Nicolet Bankshares (NIC) 10-K 28 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 27, 2020	Jun. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	NICOLET BANKSHARES INC
Entity Central Index Key	0001174850
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding		10,495,311
Entity Public Float			$ 505.1
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth	false
Entity Shell Company	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks		$ 75,433	$ 85,896
Interest-earning deposits		106,626	163,630
Federal funds sold		0	0
Cash and cash equivalents	[1]	182,059	249,526
Certificates of deposit in other banks		19,305	993
Securities available for sale (“AFS”), at fair value		449,302	400,144
Other investments		24,072	17,997
Loans held for sale		2,706	1,639
Loans		2,573,751	2,166,181
Allowance for loan losses		(13,972)	(13,153)
Loans, net		2,559,779	2,153,028
Premises and equipment, net		56,469	48,173
Bank owned life insurance (“BOLI”)		78,140	66,310
Goodwill and other intangibles, net		165,967	124,307
Accrued interest receivable and other assets		39,461	34,418
Total assets		3,577,260	3,096,535
Liabilities:
Noninterest-bearing demand deposits		819,055	753,065
Interest-bearing deposits		2,135,398	1,861,073
Total deposits		2,954,453	2,614,138
Short-term borrowings		0	0
Long-term borrowings		67,629	77,305
Accrued interest payable and other liabilities		38,188	17,740
Total liabilities		3,060,270	2,709,183
Stockholders’ Equity:
Common stock		106	95
Additional paid-in capital		312,733	247,790
Retained earnings		199,005	144,364
Accumulated other comprehensive income (loss)		4,418	(5,640)
Total Nicolet Bankshares, Inc. stockholders’ equity		516,262	386,609
Noncontrolling interest		728	743
Total stockholders’ equity and noncontrolling interest		516,990	387,352
Total liabilities, noncontrolling interest and stockholders’ equity		$ 3,577,260	$ 3,096,535
Preferred shares authorized (no par value) (in shares)		10,000,000	10,000,000
Preferred shares issued and outstanding (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)		10,587,738	9,495,265
Common shares issued (in shares)		10,610,259	9,524,777
[1]	Cash and cash equivalents include restricted cash of $6.0 million, $6.3 million, and $5.4 million at December 31, 2019, 2018, and 2017, respectively, for the reserve balance required with the Federal Reserve Bank. At December 31, 2019, cash and cash equivalents also includes restricted cash of $1.3 million pledged as collateral on interest rate swaps.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred shares, no par value (in dollars per share)	$ 0	$ 0
Common shares, 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, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income:
Loans, including loan fees	$ 125,524	$ 113,953	$ 100,541
Investment securities:
Taxable	7,584	6,068	4,728
Tax-exempt	2,075	2,296	2,360
Other interest income	3,405	3,220	1,624
Total interest income	138,588	125,537	109,253
Interest expense:
Deposits	18,965	15,420	7,686
Short-term borrowings	5	9	84
Long-term borrowings	3,540	3,460	2,741
Total interest expense	22,510	18,889	10,511
Net interest income	116,078	106,648	98,742
Provision for loan losses	1,200	1,600	2,325
Net interest income after provision for loan losses	114,878	105,048	96,417
Noninterest income:
Mortgage income, net	11,878	6,344	5,361
BOLI income	2,369	2,418	1,778
Asset gains (losses), net	7,897	1,169	2,029
Other income	5,559	5,528	4,454
Total noninterest income	53,367	39,509	34,639
Noninterest expense:
Personnel	54,437	49,476	44,458
Occupancy, equipment and office	14,788	14,574	13,308
Business development and marketing	5,685	5,324	4,700
Data processing	9,950	9,514	8,715
Intangibles amortization	3,872	4,389	4,695
Other expense	8,067	6,481	5,480
Total noninterest expense	96,799	89,758	81,356
Income before income tax expense	71,446	54,799	49,700
Income tax expense	16,458	13,446	16,267
Net income	54,988	41,353	33,433
Less: Net income attributable to noncontrolling interest	347	317	283
Net income attributable to Nicolet Bankshares, Inc.	$ 54,641	$ 41,036	$ 33,150
Earnings per common share:
Basic (in dollars per share)	$ 5.71	$ 4.26	$ 3.51
Diluted (in dollars per share)	$ 5.52	$ 4.12	$ 3.33
Weighted average common shares outstanding:
Basic (in shares)	9,561,978	9,640,258	9,439,951
Diluted (in shares)	9,900,319	9,956,353	9,958,160
Trust services fee income
Noninterest income:
Fees and commisions	$ 6,227	$ 6,498	$ 6,031
Brokerage fee income
Noninterest income:
Fees and commisions	8,115	7,042	5,736
Service charges on deposit accounts
Noninterest income:
Fees and commisions	4,824	4,845	4,604
Card interchange income
Noninterest income:
Fees and commisions	$ 6,498	$ 5,665	$ 4,646

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 54,988	$ 41,353	$ 33,433
Unrealized gains (losses) on securities AFS:
Net unrealized holding gains (losses) arising during the period	13,758	(3,715)	2,752
Reclassification adjustment for net (gains) losses included in net income	22	212	(1,220)
Income tax (expense) benefit	(3,722)	946	(598)
Total other comprehensive income (loss), net of tax	10,058	(2,557)	934
Comprehensive income	$ 65,046	$ 38,796	$ 34,367

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non- controlling Interest
Balance at Dec. 31, 2016	$ 276,365	$ 86	$ 209,700	$ 68,888	$ (2,727)	$ 418
Comprehensive income:
Net income	33,433			33,150		283
Other comprehensive income (loss)	934				934
Stock-based compensation expense	3,064		3,064
Exercise of stock options, net	3,801	2	3,799
Issuance of common stock in acquisitions, net of capitalized issuance costs	62,060	13	62,047
Issuance of common stock	229		229
Purchase and retirement of common stock	(15,007)	(3)	(15,004)
Reclassification of stranded tax effects in accumulated other comprehensive income	0			353	(353)
Balance at Dec. 31, 2017	364,879	98	263,835	102,391	(2,146)	701
Comprehensive income:
Net income	41,353			41,036		317
Other comprehensive income (loss)	(2,557)				(2,557)
Stock-based compensation expense	4,901		4,901
Exercise of stock options, net	1,518	1	1,517
Issuance of common stock	282		282
Purchase and retirement of common stock	(22,749)	(4)	(22,745)
Distribution to noncontrolling interest	(275)					(275)
Balance at Dec. 31, 2018	387,352	95	247,790	144,364	(5,640)	743
Comprehensive income:
Net income	54,988			54,641		347
Other comprehensive income (loss)	10,058				10,058
Stock-based compensation expense	5,038		5,038
Exercise of stock options, net	8,150	3	8,147
Issuance of common stock in acquisitions, net of capitalized issuance costs	79,634	12	79,622
Issuance of common stock	592		592
Purchase and retirement of common stock	(28,460)	(4)	(28,456)
Distribution to noncontrolling interest	(362)					(362)
Balance at Dec. 31, 2019	$ 516,990	$ 106	$ 312,733	$ 199,005	$ 4,418	$ 728

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Capitalized issuance costs	$ 163	$ 186

