL-Loans (9) 7 (2) Premises and equipment 9 1 10 BOLI 29 — 29 Core deposit intangible — 19 19 Other assets 5 5 10 Total assets $ 1,110 $ 11 $ 1,121 Liabilities Assumed: Deposits $ 869 $ 1 $ 870 Borrowings 161 — 161 Other liabilities 3 — 3 Total liabilities $ 1,033 $ 1 $ 1,034 Net assets acquired $ 87 Purchase Price: Nicolet common stock issued (in shares) 1,262,360 Value of Nicolet common stock consideration $ 98 Cash consideration paid 39 Total purchase price $ 137 Goodwill $ 50 (In thousands) August 26, 2022 Purchase price of PCD loans at acquisition $ 24,031 Allowance for credit losses on PCD loans at acquisition 1,709 Par value of PCD acquired loans at acquisition $ 25,740 A summary of the assets acquired and liabilities assumed in the County transaction, as of the acquisition date, including the purchase price allocation was as follows. (In millions, except share data) Acquired from County Fair Value Adjustments Estimated Fair Value Assets Acquired: Cash and cash equivalents $ 20 $ — $ 20 Investment securities 301 (1) 300 Loans 1,015 (1) 1,014 ACL-Loans (11) 8 (3) Premises and equipment 21 (4) 17 BOLI 33 — 33 Core deposit intangible — 7 7 Loan servicing rights 20 — 20 Other assets 6 (2) 4 Total assets $ 1,405 $ 7 $ 1,412 Liabilities Assumed: Deposits $ 1,027 $ 3 $ 1,030 Borrowings 218 1 219 Other liabilities 8 — 8 Total liabilities $ 1,253 $ 4 $ 1,257 Net assets acquired $ 155 Purchase Price: Nicolet common stock issued (in shares) 2,366,243 Value of Nicolet common stock consideration $ 176 Cash consideration paid 48 Total purchase price $ 224 Write-off prior investment in County (1) Goodwill $ 70 (In thousands) December 3, 2021 Purchase price of PCD loans at acquisition $ 64,720 Allowance for credit losses on PCD loans at acquisition 3,490 Par value of PCD acquired loans at acquisition $ 68,210 A summary of the assets acquired and liabilities assumed in the Mackinac transaction, as of the acquisition date, including the purchase price allocation was as follows. (In millions, except share data) Acquired from Mackinac Fair Value Adjustments Estimated Fair Value Assets Acquired: Cash and cash equivalents $ 448 $ — $ 448 Investment securities 104 — 104 Loans 930 10 940 ACL-Loans (6) 4 (2) Premises and equipment 24 (3) 21 BOLI 16 — 16 Goodwill 20 (20) — Other intangibles 4 3 7 Other assets 25 (3) 22 Total assets $ 1,565 $ (9) $ 1,556 Liabilities Assumed: Deposits $ 1,365 $ 1 $ 1,366 Borrowings 28 1 29 Other liabilities 13 1 14 Total liabilities $ 1,406 $ 3 $ 1,409 Net assets acquired $ 147 Purchase Price: Nicolet common stock issued (in shares) 2,337,230 Value of Nicolet common stock consideration $ 180 Cash consideration paid 49 Total purchase price $ 229 Write-off prior investment in Mackinac (2) Goodwill $ 84 (In thousands) September 3, 2021 Purchase price of PCD loans at acquisition $ 10,605 Allowance for credit losses on PCD loans at acquisition 1,896 Par value of PCD acquired loans at acquisition $ 12,501
Schedule of unaudited pro forma information	The following unaudited pro forma information is presented for illustrative purposes only, and gives effect to the acquisitions of County and Mackinac as if the acquisitions had occurred on January 1, 2021, the beginning of the earliest period presented. The pro forma information should not be relied upon as being indicative of the historical results of operations the companies would have had if the acquisitions had occurred before such periods or the future results of operations that the companies will experience as a result of the mergers. The pro forma information, although helpful in illustrating the financial characteristics of the combined company under one set of assumptions, does not reflect the benefits of expected cost savings, opportunities to earn additional revenue, the impact of restructuring and merger-related expenses, or other factors that may result as a consequence of the mergers and, accordingly, does not attempt to predict or suggest future results. Years Ended (In thousands, except per share data) December 31, 2021 Total revenue, net of interest expense $ 320,307 Net income $ 87,860 Diluted earnings per common share $ 5.91

SECURITIES AND OTHER INVESTME_2

SECURITIES AND OTHER INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of amortized costs and fair values of securities AFS	The amortized cost and fair value of securities available for sale and held to maturity are summarized as follows. December 31, 2023 (in thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Fair Securities AFS: U.S. Treasury securities $ 15,988 $ — $ 1,865 $ 14,123 U.S. government agency securities 7,430 — 46 7,384 State, county and municipals 360,496 651 26,325 334,822 Mortgage-backed securities 388,378 1,437 37,193 352,622 Corporate debt securities 102,895 26 9,299 93,622 Total securities AFS $ 875,187 $ 2,114 $ 74,728 $ 802,573 December 31, 2022 (in thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Fair Securities AFS: U.S. Treasury securities $ 192,116 $ — $ 8,286 $ 183,830 U.S. government agency securities 2,133 — 33 2,100 State, county and municipals 433,733 123 35,668 398,188 Mortgage-backed securities 227,650 10 26,728 200,932 Corporate debt securities 140,712 3 8,147 132,568 Total securities AFS $ 996,344 $ 136 $ 78,862 $ 917,618 Securities HTM: U.S. Treasury securities $ 497,648 $ — $ 35,722 $ 461,926 U.S. government agency securities 8,744 46 — 8,790 State, county and municipals 34,874 — 3,349 31,525 Mortgage-backed securities 137,862 — 16,751 121,111 Total securities HTM $ 679,128 $ 46 $ 55,822 $ 623,352
Schedule of amortized costs and fair values of securities HTM	The amortized cost and fair value of securities available for sale and held to maturity are summarized as follows. December 31, 2023 (in thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Fair Securities AFS: U.S. Treasury securities $ 15,988 $ — $ 1,865 $ 14,123 U.S. government agency securities 7,430 — 46 7,384 State, county and municipals 360,496 651 26,325 334,822 Mortgage-backed securities 388,378 1,437 37,193 352,622 Corporate debt securities 102,895 26 9,299 93,622 Total securities AFS $ 875,187 $ 2,114 $ 74,728 $ 802,573 December 31, 2022 (in thousands) Amortized Gross Unrealized Gains Gross Unrealized Losses Fair Securities AFS: U.S. Treasury securities $ 192,116 $ — $ 8,286 $ 183,830 U.S. government agency securities 2,133 — 33 2,100 State, county and municipals 433,733 123 35,668 398,188 Mortgage-backed securities 227,650 10 26,728 200,932 Corporate debt securities 140,712 3 8,147 132,568 Total securities AFS $ 996,344 $ 136 $ 78,862 $ 917,618 Securities HTM: U.S. Treasury securities $ 497,648 $ — $ 35,722 $ 461,926 U.S. government agency securities 8,744 46 — 8,790 State, county and municipals 34,874 — 3,349 31,525 Mortgage-backed securities 137,862 — 16,751 121,111 Total securities HTM $ 679,128 $ 46 $ 55,822 $ 623,352 The following tables present gross unrealized losses and the related estimated fair value of investment securities for which an allowance for credit losses has not been recorded, aggregated by investment category and the length of time the individual securities have been in a continuous unrealized loss position. December 31, 2023 Less than 12 months 12 months or more Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized Number of Securities Securities AFS: U.S. Treasury securities $ — $ — $ 14,123 $ 1,865 $ 14,123 $ 1,865 1 U.S. government agency securities 4,621 31 1,793 15 6,414 46 10 State, county and municipals 29,336 330 257,916 25,995 287,252 26,325 528 Mortgage-backed securities 6 — 291,124 37,193 291,130 37,193 433 Corporate debt securities — — 85,265 9,299 85,265 9,299 59 Total $ 33,963 $ 361 $ 650,221 $ 74,367 $ 684,184 $ 74,728 1,031 December 31, 2022 Less than 12 months 12 months or more Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized Number of Securities Securities AFS: U.S. Treasury securities $ 448 $ 14 $ 183,382 $ 8,272 $ 183,830 $ 8,286 9 U.S. government agency securities 2,083 32 17 1 2,100 33 9 State, county and municipals 277,546 18,041 86,569 17,627 364,115 35,668 812 Mortgage-backed securities 102,108 11,320 95,614 15,408 197,722 26,728 376 Corporate debt securities 114,887 6,186 12,938 1,961 127,825 8,147 90 Total $ 497,072 $ 35,593 $ 378,520 $ 43,269 $ 875,592 $ 78,862 1,296 Securities HTM: U.S. Treasury securities $ — $ — $ 461,926 $ 35,722 $ 461,926 $ 35,722 6 State, county and municipals 17,591 1,594 11,654 1,755 29,245 3,349 58 Mortgage-backed securities 68,108 8,029 53,003 8,722 121,111 16,751 106 Total $ 85,699 $ 9,623 $ 526,583 $ 46,199 $ 612,282 $ 55,822 170
Schedule of proceeds and realized gains or losses from the sale of AFS securities	Proceeds and realized gains / losses from the sale of securities AFS were as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Securities AFS: Gross gains $ 268 $ 28 $ 5 Gross losses (3,581) (272) (288) Gains (losses) on sales of securities AFS, net $ (3,313) $ (244) $ (283) Proceeds from sales of securities AFS * $ 65,749 $ 28,438 $ 42,973 Securities HTM: Gross gains $ — $ — $ — Gross losses (37,723) — — Gains (losses) on sales of securities HTM, net $ (37,723) $ — $ — Proceeds from sales of securities HTM $ 460,051 $ — $ — * Includes proceeds of $21 million recognized on the sale of securities AFS upon acquisition of Charter in August 2022 for which no gain or loss was recognized in the income statement as the investment securities were marked to fair value through purchase accounting.
Schedule of Available for sale securities in a continuous loss position	The following tables present gross unrealized losses and the related estimated fair value of investment securities for which an allowance for credit losses has not been recorded, aggregated by investment category and the length of time the individual securities have been in a continuous unrealized loss position. December 31, 2023 Less than 12 months 12 months or more Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized Number of Securities Securities AFS: U.S. Treasury securities $ — $ — $ 14,123 $ 1,865 $ 14,123 $ 1,865 1 U.S. government agency securities 4,621 31 1,793 15 6,414 46 10 State, county and municipals 29,336 330 257,916 25,995 287,252 26,325 528 Mortgage-backed securities 6 — 291,124 37,193 291,130 37,193 433 Corporate debt securities — — 85,265 9,299 85,265 9,299 59 Total $ 33,963 $ 361 $ 650,221 $ 74,367 $ 684,184 $ 74,728 1,031 December 31, 2022 Less than 12 months 12 months or more Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized Number of Securities Securities AFS: U.S. Treasury securities $ 448 $ 14 $ 183,382 $ 8,272 $ 183,830 $ 8,286 9 U.S. government agency securities 2,083 32 17 1 2,100 33 9 State, county and municipals 277,546 18,041 86,569 17,627 364,115 35,668 812 Mortgage-backed securities 102,108 11,320 95,614 15,408 197,722 26,728 376 Corporate debt securities 114,887 6,186 12,938 1,961 127,825 8,147 90 Total $ 497,072 $ 35,593 $ 378,520 $ 43,269 $ 875,592 $ 78,862 1,296 Securities HTM: U.S. Treasury securities $ — $ — $ 461,926 $ 35,722 $ 461,926 $ 35,722 6 State, county and municipals 17,591 1,594 11,654 1,755 29,245 3,349 58 Mortgage-backed securities 68,108 8,029 53,003 8,722 121,111 16,751 106 Total $ 85,699 $ 9,623 $ 526,583 $ 46,199 $ 612,282 $ 55,822 170
Schedule of amortized cost and fair value of investment securities by contractual maturity	The amortized cost and fair value of investment securities by contractual maturity are shown below. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties; as this is particularly inherent in mortgage-backed securities, these securities are not included in the maturity categories below. As of December 31, 2023 Securities AFS (in thousands) Amortized Cost Fair Value Due in less than one year $ 55,132 $ 54,675 Due in one year through five years 117,392 109,079 Due after five years through ten years 208,859 186,493 Due after ten years 105,426 99,704 486,809 449,951 Mortgage-backed securities 388,378 352,622 Total $ 875,187 $ 802,573
Schedule of Carrying Value of other Investments	The carrying value of other investments are summarized as follows. (in thousands) December 31, 2023 December 31, 2022 Federal Reserve Bank stock $ 33,087 $ 32,219 FHLB stock 9,674 18,625 Equity securities with readily determinable fair values 4,240 4,376 Other investments 10,559 10,066 Total other investments $ 57,560 $ 65,286

LOANS, ALLOWANCE FOR CREDIT LOS

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY (Tables)	12 Months Ended
	Dec. 31, 2023
Receivables [Abstract]
Schedule of loan composition by portfolio segment	The loan composition was as follows. December 31, 2023 December 31, 2022 (in thousands) Amount % of Total Amount % of Total Commercial & industrial $ 1,284,009 20 % $ 1,304,819 21 % Owner-occupied commercial real estate (“CRE”) 956,594 15 954,599 15 Agricultural 1,161,531 18 1,088,607 18 Commercial 3,402,134 53 3,348,025 54 CRE investment 1,142,251 18 1,149,949 19 Construction & land development 310,110 5 318,600 5 Commercial real estate 1,452,361 23 1,468,549 24 Commercial-based loans 4,854,495 76 4,816,574 78 Residential construction 75,726 1 114,392 2 Residential first mortgage 1,167,109 19 1,016,935 16 Residential junior mortgage 200,884 3 177,332 3 Residential real estate 1,443,719 23 1,308,659 21 Retail & other 55,728 1 55,266 1 Retail-based loans 1,499,447 24 1,363,925 22 Loans 6,353,942 100 % 6,180,499 100 % Less ACL-Loans 63,610 61,829 Loans, net $ 6,290,332 $ 6,118,670 ACL-Loans to loans 1.00 % 1.00 %
Schedule of changes in the allowance for credit losses - loans by portfolio segment	A roll forward of the allowance for credit losses - loans was as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Beginning balance $ 61,829 $ 49,672 $ 32,173 ACL on PCD loans acquired — 1,937 5,159 Provision for credit losses 2,650 10,950 12,500 Charge-offs (1,653) (1,033) (513) Recoveries 784 303 353 Net (charge-offs) recoveries (869) (730) (160) Ending balance $ 63,610 $ 61,829 $ 49,672 The following table presents the balance and activity in the ACL-Loans by portfolio segment. Year Ended December 31, 2023 (in thousands) Commercial Owner- Agricultural CRE Construction & land Residential Residential Residential Retail Total ACL-Loans Beginning balance $ 16,350 $ 9,138 $ 9,762 $ 12,744 $ 2,572 $ 1,412 $ 6,976 $ 1,846 $ 1,029 $ 61,829 Provision (1,205) 470 2,930 (51) (132) (496) 346 347 441 2,650 Charge-offs (440) (773) (66) — — — (5) (96) (273) (1,653) Recoveries 520 247 3 — — — 3 1 10 784 Net (charge-offs) recoveries 80 (526) (63) — — — (2) (95) (263) (869) Ending balance $ 15,225 $ 9,082 $ 12,629 $ 12,693 $ 2,440 $ 916 $ 7,320 $ 2,098 $ 1,207 $ 63,610 As % of ACL-Loans 24 % 14 % 20 % 20 % 4 % — % 12 % 4 % 2 % 100 % For comparison purposes, the following table presents the balance and activity in the ACL-Loans by portfolio segment for the prior year-end period. Year Ended December 31, 2022 (in thousands) Commercial Owner- Agricultural CRE Construction & land Residential Residential Residential Retail Total ACL-Loans Beginning balance $ 12,613 $ 7,222 $ 9,547 $ 8,462 $ 1,812 $ 900 $ 6,844 $ 1,340 $ 932 $ 49,672 ACL on PCD loans 1,408 384 — 38 2 — 93 12 — 1,937 Provision 2,415 2,087 215 4,075 758 512 96 493 299 10,950 Charge-offs (190) (555) — — — — (65) — (223) (1,033) Recoveries 104 — — 169 — — 8 1 21 303 Net (charge-offs) recoveries (86) (555) — 169 — — (57) 1 (202) (730) Ending balance $ 16,350 $ 9,138 $ 9,762 $ 12,744 $ 2,572 $ 1,412 $ 6,976 $ 1,846 $ 1,029 $ 61,829 As % of ACL-Loans 26 % 15 % 16 % 21 % 4 % 2 % 11 % 3 % 2 % 100 %
Schedule of provision of credit losses	The following table presents the components of the provision for credit losses. Years Ended December 31, (in thousands) 2023 2022 2021 Provision for credit losses on: Loans $ 2,650 $ 10,950 $ 12,500 Unfunded commitments — 550 2,400 Investment securities 2,340 — — Total provision for credit losses $ 4,990 $ 11,500 $ 14,900
Schedule of collateral dependent loans by portfolio segment	The following table presents collateral dependent loans by portfolio segment and collateral type, including those loans with and without a related allowance allocation. December 31, 2023 Collateral Type (in thousands) Real Estate Other Business Assets Total Without an Allowance With an Allowance Allowance Allocation Commercial & industrial $ — $ 2,576 $ 2,576 $ 2,164 $ 412 $ 196 Owner-occupied CRE 3,614 — 3,614 3,465 149 24 Agricultural 6,931 5,219 12,150 7,261 4,889 117 CRE investment 1,261 — 1,261 871 390 18 Construction & land development — — — — — — Residential construction — — — — — — Residential first mortgage 674 — 674 674 — — Residential junior mortgage — — — — — — Retail & other — — — — — — Total loans $ 12,480 $ 7,795 $ 20,275 $ 14,435 $ 5,840 $ 355 December 31, 2022 Collateral Type (in thousands) Real Estate Other Business Assets Total Without an Allowance With an Allowance Allowance Allocation Commercial & industrial $ — $ 3,475 $ 3,475 $ 1,927 $ 1,548 $ 595 Owner-occupied CRE 4,907 — 4,907 4,699 208 53 Agricultural 13,758 6,458 20,216 14,358 5,858 261 CRE investment 2,713 — 2,713 979 1,734 212 Construction & land development 670 — 670 670 — — Residential construction — — — — — — Residential first mortgage 91 — 91 91 — — Residential junior mortgage — — — — — — Retail & other — — — — — — Total loans $ 22,139 $ 9,933 $ 32,072 $ 22,724 $ 9,348 $ 1,121
Schedule of past due loans by portfolio segment	The following tables present past due loans by portfolio segment. December 31, 2023 (in thousands) 30-89 Days Past 90 Days & Over Current Total Commercial & industrial $ 540 $ 4,046 $ 1,279,423 $ 1,284,009 Owner-occupied CRE 2,123 4,399 950,072 956,594 Agricultural 12 12,185 1,149,334 1,161,531 CRE investment 3,060 1,453 1,137,738 1,142,251 Construction & land development 171 161 309,778 310,110 Residential construction — — 75,726 75,726 Residential first mortgage 2,663 4,059 1,160,387 1,167,109 Residential junior mortgage 547 150 200,187 200,884 Retail & other 327 172 55,229 55,728 Total loans $ 9,443 $ 26,625 $ 6,317,874 $ 6,353,942 Percent of total loans 0.1 % 0.4 % 99.5 % 100.0 % December 31, 2022 (in thousands) 30-89 Days Past 90 Days & Over Current Total Commercial & industrial $ 210 $ 3,328 $ 1,301,281 $ 1,304,819 Owner-occupied CRE 833 5,647 948,119 954,599 Agricultural 20 20,416 1,068,171 1,088,607 CRE investment — 3,832 1,146,117 1,149,949 Construction & land development — 771 317,829 318,600 Residential construction — — 114,392 114,392 Residential first mortgage 3,628 3,780 1,009,527 1,016,935 Residential junior mortgage 236 224 176,872 177,332 Retail & other 261 82 54,923 55,266 Total loans $ 5,188 $ 38,080 $ 6,137,231 $ 6,180,499 Percent of total loans 0.1 % 0.6 % 99.3 % 100.0 %
Schedule of nonaccrual loans by portfolio segment	The following table presents nonaccrual loans by portfolio segment. The nonaccrual loans without a related allowance for credit losses have been reflected in the collateral dependent loans table above. Total Nonaccrual Loans (in thousands) December 31, 2023 % to Total December 31, 2022 % to Total Commercial & industrial $ 4,046 15 % $ 3,328 9 % Owner-occupied CRE 4,399 16 5,647 15 Agricultural 12,185 46 20,416 53 CRE investment 1,453 5 3,832 10 Construction & land development 161 1 771 2 Residential construction — — — — Residential first mortgage 4,059 15 3,780 10 Residential junior mortgage 150 1 224 1 Retail & other 172 1 82 — Nonaccrual loans $ 26,625 100 % $ 38,080 100 % Percent of total loans 0.4 % 0.6 %
Schedule of total loans by risk categories and year of origination	The following tables present total loans by risk categories and year of origination. Acquired loans have been included based upon the actual origination date. December 31, 2023 Amortized Cost Basis by Origination Year (in thousands) 2023 2022 2021 2020 2019 Prior Revolving Revolving to Term TOTAL Commercial & industrial Grades 1-4 $ 223,515 $ 234,193 $ 171,555 $ 66,026 $ 49,054 $ 81,272 $ 359,284 $ — $ 1,184,899 Grade 5 3,252 13,656 7,516 3,388 5,074 7,020 18,753 — 58,659 Grade 6 — 562 502 187 3 1,009 10,974 — 13,237 Grade 7 5,742 3,702 2,655 2,409 1,769 9,244 1,693 — 27,214 Total $ 232,509 $ 252,113 $ 182,228 $ 72,010 $ 55,900 $ 98,545 $ 390,704 $ — $ 1,284,009 Current period gross charge-offs $ — $ (89) $ (114) $ — $ — $ (222) $ (15) $ — $ (440) Owner-occupied CRE Grades 1-4 $ 114,704 $ 156,723 $ 181,128 $ 91,038 $ 85,430 $ 247,730 $ 4,181 $ — $ 880,934 Grade 5 5,416 4,024 7,858 5,092 3,994 27,585 52 — 54,021 Grade 6 — — 3,905 — 1,531 12 — — 5,448 Grade 7 — 1,304 1,071 6,988 338 6,340 150 — 16,191 Total $ 120,120 $ 162,051 $ 193,962 $ 103,118 $ 91,293 $ 281,667 $ 4,383 $ — $ 956,594 Current period gross charge-offs $ — $ — $ — $ — $ — $ (773) $ — $ — $ (773) Agricultural Grades 1-4 $ 120,200 $ 274,491 $ 134,706 $ 78,944 $ 22,985 $ 139,212 $ 277,170 $ — $ 1,047,708 Grade 5 6,345 11,975 5,718 703 394 33,658 15,522 — 74,315 Grade 6 — 130 1,017 — 51 2,256 194 — 3,648 Grade 7 2,519 6,691 5,360 428 1,679 12,098 7,085 — 35,860 Total $ 129,064 $ 293,287 $ 146,801 $ 80,075 $ 25,109 $ 187,224 $ 299,971 $ — $ 1,161,531 Current period gross charge-offs $ — $ — $ — $ — $ — $ (66) $ — $ — $ (66) CRE investment Grades 1-4 $ 30,720 $ 194,442 $ 256,765 $ 169,078 $ 113,510 $ 283,339 $ 11,146 $ — $ 1,059,000 Grade 5 2,790 7,746 17,899 9,857 11,232 23,108 49 — 72,681 Grade 6 — — — — — 1,340 65 — 1,405 Grade 7 — 51 21 — 1,034 8,059 — — 9,165 Total $ 33,510 $ 202,239 $ 274,685 $ 178,935 $ 125,776 $ 315,846 $ 11,260 $ — $ 1,142,251 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Construction & land development Grades 1-4 $ 51,253 $ 149,155 $ 64,761 $ 9,441 $ 4,939 $ 22,548 $ 2,883 $ — $ 304,980 Grade 5 — 23 3,044 1,264 504 88 — — 4,923 Grade 7 46 — — — — 86 75 — 207 Total $ 51,299 $ 149,178 $ 67,805 $ 10,705 $ 5,443 $ 22,722 $ 2,958 $ — $ 310,110 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential construction Grades 1-4 $ 57,033 $ 13,035 $ 3,316 $ 1,118 $ 130 $ 1,094 $ — $ — $ 75,726 Total $ 57,033 $ 13,035 $ 3,316 $ 1,118 $ 130 $ 1,094 $ — $ — $ 75,726 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential first mortgage Grades 1-4 $ 164,917 $ 389,246 $ 247,957 $ 130,857 $ 56,223 $ 162,424 $ 887 $ 2 $ 1,152,513 Grade 5 — 1,286 1,088 1,250 2,239 2,913 — — 8,776 Grade 7 28 392 616 388 1,117 3,279 — — 5,820 Total $ 164,945 $ 390,924 $ 249,661 $ 132,495 $ 59,579 $ 168,616 $ 887 $ 2 $ 1,167,109 Current period gross charge-offs $ — $ — $ — $ — $ — $ (5) $ — $ — $ (5) Residential junior mortgage Grades 1-4 $ 14,020 $ 7,277 $ 4,053 $ 4,187 $ 2,753 $ 3,909 $ 157,960 $ 6,342 $ 200,501 Grade 7 31 31 202 — — 27 92 — 383 Total $ 14,051 $ 7,308 $ 4,255 $ 4,187 $ 2,753 $ 3,936 $ 158,052 $ 6,342 $ 200,884 Current period gross charge-offs $ — $ — $ — $ — $ — $ (96) $ — $ — $ (96) Retail & other Grades 1-4 $ 8,207 $ 8,107 $ 5,345 $ 2,434 $ 1,689 $ 3,869 $ 25,891 $ — $ 55,542 Grade 5 — — 38 — — — — — 38 Grade 7 31 — 25 8 19 65 — — 148 Total $ 8,238 $ 8,107 $ 5,408 $ 2,442 $ 1,708 $ 3,934 $ 25,891 $ — $ 55,728 Current period gross charge-offs $ (7) $ (1) $ — $ (1) $ — $ (52) $ (212) $ — $ (273) Total loans $ 810,769 $ 1,478,242 $ 1,128,121 $ 585,085 $ 367,691 $ 1,083,584 $ 894,106 $ 6,344 $ 6,353,942 December 31, 2022 Amortized Cost Basis by Origination Year (in thousands) 2022 2021 2020 2019 2018 Prior Revolving Revolving to Term TOTAL Commercial & industrial Grades 1-4 $ 317,394 $ 226,065 $ 101,374 $ 68,884 $ 50,189 $ 77,589 $ 360,978 $ — $ 1,202,473 Grade 5 9,938 5,902 10,811 1,530 3,986 4,562 20,617 — 57,346 Grade 6 1,459 2,283 629 511 402 11,653 14,047 — 30,984 Grade 7 556 293 3,211 2,990 775 1,070 5,121 — 14,016 Total $ 329,347 $ 234,543 $ 116,025 $ 73,915 $ 55,352 $ 94,874 $ 400,763 $ — $ 1,304,819 Current period gross charge-offs $ (38) $ (41) $ (2) $ — $ (109) $ — $ — $ — $ (190) Owner-occupied CRE Grades 1-4 $ 151,391 $ 190,313 $ 105,156 $ 100,606 $ 91,479 $ 252,574 $ 6,734 $ — $ 898,253 Grade 5 5,241 3,192 4,287 2,163 4,791 14,632 348 — 34,654 Grade 6 — — 763 2,361 — 877 — — 4,001 Grade 7 227 706 6,344 616 — 9,798 — — 17,691 Total $ 156,859 $ 194,211 $ 116,550 $ 105,746 $ 96,270 $ 277,881 $ 7,082 $ — $ 954,599 Current period gross charge-offs $ — $ — $ — $ — $ — $ (555) $ — $ — $ (555) Agricultural Grades 1-4 $ 275,208 $ 145,272 $ 85,413 $ 25,463 $ 19,687 $ 130,849 $ 249,033 $ — $ 930,925 Grade 5 13,295 18,178 2,694 1,992 517 43,927 21,199 — 101,802 Grade 6 115 1,457 28 33 — 5,258 429 — 7,320 Grade 7 7,165 2,632 720 1,977 4,611 19,948 11,507 — 48,560 Total $ 295,783 $ 167,539 $ 88,855 $ 29,465 $ 24,815 $ 199,982 $ 282,168 $ — $ 1,088,607 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — CRE investment Grades 1-4 $ 205,930 $ 229,252 $ 192,527 $ 134,301 $ 79,649 $ 248,595 $ 11,383 $ — $ 1,101,637 Grade 5 567 1,649 3,578 4,266 3,086 24,897 — — 38,043 Grade 6 — — — 1,170 2,396 2,483 206 — 6,255 Grade 7 — — 121 299 245 3,140 209 — 4,014 Total $ 206,497 $ 230,901 $ 196,226 $ 140,036 $ 85,376 $ 279,115 $ 11,798 $ — $ 1,149,949 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Construction & land development Grades 1-4 $ 104,804 $ 140,727 $ 12,188 $ 9,747 $ 23,811 $ 13,138 $ 13,235 $ — $ 317,650 Grade 5 37 — — 14 — 95 — — 146 Grade 7 33 — — — — 771 — — 804 Total $ 104,874 $ 140,727 $ 12,188 $ 9,761 $ 23,811 $ 14,004 $ 13,235 $ — $ 318,600 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential construction Grades 1-4 $ 92,417 $ 16,774 $ 966 $ 123 $ 336 $ 229 $ 3,547 $ — $ 114,392 Total $ 92,417 $ 16,774 $ 966 $ 123 $ 336 $ 229 $ 3,547 $ — $ 114,392 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Residential first mortgage Grades 1-4 $ 318,628 $ 272,011 $ 147,857 $ 68,975 $ 31,208 $ 162,153 $ 2,080 $ 3 $ 1,002,915 Grade 5 1,494 758 997 1,803 2,272 465 — — 7,789 Grade 6 — — — 711 — — — — 711 Grade 7 154 329 188 349 197 4,303 — — 5,520 Total $ 320,276 $ 273,098 $ 149,042 $ 71,838 $ 33,677 $ 166,921 $ 2,080 $ 3 $ 1,016,935 Current period gross charge-offs $ — $ — $ — $ — $ — $ (65) $ — $ — $ (65) Residential junior mortgage Grades 1-4 $ 10,119 $ 4,580 $ 5,207 $ 3,151 $ 1,573 $ 3,409 $ 142,784 $ 5,762 $ 176,585 Grade 5 — — — — — 143 165 — 308 Grade 7 — 206 — — — 24 209 — 439 Total $ 10,119 $ 4,786 $ 5,207 $ 3,151 $ 1,573 $ 3,576 $ 143,158 $ 5,762 $ 177,332 Current period gross charge-offs $ — $ — $ — $ — $ — $ — $ — $ — $ — Retail & other Grades 1-4 $ 12,318 $ 8,957 $ 4,221 $ 3,188 $ 1,035 $ 24,950 $ 492 $ — $ 55,161 Grade 5 — 23 — — — — — — 23 Grade 7 — 23 22 2 30 5 — — 82 Total $ 12,318 $ 9,003 $ 4,243 $ 3,190 $ 1,065 $ 24,955 $ 492 $ — $ 55,266 Current period gross charge-offs $ — $ (1) $ (6) $ (1) $ — $ — $ (215) $ — $ (223) Total loans $ 1,528,490 $ 1,271,582 $ 689,302 $ 437,225 $ 322,275 $ 1,061,537 $ 864,323 $ 5,765 $ 6,180,499
Schedule of aggregated by portfolio segment and type of modification	The following table presents the amortized cost of loans that were both experiencing financial difficulty and were modified during the year ended December 31, 2023, aggregated by portfolio segment and type of modification. (in thousands) Payment Delay Term Extension Interest Rate Reduction Term Extension & Interest Rate Reduction Total % of Total Loans Commercial & industrial $ 412 $ — $ 85 $ — $ 497 0.04 % Owner-occupied CRE — — — — — — % Agricultural 105 — — — 105 0.01 % CRE investment — — — — — — % Construction & land development — — — — — — % Residential first mortgage — — — — — — % Total $ 517 $ — $ 85 $ — $ 602 0.01 %

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of premises and equipment, less accumulated depreciation and amortization	Premises and equipment, less accumulated depreciation and amortization, is summarized as follows. (in thousands) December 31, 2023 December 31, 2022 Land $ 18,015 $ 14,841 Land improvements 5,461 5,361 Building and improvements 99,664 89,630 Leasehold improvements 7,228 7,079 Furniture and equipment 38,838 35,717 169,206 152,628 Less accumulated depreciation and amortization 50,450 43,672 Premises and equipment, net $ 118,756 $ 108,956
Schedule of operating lease	A summary of net lease cost and selected other information related to operating leases was as follows. Years Ended ($ in thousands) December 31, 2023 December 31, 2022 December 31, 2021 Net lease cost: Operating lease cost $ 2,004 $ 1,778 $ 1,018 Variable lease cost 631 448 234 Net lease cost $ 2,635 $ 2,226 $ 1,252 Selected other operating lease information: Weighted average remaining lease term (years) 5.8 5.4 6.3 Weighted average discount rate 2.7 % 2.3 % 1.5 %
Schedule of maturity of remaining lease liabilities	The following table summarizes the maturity of remaining lease liabilities. Years Ending December 31, (in thousands) 2024 $ 2,486 2025 2,176 2026 1,994 2027 1,831 2028 1,312 Thereafter 1,842 Total future minimum lease payments 11,641 Less: amount representing interest (315) Present value of net future minimum lease payments $ 11,326

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS (Tables)	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill and other intangibles	A summary of goodwill and other intangibles was as follows. (in thousands) December 31, 2023 December 31, 2022 Goodwill $ 367,387 $ 367,387 Core deposit intangibles 25,112 32,701 Customer list intangibles 1,867 2,350 Other intangibles 26,979 35,051 Goodwill and other intangibles, net $ 394,366 $ 402,438
Schedule of goodwill	(in thousands) December 31, 2023 December 31, 2022 Goodwill: Goodwill at beginning of year $ 367,387 $ 317,189 Acquisitions — 49,970 Purchase accounting adjustment — 228 Goodwill at end of year $ 367,387 $ 367,387
Schedule of other intangibles	(in thousands) December 31, 2023 December 31, 2022 Core deposit intangibles: Gross carrying amount $ 60,724 $ 60,724 Accumulated amortization (35,612) (28,023) Net book value $ 25,112 $ 32,701 Additions during the period $ — $ 19,364 Amortization during the period $ 7,589 $ 6,108 Customer list intangibles: Gross carrying amount $ 5,523 $ 5,523 Accumulated amortization (3,656) (3,173) Net book value $ 1,867 $ 2,350 Amortization during the period $ 483 $ 508
Schedule of mortgage servicing rights	A summary of the changes in the MSR asset was as follows. (in thousands) December 31, 2023 December 31, 2022 MSR asset: MSR asset at beginning of year $ 13,080 $ 13,636 Capitalized MSR 1,540 2,327 Amortization during the period (2,965) (2,883) MSR asset at end of year $ 11,655 $ 13,080 Valuation allowance at beginning of year $ (500) $ (1,200) Reversals 500 700 Valuation allowance at end of year $ — $ (500) MSR asset, net $ 11,655 $ 12,580 Fair value of MSR asset at end of period $ 16,810 $ 17,215 Residential mortgage loans serviced for others $ 1,609,395 $ 1,637,109 Net book value of MSR asset to loans serviced for others 0.72 % 0.77 % (in thousands) December 31, 2023 December 31, 2022 LSR asset: LSR asset at beginning of year $ 11,039 $ 20,055 Amortization during the period (2,208) (9,016) LSR asset at end of year $ 8,831 $ 11,039 Agricultural loans serviced for others $ 492,137 $ 538,392
Schedule of estimated future amortization expense for amortizing intangible assets and the MSR asset	The following table shows the estimated future amortization expense for amortizing intangible assets and servicing assets. The projections are based on existing asset balances, the current interest rate environment and prepayment speeds as of December 31, 2023. The actual amortization expense the Company recognizes in any given period may be significantly different depending upon acquisition or sale activities, changes in interest rates, prepayment speeds, market conditions, regulatory requirements and events or circumstances that indicate the carrying amount of an asset may not be recoverable. (in thousands) Core deposit Customer list MSR asset LSR asset Years Ending December 31, 2024 $ 6,298 $ 449 $ 2,704 $ 1,962 2025 5,161 449 2,037 1,717 2026 3,983 249 1,495 1,472 2027 3,218 166 1,495 1,227 2028 2,622 166 1,494 981 Thereafter 3,830 388 2,430 1,472 Total $ 25,112 $ 1,867 $ 11,655 $ 8,831