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Cash Flows From Operating Activities:
Net income		$ 54,988		$ 41,353		$ 33,433
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion		7,311		6,282		7,067
Provision for loan losses		1,200		1,600		2,325
Provision for deferred taxes		(2,652)		(1,521)		6,962
Increase in cash surrender value of life insurance		(1,967)		(1,857)		(1,778)
Stock-based compensation expense		5,038		4,901		3,064
Assets (gains) losses, net		(7,897)		(1,169)		(2,029)
Gain on sale of loans held for sale, net		(11,244)		(5,499)		(4,777)
Proceeds from sale of loans held for sale		425,530		241,739		222,879
Origination of loans held for sale		(418,229)		(234,416)		(219,696)
Net change in accrued interest receivable and other assets		(2,951)		(666)		(5,360)
Net change in accrued interest payable and other liabilities		9,010		242		(1,377)
Net cash provided by operating activities		58,137		50,989		40,713
Cash Flows From Investing Activities:
Net (increase) decrease in certificates of deposit in other banks		(1,924)		753		2,238
Purchases of securities AFS		(95,627)		(76,564)		(63,117)
Proceeds from sales of securities AFS		23,405		5,280		10,798
Proceeds from calls and maturities of securities AFS		53,933		66,706		47,569
Net (increase) decrease in loans		(57,156)		(71,629)		(160,624)
Purchases of other investments		(2,669)		(1,550)		(3,320)
Proceeds from sales of other investments		17,144		807		6,678
Net increases in premises and equipment		(4,392)		(4,260)		(2,018)
Proceeds from sales of other real estate and other assets		457		2,824		1,724
Purchase of BOLI		(5,000)		0
Proceeds from redemption of BOLI		1,348		561
Net cash received in business combinations		7,331		0		9,119
Net cash provided by (used in) investing activities		(63,150)		(77,072)		(150,953)
Cash Flows From Financing Activities:
Net increase in deposits		49,259		143,153		126,782
Net decrease in short-term borrowings		(4,233)		0		0
Proceeds from long-term borrowings		0		0		30,000
Repayments of long-term borrowings		(87,237)		(1,253)		(9,549)
Distribution to noncontrolling interest		(362)		(275)		0
Capitalized issuance costs, net		(163)		0		(186)
Purchase and retirement of common stock		28,460		22,749		15,007
Proceeds from issuance of common stock, net		8,742		1,800		4,030
Net cash provided by (used in) financing activities		(62,454)		120,676		136,070
Net increase (decrease) in cash and cash equivalents		(67,467)		94,593		25,830
Cash and cash equivalents:
Beginning cash and cash equivalents		249,526	[1]	154,933	[1]	129,103
Ending cash and cash equivalents	[1]	182,059		249,526		154,933
Supplemental Disclosures of Cash Flow Information:
Cash paid for interest		22,334		18,537		10,932
Cash paid for taxes		16,140		10,821		12,789
Transfer of loans and bank premises to other real estate owned		1,025		607		828
Capitalized mortgage servicing rights		2,876		1,203		876
Transfer of loans from held for sale to held for investment		0		0		3,236
Acquisitions:
Fair value of assets acquired		412,000		0		439,000
Fair value of liabilities assumed		377,000		0		398,000
Net assets acquired		35,000		0		41,000
Common stock issued in acquisitions		$ 79,797		$ 0		$ 62,246
[1]	Cash and cash equivalents include restricted cash of $6.0 million, $6.3 million, and $5.4 million at December 31, 2019, 2018, and 2017, respectively, for the reserve balance required with the Federal Reserve Bank. At December 31, 2019, cash and cash equivalents also includes restricted cash of $1.3 million pledged as collateral on interest rate swaps.

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Restricted cash	$ 6	$ 6.3	$ 5.4
Restricted cash pledged as collateral	$ 1.3

NATURE OF BUSINESS AND SIGNIFIC

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2019
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. See Note 2 for additional information on the Company’s recent acquisitions. The Company partnered with Nicolet Joint Ventures, LLC (the “JV”), a real estate development and investment firm (the “Firm”), to develop and own the Company’s headquarters facility. The Firm is considered a related party, as one of its principals is a Board member and shareholder of the Company. The JV involves a 50% ownership by the Company. See Note 14 for additional related party disclosures. The Company also owns Brookfield Investment Partners, LLC (“Brookfield Investments”), a wholly owned investment advisory firm that provides investment strategy and transactional services to financial institutions. During late 2016, the Company formed Nicolet Advisory Services, LLC (“Nicolet Advisory”), a wholly owned registered investment advisor subsidiary that provides brokerage and investment advisory services to customers. During 2019, the Bank liquidated a portion of its equity interest in United Financial Services, LLC (“LLC”), a data processing and e-banking entity. Prior to the partial liquidation, the Bank owned a 49.8% indirect interest in LLC through its stock ownership of United Financial Services, Inc. (“INC”), collectively referred to as “UFS”. In May 2019, LLC sold membership units to various community banks through a private placement offering, with the full proceeds used to redeem a portion of the membership units held in INC. In turn, INC used the full proceeds net of tax to redeem 80% of the shares of its stock owned by Nicolet, and Nicolet recognized an after-tax gain of $7.4 million on the partial sale. Given the level of control, the investment in UFS is carried in other assets under the equity method of accounting. The carrying value of the Bank’s investment in UFS was $2.8 million and $11.5 million at December 31, 2019 and 2018 , respectively. The Bank’s pro rata share of UFS income is included in other noninterest income, and was $0.9 million , $1.8 million , and $1.3 million for the years ended December 31, 2019 , 2018 , and 2017 , respectively. Amounts paid to UFS for data processing services by the Bank were $3.2 million , $2.8 million , and $2.6 million in 2019 , 2018 , and 2017 , respectively. Principles of Consolidation : The consolidated financial statements of the Company include the accounts of the Bank, Brookfield Investments, Nicolet Advisory and the JV. The JV underlies the noncontrolling interest reflected in the consolidated financial statements. 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. Operating Segment: The consolidated income of the Company is derived principally from the Bank, which conducts lending (primarily commercial-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 northeastern and central Wisconsin, and Menominee, Michigan, 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. The individual contributions of the JV, Brookfield Investments and Nicolet Advisory were not significant to the consolidated balance sheet or net income for 2019 , 2018 , or 2017 . 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 : Preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying disclosures. These estimates are based on management’s best knowledge of current events and actions the Company may undertake in the future. Estimates are used in accounting for, among other items, the allowance for loan losses, valuation of loans in acquisition transactions, useful lives for depreciation and amortization, fair value of financial instruments, other-than-temporary impairment calculations, valuation of deferred tax assets, uncertain income tax positions, and contingencies. Estimates that are particularly susceptible to significant change for the Company include the determination of the allowance for loan losses, determination and assessment of deferred tax assets and liabilities, and the valuation of loans acquired in acquisition transactions; therefore, these are critical accounting policies. Factors that may cause sensitivity to the aforementioned estimates include but are not limited to: external market factors such as market interest rates and employment rates, changes to operating policies and procedures, changes in applicable banking or tax regulations, and changes to deferred tax estimates. Actual results may ultimately differ from estimates, although management does not generally believe such differences would materially affect the consolidated financial statements in any individual reporting period presented. 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. There is no separate recognition of the acquired allowance for loan losses on the acquirer’s balance sheet as credit related factors are incorporated directly into the fair value of the net tangible and intangible assets acquired. 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. Additional information regarding recent acquisitions is provided in Note 2 . 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, if any, 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. The Bank has not experienced any losses in such accounts. The Bank may have restrictions on cash and due from banks as it is required to maintain certain vault cash and reserve balances with the Federal Reserve Bank to meet specific reserve requirements. At December 31, 2019 and 2018 , the reserve balance required with the Federal Reserve Bank approximated $6.0 million and $6.3 million , respectively, of which there was sufficient cash to cover the reserve requirement. In addition, cash and cash equivalents includes restricted cash of $1.3 million pledged as collateral on an interest rate swap. Securities Available for Sale : Securities classified as AFS are those securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity, and includes U.S. government agency securities; state, county and municipal securities; mortgage-backed securities; and corporate debt securities. Effective January 1, 2018, the Company adopted a new accounting standard, which requires equity securities with readily determinable fair values to be measured at fair value with changes in the fair value recognized through net income (see Recent Accounting Pronouncements Adopted within Note 1 for the impact of this new accounting guidance). Such securities are no longer reflected as securities AFS, and are now reflected within other investments on the consolidated balance sheets. Prior periods have not been restated for the impact of this accounting change. 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. Realized gains or losses on sales of securities AFS (using the specific identification method) and declines in value judged to be other-than-temporary 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 life of the related securities using the effective interest method. See Note 3 for additional disclosures on AFS securities. Management evaluates securities AFS for other-than-temporary impairment on a quarterly basis. A decline in the market value of any investment below amortized cost that is deemed other-than-temporary is charged to earnings for the decline in value deemed to be credit related and a new cost basis in the security is established. The decline in value attributed to non-credit related factors considered temporary in nature is recognized in other comprehensive income. In evaluating other-than-temporary impairment, management considers the length of time and extent to which the fair value has been less than cost, and the financial condition and near-term prospects of the issuer for a period sufficient to allow for any anticipated recovery in fair value in the near term. Other Investments : Other investments include equity securities with readily determinable fair values, “restricted” equity securities, and private company securities. At December 31, 2019 , other investments included $3.4 million of equity securities with readily determinable fair values, $16.8 million of "restricted" equity securities, and $3.9 million of private company securities. As a member of the Federal Reserve Bank System, Federal Agricultural Mortgage Corporation, 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 other-than-temporary 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 mortgages. The amount by which cost exceeds market value is recorded as a valuation allowance and charged to earnings. Changes, if any, in the valuation allowance are also included in earnings in the period in which the change occurs. As of December 31, 2019 and 2018 , 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 and Allowance for Loan Losses (“ALLL”) – Originated Loans : Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are carried at their principal amount outstanding, net of deferred loan fees and costs. 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. See Note 4 for additional information and disclosures on originated loans. Management considers a loan to be impaired when it is probable the Company will be unable to collect all contractual principal and interest payments due in accordance with the terms of the loan agreement. For determining the appropriateness of the ALLL, management defines impaired loans as nonaccrual credit relationships over $250,000 , all loans determined to be troubled debt restructurings, plus additional loans with impairment risk characteristics. At the time an individual loan goes into nonaccrual status, management evaluates the loan for impairment and possible charge-off regardless of loan size. Typically, impairment amounts for loans under the scope criteria are charged off when the impairment amount is determined. The ALLL represents management’s estimate of probable and inherent credit losses in the Company’s loan portfolio at the balance sheet date. In general, estimating the amount of the ALLL 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 impaired 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 ALLL. Loans are charged off when management believes that the collectability of the principal is unlikely. Subsequent recoveries, if any, are credited to the ALLL. A provision for loan losses, which is a charge against income, is recorded to bring the ALLL to a level that, in management’s judgment, is appropriate to absorb probable losses in the loan portfolio. The allocation methodology applied by the Company is designed to assess the overall appropriateness of the ALLL and includes allocations for specifically identified impaired loans and loss factors for all remaining loans, with a component primarily based on historical loss rates and another component primarily based on other qualitative factors. Impaired loans are individually assessed and are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate or, as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. Loans that are determined not to be impaired are collectively evaluated for impairment, stratified by type and allocated loss ranges based on the Company’s actual historical loss ratios for each strata, and adjustments are also provided for certain current environmental and qualitative factors. An internal loan review function rates loans using a grading system based on nine different categories. Loans with grades of seven or higher (“classified loans”) represent loans with a greater risk of loss and may be assigned allocations for loss based on specific review of the weaknesses observed in the individual credits if classified as impaired. Classified loans are constantly monitored by the loan review function to ensure early identification of any deterioration. Allocations to the ALLL may be made for specific loans but the entire ALLL 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. Loans and ALLL – Acquired Loans: The loans purchased in acquisition transactions are acquired loans. Acquired loans are recorded at their estimated fair value at the acquisition date, and are initially classified as either purchase credit impaired (“PCI”) loans (i.e., loans that reflect credit deterioration since origination and it is probable at acquisition that the Company will be unable to collect all contractually required payments) or purchased non-impaired loans (i.e., “performing acquired loans”). See Note 4 for additional information and disclosures on acquired loans. PCI loans are accounted for under the accounting guidance for loans and debt securities acquired with deteriorated credit quality, found in Financial Accounting Standards Board (“FASB”) ASC Topic 310-30, Receivables—Loans and Debt Securities Acquired with Deteriorated Credit Quality . The Company estimates the amount and timing of expected principal, interest and other cash flows for each loan or pool of loans meeting the criteria above, and determines the excess of the loan’s scheduled contractual principal and contractual interest payments over all cash flows expected to be collected at acquisition as an amount that should not be accreted. These credit discounts (“nonaccretable marks”) are included in the determination of the initial fair value for acquired loans; therefore, an allowance for loan losses is not recorded at the acquisition date. Differences between the estimated fair values and expected cash flows of acquired loans at the acquisition date that are not credit-based (“accretable marks”) are subsequently accreted to interest income over the estimated life of the loans using a method that approximates a level yield if the timing and amount of the future cash flows is reasonably estimable. Subsequent to the acquisition date for PCI loans, increases in cash flows over those expected at the acquisition date result in a move of the discount from nonaccretable to accretable. Decreases in expected cash flows after the acquisition date are recognized through the provision for loan losses. All fair value discounts initially recorded on PCI loans were deemed to be credit related. Performing acquired loans are accounted for under FASB ASC Topic 310-20, Receivables—Nonrefundable Fees and Other Costs . Performance of certain loans may be monitored, and based on management’s assessment of the cash flows and other facts available, portions of the accretable difference may be delayed or suspended if management deems appropriate. The Company’s policy for determining when to discontinue accruing interest on performing acquired loans and the subsequent accounting for such loans is essentially the same as the policy for originated loans described above. An ALLL is calculated using a methodology similar to that described for originated loans. Performing acquired loans are subsequently evaluated for any required allowance at each reporting date. Such required allowance for each loan pool is compared to the remaining fair value discount for that pool. If greater, the excess is recognized as an addition to the allowance through a provision for loan losses charge. If less than the discount, no additional allowance is recorded. Charge-offs and losses first reduce any remaining fair value discount for the loan pool and once the discount is depleted, losses are applied against the allowance established for that pool. For PCI loans after acquisition, cash flows expected to be collected are recast for each loan periodically as determined appropriate by management. If the present value of expected cash flows for a loan is less than its carrying value, impairment is reflected by an increase in the ALLL and a charge to the provision for loan losses. If the present value of the expected cash flows for a loan is greater than its carrying value, any previously established ALLL is reversed and any remaining difference increases the accretable yield which will be taken into income over the remaining life of the loan. Loans which were considered troubled debt restructurings prior to the acquisition transaction are not required to be classified as troubled debt restructurings in the Company’s consolidated financial statements unless or until such loans would subsequently meet criteria to be classified as such, since acquired loans were recorded at their estimated fair values at the time of the acquisition. 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. See Note 13 for additional information and disclosures on credit-related financial instruments. 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 the straight-line method 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. See Note 5 for additional information on 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 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 ALLL or to write-down of assets, respectively. OREO properties acquired in conjunction with the 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. At December 31, 2019 and 2018 , OREO was $1.0 million and $0.4 million , respectively. 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 and are amortized on a straight-line basis to expense over their initial weighted average life of approximately 12 years as of acquisition. See Note 6 for additional information on goodwill and other intangibles. 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. The Company’s annual assessments resulted in a $0.8 million impairment charge on goodwill in late 2019 for a recent change in business strategy, while no other impairment was indicated on the remaining goodwill and other intangibles for 2019 or 2018 . Mortgage Servicing Rights (“MSRs”): If the Company sells originated residential mortgages into the secondary market and retains the right to service the loans sold, then a mortgage servicing right asset (liability) is capitalized upon sale 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. Loan servicing fee income for servicing loans 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). The Company periodically evaluates its MSRs 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 stratifications based on the risk characteristics of the underlying loans (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 carried. An other-than-temporary impairment (i.e., recoverability is considered remote when considering interest rates and loan payoff activity) is recognized as a write-down of the MSRs and the related valuation allowance (to the extent a valuation allowance is available) and then against earnings. A direct write-down permanently reduces the carrying value of the MSRs and valuation allowance, precluding subsequent recoveries. No valuation allowance or impairment charge was recorded for 2019 or 2018 . See Note 6 for additional information on MSRs. 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 noninterest income. Short-term Borrowings : Short-term borrowings consist primarily of overnight Federal funds purchased and securities sold under agreements to repurchase (“repos”), or other short-term borrowing arrangements with an original maturity of one year or less. Repos are with commercial deposit customers, and are treated as financing activities carried at the amounts that will be subsequently repurchased as specified in the respective agreements. Repos generally mature within one to four days from the transaction date. The Company may be required to provide additional collateral based on the fair value of the underlying securities. There were no outstanding agreements at December 31, 2019 or 2018 . Stock-based Compensation: Share-based payments to employees, including grants of restricted stock or stock options, are valued at fair value of the award on the date of grant and expensed on a straight-line basis as compensation expense over the applicable vesting period. A Black-Scholes model is utilized to estimate the fair value of stock options and the quoted market price of the Company’s stock at the date of grant is used to estimate the fair value of restricted stock awards. See Note 10 for additional information on stock-based compensation. Income Taxes : The Company files a consolidated federal income tax return and a combined state income tax return (both of which include the Company and its wholly owned subsidiaries). Accordingly, amounts equal to tax benefits of those companies having taxable federal losses or credits are reimbursed by the companies that incur federal 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 ass