OTHER REAL ESTATE OWNED (Tables

OTHER REAL ESTATE OWNED (Tables)	12 Months Ended
	Dec. 31, 2023
Real Estate [Abstract]
Schedule of summary of OREO	A summary of OREO, which is included in other assets in the consolidated balance sheets, for the periods indicated was as follows. Years Ended December 31, (in thousands) 2023 2022 Balance at beginning of period $ 1,975 $ 11,955 Transfer in loans at net realizable value 985 183 Transfer in former bank branch properties at net realizable value — 25 Sales proceeds (1,933) (13,150) Net gain from sales 421 3,206 Write-downs (181) (244) Balance at end of period $ 1,267 $ 1,975

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2023
Deposits [Abstract]
Schedule of deposit composition	The deposit composition was as follows. December 31, 2023 December 31, 2022 (in thousands) Amount % of Total Amount % of Total Noninterest-bearing demand $ 1,958,709 27 % $ 2,361,816 33 % Interest-bearing demand 1,055,520 15 % 1,279,850 18 % Money market 1,891,287 26 % 1,707,619 24 % Savings 768,401 11 % 931,417 13 % Time 1,523,883 21 % 898,219 12 % Total deposits $ 7,197,800 100 % $ 7,178,921 100 %
Schedule of maturities of time deposits	At December 31, 2023, the scheduled maturities of time deposits were as follows. Years Ending December 31, (in thousands) 2024 $ 1,171,328 2025 311,446 2026 19,455 2027 14,860 2028 6,684 Thereafter 110 Total time deposits $ 1,523,883

SHORT AND LONG-TERM BORROWINGS

SHORT AND LONG-TERM BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of long-term borrowings	The components of long-term borrowings were as follows. (in thousands) December 31, 2023 December 31, 2022 FHLB advances $ 5,000 $ 33,000 Junior subordinated debentures 40,552 39,720 Subordinated notes 121,378 152,622 Total long-term borrowings $ 166,930 $ 225,342
Schedule of maturity of FHLB advances	The following table shows the maturity schedule of the FHLB advances as of December 31, 2023. Maturing in: (in thousands) 2024 $ — 2025 5,000 2026 — 2027 — 2028 — Thereafter — $ 5,000
Schedule of junior subordinated debentures	The following table shows the breakdown of junior subordinated debentures and subordinated notes. As of 12/31/2023 As of 12/31/2022 (in thousands) Maturity Interest Par Unamortized Premium /(Discount) / Debt Issue Costs (1) Carrying Interest Carrying Junior Subordinated Debentures: Mid-Wisconsin Statutory Trust I (2) 12/15/2035 7.08 % $ 10,310 $ (2,380) $ 7,930 6.20 % $ 7,734 Baylake Capital Trust II (3) 9/30/2036 6.94 % 16,598 (2,938) 13,660 6.08 % 13,424 First Menasha Statutory Trust (4) 3/17/2034 8.43 % 5,155 (443) 4,712 7.53 % 4,668 County Bancorp Statutory Trust II (5) 9/15/2035 7.18 % 6,186 (753) 5,433 6.30 % 5,277 County Bancorp Statutory Trust III (6) 6/15/2036 7.34 % 6,186 (811) 5,375 6.46 % 5,219 Fox River Valley Capital Trust (7) 5/30/2033 7.89 % 3,610 (168) 3,442 6.40 % 3,398 Total $ 48,045 $ (7,493) $ 40,552 $ 39,720 Subordinated Notes: Subordinated Notes due 2031 7/15/2031 3.13 % $ 99,000 $ (524) $ 98,476 3.13 % $ 99,267 County Subordinated Notes due 2028 6/1/2028 — % — — — 5.88 % 30,119 County Subordinated Notes due 2030 6/30/2030 7.00 % 22,400 502 22,902 7.00 % 23,236 Total $ 121,400 $ (22) $ 121,378 $ 152,622 1. Represents the remaining unamortized premium or discount on debt issuances assumed in acquisitions, and represents the unamortized debt issue costs for the debt issued directly by Nicolet. 2. The debentures, assumed in April 2013 as the result of an acquisition, have a floating rate of three-month SOFR plus 1.43%, adjusted quarterly. * 3. The debentures, assumed in April 2016 as a result of an acquisition, have a floating rate of three-month SOFR plus 1.35%, adjusted quarterly. * 4. The debentures, assumed in April 2017 as the result of an acquisition, have a floating rate of three-month SOFR plus 2.79%, adjusted quarterly. * 5. The debentures, assumed in December 2021 as the result of an acquisition, have a floating rate of three-month SOFR plus 1.53%, adjusted quarterly. * 6. The debentures, assumed in December 2021 as the result of an acquisition, have a floating rate of three-month SOFR plus 1.69%, adjusted quarterly. * 7. The debentures, assumed in December 2021 as the result of an acquisition, have a floating rate of 5-year swap rate plus 3.40%, which resets every five years.

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of weighted average assumptions for valuing stock option grants	The weighted average assumptions used in the model for valuing stock option grants were as follows. 2023 2022 2021 Dividend yield 1.55 % — % — % Expected volatility 30 % 30 % 30 % Risk-free interest rate 4.22 % 3.03 % 1.19 % Expected average life 7 years 7 years 7 years Weighted average per share fair value of options $ 24.24 $ 30.99 $ 26.33
Schedule of stock option activity	A summary of the Company’s stock option activity is summarized below. Stock Options Option Shares Weighted Average Weighted Average Remaining Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding – December 31, 2020 1,437,460 $ 50.47 Granted 450,000 77.99 Exercise of stock options * (53,214) 34.40 Forfeited (1,000) 48.85 Outstanding – December 31, 2021 1,833,246 $ 57.69 6.6 $ 51,426 Granted 132,929 81.04 Exercise of stock options * (82,611) 41.84 Forfeited (30,500) 75.08 Outstanding – December 31, 2022 1,853,064 $ 59.79 5.9 $ 37,526 Granted 39,000 71.99 Exercise of stock options * (241,876) 43.54 Forfeited (27,100) 84.37 Outstanding – December 31, 2023 1,623,088 $ 62.09 5.3 $ 30,126 Exercisable – December 31, 2023 1,184,045 $ 56.63 4.4 $ 28,297 *The terms of the stock option agreements permit having a number of shares of stock withheld, the fair market value of which as of the date of exercise is sufficient to satisfy the exercise price and/or tax withholding requirements, and accordingly 55,467 shares, 7,957 shares, and 10,354 shares were surrendered during 2023, 2022, and 2021, respectively.
Schedule of options outstanding	The following options were outstanding at December 31, 2023. Number of Shares Weighted Average Weighted Average Outstanding Exercisable Outstanding Exercisable Outstanding Exercisable $23.80 – $40.00 76,659 76,659 $ 32.45 $ 32.45 2.0 2.0 $40.01 – $50.00 589,250 589,250 48.85 48.85 3.4 3.4 $50.01 – $65.00 169,850 157,850 56.77 56.39 4.3 4.0 $65.01 – $75.00 307,400 191,300 71.28 70.77 6.6 6.1 $75.01 – $93.09 479,929 168,986 79.08 78.95 7.7 7.5 1,623,088 1,184,045 $ 62.09 $ 56.63 5.3 4.4
Schedule of restricted stock	A summary of the Company’s restricted stock activity is summarized below. Restricted Stock Restricted Shares Weighted Average Grant Outstanding – December 31, 2020 18,925 $ 53.57 Granted 33,153 75.83 Vested * (25,831) 64.53 Forfeited (446) 41.44 Outstanding – December 31, 2021 25,801 $ 71.42 Granted 72,948 76.81 Vested * (24,659) 72.64 Forfeited (600) 56.01 Outstanding – December 31, 2022 73,490 $ 76.49 Granted 19,213 64.28 Vested * (35,545) 69.69 Forfeited — — Outstanding – December 31, 2023 57,158 $ 76.61 *The terms of the restricted stock agreements permit the surrender of shares to the Company upon vesting in order to satisfy applicable tax withholding at the minimum statutory withholding rate, and accordingly 3,637 shares, 2,249 shares, and 3,215 shares were surrendered during 2023, 2022, and 2021, respectively.

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of current and deferred amounts of income tax expense	The current and deferred amounts of income tax expense were as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Current $ 17,898 $ 44,384 $ 14,138 Deferred 3,027 (12,907) 6,332 Valuation allowance for securities AFS, net 4,191 — — Income tax expense $ 25,116 $ 31,477 $ 20,470
Schedule of income tax reconciliation	The differences between the income tax expense recognized and the amount computed by applying the statutory federal income tax rate of 21% to the income before income tax expense for the years ended as indicated are included in the following table. Years Ended December 31, (in thousands) 2023 2022 2021 Tax on pretax income, at statutory rates $ 18,193 $ 26,405 $ 17,023 State income taxes, net of federal effect — 7,847 5,064 Tax-exempt interest income (1,072) (1,037) (517) Increase in cash surrender value life insurance (950) (1,040) (570) Stock-based employee compensation (811) (1,101) (618) Executive compensation 1,094 82 163 Valuation allowance, net 8,677 — — Other, net (15) 321 (75) Income tax expense $ 25,116 $ 31,477 $ 20,470
Schedule of net deferred tax asset	The net deferred tax asset includes the following amounts of deferred tax assets and liabilities. (in thousands) December 31, 2023 December 31, 2022 Deferred tax assets: ACL-Loans $ 16,937 $ 16,315 Net operating loss carryforwards 2,142 2,721 Compensation 10,971 10,274 Purchase accounting adjustments 1,963 9,400 Other real estate 132 672 Unrealized loss on securities AFS 19,196 21,011 Valuation allowance - securities AFS (4,191) — Valuation allowance - other timing differences (4,486) — Total deferred tax assets 42,664 60,393 Deferred tax liabilities: Premises and equipment (3,138) (3,000) Prepaid expenses (662) (801) Core deposit and other intangibles (5,917) (8,817) MSR and LSR assets (5,455) (6,570) Other (319) (513) Total deferred tax liabilities (15,491) (19,701) Net deferred tax assets $ 27,173 $ 40,692

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of summary of the contract or notional amount of exposure to off-balance-sheet risk	A summary of the contract or notional amount of the Company’s exposure to off-balance sheet risk was as follows. (in thousands) December 31, 2023 December 31, 2022 Commitments to extend credit $ 1,877,327 $ 1,850,601 Financial standby letters of credit 17,500 26,530 Performance standby letters of credit 11,381 9,375

RELATED PARTY TRANSACTIONS (Tab

RELATED PARTY TRANSACTIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Schedule of Loans to Related Parties	A summary of the loans to related parties was as follows. (in thousands) December 31, 2023 Balance at beginning of year $ 110,707 New loans 15,265 Repayments (10,962) Changes due to status of executive officers and directors (3,308) Balance at end of year $ 111,702

ASSETS GAINS (LOSSES), NET (Tab

ASSETS GAINS (LOSSES), NET (Tables)	12 Months Ended
	Dec. 31, 2023
Assets Gains (Losses), Net [Abstract]
Schedule of components of the net gain (losses) on assets	Components of the net gains (losses) on assets are as follows. Years Ended December 31, (in thousands) 2023 2022 2021 Gains (losses) on sales of securities AFS, net $ (3,313) $ (244) $ (283) Gains (losses) on sales of securities HTM, net (37,723) — — Gains (losses) on equity securities, net (252) (127) 3,445 Gains (losses) on sales of OREO, net 421 3,206 597 Write-downs of OREO (181) (244) (28) Write-down of other investment (954) — — Gains (losses) on sales of other investments, net 9,372 531 550 Gains (losses) on sales or dispositions of other assets, net (178) 8 (100) Asset gains (losses), net $ (32,808) $ 3,130 $ 4,181

REGULATORY CAPITAL REQUIREMEN_2

REGULATORY CAPITAL REQUIREMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Regulatory Capital Requirements Under Banking Regulations [Abstract]
Schedule of Bank's actual regulatory capital amounts and ratios	The Company’s and the Bank’s actual regulatory capital amounts and ratios are presented in the following table. Actual For Capital Adequacy To Be Well Capitalized Under Prompt Corrective Action Provisions (2) (in thousands) Amount Ratio (1) Amount Ratio (1) Amount Ratio (1) December 31, 2023 Company Total risk-based capital $ 930,804 13.0 % $ 574,231 8.0 % Tier 1 risk-based capital 750,811 10.5 430,673 6.0 Common equity Tier 1 capital 712,040 9.9 323,005 4.5 Leverage 750,811 9.2 326,483 4.0 Bank Total risk-based capital $ 827,341 11.5 % $ 573,221 8.0 % $ 716,527 10.0 % Tier 1 risk-based capital 768,726 10.7 429,916 6.0 573,221 8.0 Common equity Tier 1 capital 768,726 10.7 322,437 4.5 465,742 6.5 Leverage 768,726 9.4 325,868 4.0 407,334 5.0 December 31, 2022 Company Total risk-based capital $ 889,763 12.3 % $ 577,138 8.0 % Tier 1 risk-based capital 684,280 9.5 432,853 6.0 Common equity Tier 1 capital 646,341 9.0 324,640 4.5 Leverage 684,280 8.2 335,621 4.0 Bank Total risk-based capital $ 816,951 11.3 % $ 576,241 8.0 % $ 720,301 10.0 % Tier 1 risk-based capital 764,090 10.6 432,181 6.0 576,241 8.0 Common equity Tier 1 capital 764,090 10.6 324,135 4.5 468,196 6.5 Leverage 764,090 9.1 334,916 4.0 418,645 5.0 (1) The Total risk-based capital ratio is defined as Tier 1 capital plus tier 2 capital divided by total risk-weighted assets. The Tier 1 risk-based capital ratio is defined as Tier 1 capital divided by total risk-weighted assets. CET1 risk-based capital ratio is defined as Tier 1 capital, with deductions for goodwill and other intangible assets (other than mortgage servicing assets), net of associated deferred tax liabilities, and limitations on the inclusion of deferred tax assets, mortgage servicing assets and investments in other financial institutions, in each case as provided further in the rules, divided by total risk-weighted assets. The Leverage ratio is defined as Tier 1 capital divided by the most recent quarter’s average total assets as adjusted. (2) Prompt corrective action provisions are not applicable at the bank holding company level.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities measured at fair value on a recurring basis	The following table presents the balances of assets and liabilities measured at fair value on a recurring basis. (in thousands) Fair Value Measurements Using Measured at Fair Value on a Recurring Basis: Total Level 1 Level 2 Level 3 December 31, 2023 U.S. Treasury securities $ 14,123 $ — $ 14,123 $ — U.S. government agency securities 7,384 — 7,384 — State, county and municipals 334,822 — 333,401 1,421 Mortgage-backed securities 352,622 — 351,658 964 Corporate debt securities 93,622 — 89,944 3,678 Securities AFS $ 802,573 $ — $ 796,510 $ 6,063 Other investments (equity securities) $ 4,240 $ 4,240 $ — $ — Derivative assets 152 — — 152 Derivative liabilities 79 — — 79 December 31, 2022 U.S. Treasury securities $ 183,830 $ — $ 183,830 $ — U.S. government agency securities 2,100 — 2,100 — State, county and municipals 398,188 — 396,315 1,873 Mortgage-backed securities 200,932 — 199,951 981 Corporate debt securities 132,568 — 127,269 5,299 Securities AFS $ 917,618 $ — $ 909,465 $ 8,153 Other investments (equity securities) $ 4,376 $ 4,376 $ — $ — Derivative assets 60 — — 60 Derivative liabilities 10 — — 10
Schedule of changes in Level 3 securities AFS measured at fair value on a recurring basis	The following table presents the changes in Level 3 securities AFS measured at fair value on a recurring basis. (in thousands) Years Ended Level 3 Fair Value Measurements: December 31, 2023 December 31, 2022 Balance at beginning of year $ 8,153 $ 8,065 Acquired balances — 750 Paydowns/Sales/Settlements (2,425) (451) Unrealized gains / (losses) 335 (211) Balance at end of year $ 6,063 $ 8,153
Schedule of assets measured at fair value on a nonrecurring basis	The following table presents the Company’s assets measured at fair value on a nonrecurring basis, aggregated by the level in the fair value hierarchy within which those measurements fall. (in thousands) Fair Value Measurements Using Measured at Fair Value on a Nonrecurring Basis: Total Level 1 Level 2 Level 3 December 31, 2023 Collateral dependent loans $ 19,920 $ — $ — $ 19,920 OREO 1,267 — — 1,267 MSR asset 11,655 — — 11,655 December 31, 2022 Collateral dependent loans $ 30,951 $ — $ — $ 30,951 OREO 1,975 — — 1,975 MSR asset 12,580 — — 12,580
Schedule of estimated fair values of financial instruments	The carrying amounts and estimated fair values of the Company’s financial instruments are shown below. December 31, 2023 (in thousands) Carrying Estimated Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 491,431 $ 491,431 $ 491,431 $ — $ — Certificates of deposit in other banks 6,374 6,293 — 6,293 — Securities AFS 802,573 802,573 — 796,510 6,063 Other investments 57,560 57,560 4,240 44,010 9,310 Loans held for sale 4,160 4,276 — 4,276 — Loans, net 6,290,332 6,083,942 — — 6,083,942 MSR asset 11,655 16,810 — — 16,810 LSR asset 8,831 8,831 — — 8,831 Accrued interest receivable 24,237 24,237 24,237 — — Financial liabilities: Deposits $ 7,197,800 $ 7,184,712 $ — $ — $ 7,184,712 Short-term borrowings — — — — — Long-term borrowings 166,930 155,179 — 4,820 150,359 Accrued interest payable 7,765 7,765 7,765 — — December 31, 2022 (in thousands) Carrying Estimated Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 154,723 $ 154,723 $ 154,723 $ — $ — Certificates of deposit in other banks 12,518 12,407 — 12,407 — Securities AFS 917,618 917,618 — 909,465 8,153 Securities HTM 679,128 623,352 — 623,352 — Other investments 65,286 65,286 4,376 52,093 8,817 Loans held for sale 1,482 1,529 — 1,529 — Loans, net 6,118,670 5,863,570 — — 5,863,570 MSR asset 12,580 17,215 — — 17,215 LSR asset 11,039 11,039 — — 11,039 Accrued interest receivable 21,275 21,275 21,275 — — Financial liabilities: Deposits $ 7,178,921 $ 7,172,779 $ — $ — $ 7,172,779 Short-term borrowings 317,000 317,000 317,000 — — Long-term borrowings 225,342 220,513 — 33,001 187,512 Accrued interest payable 4,265 4,265 4,265 — —

PARENT COMPANY ONLY FINANCIAL_2

PARENT COMPANY ONLY FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
Condensed Financial Information Disclosure [Abstract]
Schedule of parent company only condensed financial statements	Condensed Parent Company only financial statements of Nicolet Bankshares, Inc. follow. Balance Sheets December 31, (in thousands) 2023 2022 Assets Cash and due from subsidiary $ 88,365 $ 63,927 Investments 10,535 10,313 Investments in subsidiaries 1,104,356 1,094,063 Other assets 680 392 Total assets $ 1,203,936 $ 1,168,695 Liabilities and Stockholders’ Equity Junior subordinated debentures $ 40,552 $ 39,720 Subordinated notes 121,378 152,622 Other liabilities 2,999 3,824 Stockholders’ equity 1,039,007 972,529 Total liabilities and stockholders’ equity $ 1,203,936 $ 1,168,695 Statements of Income Years Ended December 31, (in thousands) 2023 2022 2021 Interest income $ 126 $ 81 $ 18 Interest expense 10,633 8,687 2,959 Net interest expense (10,507) (8,606) (2,941) Dividend income from subsidiaries 70,000 77,775 65,000 Operating expense (107) (457) (2,562) Gain (loss) on investments, net (1,164) 395 3,995 Income tax benefit 3,803 2,373 437 Earnings before equity in undistributed income (loss) of subsidiaries 62,025 71,480 63,929 Equity in undistributed income (loss) of subsidiaries (509) 22,780 (3,277) Net income $ 61,516 $ 94,260 $ 60,652 Statements of Cash Flows Years Ended December 31, (in thousands) 2023 2022 2021 Cash Flows From Operating Activities: Net income $ 61,516 $ 94,260 $ 60,652 Adjustments to reconcile net income to net cash provided by operating activities: Accretion of discounts on borrowings 588 427 584 (Gain) loss on investments, net 1,164 (395) (3,995) Change in other assets and liabilities, net (1,190) (1,775) 1,013 Equity in undistributed (income) loss of subsidiaries, net of dividends 509 (22,780) 3,277 Net cash provided by operating activities 62,587 69,737 61,531 Cash Flows from Investing Activities: Proceeds from sale of investments 75 1,835 4,105 Purchases of investments (1,451) (2,116) (5,049) Net cash paid in business combinations — (31,970) (63,892) Net cash used in investing activities (1,376) (32,251) (64,836) Cash Flows From Financing Activities: Purchase and retirement of common stock (1,521) (61,497) (62,583) Proceeds from issuance of common stock, net 6,867 3,282 2,382 Cash dividends on common stock (11,119) — — Capitalized issuance costs, net — — (789) Repayment of long-term borrowings (31,000) — — Proceeds from issuance of subordinated notes, net — — 98,953 Net cash provided by (used in) financing activities (36,773) (58,215) 37,963 Net increase (decrease) in cash and due from subsidiary 24,438 (20,729) 34,658 Beginning cash and due from subsidiary 63,927 84,656 49,998 Ending cash and due from subsidiary $ 88,365 $ 63,927 $ 84,656

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of earnings per common share	Presented below are the calculations for basic and diluted earnings per common share. Years Ended December 31, (in thousands, except per share data) 2023 2022 2021 Net income $ 61,516 $ 94,260 $ 60,652 Weighted average common shares outstanding 14,743 13,909 10,736 Effect of dilutive common stock awards 328 466 409 Diluted weighted average common shares outstanding 15,071 14,375 11,145 Basic earnings per common share $ 4.17 $ 6.78 $ 5.65 Diluted earnings per common share $ 4.08 $ 6.56 $ 5.44

NATURE OF BUSINESS AND SIGNIF_4

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) subsidiary segment	Dec. 31, 2022
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of wholly owned subsidiaries | subsidiary	3
Number of reportable segments	1
Number of operating segments	1
Loans, threshold period past due	90 days
Material loans criteria for ACL-Loans adequacy calculation | $	$ 250,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Interest Receivable and Other Assets	Interest Receivable and Other Assets
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Accrued interest payable and other liabilities	Accrued interest payable and other liabilities
Core deposit intangibles:
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortized period of core deposit intangible	10 years
Customer list intangibles
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amortized period of core deposit intangible	12 years

NATURE OF BUSINESS AND SIGNIF_5

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES - Estimated Useful Lives Of Premises and Equipment (Details)	Dec. 31, 2023
Minimum | Building and improvements
Property, Plant and Equipment [Line Items]
Estimated useful lives of new premises and equipment	25 years
Minimum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful lives of new premises and equipment	5 years
Minimum | Furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of new premises and equipment	3 years
Maximum | Building and improvements
Property, Plant and Equipment [Line Items]
Estimated useful lives of new premises and equipment	40 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful lives of new premises and equipment	15 years
Maximum | Furniture and equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of new premises and equipment	10 years

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) - USD ($) $ in Millions	Aug. 26, 2022	Dec. 03, 2021	Sep. 03, 2021
Charter Bankshares, Inc.
Business Acquisition [Line Items]
Nicolet common stock issued (in shares)	1,262,360
Value of Nicolet common stock consideration	$ 98
Cash consideration paid	39
Total purchase price	$ 137
County Bancorp, Inc.
Business Acquisition [Line Items]
Nicolet common stock issued (in shares)		2,366,243
Value of Nicolet common stock consideration		$ 176
Cash consideration paid		48
Total purchase price		$ 224
Mackinac Financial Corporation
Business Acquisition [Line Items]
Nicolet common stock issued (in shares)			2,337,230
Value of Nicolet common stock consideration			$ 180
Cash consideration paid			49
Total purchase price			$ 229

ACQUISITIONS - Summary of the A

ACQUISITIONS - Summary of the Assets Acquired and Liabilities Assumed, including Preliminary Purchase Price Allocation (Details) - USD ($) $ in Thousands			4 Months Ended	12 Months Ended		13 Months Ended
	Aug. 26, 2022	Dec. 03, 2021	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2022
Purchase Price:
Goodwill				$ 0	$ 49,970
Charter Bankshares, Inc.
Assets Acquired:
Cash and cash equivalents	$ 10,000			10,000
Investment securities	218,000			218,000
Loans	848,000			827,000
ACL-Loans	(9,000)			(2,000)
Premises and equipment	9,000			10,000
BOLI	29,000			29,000
Core deposit intangible and Other intangibles	0			19,000
Other assets	5,000			10,000
Total assets	1,110,000			1,121,000
Liabilities Assumed:
Deposits	869,000			870,000
Borrowings	161,000			161,000
Other liabilities	3,000			3,000
Total liabilities	$ 1,033,000			1,034,000
Net assets acquired				87,000
Assets Acquired:
Cash and cash equivalents			$ 0
Investment securities			0
Loans			(21,000)
ACL-Loans			7,000
Premises and equipment			1,000
BOLI			0
Core deposit intangible and Other intangibles			19,000
Other assets			5,000
Total assets			11,000
Liabilities Assumed:
Deposits			1,000
Borrowings			0
Other liabilities			0
Total liabilities			$ 1,000
Purchase Price:
Nicolet common stock issued (in shares)	1,262,360
Value of Nicolet common stock consideration	$ 98,000
Cash consideration paid	39,000
Total purchase price	137,000
Goodwill	$ 50,000
County Bancorp, Inc.
Assets Acquired:
Cash and cash equivalents		$ 20,000		20,000
Investment securities		301,000		300,000
Loans		1,015,000		1,014,000
ACL-Loans		(11,000)		(3,000)
Premises and equipment		21,000		17,000
BOLI		33,000		33,000
Core deposit intangible and Other intangibles		0		7,000
Loan servicing rights		20,000		20,000
Other assets		6,000		4,000
Total assets		1,405,000		1,412,000
Liabilities Assumed:
Deposits		1,027,000		1,030,000
Borrowings		218,000		219,000
Other liabilities		8,000		8,000
Total liabilities		$ 1,253,000		1,257,000
Net assets acquired				$ 155,000
Assets Acquired:
Cash and cash equivalents						$ 0
Investment securities						(1,000)
Loans						(1,000)
ACL-Loans						8,000
Premises and equipment						(4,000)
BOLI						0
Core deposit intangible and Other intangibles						7,000
Loan servicing rights						0
Other assets						(2,000)
Total assets						7,000
Liabilities Assumed:
Deposits						3,000
Borrowings						1,000
Other liabilities						0
Total liabilities						$ 4,000
Purchase Price:
Nicolet common stock issued (in shares)		2,366,243
Value of Nicolet common stock consideration		$ 176,000
Cash consideration paid		48,000
Total purchase price		224,000
Write-off prior investment in County		(1,000)
Goodwill		$ 70,000

ACQUISITIONS - Summary of the_2

ACQUISITIONS - Summary of the Assets Acquired (Including Goodwill) and Liabilities Assumed, including Preliminary Purchase Price Allocation (Details) - USD ($) $ in Thousands		12 Months Ended		16 Months Ended
	Sep. 03, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Assets Acquired:
Goodwill		$ 367,387	$ 367,387	$ 367,387	$ 317,189
Assets Acquired:
Goodwill		0	228
Purchase Price:
Goodwill		0	$ 49,970
Mackinac Financial Corporation
Assets Acquired:
Cash and cash equivalents	$ 448,000	448,000
Investment securities	104,000	104,000
Loans	930,000	940,000
ACL-Loans	(6,000)	(2,000)
Premises and equipment	24,000	21,000
BOLI	16,000	16,000
Goodwill	20,000	0
Other intangibles	4,000	7,000
Other assets	25,000	22,000
Total assets	1,565,000	1,556,000
Liabilities Assumed:
Deposits	1,365,000	1,366,000
Borrowings	28,000	29,000
Other liabilities	13,000	14,000
Total liabilities	$ 1,406,000	1,409,000
Net assets acquired		$ 147,000
Assets Acquired:
Cash and cash equivalents				0
Investment securities				0
Loans				10,000
ACL-Loans				4,000
Premises and equipment				(3,000)
BOLI				0
Goodwill				(20,000)
Other intangibles				3,000
Other assets				(3,000)
Total assets				(9,000)
Liabilities Assumed:
Deposits				1,000
Borrowings				1,000
Other liabilities				1,000
Total liabilities				$ 3,000
Purchase Price:
Nicolet common stock issued (in shares)	2,337,230
Value of Nicolet common stock consideration	$ 180,000
Cash consideration paid	49,000
Total purchase price	229,000
Write-off prior investment in Mackinac	(2,000)
Goodwill	$ 84,000

ACQUISITIONS - Carrying Value o

ACQUISITIONS - Carrying Value of PCD Loans Acquired (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Aug. 26, 2022	Dec. 03, 2021	Sep. 03, 2021
Charter Bankshares, Inc.
Business Acquisition [Line Items]
Allowance for credit losses on PCD loans at acquisition	$ 2,000	$ 9,000
Par value of PCD acquired loans at acquisition	827,000	848,000
Charter Bankshares, Inc. | PCD loans aquired
Business Acquisition [Line Items]
Purchase price of PCD loans at acquisition		24,031
Allowance for credit losses on PCD loans at acquisition		1,709
Par value of PCD acquired loans at acquisition		$ 25,740
County Bancorp, Inc.
Business Acquisition [Line Items]
Allowance for credit losses on PCD loans at acquisition	3,000		$ 11,000
Par value of PCD acquired loans at acquisition	1,014,000		1,015,000
County Bancorp, Inc. | PCD loans aquired
Business Acquisition [Line Items]
Purchase price of PCD loans at acquisition			64,720
Allowance for credit losses on PCD loans at acquisition			3,490
Par value of PCD acquired loans at acquisition			$ 68,210
Mackinac Financial Corporation
Business Acquisition [Line Items]
Allowance for credit losses on PCD loans at acquisition	2,000			$ 6,000
Par value of PCD acquired loans at acquisition	$ 940,000			930,000
Mackinac Financial Corporation | PCD loans aquired
Business Acquisition [Line Items]
Purchase price of PCD loans at acquisition				10,605
Allowance for credit losses on PCD loans at acquisition				1,896
Par value of PCD acquired loans at acquisition				$ 12,501

ACQUISITIONS - Unaudited Pro Fo

ACQUISITIONS - Unaudited Pro Forma Information (Details) - County Bancorp, Inc and Mackinac Financial Corporation $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares
Business Acquisition [Line Items]
Total revenue, net of interest expense	$ 320,307
Net income	$ 87,860
Diluted earnings per common share (in dollars per share) | $ / shares	$ 5.91

SECURITIES AND OTHER INVESTME_3

SECURITIES AND OTHER INVESTMENTS - Amortized Costs and Fair Values of Securities AFS and HTM (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 875,187	$ 996,344
Gross Unrealized Gains	2,114	136
Gross Unrealized Losses	74,728	78,862
Securities available for sale (“AFS”), at fair value	802,573	917,618
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0	679,128
Gross Unrealized Gains		46
Gross Unrealized Losses		55,822
Fair Value		623,352
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,988	192,116
Gross Unrealized Gains	0	0
Gross Unrealized Losses	1,865	8,286
Securities available for sale (“AFS”), at fair value	14,123	183,830
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		497,648
Gross Unrealized Gains		0
Gross Unrealized Losses		35,722
Fair Value		461,926
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,430	2,133
Gross Unrealized Gains	0	0
Gross Unrealized Losses	46	33
Securities available for sale (“AFS”), at fair value	7,384	2,100
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		8,744
Gross Unrealized Gains		46
Gross Unrealized Losses		0
Fair Value		8,790
State, county and municipals
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	360,496	433,733
Gross Unrealized Gains	651	123
Gross Unrealized Losses	26,325	35,668
Securities available for sale (“AFS”), at fair value	334,822	398,188
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		34,874
Gross Unrealized Gains		0
Gross Unrealized Losses		3,349
Fair Value		31,525
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	388,378	227,650
Gross Unrealized Gains	1,437	10
Gross Unrealized Losses	37,193	26,728
Securities available for sale (“AFS”), at fair value	352,622	200,932
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost		137,862
Gross Unrealized Gains		0
Gross Unrealized Losses		16,751
Fair Value		121,111
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	102,895	140,712
Gross Unrealized Gains	26	3
Gross Unrealized Losses	9,299	8,147
Securities available for sale (“AFS”), at fair value	$ 93,622	$ 132,568

SECURITIES AND OTHER INVESTME_4

SECURITIES AND OTHER INVESTMENTS - Narrative (Details) - USD ($)		3 Months Ended	12 Months Ended
	Mar. 07, 2023	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Pre-tax loss			$ 37,723,000	$ 0	$ 0
Other comprehensive loss			(4,297,000)	60,572,000	9,645,000
Securities pledged as collateral			364,000,000	883,000,000
Accrued interest on securities			5,000,000	6,000,000
Investment securities		$ 2,300,000	2,340,000	0	0
Allowance for credit losses on securities AFS			$ 0	0	$ 0
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Sale of held-to-maturity debt securities at par value	$ 500,000,000
Pre-tax loss	37,700,000
After-tax loss	28,000,000
Carrying value	157,000,000
U.S. Treasury securities | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent
Debt Securities, Available-for-sale [Line Items]
Unrealized loss	20,000,000
Other comprehensive loss	$ 15,000,000
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses on securities HTM				$ 0

SECURITIES AND OTHER INVESTME_5

SECURITIES AND OTHER INVESTMENTS - Proceeds from Sales of Securities AFS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Securities AFS:
Gross gains	$ 268	$ 28	$ 5
Gross losses	(3,581)	(272)	(288)
Gains (losses) on sales of securities AFS, net	(3,313)	(244)	(283)
Proceeds from sales of securities AFS	65,749	28,438	42,973
Securities HTM:
Gross gains	0	0	0
Gross losses	(37,723)	0	0
Gains (losses) on sales of securities HTM, net	(37,723)	0	0
Proceeds from sales of securities HTM	460,051	0	0
Proceeds from sales of securities AFS	65,749	$ 28,438	$ 42,973
Charter Bankshares, Inc.
Securities AFS:
Proceeds from sales of securities AFS	21,000
Securities HTM:
Proceeds from sales of securities AFS	$ 21,000

SECURITIES AND OTHER INVESTME_6

SECURITIES AND OTHER INVESTMENTS - Gross Unrealized Losses and the Related fair Value of Securities Available for Sale (Details) $ in Thousands	Dec. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 33,963	$ 497,072
Less than 12 months, unrealized losses	361	35,593
12 months or more, fair value	650,221	378,520
12 months or more, unrealized losses	74,367	43,269
Total, fair value	684,184	875,592
Total, unrealized losses	$ 74,728	$ 78,862
Total, number of securities | security	1,031	1,296
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value		$ 85,699
Less than 12 months, unrealized losses		9,623
12 months or more, fair value		526,583
12 months or more, unrealized losses		46,199
Total, unrealized losses		612,282
Total, fair value		$ 55,822
Total, number of securities | security		170
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 0	$ 448
Less than 12 months, unrealized losses	0	14
12 months or more, fair value	14,123	183,382
12 months or more, unrealized losses	1,865	8,272
Total, fair value	14,123	183,830
Total, unrealized losses	$ 1,865	$ 8,286
Total, number of securities | security	1	9
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value		$ 0
Less than 12 months, unrealized losses		0
12 months or more, fair value		461,926
12 months or more, unrealized losses		35,722
Total, unrealized losses		461,926
Total, fair value		$ 35,722
Total, number of securities | security		6
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 4,621	$ 2,083
Less than 12 months, unrealized losses	31	32
12 months or more, fair value	1,793	17
12 months or more, unrealized losses	15	1
Total, fair value	6,414	2,100
Total, unrealized losses	$ 46	$ 33
Total, number of securities | security	10	9
State, county and municipals
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 29,336	$ 277,546
Less than 12 months, unrealized losses	330	18,041
12 months or more, fair value	257,916	86,569
12 months or more, unrealized losses	25,995	17,627
Total, fair value	287,252	364,115
Total, unrealized losses	$ 26,325	$ 35,668
Total, number of securities | security	528	812
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value		$ 17,591
Less than 12 months, unrealized losses		1,594
12 months or more, fair value		11,654
12 months or more, unrealized losses		1,755
Total, unrealized losses		29,245
Total, fair value		$ 3,349
Total, number of securities | security		58
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 6	$ 102,108
Less than 12 months, unrealized losses	0	11,320
12 months or more, fair value	291,124	95,614
12 months or more, unrealized losses	37,193	15,408
Total, fair value	291,130	197,722
Total, unrealized losses	$ 37,193	$ 26,728
Total, number of securities | security	433	376
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value		$ 68,108
Less than 12 months, unrealized losses		8,029
12 months or more, fair value		53,003
12 months or more, unrealized losses		8,722
Total, unrealized losses		121,111
Total, fair value		$ 16,751
Total, number of securities | security		106
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, fair value	$ 0	$ 114,887
Less than 12 months, unrealized losses	0	6,186
12 months or more, fair value	85,265	12,938
12 months or more, unrealized losses	9,299	1,961
Total, fair value	85,265	127,825
Total, unrealized losses	$ 9,299	$ 8,147
Total, number of securities | security	59	90