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Choice Bancorp, Inc. (“Choice”): On November 8, 2019, the Company consummated its merger with Choice, pursuant to the terms of the Agreement and Plan of Merger dated June 26, 2019, (the “Choice Merger Agreement”), whereby Choice was merged with and into Nicolet, and Choice Bank, the wholly owned bank subsidiary of Choice, was merged with and into the Bank. The system integration was completed, and the two branches of Choice opened on November 12, 2019, as Nicolet National Bank branches, expanding its presence in the Oshkosh marketplace. The Company closed its legacy Oshkosh location concurrently with the consummation of the Choice merger. The purpose of the merger was to continue Nicolet’s interest in strategic growth, consistent with its plan to improve profitability through efficiency, leverage the strengths of each bank across the combined customer base, and add shareholder value. With the merger, Nicolet became the leading community bank to serve the Oshkosh marketplace. Pursuant to the Choice Merger Agreement, the final purchase price consisted of issuing 1,184,102 shares of the Company's common stock (given the final stock-for-stock exchange ratio of 0.497 , and not exchanging the Choice shares owned by the Company immediately prior to the time of the merger), for common stock consideration of $79.8 million (based on $67.39 per share, the volume weighted average closing price of the Company's common stock over the preceding 30 trading day period) plus cash consideration of $1.7 million . Approximately $0.2 million in direct stock issuance costs for the merger were incurred and charged against additional paid-in capital. Upon consummation, the Company added $457 million in assets, including $348 million in loans, $289 million in deposits, $1.7 million in core deposit intangible, and $45 million of goodwill. The Company accounted for the transaction under the acquisition method of accounting, and thus, the financial position and results of operations of Choice 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. Brokerage business acquired: During the third quarter of 2018, Nicolet purchased a small brokerage book of business from a retiring financial advisor in support of the Company's initiative to expand its wealth management business. As a result of this purchase, the Company recorded a customer list intangible of $290,000 which will be amortized on a straight-line basis. First Menasha Bancshares, Inc. (“First Menasha”): On April 28, 2017, the Company consummated its merger with First Menasha pursuant to the Agreement and Plan of Merger dated November 3, 2016, (the “First Menasha Merger Agreement”), whereby First Menasha was merged with and into the Company, and The First National Bank-Fox Valley, the wholly owned commercial bank subsidiary of First Menasha, was merged with and into the Bank. The system integration was completed, and five branches of First Menasha opened on May 1, 2017, as Nicolet National Bank branches, expanding its presence in Calumet and Winnebago Counties, Wisconsin. The Company closed one of its Calumet County locations concurrently with the consummation of the First Menasha merger. Pursuant to the First Menasha Merger Agreement, the final purchase price consisted of issuing 1,309,885 shares of the Company’s common stock (given the final stock-for-stock exchange ratio of 3.126 , and not exchanging the First Menasha shares owned by the Company immediately prior to the time of the merger), for common stock consideration of $62.2 million (based on $47.52 per share, the volume weighted average closing price of the Company’s common stock over the preceding 20 trading day period) plus cash consideration of $19.3 million . Approximately $0.2 million in direct stock issuance costs for the merger were incurred and charged against additional paid-in capital. Upon consummation, the Company added $480 million in assets, $351 million in loans, $375 million in deposits, $4 million in core deposit intangible, and $41 million of goodwill. The Company accounted for the transaction under the acquisition method of accounting, and thus, the financial position and results of operations of First Menasha 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.

SECURITIES AVAILABLE FOR SALE

SECURITIES AVAILABLE FOR SALE	12 Months Ended
	Dec. 31, 2019
Debt Securities, Available-for-sale [Abstract]
SECURITIES AVAILABLE FOR SALE	SECURITIES AVAILABLE FOR SALE Amortized cost and fair value of securities available for sale are summarized as follows. December 31, 2019 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency securities $ 16,516 $ 4 $ 60 $ 16,460 State, county and municipals 155,501 1,049 157 156,393 Mortgage-backed securities 193,223 2,492 697 195,018 Corporate debt securities 78,009 3,422 — 81,431 $ 443,249 $ 6,967 $ 914 $ 449,302 December 31, 2018 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency securities $ 22,467 $ — $ 818 $ 21,649 State, county and municipals 163,702 76 3,252 160,526 Mortgage-backed securities 134,350 328 3,034 131,644 Corporate debt securities 87,352 66 1,093 86,325 $ 407,871 $ 470 $ 8,197 $ 400,144 The following table presents gross unrealized losses and the related estimated fair value of investment securities available for sale, aggregated by investment category and the length of time the individual securities have been in a continuous unrealized loss position. December 31, 2019 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Number of Securities U.S. government agency securities $ 1,035 $ 2 $ 11,091 $ 58 $ 12,126 $ 60 6 State, county and municipals 22,451 132 7,605 25 30,056 157 56 Mortgage-backed securities 49,626 245 47,271 452 96,897 697 150 Corporate debt securities — — — — — — — $ 73,112 $ 379 $ 65,967 $ 535 $ 139,079 $ 914 212 December 31, 2018 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Number of Securities U.S. government agency securities $ — $ — $ 21,649 $ 818 $ 21,649 $ 818 3 State, county and municipals 16,136 98 130,975 3,154 147,111 3,252 440 Mortgage-backed securities 20,568 132 89,189 2,902 109,757 3,034 204 Corporate debt securities 51,592 677 9,757 416 61,349 1,093 33 $ 88,296 $ 907 $ 251,570 $ 7,290 $ 339,866 $ 8,197 680 As of December 31, 2019 , the Company does not consider its securities AFS with unrealized losses to be other-than-temporarily impaired as the unrealized losses in each category have occurred as a result of changes in interest rates, market spreads, and market conditions subsequent to purchase, not credit deterioration. The Company has the ability and intent to hold its securities to maturity. There were no other-than-temporary impairment charges recognized in earnings on securities AFS during 2019 , 2018 , or 2017 . The amortized cost and fair value of securities AFS 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. See Note 17 for additional information on the Company’s fair value measurements. December 31, 2019 (in thousands) Amortized Cost Fair Value Due in less than one year $ 18,662 $ 18,679 Due in one year through five years 187,010 190,149 Due after five years through ten years 35,440 35,829 Due after ten years 8,914 9,627 250,026 254,284 Mortgage-backed securities 193,223 195,018 Securities AFS $ 443,249 $ 449,302 AFS securities with a carrying value of $166 million and $157 million as of December 31, 2019 and 2018 , respectively, were pledged as collateral on public deposits and for other purposes as required or permitted by law. Proceeds from sales of securities AFS is summarized as follows. Years Ended December 31, (in thousands) 2019 2018 2017 Gross gains $ 152 $ — $ 1,227 Gross losses (174 ) (212 ) (7 ) Gains (losses) on sales of securities AFS, net $ (22 ) $ (212 ) $ 1,220 Proceeds from sales of securities AFS $ 23,405 $ 5,280 $ 10,798

LOANS, ALLOWANCE FOR LOAN LOSSE

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY	LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY The loan composition is summarized as follows. December 31, 2019 December 31, 2018 (in thousands) Amount % of Total Amount % of Total Commercial & industrial $ 806,189 31 % $ 684,920 32 % Owner-occupied commercial real estate (“CRE”) 496,372 19 441,353 20 Agricultural (“AG”) production 35,982 2 35,625 2 AG real estate 59,468 2 53,444 2 CRE investment 443,218 17 343,652 16 Construction & land development 92,970 4 80,599 4 Residential construction 54,403 2 30,926 1 Residential first mortgage 432,167 17 357,841 17 Residential junior mortgage 122,771 5 111,328 5 Retail & other 30,211 1 26,493 1 Loans 2,573,751 100 % 2,166,181 100 % Less ALLL 13,972 13,153 Loans, net $ 2,559,779 $ 2,153,028 ALLL to loans 0.54 % 0.61 % As a further breakdown, loans are summarized by originated and acquired as follows. December 31, 2019 December 31, 2018 (in thousands) Originated Amount % of Total Acquired Amount % of Total Originated Amount % of Total Acquired Amount % of Total Commercial & industrial $ 641,341 39 % $ 164,848 18 % $ 568,100 38 % $ 116,820 17 % Owner-occupied CRE 329,138 20 167,234 18 283,531 19 157,822 23 AG production 11,824 1 24,158 3 11,113 1 24,512 4 AG real estate 38,983 2 20,485 2 31,374 2 22,070 3 CRE investment 183,746 11 259,472 28 171,087 12 172,565 25 Construction & land development 56,086 3 36,884 4 66,478 4 14,121 2 Residential construction 43,460 3 10,943 1 30,926 2 — — Residential first mortgage 232,580 14 199,587 22 220,368 15 137,473 20 Residential junior mortgage 90,284 5 32,487 4 78,379 5 32,949 5 Retail & other 28,373 2 1,838 — 23,809 2 2,684 1 Loans 1,655,815 100 % 917,936 100 % 1,485,165 100 % 681,016 100 % Less ALLL 12,116 1,856 11,448 1,705 Loans, net $ 1,643,699 $ 916,080 $ 1,473,717 $ 679,311 ALLL to loans 0.73 % 0.20 % 0.77 % 0.25 % Practically all 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. See Note 1 for the Company’s accounting policy on loans and the allowance for loan losses. A roll forward of the allowance for loan losses is summarized as follows. Years Ended December 31, (in thousands) 2019 2018 2017 Beginning balance $ 13,153 $ 12,653 $ 11,820 Provision for loan losses 1,200 1,600 2,325 Charge-offs (927 ) (1,213 ) (1,604 ) Recoveries 546 113 112 Net charge-offs (381 ) (1,100 ) (1,492 ) Ending balance $ 13,972 $ 13,153 $ 12,653 The following tables present the balance and activity in the ALLL by portfolio segment and the recorded investment in loans by portfolio segment for the year ended December 31, 2019 . TOTAL – Year Ended December 31, 2019 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 5,271 $ 2,847 $ 121 $ 301 $ 1,470 $ 510 $ 211 $ 1,646 $ 472 $ 304 $ 13,153 Provision (61 ) 254 89 68 130 (96 ) 383 9 86 338 1,200 Charge-offs (159 ) (93 ) — — — — (226 ) (22 ) (80 ) (347 ) (927 ) Recoveries 420 2 — — — — — 36 39 49 546 Net charge-offs 261 (91 ) — — — — (226 ) 14 (41 ) (298 ) (381 ) Ending balance $ 5,471 $ 3,010 $ 210 $ 369 $ 1,600 $ 414 $ 368 $ 1,669 $ 517 $ 344 $ 13,972 As % of ALLL 39 % 22 % 1 % 3 % 11 % 3 % 3 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ 625 $ — $ 116 $ — $ — $ — $ — $ — $ — $ — $ 741 Collectively evaluated 4,846 3,010 94 369 1,600 414 368 1,669 517 344 13,231 Ending balance $ 5,471 $ 3,010 $ 210 $ 369 $ 1,600 $ 414 $ 368 $ 1,669 $ 517 $ 344 $ 13,972 Loans: Individually evaluated $ 5,932 $ 3,430 $ 1,061 $ 1,073 $ 2,426 $ 382 $ — $ 2,357 $ 218 $ 12 $ 16,891 Collectively evaluated 800,257 492,942 34,921 58,395 440,792 92,588 54,403 429,810 122,553 30,199 2,556,860 Total loans $ 806,189 $ 496,372 $ 35,982 $ 59,468 $ 443,218 $ 92,970 $ 54,403 $ 432,167 $ 122,771 $ 30,211 $ 2,573,751 Less ALLL 5,471 3,010 210 369 1,600 414 368 1,669 517 344 13,972 Net loans $ 800,718 $ 493,362 $ 35,772 $ 59,099 $ 441,618 $ 92,556 $ 54,035 $ 430,498 $ 122,254 $ 29,867 $ 2,559,779 As a further breakdown, the ALLL is summarized by originated and acquired as follows. Originated – Year Ended December 31, 2019 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 4,683 $ 2,439 $ 110 $ 255 $ 1,230 $ 431 $ 211 $ 1,400 $ 408 $ 281 $ 11,448 Provision (207 ) 212 85 57 124 (81 ) 340 5 25 335 895 Charge-offs (59 ) (93 ) — — — — (226 ) (22 ) (20 ) (347 ) (767 ) Recoveries 420 2 — — — — — 36 33 49 540 Net charge-offs 361 (91 ) — — — — (226 ) 14 13 (298 ) (227 ) Ending balance $ 4,837 $ 2,560 $ 195 $ 312 $ 1,354 $ 350 $ 325 $ 1,419 $ 446 $ 318 $ 12,116 As % of ALLL 40 % 21 % 2 % 2 % 11 % 3 % 3 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ 625 $ — $ 116 $ — $ — $ — $ — $ — $ — $ — $ 741 Collectively evaluated 4,212 2,560 79 312 1,354 350 325 1,419 446 318 11,375 Ending balance $ 4,837 $ 2,560 $ 195 $ 312 $ 1,354 $ 350 $ 325 $ 1,419 $ 446 $ 318 $ 12,116 Loans: Individually evaluated $ 1,993 $ 1,845 $ 1,008 $ 862 $ — $ — $ — $ — $ — $ — $ 5,708 Collectively evaluated 639,348 327,293 10,816 38,121 183,746 56,086 43,460 232,580 90,284 28,373 1,650,107 Total loans $ 641,341 $ 329,138 $ 11,824 $ 38,983 $ 183,746 $ 56,086 $ 43,460 $ 232,580 $ 90,284 $ 28,373 $ 1,655,815 Less ALLL 4,837 2,560 195 312 1,354 350 325 1,419 446 318 12,116 Net loans $ 636,504 $ 326,578 $ 11,629 $ 38,671 $ 182,392 $ 55,736 $ 43,135 $ 231,161 $ 89,838 $ 28,055 $ 1,643,699 Acquired – Year Ended December 31, 2019 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 588 $ 408 $ 11 $ 46 $ 240 $ 79 $ — $ 246 $ 64 $ 23 $ 1,705 Provision 146 42 4 11 6 (15 ) 43 4 61 3 305 Charge-offs (100 ) — — — — — — — (60 ) — (160 ) Recoveries — — — — — — — — 6 — 6 Net charge-offs (100 ) — — — — — — — (54 ) — (154 ) Ending balance $ 634 $ 450 $ 15 $ 57 $ 246 $ 64 $ 43 $ 250 $ 71 $ 26 $ 1,856 As % of ALLL 34 % 24 % 1 % 3 % 13 % 4 % 2 % 14 % 4 % 1 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 634 450 15 57 246 64 43 250 71 26 1,856 Ending balance $ 634 $ 450 $ 15 $ 57 $ 246 $ 64 $ 43 $ 250 $ 71 $ 26 $ 1,856 Loans: Individually evaluated $ 3,939 $ 1,585 $ 53 $ 211 $ 2,426 $ 382 $ — $ 2,357 $ 218 $ 12 $ 11,183 Collectively evaluated 160,909 165,649 24,105 20,274 257,046 36,502 10,943 197,230 32,269 1,826 906,753 Total loans $ 164,848 $ 167,234 $ 24,158 $ 20,485 $ 259,472 $ 36,884 $ 10,943 $ 199,587 $ 32,487 $ 1,838 $ 917,936 Less ALLL 634 450 15 57 246 64 43 250 71 26 1,856 Net loans $ 164,214 $ 166,784 $ 24,143 $ 20,428 $ 259,226 $ 36,820 $ 10,900 $ 199,337 $ 32,416 $ 1,812 $ 916,080 For comparison, the following tables present the balance and activity in the ALLL by portfolio segment and the recorded investment in loans by portfolio segment for the year ended December 31, 2018 . TOTAL – Year Ended December 31, 2018 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 4,934 $ 2,607 $ 129 $ 296 $ 1,388 $ 726 $ 251 $ 1,609 $ 488 $ 225 $ 12,653 Provision 1,107 300 (8 ) 5 119 (216 ) (40 ) 117 (51 ) 267 1,600 Charge-offs (813 ) (74 ) — — (37 ) — — (85 ) — (204 ) (1,213 ) Recoveries 43 14 — — — — — 5 35 16 113 Net charge-offs (770 ) (60 ) — — (37 ) — — (80 ) 35 (188 ) (1,100 ) Ending balance $ 5,271 $ 2,847 $ 121 $ 301 $ 1,470 $ 510 $ 211 $ 1,646 $ 472 $ 304 $ 13,153 As % of ALLL 40 % 22 % 1 % 2 % 11 % 4 % 2 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 5,271 2,847 121 301 1,470 510 211 1,646 472 304 13,153 Ending balance $ 5,271 $ 2,847 $ 121 $ 301 $ 1,470 $ 510 $ 211 $ 1,646 $ 472 $ 304 $ 13,153 Loans: Individually evaluated $ 2,927 $ 1,506 $ — $ 222 $ 1,686 $ 603 $ — $ 2,750 $ 233 $ 12 $ 9,939 Collectively evaluated 681,993 439,847 35,625 53,222 341,966 79,996 30,926 355,091 111,095 26,481 2,156,242 Total loans $ 684,920 $ 441,353 $ 35,625 $ 53,444 $ 343,652 $ 80,599 $ 30,926 $ 357,841 $ 111,328 $ 26,493 $ 2,166,181 Less ALLL 5,271 2,847 121 301 1,470 510 211 1,646 472 304 13,153 Net loans $ 679,649 $ 438,506 $ 35,504 $ 53,143 $ 342,182 $ 80,089 $ 30,715 $ 356,195 $ 110,856 $ 26,189 $ 2,153,028 As a further breakdown, the December 31, 2018 ALLL is summarized by originated and acquired as follows. Originated – Year Ended December 31, 2018 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 4,192 $ 2,115 $ 112 $ 235 $ 1,154 $ 628 $ 200 $ 1,297 $ 409 $ 200 $ 10,542 Provision 1,262 385 (2 ) 20 113 (197 ) 11 187 (31 ) 266 2,014 Charge-offs (813 ) (64 ) — — (37 ) — — (85 ) — (201 ) (1,200 ) Recoveries 42 3 — — — — — 1 30 16 92 Net charge-offs (771 ) (61 ) — — (37 ) — — (84 ) 30 (185 ) (1,108 ) Ending balance $ 4,683 $ 2,439 $ 110 $ 255 $ 1,230 $ 431 $ 211 $ 1,400 $ 408 $ 281 $ 11,448 As % of ALLL 41 % 21 % 1 % 2 % 11 % 4 % 2 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 4,683 2,439 110 255 1,230 431 211 1,400 408 281 11,448 Ending balance $ 4,683 $ 2,439 $ 110 $ 255 $ 1,230 $ 431 $ 211 $ 1,400 $ 408 $ 281 $ 11,448 Loans: Individually evaluated $ 227 $ 321 $ — $ — $ — $ — $ — $ — $ — $ — $ 548 Collectively evaluated 567,873 283,210 11,113 31,374 171,087 66,478 30,926 220,368 78,379 23,809 1,484,617 Total loans $ 568,100 $ 283,531 $ 11,113 $ 31,374 $ 171,087 $ 66,478 $ 30,926 $ 