SECURITIES AND OTHER INVESTME_7

SECURITIES AND OTHER INVESTMENTS - Amortized Cost and Fair Values of Securities Available for Sale at by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost
Due in less than one year	$ 55,132
Due in one year through five years	117,392
Due after five years through ten years	208,859
Due after ten years	105,426
Allocated and single maturity date	486,809
Amortized Cost	875,187
Fair Value
Due in less than one year	54,675
Due in one year through five years	109,079
Due after five years through ten years	186,493
Due after ten years	99,704
Allocated and single maturity date	449,951
Fair Value	802,573	$ 917,618
Mortgage-backed securities
Amortized Cost
Mortgage-backed securities	388,378
Fair Value
Mortgage-backed securities	352,622
Fair Value	$ 352,622	$ 200,932

SECURITIES AND OTHER INVESTME_8

SECURITIES AND OTHER INVESTMENTS - Other Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Federal Reserve Bank stock	$ 33,087	$ 32,219
FHLB stock	9,674	18,625
Equity securities with readily determinable fair values	4,240	4,376
Other investments	10,559	10,066
Total other investments	$ 57,560	$ 65,286

LOANS, ALLOWANCE FOR CREDIT L_2

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Summary of Loan Composition (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 6,353,942	$ 6,180,499
Less ACL-Loans	63,610	61,829	$ 49,672	$ 32,173
Loans, net	$ 6,290,332	$ 6,118,670
ACL-Loans to loans (in percent)	1%	1%
% of Total	100%	100%
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 55,728	$ 55,266
Less ACL-Loans	$ 1,207	$ 1,029	932
% of Total	1%	1%
Retail-based loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,499,447	$ 1,363,925
% of Total	24%	22%
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 3,402,134	$ 3,348,025
% of Total	53%	54%
Commercial | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,284,009	$ 1,304,819
Less ACL-Loans	$ 15,225	$ 16,350	12,613
% of Total	20%	21%
Commercial | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 956,594	$ 954,599
Less ACL-Loans	$ 9,082	$ 9,138	7,222
% of Total	15%	15%
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,161,531	$ 1,088,607
Less ACL-Loans	$ 12,629	$ 9,762	9,547
% of Total	18%	18%
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,452,361	$ 1,468,549
% of Total	23%	24%
Commercial real estate | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,142,251	$ 1,149,949
Less ACL-Loans	$ 12,693	$ 12,744	8,462
% of Total	18%	19%
Commercial real estate | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 310,110	$ 318,600
Less ACL-Loans	$ 2,440	$ 2,572	1,812
% of Total	5%	5%
Commercial-based loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 4,854,495	$ 4,816,574
% of Total	76%	78%
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,443,719	$ 1,308,659
% of Total	23%	21%
Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,167,109	$ 1,016,935
Less ACL-Loans	$ 7,320	$ 6,976	6,844
% of Total	19%	16%
Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 200,884	$ 177,332
Less ACL-Loans	$ 2,098	$ 1,846	1,340
% of Total	3%	3%
Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 75,726	$ 114,392
Less ACL-Loans	$ 916	$ 1,412	$ 900
% of Total	1%	2%

LOANS, ALLOWANCE FOR CREDIT L_3

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY- Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023
Receivables [Abstract]
Accrued interest on loans	$ 15	$ 19
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Interest Receivable and Other Assets	Interest Receivable and Other Assets
Reserve for unfunded commitments	$ 3	$ 3
Troubled debt restructurings	18
Pre-modification balance	$ 24

LOANS, ALLOWANCE FOR CREDIT L_4

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Summary of Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 61,829	$ 49,672	$ 32,173
ACL on PCD loans acquired	0	1,937	5,159
Provision for credit losses	2,650	10,950	12,500
Charge-offs	(1,653)	(1,033)	(513)
Recoveries	784	303	353
Net (charge-offs) recoveries	(869)	(730)	(160)
Ending balance	$ 63,610	$ 61,829	$ 49,672

LOANS, ALLOWANCE FOR CREDIT L_5

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Summary of Changes in ACL-Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
ACL-Loans
Beginning balance	$ 61,829	$ 49,672	$ 32,173
ACL on PCD loans	0	1,937	5,159
Provision	2,650	10,950	12,500
Charge-offs	(1,653)	(1,033)	(513)
Recoveries	784	303	353
Net (charge-offs) recoveries	(869)	(730)	(160)
Ending balance	$ 63,610	$ 61,829	49,672
As % of ACL-Loans	100%	100%
Retail & other
ACL-Loans
Beginning balance	$ 1,029	$ 932
ACL on PCD loans		0
Provision	441	299
Charge-offs	(273)	(223)
Recoveries	10	21
Net (charge-offs) recoveries	(263)	(202)
Ending balance	$ 1,207	$ 1,029	932
As % of ACL-Loans	2%	2%
Commercial | Commercial & industrial
ACL-Loans
Beginning balance	$ 16,350	$ 12,613
ACL on PCD loans		1,408
Provision	(1,205)	2,415
Charge-offs	(440)	(190)
Recoveries	520	104
Net (charge-offs) recoveries	80	(86)
Ending balance	$ 15,225	$ 16,350	12,613
As % of ACL-Loans	24%	26%
Commercial | Owner- occupied CRE
ACL-Loans
Beginning balance	$ 9,138	$ 7,222
ACL on PCD loans		384
Provision	470	2,087
Charge-offs	(773)	(555)
Recoveries	247	0
Net (charge-offs) recoveries	(526)	(555)
Ending balance	$ 9,082	$ 9,138	7,222
As % of ACL-Loans	14%	15%
Commercial | Agricultural
ACL-Loans
Beginning balance	$ 9,762	$ 9,547
ACL on PCD loans		0
Provision	2,930	215
Charge-offs	(66)	0
Recoveries	3	0
Net (charge-offs) recoveries	(63)	0
Ending balance	$ 12,629	$ 9,762	9,547
As % of ACL-Loans	20%	16%
Commercial real estate | CRE investment
ACL-Loans
Beginning balance	$ 12,744	$ 8,462
ACL on PCD loans		38
Provision	(51)	4,075
Charge-offs	0	0
Recoveries	0	169
Net (charge-offs) recoveries	0	169
Ending balance	$ 12,693	$ 12,744	8,462
As % of ACL-Loans	20%	21%
Commercial real estate | Construction & land development
ACL-Loans
Beginning balance	$ 2,572	$ 1,812
ACL on PCD loans		2
Provision	(132)	758
Charge-offs	0	0
Recoveries	0	0
Net (charge-offs) recoveries	0	0
Ending balance	$ 2,440	$ 2,572	1,812
As % of ACL-Loans	4%	4%
Residential | Residential first mortgage
ACL-Loans
Beginning balance	$ 6,976	$ 6,844
ACL on PCD loans		93
Provision	346	96
Charge-offs	(5)	(65)
Recoveries	3	8
Net (charge-offs) recoveries	(2)	(57)
Ending balance	$ 7,320	$ 6,976	6,844
As % of ACL-Loans	12%	11%
Residential | Residential junior mortgage
ACL-Loans
Beginning balance	$ 1,846	$ 1,340
ACL on PCD loans		12
Provision	347	493
Charge-offs	(96)	0
Recoveries	1	1
Net (charge-offs) recoveries	(95)	1
Ending balance	$ 2,098	$ 1,846	1,340
As % of ACL-Loans	4%	3%
Residential | Residential construction
ACL-Loans
Beginning balance	$ 1,412	$ 900
ACL on PCD loans		0
Provision	(496)	512
Charge-offs	0	0
Recoveries	0	0
Net (charge-offs) recoveries	0	0
Ending balance	$ 916	$ 1,412	$ 900
As % of ACL-Loans	0%	2%

LOANS, ALLOWANCE FOR CREDIT L_6

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Provision for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Receivables [Abstract]
Loans		$ 2,650	$ 10,950	$ 12,500
Unfunded commitments		0	550	2,400
Investment securities	$ 2,300	2,340	0	0
Total provision for credit losses		$ 4,990	$ 11,500	$ 14,900

LOANS, ALLOWANCE FOR CREDIT L_7

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Collateral Dependent Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 20,275	$ 32,072
Without an Allowance	14,435	22,724
With an Allowance	5,840	9,348
Allowance Allocation	355	1,121
Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	12,480	22,139
Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	7,795	9,933
Retail & other
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Without an Allowance	0	0
With an Allowance	0	0
Allowance Allocation	0	0
Retail & other | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Retail & other | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Commercial | Commercial & industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	2,576	3,475
Without an Allowance	2,164	1,927
With an Allowance	412	1,548
Allowance Allocation	196	595
Commercial | Commercial & industrial | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Commercial | Commercial & industrial | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	2,576	3,475
Commercial | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	3,614	4,907
Without an Allowance	3,465	4,699
With an Allowance	149	208
Allowance Allocation	24	53
Commercial | Owner-occupied commercial real estate (“CRE”) | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	3,614	4,907
Commercial | Owner-occupied commercial real estate (“CRE”) | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Commercial | Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	12,150	20,216
Without an Allowance	7,261	14,358
With an Allowance	4,889	5,858
Allowance Allocation	117	261
Commercial | Agricultural | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	6,931	13,758
Commercial | Agricultural | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	5,219	6,458
Commercial real estate | CRE investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,261	2,713
Without an Allowance	871	979
With an Allowance	390	1,734
Allowance Allocation	18	212
Commercial real estate | CRE investment | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,261	2,713
Commercial real estate | CRE investment | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Commercial real estate | Construction & land development
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	670
Without an Allowance	0	670
With an Allowance	0	0
Allowance Allocation	0	0
Commercial real estate | Construction & land development | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	670
Commercial real estate | Construction & land development | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Residential | Residential first mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	674	91
Without an Allowance	674	91
With an Allowance	0	0
Allowance Allocation	0	0
Residential | Residential first mortgage | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	674	91
Residential | Residential first mortgage | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Residential | Residential junior mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Without an Allowance	0	0
With an Allowance	0	0
Allowance Allocation	0	0
Residential | Residential junior mortgage | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Residential | Residential junior mortgage | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Residential | Residential construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Without an Allowance	0	0
With an Allowance	0	0
Allowance Allocation	0	0
Residential | Residential construction | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0	0
Residential | Residential construction | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 0	$ 0

LOANS, ALLOWANCE FOR CREDIT L_8

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Summary of Loans by Past due Status (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 6,353,942	$ 6,180,499
Percent of total loans	100%	100%
30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 9,443	$ 5,188
Percent past due	0.10%	0.10%
90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 26,625	$ 38,080
Percent past due	0.40%	0.60%
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 6,317,874	$ 6,137,231
Percent of current loans	99.50%	99.30%
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 55,728	$ 55,266
Retail & other | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	327	261
Retail & other | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	172	82
Retail & other | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	55,229	54,923
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,402,134	3,348,025
Commercial | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,284,009	1,304,819
Commercial | Commercial & industrial | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	540	210
Commercial | Commercial & industrial | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,046	3,328
Commercial | Commercial & industrial | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,279,423	1,301,281
Commercial | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	956,594	954,599
Commercial | Owner-occupied commercial real estate (“CRE”) | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,123	833
Commercial | Owner-occupied commercial real estate (“CRE”) | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,399	5,647
Commercial | Owner-occupied commercial real estate (“CRE”) | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	950,072	948,119
Commercial | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,161,531	1,088,607
Commercial | Agricultural | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12	20
Commercial | Agricultural | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	12,185	20,416
Commercial | Agricultural | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,149,334	1,068,171
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,452,361	1,468,549
Commercial real estate | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,142,251	1,149,949
Commercial real estate | CRE investment | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,060	0
Commercial real estate | CRE investment | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,453	3,832
Commercial real estate | CRE investment | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,137,738	1,146,117
Commercial real estate | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	310,110	318,600
Commercial real estate | Construction & land development | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	171	0
Commercial real estate | Construction & land development | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	161	771
Commercial real estate | Construction & land development | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	309,778	317,829
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,443,719	1,308,659
Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,167,109	1,016,935
Residential | Residential first mortgage | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	2,663	3,628
Residential | Residential first mortgage | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,059	3,780
Residential | Residential first mortgage | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,160,387	1,009,527
Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	200,884	177,332
Residential | Residential junior mortgage | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	547	236
Residential | Residential junior mortgage | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	150	224
Residential | Residential junior mortgage | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	200,187	176,872
Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	75,726	114,392
Residential | Residential construction | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Residential | Residential construction | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0	0
Residential | Residential construction | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 75,726	$ 114,392

LOANS, ALLOWANCE FOR CREDIT L_9

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Nonaccrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 26,625	$ 38,080
Percent of total loans	0.40%	0.60%
% to Total	100%	100%
Retail & other
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 172	$ 82
% to Total	1%	0%
Commercial | Commercial & industrial
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 4,046	$ 3,328
% to Total	15%	9%
Commercial | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 4,399	$ 5,647
% to Total	16%	15%
Commercial | Agricultural
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 12,185	$ 20,416
% to Total	46%	53%
Commercial real estate | CRE investment
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 1,453	$ 3,832
% to Total	5%	10%
Commercial real estate | Construction & land development
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 161	$ 771
% to Total	1%	2%
Residential | Residential first mortgage
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 4,059	$ 3,780
% to Total	15%	10%
Residential | Residential junior mortgage
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 150	$ 224
% to Total	1%	1%
Residential | Residential construction
Financing Receivable, Past Due [Line Items]
Nonaccrual loans	$ 0	$ 0
% to Total	0%	0%