220,368 $ 78,379 $ 23,809 $ 1,485,165 Less ALLL 4,683 2,439 110 255 1,230 431 211 1,400 408 281 11,448 Net loans $ 563,417 $ 281,092 $ 11,003 $ 31,119 $ 169,857 $ 66,047 $ 30,715 $ 218,968 $ 77,971 $ 23,528 $ 1,473,717 Acquired – Year Ended December 31, 2018 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 742 $ 492 $ 17 $ 61 $ 234 $ 98 $ 51 $ 312 $ 79 $ 25 $ 2,111 Provision (155 ) (85 ) (6 ) (15 ) 6 (19 ) (51 ) (70 ) (20 ) 1 (414 ) Charge-offs — (10 ) — — — — — — — (3 ) (13 ) Recoveries 1 11 — — — — — 4 5 — 21 Net charge-offs 1 1 — — — — — 4 5 (3 ) 8 Ending balance $ 588 $ 408 $ 11 $ 46 $ 240 $ 79 $ — $ 246 $ 64 $ 23 $ 1,705 As % of ALLL 34 % 24 % 1 % 3 % 14 % 5 % — % 14 % 4 % 1 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 588 408 11 46 240 79 — 246 64 23 1,705 Ending balance $ 588 $ 408 $ 11 $ 46 $ 240 $ 79 $ — $ 246 $ 64 $ 23 $ 1,705 Loans: Individually evaluated $ 2,700 $ 1,185 $ — $ 222 $ 1,686 $ 603 $ — $ 2,750 $ 233 $ 12 $ 9,391 Collectively evaluated 114,120 156,637 24,512 21,848 170,879 13,518 — 134,723 32,716 2,672 671,625 Total loans $ 116,820 $ 157,822 $ 24,512 $ 22,070 $ 172,565 $ 14,121 $ — $ 137,473 $ 32,949 $ 2,684 $ 681,016 Less ALLL 588 408 11 46 240 79 — 246 64 23 1,705 Net loans $ 116,232 $ 157,414 $ 24,501 $ 22,024 $ 172,325 $ 14,042 $ — $ 137,227 $ 32,885 $ 2,661 $ 679,311 The following tables present nonaccrual loans by portfolio segment in total and then as a further breakdown by originated or acquired. Total Nonaccrual Loans (in thousands) December 31, 2019 % to Total December 31, 2018 % to Total Commercial & industrial $ 6,249 44 % $ 2,816 52 % Owner-occupied CRE 3,311 23 673 12 AG production 1,062 8 — — AG real estate 836 6 164 3 CRE investment 1,073 8 210 4 Construction & land development 20 — 80 1 Residential construction — — 1 — Residential first mortgage 1,090 8 1,265 23 Residential junior mortgage 480 3 262 5 Retail & other 1 — — — Nonaccrual loans $ 14,122 100 % $ 5,471 100 % Percent of total loans 0.5 % 0.2 % Originated and Acquired Nonaccrual Loans December 31, 2019 December 31, 2018 (in thousands) Originated Amount % of Total Acquired Amount % of Total Originated Amount % of Total Acquired Amount % of Total Commercial & industrial $ 2,283 36 % $ 3,966 51 % $ 352 25 % $ 2,464 61 % Owner-occupied CRE 1,846 29 1,465 19 362 26 311 8 AG production 1,009 16 53 1 — — — — AG real estate 625 10 211 3 — — 164 4 CRE investment — — 1,073 14 — — 210 5 Construction & land development — — 20 — — — 80 2 Residential construction — — — — 1 — — — Residential first mortgage 434 7 656 8 629 45 636 15 Residential junior mortgage 126 2 354 4 65 4 197 5 Retail & other 1 — — — — — — — Nonaccrual loans $ 6,324 100 % $ 7,798 100 % $ 1,409 100 % $ 4,062 100 % Percent of nonaccrual loans 45 % 55 % 26 % 74 % The following tables present past due loans by portfolio segment. December 31, 2019 (in thousands) 30-89 Days Past Due (accruing) 90 Days & Over or nonaccrual Current Total Commercial & industrial $ 1,729 $ 6,249 $ 798,211 $ 806,189 Owner-occupied CRE 112 3,311 492,949 496,372 AG production — 1,062 34,920 35,982 AG real estate — 836 58,632 59,468 CRE investment — 1,073 442,145 443,218 Construction & land development 2,063 20 90,887 92,970 Residential construction 302 — 54,101 54,403 Residential first mortgage 2,736 1,090 428,341 432,167 Residential junior mortgage 217 480 122,074 122,771 Retail & other 110 1 30,100 30,211 Total loans $ 7,269 $ 14,122 $ 2,552,360 $ 2,573,751 Percent of total loans 0.3 % 0.5 % 99.2 % 100.0 % December 31, 2018 (in thousands) 30-89 Days Past Due (accruing) 90 Days & Over or nonaccrual Current Total Commercial & industrial $ — $ 2,816 $ 682,104 $ 684,920 Owner-occupied CRE 557 673 440,123 441,353 AG production 19 — 35,606 35,625 AG real estate 35 164 53,245 53,444 CRE investment 180 210 343,262 343,652 Construction & land development — 80 80,519 80,599 Residential construction — 1 30,925 30,926 Residential first mortgage 758 1,265 355,818 357,841 Residential junior mortgage 12 262 111,054 111,328 Retail & other 10 — 26,483 26,493 Total loans $ 1,571 $ 5,471 $ 2,159,139 $ 2,166,181 Percent of total loans 0.1 % 0.2 % 99.7 % 100.0 % 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. Grade 8, Doubtful: Assets with this rating exhibit all the weaknesses as one rated Substandard with the added characteristic that such weaknesses make collection or liquidation in full highly questionable. Grade 9, Loss: Assets in this category are considered uncollectible. Pursuing any recovery or salvage value is impractical but does not preclude partial recovery in the future. The following tables present total loans by risk categories. December 31, 2019 (in thousands) Grades 1-4 Grade 5 Grade 6 Grade 7 Grades 8-9 Total Commercial & industrial $ 765,073 $ 20,199 $ 7,663 $ 13,254 $ — $ 806,189 Owner-occupied CRE 464,661 20,855 953 9,903 — 496,372 AG production 27,521 3,174 1,229 4,058 — 35,982 AG real estate 49,561 3,611 2,046 4,250 — 59,468 CRE investment 430,794 8,085 2,578 1,761 — 443,218 Construction & land development 90,523 2,213 15 219 — 92,970 Residential construction 53,286 1,117 — — — 54,403 Residential first mortgage 424,044 4,677 668 2,778 — 432,167 Residential junior mortgage 122,249 35 — 487 — 122,771 Retail & other 30,210 — — 1 — 30,211 Total loans $ 2,457,922 $ 63,966 $ 15,152 $ 36,711 $ — $ 2,573,751 Percent of total loans 95.5 % 2.5 % 0.6 % 1.4 % — % 100.0 % December 31, 2018 (in thousands) Grades 1-4 Grade 5 Grade 6 Grade 7 Grades 8-9 Total Commercial & industrial $ 649,475 $ 16,145 $ 6,178 $ 13,122 $ — $ 684,920 Owner-occupied CRE 405,198 22,776 6,569 6,810 — 441,353 AG production 29,363 3,302 2,351 609 — 35,625 AG real estate 46,248 3,246 2,983 967 — 53,444 CRE investment 334,080 6,792 — 2,780 — 343,652 Construction & land development 75,365 5,138 16 80 — 80,599 Residential construction 30,926 — — — — 30,926 Residential first mortgage 353,239 1,406 510 2,686 — 357,841 Residential junior mortgage 111,037 17 — 274 — 111,328 Retail & other 26,493 — — — — 26,493 Total loans $ 2,061,424 $ 58,822 $ 18,607 $ 27,328 $ — $ 2,166,181 Percent of total loans 95.1 % 2.7 % 0.9 % 1.3 % — % 100.0 % The following tables present impaired loans. December 31, 2019 (in thousands) Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized Commercial & industrial $ 5,932 $ 7,950 $ 625 $ 5,405 $ 1,170 Owner-occupied CRE 3,430 4,016 — 3,677 256 AG production 1,061 1,090 116 1,221 28 AG real estate 1,073 1,082 — 1,090 9 CRE investment 2,426 2,790 — 2,497 364 Construction & land development 382 382 — 460 — Residential construction — — — — — Residential first mortgage 2,357 2,629 — 2,412 178 Residential junior mortgage 218 349 — 224 58 Retail & other 12 12 — 12 — Total $ 16,891 $ 20,300 $ 741 $ 16,998 $ 2,063 Originated impaired loans $ 5,708 $ 5,938 $ 741 $ 5,978 $ 230 Acquired impaired loans 11,183 14,362 — 11,020 1,833 Total $ 16,891 $ 20,300 $ 741 $ 16,998 $ 2,063 December 31, 2018 (in thousands) Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized Commercial & industrial $ 2,927 $ 6,736 $ — $ 4,041 $ 660 Owner-occupied CRE 1,506 1,833 — 1,659 137 AG production — — — — — AG real estate 222 281 — 238 26 CRE investment 1,686 2,484 — 1,606 163 Construction & land development 603 1,506 — 603 21 Residential construction — — — — — Residential first mortgage 2,750 2,907 — 2,478 176 Residential junior mortgage 233 262 — 62 15 Retail & other 12 12 — 12 1 Total $ 9,939 $ 16,021 $ — $ 10,699 $ 1,199 Originated impaired loans $ 548 $ 548 $ — $ 899 $ 154 Acquired impaired loans 9,391 15,473 — 9,800 1,045 Total $ 9,939 $ 16,021 $ — $ 10,699 $ 1,199 Total purchased credit impaired loans (in aggregate since the Company’s 2013 acquisitions) were initially recorded at a fair value of $45.5 million on their respective acquisition dates, net of an initial $35.3 million nonaccretable mark and a zero accretable mark. At December 31, 2019 , $11.2 million of the $45.5 million remain in impaired loans. Nonaccretable discount on PCI loans: Years Ended December 31, (in thousands) 2019 2018 Balance at beginning of period $ 6,408 $ 9,471 Acquired balance, net 911 — Accretion to loan interest income (4,713 ) (1,976 ) Transferred to accretable — (990 ) Disposals of loans (679 ) (97 ) Balance at end of period $ 1,927 $ 6,408 Troubled Debt Restructurings At December 31, 2019 , there were five loans classified as troubled debt restructurings with a current outstanding balance of $1.1 million and a pre-modification balance of $1.4 million . In comparison, at December 31, 2018 , there were four loans classified as troubled debt restructurings with an outstanding balance of $0.6 million and a pre-modification balance of $2.7 million . There were no loans which were classified as troubled debt restructurings during the previous twelve months that subsequently defaulted during 2019 . As of December 31, 2019 , there were no commitments to lend additional funds to debtors whose terms have been modified in troubled debt restructurings.

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
	Dec. 31, 2019
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, 2019 December 31, 2018 Land $ 7,418 $ 6,220 Land improvements 3,865 3,842 Building and improvements 50,818 42,238 Leasehold improvements 4,580 4,092 Furniture and equipment 20,262 18,590 86,943 74,982 Less accumulated depreciation and amortization 30,474 26,809 Premises and equipment, net $ 56,469 $ 48,173 Depreciation and amortization expense amounted to $3.8 million in 2019 , $4.4 million in 2018 , and $4.2 million in 2017 . The Company and certain of its subsidiaries are obligated under non-cancelable operating leases for facilities, certain of which provide for increased rentals based upon increases in cost of living adjustments and other indices. Rent expense under leases totaled $1.2 million in 2019 , $1.4 million in 2018 , and $1.1 million in 2017 . As of January 1, 2019, the Company adopted ASU 2016-02 (Topic 842) on a prospective basis using the effective date method. The adoption of the new standard did not have a material impact on Nicolet's financial statements; however, additional disclosures have been added in accordance with the ASU. See Note 1 for additional information on this new accounting standard. The operating lease ROU asset represents the right to use an underlying asset during the lease term, while the operating lease liability represents the obligation to make lease payments arising from the lease. The ROU asset and lease liability are recognized at lease commencement based on the present value of the remaining lease payments, considering a discount rate that represents Nicolet's incremental borrowing rate. Operating lease expense is recognized on a straight-line basis over the lease term and is recognized in occupancy, equipment, and office on the consolidated statements of income. Nicolet leases space under non-cancelable operating lease agreements for certain bank and nonbank branch facilities with remaining lease terms of 2 to 6 years. Certain lease arrangements contain extension options which typically range from 5 to 10 years at the then fair market rental rates. The lease asset and liability considers renewal options when they are reasonably certain of being exercised. A summary of net lease cost and selected other information related to operating leases was as follows. Year Ended ($ in thousands) December 31, 2019 Net lease cost: Operating lease cost $ 970 Variable lease cost 233 Net lease cost $ 1,203 Selected other operating lease information: Weighted average remaining lease term (years) 4.3 Weighted average discount rate 2.5 % The following table summarizes the maturity of remaining lease liabilities. Years Ending December 31, (in thousands) 2020 $ 1,088 2021 962 2022 851 2023 607 2024 499 Thereafter 16 Total future minimum lease payments 4,023 Less: amount representing interest (100 ) Present value of net future minimum lease payments $ 3,923 During the fourth quarter of 2019, a $0.7 million lease termination charge was recorded to other expense due to the closure of a branch, concurrent with the consummation date of the Choice merger.