LOANS, ALLOWANCE FOR CREDIT _10

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Summary of Loans by Loan Risk Categories (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	$ 810,769	$ 1,528,490
2022/2021	1,478,242	1,271,582
2021/2020	1,128,121	689,302
2020/2019	585,085	437,225
2019/2018	367,691	322,275
Prior	1,083,584	1,061,537
Revolving	894,106	864,323
Revolving to Term	6,344	5,765
Loans	6,353,942	6,180,499
Residential first mortgage
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	(5)	(65)
Revolving	0	0
Revolving to Term	0	0
Total loans	(5)	(65)
Residential junior mortgage
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	(96)	0
Revolving	0	0
Revolving to Term	0	0
Total loans	(96)	0
Retail & other
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022		0
2022/2021		(1)
2021/2020		(6)
2020/2019		(1)
2019/2018		0
Prior		0
Revolving		(215)
Revolving to Term		0
Total loans		(223)
Commercial & industrial
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	(38)
2022/2021	(89)	(41)
2021/2020	(114)	(2)
2020/2019	0	0
2019/2018	0	(109)
Prior	(222)	0
Revolving	(15)	0
Revolving to Term	0	0
Total loans	(440)	(190)
Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	(773)	(555)
Revolving	0	0
Revolving to Term	0	0
Total loans	(773)	(555)
Agricultural
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	(66)	0
Revolving	0	0
Revolving to Term	0	0
Total loans	(66)	0
CRE investment
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving	0	0
Revolving to Term	0	0
Total loans	0	0
Construction & land development
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving	0	0
Revolving to Term	0	0
Total loans	0	0
Residential construction
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving	0	0
Revolving to Term	0	0
Total loans	0	0
Retail & other
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	8,238	12,318
2022/2021	8,107	9,003
2021/2020	5,408	4,243
2020/2019	2,442	3,190
2019/2018	1,708	1,065
Prior	3,934	24,955
Revolving	25,891	492
Revolving to Term	0	0
Loans	55,728	55,266
Financing Receivable, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
2023/2022	(7)
2022/2021	(1)
2021/2020	0
2020/2019	(1)
2019/2018	0
Prior	(52)
Revolving	(212)
Revolving to Term	0
Total loans	(273)
Retail & other | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	8,207	12,318
2022/2021	8,107	8,957
2021/2020	5,345	4,221
2020/2019	2,434	3,188
2019/2018	1,689	1,035
Prior	3,869	24,950
Revolving	25,891	492
Revolving to Term	0	0
Loans	55,542	55,161
Retail & other | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	23
2021/2020	38	0
2020/2019	0	0
2019/2018	0	0
Prior	0	0
Revolving	0	0
Revolving to Term	0	0
Loans	38	23
Retail & other | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	31	0
2022/2021	0	23
2021/2020	25	22
2020/2019	8	2
2019/2018	19	30
Prior	65	5
Revolving	0	0
Revolving to Term	0	0
Loans	148	82
Commercial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Loans	3,402,134	3,348,025
Commercial | Commercial & industrial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	232,509	329,347
2022/2021	252,113	234,543
2021/2020	182,228	116,025
2020/2019	72,010	73,915
2019/2018	55,900	55,352
Prior	98,545	94,874
Revolving	390,704	400,763
Revolving to Term	0	0
Loans	1,284,009	1,304,819
Commercial | Commercial & industrial | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	223,515	317,394
2022/2021	234,193	226,065
2021/2020	171,555	101,374
2020/2019	66,026	68,884
2019/2018	49,054	50,189
Prior	81,272	77,589
Revolving	359,284	360,978
Revolving to Term	0	0
Loans	1,184,899	1,202,473
Commercial | Commercial & industrial | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	3,252	9,938
2022/2021	13,656	5,902
2021/2020	7,516	10,811
2020/2019	3,388	1,530
2019/2018	5,074	3,986
Prior	7,020	4,562
Revolving	18,753	20,617
Revolving to Term	0	0
Loans	58,659	57,346
Commercial | Commercial & industrial | Grade 6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	1,459
2022/2021	562	2,283
2021/2020	502	629
2020/2019	187	511
2019/2018	3	402
Prior	1,009	11,653
Revolving	10,974	14,047
Revolving to Term	0	0
Loans	13,237	30,984
Commercial | Commercial & industrial | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	5,742	556
2022/2021	3,702	293
2021/2020	2,655	3,211
2020/2019	2,409	2,990
2019/2018	1,769	775
Prior	9,244	1,070
Revolving	1,693	5,121
Revolving to Term	0	0
Loans	27,214	14,016
Commercial | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	120,120	156,859
2022/2021	162,051	194,211
2021/2020	193,962	116,550
2020/2019	103,118	105,746
2019/2018	91,293	96,270
Prior	281,667	277,881
Revolving	4,383	7,082
Revolving to Term	0	0
Loans	956,594	954,599
Commercial | Owner-occupied commercial real estate (“CRE”) | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	114,704	151,391
2022/2021	156,723	190,313
2021/2020	181,128	105,156
2020/2019	91,038	100,606
2019/2018	85,430	91,479
Prior	247,730	252,574
Revolving	4,181	6,734
Revolving to Term	0	0
Loans	880,934	898,253
Commercial | Owner-occupied commercial real estate (“CRE”) | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	5,416	5,241
2022/2021	4,024	3,192
2021/2020	7,858	4,287
2020/2019	5,092	2,163
2019/2018	3,994	4,791
Prior	27,585	14,632
Revolving	52	348
Revolving to Term	0	0
Loans	54,021	34,654
Commercial | Owner-occupied commercial real estate (“CRE”) | Grade 6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	3,905	763
2020/2019	0	2,361
2019/2018	1,531	0
Prior	12	877
Revolving	0	0
Revolving to Term	0	0
Loans	5,448	4,001
Commercial | Owner-occupied commercial real estate (“CRE”) | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	227
2022/2021	1,304	706
2021/2020	1,071	6,344
2020/2019	6,988	616
2019/2018	338	0
Prior	6,340	9,798
Revolving	150	0
Revolving to Term	0	0
Loans	16,191	17,691
Commercial | Agricultural
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	129,064	295,783
2022/2021	293,287	167,539
2021/2020	146,801	88,855
2020/2019	80,075	29,465
2019/2018	25,109	24,815
Prior	187,224	199,982
Revolving	299,971	282,168
Revolving to Term	0	0
Loans	1,161,531	1,088,607
Commercial | Agricultural | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	120,200	275,208
2022/2021	274,491	145,272
2021/2020	134,706	85,413
2020/2019	78,944	25,463
2019/2018	22,985	19,687
Prior	139,212	130,849
Revolving	277,170	249,033
Revolving to Term	0	0
Loans	1,047,708	930,925
Commercial | Agricultural | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	6,345	13,295
2022/2021	11,975	18,178
2021/2020	5,718	2,694
2020/2019	703	1,992
2019/2018	394	517
Prior	33,658	43,927
Revolving	15,522	21,199
Revolving to Term	0	0
Loans	74,315	101,802
Commercial | Agricultural | Grade 6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	115
2022/2021	130	1,457
2021/2020	1,017	28
2020/2019	0	33
2019/2018	51	0
Prior	2,256	5,258
Revolving	194	429
Revolving to Term	0	0
Loans	3,648	7,320
Commercial | Agricultural | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	2,519	7,165
2022/2021	6,691	2,632
2021/2020	5,360	720
2020/2019	428	1,977
2019/2018	1,679	4,611
Prior	12,098	19,948
Revolving	7,085	11,507
Revolving to Term	0	0
Loans	35,860	48,560
Commercial real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Loans	1,452,361	1,468,549
Commercial real estate | CRE investment
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	33,510	206,497
2022/2021	202,239	230,901
2021/2020	274,685	196,226
2020/2019	178,935	140,036
2019/2018	125,776	85,376
Prior	315,846	279,115
Revolving	11,260	11,798
Revolving to Term	0	0
Loans	1,142,251	1,149,949
Commercial real estate | CRE investment | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	30,720	205,930
2022/2021	194,442	229,252
2021/2020	256,765	192,527
2020/2019	169,078	134,301
2019/2018	113,510	79,649
Prior	283,339	248,595
Revolving	11,146	11,383
Revolving to Term	0	0
Loans	1,059,000	1,101,637
Commercial real estate | CRE investment | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	2,790	567
2022/2021	7,746	1,649
2021/2020	17,899	3,578
2020/2019	9,857	4,266
2019/2018	11,232	3,086
Prior	23,108	24,897
Revolving	49	0
Revolving to Term	0	0
Loans	72,681	38,043
Commercial real estate | CRE investment | Grade 6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	0	0
2021/2020	0	0
2020/2019	0	1,170
2019/2018	0	2,396
Prior	1,340	2,483
Revolving	65	206
Revolving to Term	0	0
Loans	1,405	6,255
Commercial real estate | CRE investment | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	0
2022/2021	51	0
2021/2020	21	121
2020/2019	0	299
2019/2018	1,034	245
Prior	8,059	3,140
Revolving	0	209
Revolving to Term	0	0
Loans	9,165	4,014
Commercial real estate | Construction & land development
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	51,299	104,874
2022/2021	149,178	140,727
2021/2020	67,805	12,188
2020/2019	10,705	9,761
2019/2018	5,443	23,811
Prior	22,722	14,004
Revolving	2,958	13,235
Revolving to Term	0	0
Loans	310,110	318,600
Commercial real estate | Construction & land development | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	51,253	104,804
2022/2021	149,155	140,727
2021/2020	64,761	12,188
2020/2019	9,441	9,747
2019/2018	4,939	23,811
Prior	22,548	13,138
Revolving	2,883	13,235
Revolving to Term	0	0
Loans	304,980	317,650
Commercial real estate | Construction & land development | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	37
2022/2021	23	0
2021/2020	3,044	0
2020/2019	1,264	14
2019/2018	504	0
Prior	88	95
Revolving	0	0
Revolving to Term	0	0
Loans	4,923	146
Commercial real estate | Construction & land development | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	46	33
2022/2021	0	0
2021/2020	0	0
2020/2019	0	0
2019/2018	0	0
Prior	86	771
Revolving	75	0
Revolving to Term	0	0
Loans	207	804
Residential
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Loans	1,443,719	1,308,659
Residential | Residential first mortgage
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	164,945	320,276
2022/2021	390,924	273,098
2021/2020	249,661	149,042
2020/2019	132,495	71,838
2019/2018	59,579	33,677
Prior	168,616	166,921
Revolving	887	2,080
Revolving to Term	2	3
Loans	1,167,109	1,016,935
Residential | Residential first mortgage | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	164,917	318,628
2022/2021	389,246	272,011
2021/2020	247,957	147,857
2020/2019	130,857	68,975
2019/2018	56,223	31,208
Prior	162,424	162,153
Revolving	887	2,080
Revolving to Term	2	3
Loans	1,152,513	1,002,915
Residential | Residential first mortgage | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	0	1,494
2022/2021	1,286	758
2021/2020	1,088	997
2020/2019	1,250	1,803
2019/2018	2,239	2,272
Prior	2,913	465
Revolving	0	0
Revolving to Term	0	0
Loans	8,776	7,789
Residential | Residential first mortgage | Grade 6
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022		0
2022/2021		0
2021/2020		0
2020/2019		711
2019/2018		0
Prior		0
Revolving		0
Revolving to Term		0
Loans		711
Residential | Residential first mortgage | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	28	154
2022/2021	392	329
2021/2020	616	188
2020/2019	388	349
2019/2018	1,117	197
Prior	3,279	4,303
Revolving	0	0
Revolving to Term	0	0
Loans	5,820	5,520
Residential | Residential junior mortgage
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	14,051	10,119
2022/2021	7,308	4,786
2021/2020	4,255	5,207
2020/2019	4,187	3,151
2019/2018	2,753	1,573
Prior	3,936	3,576
Revolving	158,052	143,158
Revolving to Term	6,342	5,762
Loans	200,884	177,332
Residential | Residential junior mortgage | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	14,020	10,119
2022/2021	7,277	4,580
2021/2020	4,053	5,207
2020/2019	4,187	3,151
2019/2018	2,753	1,573
Prior	3,909	3,409
Revolving	157,960	142,784
Revolving to Term	6,342	5,762
Loans	200,501	176,585
Residential | Residential junior mortgage | Grade 5
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022		0
2022/2021		0
2021/2020		0
2020/2019		0
2019/2018		0
Prior		143
Revolving		165
Revolving to Term		0
Loans		308
Residential | Residential junior mortgage | Grade 7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	31	0
2022/2021	31	206
2021/2020	202	0
2020/2019	0	0
2019/2018	0	0
Prior	27	24
Revolving	92	209
Revolving to Term	0	0
Loans	383	439
Residential | Residential construction
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	57,033	92,417
2022/2021	13,035	16,774
2021/2020	3,316	966
2020/2019	1,118	123
2019/2018	130	336
Prior	1,094	229
Revolving	0	3,547
Revolving to Term	0	0
Loans	75,726	114,392
Residential | Residential construction | Grades 1-4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
2023/2022	57,033	92,417
2022/2021	13,035	16,774
2021/2020	3,316	966
2020/2019	1,118	123
2019/2018	130	336
Prior	1,094	229
Revolving	0	3,547
Revolving to Term	0	0
Loans	$ 75,726	$ 114,392

LOANS, ALLOWANCE FOR CREDIT _11

LOANS, ALLOWANCE FOR CREDIT LOSSES - LOANS, AND CREDIT QUALITY - Schedule of Aggregated by Portfolio Segment and Type of Modification (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Financing Receivable, Impaired [Line Items]
Total	$ 602
% of Total Loans	0.01%
Payment Delay
Financing Receivable, Impaired [Line Items]
Total	$ 517
Term Extension
Financing Receivable, Impaired [Line Items]
Total	0
Interest Rate Reduction
Financing Receivable, Impaired [Line Items]
Total	85
Term Extension & Interest Rate Reduction
Financing Receivable, Impaired [Line Items]
Total	0
Commercial & industrial | Commercial
Financing Receivable, Impaired [Line Items]
Total	$ 497
% of Total Loans	0.04%
Commercial & industrial | Payment Delay | Commercial
Financing Receivable, Impaired [Line Items]
Total	$ 412
Commercial & industrial | Term Extension | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Commercial & industrial | Interest Rate Reduction | Commercial
Financing Receivable, Impaired [Line Items]
Total	85
Commercial & industrial | Term Extension & Interest Rate Reduction | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Owner-occupied commercial real estate (“CRE”) | Commercial
Financing Receivable, Impaired [Line Items]
Total	$ 0
% of Total Loans	0%
Owner-occupied commercial real estate (“CRE”) | Payment Delay | Commercial
Financing Receivable, Impaired [Line Items]
Total	$ 0
Owner-occupied commercial real estate (“CRE”) | Term Extension | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Owner-occupied commercial real estate (“CRE”) | Interest Rate Reduction | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Owner-occupied commercial real estate (“CRE”) | Term Extension & Interest Rate Reduction | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Agricultural | Commercial
Financing Receivable, Impaired [Line Items]
Total	$ 105
% of Total Loans	0.01%
Agricultural | Payment Delay | Commercial
Financing Receivable, Impaired [Line Items]
Total	$ 105
Agricultural | Term Extension | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Agricultural | Interest Rate Reduction | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
Agricultural | Term Extension & Interest Rate Reduction | Commercial
Financing Receivable, Impaired [Line Items]
Total	0
CRE investment | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	$ 0
% of Total Loans	0%
CRE investment | Payment Delay | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	$ 0
CRE investment | Term Extension | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	0
CRE investment | Interest Rate Reduction | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	0
CRE investment | Term Extension & Interest Rate Reduction | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	0
Construction & land development | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	$ 0
% of Total Loans	0%
Construction & land development | Payment Delay | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	$ 0
Construction & land development | Term Extension | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	0
Construction & land development | Interest Rate Reduction | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	0
Construction & land development | Term Extension & Interest Rate Reduction | Commercial real estate
Financing Receivable, Impaired [Line Items]
Total	0
Residential first mortgage | Residential
Financing Receivable, Impaired [Line Items]
Total	$ 0
% of Total Loans	0%
Residential first mortgage | Payment Delay | Residential
Financing Receivable, Impaired [Line Items]
Total	$ 0
Residential first mortgage | Term Extension | Residential
Financing Receivable, Impaired [Line Items]
Total	0
Residential first mortgage | Interest Rate Reduction | Residential
Financing Receivable, Impaired [Line Items]
Total	0
Residential first mortgage | Term Extension & Interest Rate Reduction | Residential
Financing Receivable, Impaired [Line Items]
Total	$ 0

PREMISES AND EQUIPMENT - Summar

PREMISES AND EQUIPMENT - Summary of Premises and Equipment, Less Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 169,206	$ 152,628
Less accumulated depreciation and amortization	50,450	43,672
Premises and equipment, net	118,756	108,956
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	18,015	14,841
Land improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	5,461	5,361
Building and improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	99,664	89,630
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	7,228	7,079
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 38,838	$ 35,717

PREMISES AND EQUIPMENT - Narrat

PREMISES AND EQUIPMENT - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) branch	Dec. 31, 2020 USD ($)
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 8.2	$ 7.6	$ 5
Rent expense	$ 2.6	$ 2.2	$ 1.3
Number of branches closed | branch			15
Accelerated depreciation				$ 0.9
Mackinac Financial Corporation
Property, Plant and Equipment [Line Items]
Number of branches closed | branch			10
Minimum
Property, Plant and Equipment [Line Items]
Renewal term on operating leases	5 years
Maximum
Property, Plant and Equipment [Line Items]
Renewal term on operating leases	10 years
Land and Building | Minimum
Property, Plant and Equipment [Line Items]
Remaining lease term on operating leases	1 year
Land and Building | Maximum
Property, Plant and Equipment [Line Items]
Remaining lease term on operating leases	10 years

PREMISES AND EQUIPMENT - Other

PREMISES AND EQUIPMENT - Other Information Related To Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Operating lease cost	$ 2,004	$ 1,778	$ 1,018
Variable lease cost	631	448	234
Net lease cost	$ 2,635	$ 2,226	$ 1,252
Weighted average remaining lease term (years)	5 years 9 months 18 days	5 years 4 months 24 days	6 years 3 months 18 days
Weighted average discount rate	2.70%	2.30%	1.50%

PREMISES AND EQUIPMENT - Minimu

PREMISES AND EQUIPMENT - Minimum Annual Rentals Under these Noncancelable Agreements with Remaining Terms in Excess of One Year (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Property, Plant and Equipment [Abstract]
2024	$ 2,486
2025	2,176
2026	1,994
2027	1,831
2028	1,312
Thereafter	1,842
Total future minimum lease payments	11,641
Less: amount representing interest	(315)
Present value of net future minimum lease payments	$ 11,326

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS - Summary of Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 367,387	$ 367,387	$ 317,189
Other intangibles	26,979	35,051
Goodwill and other intangibles, net	394,366	402,438
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Other intangibles	25,112	32,701
Customer list intangibles
Finite-Lived Intangible Assets [Line Items]
Other intangibles	$ 1,867	$ 2,350

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Goodwill:
Goodwill at beginning of year	$ 367,387	$ 317,189
Acquisitions	0	49,970
Purchase accounting adjustment	0	228
Goodwill at end of year	$ 367,387	$ 367,387

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS - Other Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Net book value	$ 26,979	$ 35,051
Amortization during the period	8,072	6,616	$ 3,494
Core deposit intangibles:
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	60,724	60,724
Accumulated Amortization	(35,612)	(28,023)
Net book value	25,112	32,701
Additions during the period	0	19,364
Amortization during the period	7,589	6,108
Customer list intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	5,523	5,523
Accumulated Amortization	(3,656)	(3,173)
Net book value	1,867	2,350
Amortization during the period	$ 483	$ 508

GOODWILL AND OTHER INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS - Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
MSR asset
Asset
Asset at beginning of year	$ 13,080	$ 13,636
Capitalized MSR	1,540	2,327
Amortization during the period	(2,965)	(2,883)
Asset at end of year	11,655	13,080
Valuation allowance:
Valuation allowance at beginning of year	(500)	(1,200)
Reversals	500	700
Valuation allowance at end of year	0	(500)
MSR asset, net	11,655	12,580
Fair value of MSR asset at end of period	16,810	17,215
Residential mortgage loans serviced for others	$ 1,609,395	$ 1,637,109
Net book value of MSR asset to loans serviced for others	0.72%	0.77%
Agricultural loans serviced for others	$ 1,609,395	$ 1,637,109
LSR asset
Asset
Asset at beginning of year	11,039	20,055
Amortization during the period	(2,208)	(9,016)
Asset at end of year	8,831	11,039
Valuation allowance:
Residential mortgage loans serviced for others	492,137	538,392
Agricultural loans serviced for others	$ 492,137	$ 538,392

GOODWILL AND OTHER INTANGIBLE_7

GOODWILL AND OTHER INTANGIBLES AND SERVICING RIGHTS - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Core Deposit and Customer List Intangibles
Net book value	$ 26,979	$ 35,051
Core deposit intangibles
Core Deposit and Customer List Intangibles
2024	6,298
2025	5,161
2026	3,983
2027	3,218
2028	2,622
Thereafter	3,830
Net book value	25,112	32,701
Customer list intangibles
Core Deposit and Customer List Intangibles
2024	449
2025	449
2026	249
2027	166
2028	166
Thereafter	388
Net book value	1,867	$ 2,350
MSR asset
Core Deposit and Customer List Intangibles
2024	2,704
2025	2,037
2026	1,495
2027	1,495
2028	1,494
Thereafter	2,430
Net book value	11,655
LSR asset
Core Deposit and Customer List Intangibles
2024	1,962
2025	1,717
2026	1,472
2027	1,227
2028	981
Thereafter	1,472
Net book value	$ 8,831

OTHER REAL ESTATE OWNED - Summa

OTHER REAL ESTATE OWNED - Summary of Other Real Estate Owned Net of Valuation Allowances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Real Estate [Roll Forward]
Balance at beginning of period	$ 1,975	$ 11,955
Transfer in loans at net realizable value	985	183
Transfer in former bank branch properties at net realizable value	0	25
Sales proceeds	(1,933)	(13,150)
Net gain from sales	421	3,206	$ 597
Write-downs	(181)	(244)
Balance at end of period	$ 1,267	$ 1,975	$ 11,955

DEPOSITS - Deposit Composition

DEPOSITS - Deposit Composition (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amount
Noninterest-bearing demand deposits	$ 1,958,709	$ 2,361,816
Interest-bearing deposits	1,055,520	1,279,850
Money market	1,891,287	1,707,619
Savings	768,401	931,417
Time	1,523,883	898,219
Total deposits	$ 7,197,800	$ 7,178,921
% of Total
Noninterest-bearing demand	27%	33%
Interest-bearing demand	15%	18%
Money market	26%	24%
Savings	11%	13%
Time	21%	12%
Total deposits	100%	100%

DEPOSITS - Maturities of Time D

DEPOSITS - Maturities of Time Deposits (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Deposits [Abstract]
2024	$ 1,171,328
2025	311,446
2026	19,455
2027	14,860
2028	6,684
Thereafter	110
Total time deposits	$ 1,523,883

DEPOSITS - Narrative (Details)

DEPOSITS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deposits [Abstract]
Aggregate amount of time deposits with minimum denomination	$ 310	$ 77
Brokered deposits	$ 615	$ 592

SHORT AND LONG-TERM BORROWING_2

SHORT AND LONG-TERM BORROWINGS - Narrative (Details)	1 Months Ended	24 Months Ended	48 Months Ended	60 Months Ended
	Dec. 31, 2021 USD ($) note	Dec. 31, 2028	Dec. 31, 2030	Jul. 15, 2031	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jul. 31, 2021 USD ($)
Debt Type [Line Items]
Short-term borrowings					$ 0	$ 317,000,000
FHLB advances collateralized pledged					807,000,000	665,000,000
Trust preferred securities qualify as Tier 1 capital					39,000,000	38,000,000
US Treasury Notes
Debt Type [Line Items]
FHLB advances collateralized pledged					$ 34,000,000	$ 500,000,000
FHLB advances
Debt Type [Line Items]
Weighted average rate of FHLB advances					1.55%	1.09%
Subordinated Notes
Debt Type [Line Items]
Face amount issued					$ 121,400,000
Number of notes assumed | note	2
Subordinated Notes | Subordinated Notes due 2031
Debt Type [Line Items]
Face amount issued							$ 100,000,000
Subordinated Notes | Subordinated Notes due 2031 | Interest Rate For The Years One Through FIve
Debt Type [Line Items]
Stated interest rate							3.125%
Subordinated Notes | Subordinated Notes due 2031 | Interest Rate After Year Five | Secured Overnight Financing Rate (SOFR) | Forecast
Debt Type [Line Items]
Floating interest rate basis spread				2.375%
Subordinated Notes | County Subordinated Notes due 2028
Debt Type [Line Items]
Face amount issued	$ 30,000,000
Subordinated Notes | County Subordinated Notes due 2028 | Interest Rate For The Years One Through FIve
Debt Type [Line Items]
Stated interest rate	5.875%
Subordinated Notes | County Subordinated Notes due 2028 | Interest Rate After Year Five | London Interbank Offered Rate | Forecast
Debt Type [Line Items]
Floating interest rate basis spread		2.88%
Subordinated Notes | County Subordinated Notes due 2030
Debt Type [Line Items]
Face amount issued	$ 22,000,000
Subordinated Notes | County Subordinated Notes due 2030 | Interest Rate For The Years One Through FIve
Debt Type [Line Items]
Stated interest rate	7%
Subordinated Notes | County Subordinated Notes due 2030 | Interest Rate After Year Five | Secured Overnight Financing Rate (SOFR) | Forecast
Debt Type [Line Items]
Floating interest rate basis spread			6.875%
FHLB advances
Debt Type [Line Items]
Short-term borrowings						$ 317,000,000
FHLB advances | Maturing January 2023
Debt Type [Line Items]
Short-term borrowings						$ 117,000,000
Weighted average interest rate on short-term debt						4.29%
FHLB advances | Maturing September 2023
Debt Type [Line Items]
Short-term borrowings						$ 200,000,000
Weighted average interest rate on short-term debt						4.30%

SHORT AND LONG-TERM BORROWING_3

SHORT AND LONG-TERM BORROWINGS - Long-Term Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-term borrowings	$ 166,930	$ 225,342
FHLB advances
Debt Instrument [Line Items]
Long-term borrowings	5,000	33,000
Junior subordinated debentures
Debt Instrument [Line Items]
Long-term borrowings	40,552	39,720
Subordinated notes
Debt Instrument [Line Items]
Long-term borrowings	$ 121,378	$ 152,622

SHORT AND LONG-TERM BORROWING_4

SHORT AND LONG-TERM BORROWINGS - Summary of Maturity of Notes Payable (Details) - FHLB advances $ in Thousands	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
2024	$ 0
2025	5,000
2026	0
2027	0
2028	0
Thereafter	0
FHLB Advances	$ 5,000

SHORT AND LONG-TERM BORROWING_5

SHORT AND LONG-TERM BORROWINGS - Junior Subordinated and Subordinated Debentures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Carrying Value	$ 166,930	$ 225,342
Mid-Wisconsin Statutory Trust I | SOFR
Debt Instrument [Line Items]
Floating interest rate basis spread	1.43%
Junior subordinated debentures
Debt Instrument [Line Items]
Par	$ 48,045
Unamortized Premium (Discount)/Debt Issue Costs	(7,493)
Carrying Value	$ 40,552	$ 39,720
Junior subordinated debentures | SOFR
Debt Instrument [Line Items]
Adjustment on variable rate	0.26161%
Junior subordinated debentures | Mid-Wisconsin Statutory Trust I
Debt Instrument [Line Items]
Interest Rate	7.08%	6.20%
Par	$ 10,310
Unamortized Premium (Discount)/Debt Issue Costs	(2,380)
Carrying Value	$ 7,930	$ 7,734
Junior subordinated debentures | Baylake Capital Trust II
Debt Instrument [Line Items]
Interest Rate	6.94%	6.08%
Par	$ 16,598
Unamortized Premium (Discount)/Debt Issue Costs	(2,938)
Carrying Value	$ 13,660	$ 13,424
Junior subordinated debentures | Baylake Capital Trust II | SOFR
Debt Instrument [Line Items]
Floating interest rate basis spread	1.35%
Junior subordinated debentures | First Menasha Statutory Trust
Debt Instrument [Line Items]
Interest Rate	8.43%	7.53%
Par	$ 5,155
Unamortized Premium (Discount)/Debt Issue Costs	(443)
Carrying Value	$ 4,712	$ 4,668
Junior subordinated debentures | First Menasha Statutory Trust | SOFR
Debt Instrument [Line Items]
Floating interest rate basis spread	2.79%
Junior subordinated debentures | County Bancorp Statutory Trust II
Debt Instrument [Line Items]
Interest Rate	7.18%	6.30%
Par	$ 6,186
Unamortized Premium (Discount)/Debt Issue Costs	(753)
Carrying Value	$ 5,433	$ 5,277
Junior subordinated debentures | County Bancorp Statutory Trust II | SOFR
Debt Instrument [Line Items]
Floating interest rate basis spread	1.53%
Junior subordinated debentures | County Bancorp Statutory Trust III
Debt Instrument [Line Items]
Interest Rate	7.34%	6.46%
Par	$ 6,186
Unamortized Premium (Discount)/Debt Issue Costs	(811)
Carrying Value	$ 5,375	$ 5,219
Junior subordinated debentures | County Bancorp Statutory Trust III | SOFR
Debt Instrument [Line Items]
Floating interest rate basis spread	1.69%
Junior subordinated debentures | Fox River Valley Capital Trust
Debt Instrument [Line Items]
Interest Rate	7.89%	6.40%
Par	$ 3,610
Unamortized Premium (Discount)/Debt Issue Costs	(168)
Carrying Value	$ 3,442	$ 3,398
Junior subordinated debentures | Fox River Valley Capital Trust | SOFR
Debt Instrument [Line Items]
Floating interest rate basis spread	3.40%
Subordinated notes
Debt Instrument [Line Items]
Par	$ 121,400
Unamortized Premium (Discount)/Debt Issue Costs	(22)
Carrying Value	$ 121,378	$ 152,622
Subordinated notes | Subordinated Notes due 2031
Debt Instrument [Line Items]
Interest Rate	3.13%	3.13%
Par	$ 99,000
Unamortized Premium (Discount)/Debt Issue Costs	(524)
Carrying Value	$ 98,476	$ 99,267
Subordinated notes | County Subordinated Notes due 2028
Debt Instrument [Line Items]
Interest Rate	5.88%	5.88%
Par	$ 0
Unamortized Premium (Discount)/Debt Issue Costs	0
Carrying Value	$ 0	$ 30,119
Subordinated notes | County Subordinated Notes due 2030
Debt Instrument [Line Items]
Interest Rate	7%	7%
Par	$ 22,400
Unamortized Premium (Discount)/Debt Issue Costs	502
Carrying Value	$ 22,902	$ 23,236

EMPLOYEE AND DIRECTOR BENEFIT_2

EMPLOYEE AND DIRECTOR BENEFIT PLANS - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) plan shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Employee percentage contribution	100%
Employer contribution matching percentage	100%
Percentage of employee's gross pay	6%
Vesting period	5 years
Company 401k expense	$ 4,100,000	$ 4,000,000	$ 2,500,000
Profit sharing contribution	$ 600,000	$ 1,000,000	$ 500,000
Employee Stock Purchase Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
ESPP discount percentage from market price, beginning of purchase period	10%
Employee Stock Purchase Plan | Minimum
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Payroll deductions, per payroll	$ 20
Employee Stock Purchase Plan | Maximum
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Payroll deductions, per payroll	$ 400
Deferred compensation plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of deferred compensation plans | plan	2
Vesting period	2 years
Deferred compensation plan | Share-Based Payment Arrangement, Tranche One
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Award vesting ratio	0.33
Deferred compensation plan | Share-Based Payment Arrangement, Tranche Two
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Award vesting ratio	0.33
Deferred compensation plan | Share-Based Payment Arrangement, Tranche Three
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Award vesting ratio	0.33
Deferred compensation plan | Director
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Maximum percentage to defer the compensation under the plan	100%
Shares purchased under deferred compensation plan (in shares) | shares	2,542	1,898
Value of shares purchased under deferred compensation plan	$ 178,000	$ 154,000
Common stock distributed, value	$ 138,000
Shares distributed under director plan (in shares) | shares	1,721	0
Deferred compensation liability offsetting equity component	$ 1,300,000	$ 1,200,000
Deferred compensation liability offsetting equity component (in shares) | shares	30,481	29,660
Deferred compensation plan | Other liabilities | Key Management Employees
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Liability for cumulative employee contributions and earnings	$ 15,900,000	$ 12,100,000
Non elective contributions to selected recipients	$ 1,300,000	$ 2,400,000

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of options	10 years
Stock based compensation expense	$ 5.8	$ 6.3	$ 6.6
Unrecognized compensation cost	$ 13.7
Remaining vesting period over which cost expected to be recognized	3 years
Stock based compensation tax benefit	$ 0.8	1.1	0.6
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised	7.7	3.9	2.2
Restricted Stock | Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	$ 0.6	$ 0.7	$ 0.8
Restricted stock grants (in shares)	11,674	8,852	9,875
2011 Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares initially covered under the plan (in shares)	3,000,000
Number of shares were available for grant (in shares)	700,000

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of Weighted Average Assumptions for Valuing Stock Option Grants (Details) - Stock Incentive Plan - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	1.55%	0%	0%
Expected volatility	30%	30%	30%
Risk-free interest rate	4.22%	3.03%	1.19%
Expected average life	7 years	7 years	7 years
Weighted average per share fair value of options (in dollars per share)	$ 24.24	$ 30.99	$ 26.33

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock Options
Weighted Average Exercise Price
Shares surrendered to satisfy exercise price and/or tax withholding requirements (in shares)	55,467	7,957	10,354
Stock Incentive Plan
Option Shares Outstanding
Outstanding, beginning of period (in shares)	1,853,064	1,833,246	1,437,460
Granted (in shares)	39,000	132,929	450,000
Exercise of stock options (in shares)	(241,876)	(82,611)	(53,214)
Forfeited (in shares)	(27,100)	(30,500)	(1,000)
Outstanding, end of period (in shares)	1,623,088	1,853,064	1,833,246
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 59.79	$ 57.69	$ 50.47
Granted (in dollars per share)	71.99	81.04	77.99
Exercise of stock options (in dollars per share)	43.54	41.84	34.40
Forfeited (in dollars per share)	84.37	75.08	48.85
Outstanding, end of period (in dollars per share)	$ 62.09	$ 59.79	$ 57.69
Exercisable (in shares)	1,184,045
Exercisable (in dollars per share)	$ 56.63
Weighted average remaining life outstanding (in years)	5 years 3 months 18 days	5 years 10 months 24 days	6 years 7 months 6 days
Weighted average remaining life exercisable (in years)	4 years 4 months 24 days
Aggregate intrinsic value outstanding	$ 30,126	$ 37,526	$ 51,426
Aggregate intrinsic value exercisable	$ 28,297

STOCK-BASED COMPENSATION - Sche

STOCK-BASED COMPENSATION - Schedule of Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding (in shares) | shares	1,623,088
Number of Shares Exercisable (in shares) | shares	1,184,045
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 62.09
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 56.63
Weighted Average Remaining Life (Years) Outstanding	5 years 3 months 18 days
Weighted Average Remaining Life (Years) Exercisable	4 years 4 months 24 days
$23.80 – $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding (in shares) | shares	76,659
Number of Shares Exercisable (in shares) | shares	76,659
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 32.45
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 32.45
Weighted Average Remaining Life (Years) Outstanding	2 years
Weighted Average Remaining Life (Years) Exercisable	2 years
$40.01 – $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding (in shares) | shares	589,250
Number of Shares Exercisable (in shares) | shares	589,250
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 48.85
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 48.85
Weighted Average Remaining Life (Years) Outstanding	3 years 4 months 24 days
Weighted Average Remaining Life (Years) Exercisable	3 years 4 months 24 days
$50.01 – $65.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding (in shares) | shares	169,850
Number of Shares Exercisable (in shares) | shares	157,850
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 56.77
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 56.39
Weighted Average Remaining Life (Years) Outstanding	4 years 3 months 18 days
Weighted Average Remaining Life (Years) Exercisable	4 years
$65.01 – $75.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding (in shares) | shares	307,400
Number of Shares Exercisable (in shares) | shares	191,300
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 71.28
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 70.77
Weighted Average Remaining Life (Years) Outstanding	6 years 7 months 6 days
Weighted Average Remaining Life (Years) Exercisable	6 years 1 month 6 days
$75.01 – $93.09
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Outstanding (in shares) | shares	479,929
Number of Shares Exercisable (in shares) | shares	168,986
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 79.08
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 78.95
Weighted Average Remaining Life (Years) Outstanding	7 years 8 months 12 days
Weighted Average Remaining Life (Years) Exercisable	7 years 6 months
Minimum | $23.80 – $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	$ 23.80
Weighted Average Exercise Price Exercisable (in dollars per share)	23.80
Minimum | $40.01 – $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	40.01
Weighted Average Exercise Price Exercisable (in dollars per share)	40.01
Minimum | $50.01 – $65.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	50.01
Weighted Average Exercise Price Exercisable (in dollars per share)	50.01
Minimum | $65.01 – $75.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	65.01
Weighted Average Exercise Price Exercisable (in dollars per share)	65.01
Minimum | $75.01 – $93.09
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	75.01
Weighted Average Exercise Price Exercisable (in dollars per share)	75.01
Maximum | $23.80 – $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	40
Weighted Average Exercise Price Exercisable (in dollars per share)	40
Maximum | $40.01 – $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	50
Weighted Average Exercise Price Exercisable (in dollars per share)	50
Maximum | $50.01 – $65.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	65
Weighted Average Exercise Price Exercisable (in dollars per share)	65
Maximum | $65.01 – $75.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	75
Weighted Average Exercise Price Exercisable (in dollars per share)	75
Maximum | $75.01 – $93.09
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Exercise Price Outstanding (in dollars per share)	93.09
Weighted Average Exercise Price Exercisable (in dollars per share)	$ 93.09

STOCK-BASED COMPENSATION - Rest

STOCK-BASED COMPENSATION - Restricted Stock Award Activity (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Weighted Average Grant Date Fair  Value
Shares surrendered to satisfy tax withholding requirements (in shares)	3,637	2,249	3,215
Stock Incentive Plan
Restricted Shares Outstanding
Outstanding, beginning of period (in shares)	73,490	25,801	18,925
Granted (in shares)	19,213	72,948	33,153
Vested (in shares)	(35,545)	(24,659)	(25,831)
Forfeited (in shares)	0	(600)	(446)
Outstanding, end of period (in shares)	57,158	73,490	25,801
Weighted Average Grant Date Fair  Value
Outstanding, beginning of period (in dollars per share)	$ 76.49	$ 71.42	$ 53.57
Granted (in dollars per share)	64.28	76.81	75.83
Vested (in dollars per share)	69.69	72.64	64.53
Forfeited (in dollars per share)	0	56.01	41.44
Outstanding, end of period (in dollars per share)	$ 76.61	$ 76.49	$ 71.42

STOCKHOLDERS' EQUITY (Details)

STOCKHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Aug. 26, 2022	Dec. 03, 2021	Sep. 03, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock Transaction [Line Items]
Stock repurchased under plan				$ 1,521	$ 61,497	$ 62,583
Common stock issued in acquisitions					98,149
Charter Bankshares, Inc.
Stock Transaction [Line Items]
Number of common stock issued for consideration (in shares)	1,262,360
Common stock issued in acquisitions	$ 98,000
Value of cash consideration	$ 39,000
Mackinac Financial Corporation
Stock Transaction [Line Items]
Number of common stock issued for consideration (in shares)			2,337,230
Common stock issued in acquisitions			$ 180,000
Value of cash consideration			49,000
Costs incurred related to stock issuance			$ 400
County Bancorp, Inc.
Stock Transaction [Line Items]
Number of common stock issued for consideration (in shares)		2,366,243
Common stock issued in acquisitions		$ 176,000
Value of cash consideration		48,000
Costs incurred related to stock issuance		$ 400
Common Stock Repurchase Program
Stock Transaction [Line Items]
Stock repurchased under plan				$ 2,000	$ 61,000
Stock repurchased (in shares)				27,000	672,000
Weighted average price of share cancelled (in dollars per share)				$ 56.57	$ 91.54
Stock repurchase remaining authorized amount				$ 46,000

INCOME TAXES - Current and Defe

INCOME TAXES - Current and Deferred Amounts of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Current	$ 17,898	$ 44,384	$ 14,138
Deferred	3,027	(12,907)	6,332
Valuation allowance for securities AFS, net	4,191	0	0
Income tax expense	$ 25,116	$ 31,477	$ 20,470

INCOME TAXES - Income Tax Recon

INCOME TAXES - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Tax on pretax income, at statutory rates	$ 18,193	$ 26,405	$ 17,023
State income taxes, net of federal effect	0	7,847	5,064
Tax-exempt interest income	(1,072)	(1,037)	(517)
Increase in cash surrender value life insurance	(950)	(1,040)	(570)
Stock-based employee compensation	(811)	(1,101)	(618)
Executive compensation	1,094	82	163
Valuation allowance, net	8,677	0	0
Other, net	(15)	321	(75)
Income tax expense	$ 25,116	$ 31,477	$ 20,470

INCOME TAXES - Net Deferred Tax

INCOME TAXES - Net Deferred Tax Asset (Details) - USD ($)	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Deferred tax assets:
ACL-Loans	$ 16,937,000		$ 16,315,000
Net operating loss carryforwards	2,142,000		2,721,000
Compensation	10,971,000		10,274,000
Purchase accounting adjustments	1,963,000		9,400,000
Other real estate	132,000		672,000
Unrealized loss on securities AFS	19,196,000		21,011,000
Valuation allowance	(8,700,000)	$ (9,100,000)	0
Total deferred tax assets	42,664,000		60,393,000
Deferred tax liabilities:
Premises and equipment	(3,138,000)		(3,000,000)
Prepaid expenses	(662,000)		(801,000)
Core deposit and other intangibles	(5,917,000)		(8,817,000)
MSR and LSR assets	(5,455,000)		(6,570,000)
Other	(319,000)		(513,000)
Total deferred tax liabilities	(15,491,000)		(19,701,000)
Net deferred tax assets	27,173,000		40,692,000
Securities AFS
Deferred tax assets:
Valuation allowance	(4,191,000)		0
Other timing differences
Deferred tax assets:
Valuation allowance	$ (4,486,000)		$ 0

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($)	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Additional Tax information [Line Items]
Valuation allowance	$ 8,700,000	$ 9,100,000	$ 0
Federal
Additional Tax information [Line Items]
Operating loss carryforwards	5,900,000
State
Additional Tax information [Line Items]
Operating loss carryforwards	$ 15,900,000

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Contract or Notional Amount of Exposure to Off-Balance-Sheet Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commitments to extend credit
Other Commitments [Line Items]
Contract and notional amounts of commitments	$ 1,877,327	$ 1,850,601
Financial standby letters of credit
Other Commitments [Line Items]
Contract and notional amounts of commitments	17,500	26,530
Performance standby letters of credit
Other Commitments [Line Items]
Contract and notional amounts of commitments	$ 11,381	$ 9,375

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Commercial-related commitments to extend credit	79%	80%
Derivative fair value, net	$ 0.1	$ 0.1
Federal funds accommodations	195	195
Interest Rate Lock Commitments
Derivative [Line Items]
Commitments to sell residential mortgage loans held for sale considered derivative instruments	$ 13	$ 9

RELATED PARTY TRANSACTIONS - Lo

RELATED PARTY TRANSACTIONS - Loans to Related Parties (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Loans and Leases Receivable, Related Parties [Roll Forward]
Balance at beginning of year	$ 110,707
New loans	15,265
Repayments	(10,962)
Changes due to status of executive officers and directors	(3,308)
Balance at end of year	$ 111,702

RELATED PARTY TRANSACTIONS - Na

RELATED PARTY TRANSACTIONS - Narrative (Details) $ in Thousands	12 Months Ended			24 Months Ended	60 Months Ended
	Dec. 31, 2023 USD ($) project branch	Dec. 31, 2022 USD ($) branch	Dec. 31, 2021 USD ($)	Dec. 31, 2023 branch	Dec. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Rent expense	$ 2,600	$ 2,200	$ 1,300
Related Party
Related Party Transaction [Line Items]
Percentage payments for branch reconstruction paid to subcontractor		75%
Related Party | New branch location in facility opened in October 2013
Related Party Transaction [Line Items]
Rent expense	$ 228	$ 153	$ 124
Related Party | 2023 New Branch Construction
Related Party Transaction [Line Items]
Number of new branch location | branch	1	1		2
Payments for branch reconstruction	$ 2,000				$ 11,500
Related Party | 2022 New Branch Construction
Related Party Transaction [Line Items]
Payments for branch reconstruction	2,300
Payments for construction in process	1,200	$ 1,100
Related Party | Two Small Branch Construction
Related Party Transaction [Line Items]
Payments for branch reconstruction	$ 199	154
Number of construction projects | project	2
Number of branch locations | branch	2
Related Party | Charter Administrative Location In Facility
Related Party Transaction [Line Items]
Rent expense	$ 149	$ 49

ASSETS GAINS (LOSSES), NET - Co

ASSETS GAINS (LOSSES), NET - Components of Net Gain (Loss) on Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets Gains (Losses), Net [Abstract]
Gains (losses) on sales of securities AFS, net	$ (3,313)	$ (244)	$ (283)
Gains (losses) on sales of securities HTM, net	(37,723)	0	0
Gains (losses) on equity securities, net	(252)	(127)	3,445
Gains (losses) on sales of OREO, net	421	3,206	597
Write-downs of OREO	(181)	(244)	(28)
Write-down of other investment	(954)	0	0
Gains (losses) on sales of other investments, net	9,372	531	550
Gains (losses) on sales or dispositions of other assets, net	(178)	8	(100)
Asset gains (losses), net	$ (32,808)	$ 3,130	$ 4,181

REGULATORY CAPITAL REQUIREMEN_3

REGULATORY CAPITAL REQUIREMENTS - Narrative (Details) $ in Millions	Dec. 31, 2023 USD ($)
Regulatory Capital Requirements Under Banking Regulations [Abstract]
Allowable amount of dividends before regulatory approval required	$ 18

REGULATORY CAPITAL REQUIREMEN_4

REGULATORY CAPITAL REQUIREMENTS - Company's and Bank's Actual Regulatory Capital Amounts and Ratios (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Nicolet Bankshares, Inc
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, Actual amount	$ 930,804	$ 889,763
Total risk-based capital, Actual ratio	0.130	0.123
Total risk-based capital, For capital adequacy purposes, Amount	$ 574,231	$ 577,138
Total risk-based capital, For capital adequacy purposes, Ratio	0.080	0.080
Tier I risk-based capital, Actual amount	$ 750,811	$ 684,280
Tier I risk-based capital, Actual ratio	0.105	0.095
Tier I risk-based capital, For capital adequacy purposes, Amount	$ 430,673	$ 432,853
Tier I risk-based capital, For capital adequacy purposes, Ratio	0.060	0.060
Common equity Tier 1 capital, Actual Amount	$ 712,040	$ 646,341
Common equity Tier 1 capital, Actual Ratio	0.099	0.090
Common equity Tier 1 capital, For Capital Adequacy Purposes, Amount	$ 323,005	$ 324,640
Common equity Tier I risk-based capital, For capital adequacy purposes, Ratio	0.045	0.045
Leverage, Actual amount	$ 750,811	$ 684,280
Leverage, Actual ratio	0.092	0.082
Leverage, For capital adequacy purposes, Amount	$ 326,483	$ 335,621
Leverage, For capital adequacy purposes, Ratio	0.040	0.040
Nicolet national bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, Actual amount	$ 827,341	$ 816,951
Total risk-based capital, Actual ratio	0.115	0.113
Total risk-based capital, For capital adequacy purposes, Amount	$ 573,221	$ 576,241
Total risk-based capital, For capital adequacy purposes, Ratio	0.080	0.080
Total risk-based capital, To be well capitalized under prompt corrective action provisions, Amount	$ 716,527	$ 720,301
Total risk-based capital, To be well capitalized under prompt corrective action provisions, Ratio	0.100	0.100
Tier I risk-based capital, Actual amount	$ 768,726	$ 764,090
Tier I risk-based capital, Actual ratio	0.107	0.106
Tier I risk-based capital, For capital adequacy purposes, Amount	$ 429,916	$ 432,181
Tier I risk-based capital, For capital adequacy purposes, Ratio	0.060	0.060
Tier I risk-based capital, To be well capitalized under prompt corrective action provisions, Amount	$ 573,221	$ 576,241
Tier I risk-based capital, To be well capitalized under prompt corrective action provisions, Ratio	0.080	0.080
Common equity Tier 1 capital, Actual Amount	$ 768,726	$ 764,090
Common equity Tier 1 capital, Actual Ratio	0.107	0.106
Common equity Tier 1 capital, For Capital Adequacy Purposes, Amount	$ 322,437	$ 324,135
Common equity Tier I risk-based capital, For capital adequacy purposes, Ratio	0.045	0.045
Common equity Tier 1 capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 465,742	$ 468,196
Common equity Tier 1 capital, To be well capitalized under prompt corrective action provisions ratio, Ratio	0.065	0.065
Leverage, Actual amount	$ 768,726	$ 764,090
Leverage, Actual ratio	0.094	0.091
Leverage, For capital adequacy purposes, Amount	$ 325,868	$ 334,916
Leverage, For capital adequacy purposes, Ratio	0.040	0.040
Leverage, To be well capitalized under prompt corrective action provisions, Amount	$ 407,334	$ 418,645
Leverage, To be well capitalized under prompt corrective action provisions, Ratio	0.050	0.050

FAIR VALUE MEASUREMENTS - Measu

FAIR VALUE MEASUREMENTS - Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	$ 802,573	$ 917,618
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	802,573	917,618
Derivative assets	152	60
Derivative liabilities	79	10
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	796,510	909,465
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	6,063	8,153
Derivative assets	152	60
Derivative liabilities	79	10
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	14,123	183,830
U.S. Treasury securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	14,123	183,830
U.S. Treasury securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
U.S. Treasury securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	14,123	183,830
U.S. Treasury securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	7,384	2,100
U.S. government agency securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	7,384	2,100
U.S. government agency securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
U.S. government agency securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	7,384	2,100
U.S. government agency securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
State, county and municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	334,822	398,188
State, county and municipals | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	334,822	398,188
State, county and municipals | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
State, county and municipals | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	333,401	396,315
State, county and municipals | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,421	1,873
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	352,622	200,932
Mortgage-backed securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	352,622	200,932
Mortgage-backed securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
Mortgage-backed securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	351,658	199,951
Mortgage-backed securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	964	981
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	93,622	132,568
Corporate debt securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	93,622	132,568
Corporate debt securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	0	0
Corporate debt securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	89,944	127,269
Corporate debt securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	3,678	5,299
Equity securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments (equity securities)	4,240	4,376
Equity securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments (equity securities)	4,240	4,376
Equity securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments (equity securities)	0	0
Equity securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments (equity securities)	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Chang

FAIR VALUE MEASUREMENTS - Changes in Level 3 Assets (Details) - Recurring - Securities AFS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Level 3 Fair Value Measurements:
Unrealized gains / (losses)	$ 335	$ (211)
Level 3
Level 3 Fair Value Measurements:
Balance at beginning of year	8,153	8,065
Acquired balances	0	750
Paydowns/Sales/Settlements	(2,425)	(451)
Balance at end of year	$ 6,063	$ 8,153

FAIR VALUE MEASUREMENTS - Fair

FAIR VALUE MEASUREMENTS - Fair Value on Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Collateral dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 19,920	$ 30,951
OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	1,267	1,975
MSR asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	11,655	12,580
Level 1 | Collateral dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	0
Level 1 | OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	0
Level 1 | MSR asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	0
Level 2 | Collateral dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	0
Level 2 | OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	0
Level 2 | MSR asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0	0
Level 3 | Collateral dependent loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	19,920	30,951
Level 3 | OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	1,267	1,975
Level 3 | MSR asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 11,655	$ 12,580

FAIR VALUE MEASUREMENTS - Carry

FAIR VALUE MEASUREMENTS - Carrying amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets:
Securities AFS	$ 802,573	$ 917,618
Securities HTM		623,352
Carrying Amount
Financial assets:
Cash and cash equivalents	491,431	154,723
Certificates of deposit in other banks	6,374	12,518
Securities AFS	802,573	917,618
Securities HTM		679,128
Other investments	57,560	65,286
Loans held for sale	4,160	1,482
Loans, net	6,290,332	6,118,670
Accrued interest receivable	24,237	21,275
Financial liabilities:
Deposits	7,197,800	7,178,921
Short-term borrowings	0	317,000
Long-term borrowings	166,930	225,342
Accrued interest payable	7,765	4,265
Carrying Amount | MSR asset
Financial assets:
MSR asset	11,655	12,580
Carrying Amount | LSR asset
Financial assets:
MSR asset	8,831	11,039
Estimated  Fair Value
Financial assets:
Cash and cash equivalents	491,431	154,723
Certificates of deposit in other banks	6,293	12,407
Securities AFS	802,573	917,618
Securities HTM		623,352
Other investments	57,560	65,286
Loans held for sale	4,276	1,529
Loans, net	6,083,942	5,863,570
Accrued interest receivable	24,237	21,275
Financial liabilities:
Deposits	7,184,712	7,172,779
Short-term borrowings	0	317,000
Long-term borrowings	155,179	220,513
Accrued interest payable	7,765	4,265
Estimated  Fair Value | MSR asset
Financial assets:
MSR asset	16,810	17,215
Estimated  Fair Value | LSR asset
Financial assets:
MSR asset	8,831	11,039
Level 1 | Estimated  Fair Value
Financial assets:
Cash and cash equivalents	491,431	154,723
Certificates of deposit in other banks	0	0
Securities AFS	0	0
Securities HTM		0
Other investments	4,240	4,376
Loans held for sale	0	0
Loans, net	0	0
Accrued interest receivable	24,237	21,275
Financial liabilities:
Deposits	0	0
Short-term borrowings	0	317,000
Long-term borrowings	0	0
Accrued interest payable	7,765	4,265
Level 1 | Estimated  Fair Value | MSR asset
Financial assets:
MSR asset	0	0
Level 1 | Estimated  Fair Value | LSR asset
Financial assets:
MSR asset	0	0
Level 2 | Estimated  Fair Value
Financial assets:
Cash and cash equivalents	0	0
Certificates of deposit in other banks	6,293	12,407
Securities AFS	796,510	909,465
Securities HTM		623,352
Other investments	44,010	52,093
Loans held for sale	4,276	1,529
Loans, net	0	0
Accrued interest receivable	0	0
Financial liabilities:
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	4,820	33,001
Accrued interest payable	0	0
Level 2 | Estimated  Fair Value | MSR asset
Financial assets:
MSR asset	0	0
Level 2 | Estimated  Fair Value | LSR asset
Financial assets:
MSR asset	0	0
Level 3 | Estimated  Fair Value
Financial assets:
Cash and cash equivalents	0	0
Certificates of deposit in other banks	0	0
Securities AFS	6,063	8,153
Securities HTM		0
Other investments	9,310	8,817
Loans held for sale	0	0
Loans, net	6,083,942	5,863,570
Accrued interest receivable	0	0
Financial liabilities:
Deposits	7,184,712	7,172,779
Short-term borrowings	0	0
Long-term borrowings	150,359	187,512
Accrued interest payable	0	0
Level 3 | Estimated  Fair Value | MSR asset
Financial assets:
MSR asset	16,810	17,215
Level 3 | Estimated  Fair Value | LSR asset
Financial assets:
MSR asset	$ 8,831	$ 11,039

PARENT COMPANY ONLY FINANCIAL_3

PARENT COMPANY ONLY FINANCIAL INFORMATION - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Assets
Cash and due from subsidiary	$ 129,898	$ 121,211
Total assets	8,468,678	8,763,969
Liabilities and Stockholders’ Equity
Other liabilities	64,941	70,177
Stockholders’ equity	1,039,007	972,529	$ 891,891	$ 539,189
Total liabilities and stockholders’ equity	8,468,678	8,763,969
Nicolet Bankshares, Inc
Assets
Cash and due from subsidiary	88,365	63,927
Investments	10,535	10,313
Investments in subsidiaries	1,104,356	1,094,063
Other assets	680	392
Total assets	1,203,936	1,168,695
Liabilities and Stockholders’ Equity
Junior subordinated debentures	40,552	39,720
Subordinated notes	121,378	152,622
Other liabilities	2,999	3,824
Stockholders’ equity	1,039,007	972,529
Total liabilities and stockholders’ equity	$ 1,203,936	$ 1,168,695

PARENT COMPANY ONLY FINANCIAL_4

PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Financial Statements, Captions [Line Items]
Interest income	$ 382,862	$ 273,918	$ 171,559
Interest expense	141,346	33,957	13,604
Net interest income	241,516	239,961	157,955
Income tax benefit	(25,116)	(31,477)	(20,470)
Net income	61,516	94,260	60,652
Nicolet Bankshares, Inc
Condensed Financial Statements, Captions [Line Items]
Interest income	126	81	18
Interest expense	10,633	8,687	2,959
Net interest income	(10,507)	(8,606)	(2,941)
Dividend income from subsidiaries	70,000	77,775	65,000
Operating expense	(107)	(457)	(2,562)
Gain (loss) on investments, net	(1,164)	395	3,995
Income tax benefit	3,803	2,373	437
Earnings before equity in undistributed income (loss) of subsidiaries	62,025	71,480	63,929
Equity in undistributed income (loss) of subsidiaries	(509)	22,780	(3,277)
Net income	$ 61,516	$ 94,260	$ 60,652

PARENT COMPANY ONLY FINANCIAL_5

PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows From Operating Activities:
Net income	$ 61,516	$ 94,260	$ 60,652
Cash Flows From Investing Activities:
Net cash paid in business combinations	0	(28,221)
Cash Flows From Financing Activities:
Purchase and retirement of common stock	(1,521)	(61,497)	(62,583)
Proceeds from issuance of common stock, net	6,867	3,282	2,382
Cash dividends paid on common stock	(11,119)	0	0
Capitalized issuance costs, net	0	0	(789)
Repayments of long-term borrowings	(59,000)	(20,000)	(187,961)
Net increase (decrease) in cash and cash equivalents	336,708	(440,569)	(207,567)
Nicolet Bankshares, Inc
Cash Flows From Operating Activities:
Net income	61,516	94,260	60,652
Adjustments to reconcile net income to net cash provided by operating activities:
Accretion of discounts on borrowings	588	427	584
(Gain) loss on investments, net	1,164	(395)	(3,995)
Change in other assets and liabilities, net	(1,190)	(1,775)	1,013
Equity in undistributed (income) loss of subsidiaries, net of dividends	509	(22,780)	3,277
Net cash provided by operating activities	62,587	69,737	61,531
Cash Flows From Investing Activities:
Proceeds from sale of investments	75	1,835	4,105
Purchases of investments	(1,451)	(2,116)	(5,049)
Net cash paid in business combinations	0	(31,970)	(63,892)
Net cash used in investing activities	(1,376)	(32,251)	(64,836)
Cash Flows From Financing Activities:
Purchase and retirement of common stock	(1,521)	(61,497)	(62,583)
Proceeds from issuance of common stock, net	6,867	3,282	2,382
Cash dividends paid on common stock	(11,119)	0	0
Capitalized issuance costs, net	0	0	(789)
Repayments of long-term borrowings	(31,000)	0	0
Proceeds from issuance of subordinated notes, net	0	0	98,953
Net cash provided by (used in) financing activities	(36,773)	(58,215)	37,963
Net increase (decrease) in cash and cash equivalents	24,438	(20,729)	34,658
Beginning cash and due from subsidiary	63,927	84,656	49,998
Ending cash and due from subsidiary	$ 88,365	$ 63,927	$ 84,656

EARNINGS PER COMMON SHARE - Cal

EARNINGS PER COMMON SHARE - Calculations for Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net income	$ 61,516	$ 94,260	$ 60,652
Weighted average common shares outstanding (in shares)	14,742,675	13,909,299	10,735,605
Effect of dilutive common stock awards (in shares)	328,000	466,000	409,000
Diluted weighted average common shares outstanding (in shares)	15,070,579	14,374,931	11,144,866
Basic earnings per common share (in dollars per share)	$ 4.17	$ 6.78	$ 5.65
Diluted earnings per common share (in dollars per share)	$ 4.08	$ 6.56	$ 5.44

EARNINGS PER COMMON SHARE - Nar

EARNINGS PER COMMON SHARE - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Shares excluded from calculation of earnings per common share (in shares)	0.2	0.1	0.1