GOODWILL AND OTHER INTANGIBLES

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS	GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS A summary of goodwill and other intangibles was as follows. (in thousands) December 31, 2019 December 31, 2018 Goodwill $ 151,198 $ 107,366 Core deposit intangibles 10,897 12,562 Customer list intangibles 3,872 4,379 Other intangibles 14,769 16,941 Goodwill and other intangibles, net $ 165,967 $ 124,307 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 2019, goodwill increased due to the Choice acquisition and impairment was recognized on goodwill initially recorded in 2008 for a recent change in business strategy. See Note 1 for the Company’s accounting policy for goodwill and see Note 2 for additional information on the Company’s acquisitions. (in thousands) December 31, 2019 December 31, 2018 Goodwill: Goodwill at beginning of year $ 107,366 $ 107,366 Acquisition 44,594 — Impairment (762 ) — Goodwill at end of year $ 151,198 $ 107,366 Other intangibles : Other intangible assets, consisting of core deposit intangibles and customer list intangibles, are amortized over their estimated finite lives. During 2019, core deposit intangibles increased due to the Choice acquisition, while during 2018 customer list intangibles increased due to the purchase of a brokerage book of business. See Note 1 for the Company’s accounting policy for other intangibles and see Note 2 for additional information on the Company’s acquisitions. (in thousands) December 31, 2019 December 31, 2018 Core deposit intangibles: Gross carrying amount $ 30,715 $ 29,015 Accumulated amortization (19,818 ) (16,453 ) Net book value $ 10,897 $ 12,562 Additions during the period $ 1,700 $ — Amortization during the period $ 3,365 $ 3,915 Customer list intangibles: Gross carrying amount $ 5,523 5,523 Accumulated amortization (1,651 ) (1,144 ) Net book value $ 3,872 $ 4,379 Additions during the period $ — $ 290 Amortization during the period $ 507 $ 474 Mortgage servicing rights : A summary of the changes in the MSR asset was as follows. (in thousands) December 31, 2019 December 31, 2018 MSR asset: MSR asset at beginning of year $ 3,749 $ 3,187 Capitalized MSR 2,876 1,203 MSR asset acquired 160 — Amortization during the period (866 ) (641 ) MSR asset at end of year $ 5,919 $ 3,749 Fair value of MSR asset at end of period $ 8,420 $ 6,347 Residential mortgage loans serviced for others $ 847,756 $ 603,446 Net book value of MSR asset to loans serviced for others 0.70 % 0.62 % The Company periodically evaluates its mortgage servicing rights asset for impairment. No valuation allowance or impairment charge was recorded for 2019 or 2018 . See Note 1 for the Company’s accounting policy for MSRs, see Note 2 for additional information on the Company’s acquisitions, and see Note 17 for additional information on the fair value of the MSR asset. The following table shows the estimated future amortization expense for amortizing intangible assets and the MSR asset. The projections are based on existing asset balances, the current interest rate environment and prepayment speeds as of December 31, 2019 . 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 intangibles Customer list intangibles MSR asset Years Ending December 31, 2020 $ 2,993 $ 507 $ 1,048 2021 2,453 507 865 2022 1,987 507 865 2023 1,490 483 835 2024 1,010 449 503 Thereafter 964 1,419 1,803 Total $ 10,897 $ 3,872 $ 5,919

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
DEPOSITS	DEPOSITS At December 31, 2019 , the scheduled maturities of time deposits were as follows. Years Ending December 31, (in thousands) 2020 $ 317,693 2021 114,728 2022 50,949 2023 45,040 2024 19,773 Thereafter 2,374 Total time deposits $ 550,557 Time deposits of $250,000 or more were $91.2 million and $77.6 million at December 31, 2019 and 2018 , respectively.

SHORT AND LONG-TERM BORROWINGS

SHORT AND LONG-TERM BORROWINGS	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
SHORT AND LONG-TERM BORROWINGS	SHORT AND LONG-TERM BORROWINGS Short-Term Borrowings: The Company did not have any short-term borrowings (borrowing with an original contractual maturity of one year or less) outstanding at December 31, 2019 or 2018 . Long-Term Borrowings: The components of long-term borrowings (borrowing with an original contractual maturity greater than one year) were as follows. (in thousands) December 31, 2019 December 31, 2018 FHLB advances $ 25,061 $ 35,252 Junior subordinated debentures 30,575 30,096 Subordinated notes 11,993 11,957 Total long-term borrowings $ 67,629 $ 77,305 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 1.57% and 1.72% at December 31, 2019 and 2018 , respectively. The FHLB advances are collateralized by a blanket lien on qualifying first mortgages, home equity loans, multi-family loans and certain farmland loans which had a pledged balance of $273.5 million and $295.3 million at December 31, 2019 and 2018 , respectively. The following table shows the maturity schedule of the FHLB advances as of December 31, 2019 . Maturing in: (in thousands) 2020 $ 10,061 2021 10,000 2022 — 2023 — 2024 — 2025 5,000 $ 25,061 The Company has a $10 million line of credit with a third party bank, bearing a variable rate of interest based on one-month LIBOR plus a 2.25% margin, but subject to a floor rate of 3.25% , with quarterly payments of interest only. At December 31, 2019 , the available line was $10 million . The outstanding balance was zero at December 31, 2019 and 2018 , and the line was not used during 2019 or 2018 . Junior Subordinated Debentures : The following table shows the breakdown of junior subordinated debentures. Interest on all debentures is current. Any applicable discounts (initially recorded to carry an acquired debenture at its then estimated fair market value) are being accreted to interest expense over the remaining life of the debentures. All the debentures below are currently callable and may be redeemed in part or in full, at par, plus any accrued but unpaid interest. Junior Subordinated Debentures (in thousands) Maturity Date Par 12/31/2019 Unamortized Discount 12/31/2019 Carrying Value 12/31/2018 Carrying Value 2004 Nicolet Bankshares Statutory Trust (1) 7/15/2034 $ 6,186 $ — $ 6,186 $ 6,186 2005 Mid-Wisconsin Financial Services, Inc. (2) 12/15/2035 10,310 (3,172 ) 7,138 6,939 2006 Baylake Corp. (3) 9/30/2036 16,598 (3,883 ) 12,715 12,478 2004 First Menasha Bancshares, Inc. (4) 3/17/2034 5,155 (619 ) 4,536 4,493 Total $ 38,249 $ (7,674 ) $ 30,575 $ 30,096 (1) The interest rate is 8.00% fixed. (2) The debentures, assumed in April 2013 as the result of an acquisition, have a floating rate of the three-month LIBOR plus 1.43% , adjusted quarterly. The interest rates were 3.32% and 4.22% as of December 31, 2019 and 2018 , respectively. (3) The debentures, assumed in April 2016 as a result of an acquisition, have a floating rate of the three-month LIBOR plus 1.35% , adjusted quarterly. The interest rates were 3.31% and 4.15% as of December 31, 2019 and 2018 , respectively. (4) The debentures, assumed in April 2017 as the result of an acquisition, have a floating rate of the three-month LIBOR plus 2.79% , adjusted quarterly. The interest rate was 4.69% and 5.58% as of December 31, 2019 and 2018 , respectively. 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. At December 31, 2019 and 2018 , $29.4 million and $28.9 million , respectively, of trust preferred securities qualify as Tier 1 capital. Subordinates Notes : In 2015, the Company placed an aggregate of $12 million in subordinated Notes in private placements with certain accredited investors. All Notes were issued with 10 -year maturities, have a fixed annual interest rate of 5% payable quarterly, are callable on or after the fifth anniversary of their respective issuances dates, and qualify for Tier 2 capital for regulatory purposes.

EMPLOYEE AND DIRECTOR BENEFIT P

EMPLOYEE AND DIRECTOR BENEFIT PLANS	12 Months Ended
	Dec. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
EMPLOYEE AND DIRECTOR BENEFIT PLANS	EMPLOYEE AND DIRECTOR BENEFIT PLANS The Company sponsors two deferred compensation plans, one for certain key management employees and another for directors. Under the management plan, which was amended in 2016, 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 contributions and earnings thereon at December 31, 2019 and 2018 totaled approximately $906,000 and $527,000 , respectively, and is included in other liabilities on the consolidated balance sheets. The Company made discretionary contributions totaling $1,800,000 and $175,000 during 2019 and 2018 , respectively, to selected recipients. The contributions made in 2019 vested immediately and were expensed upon grant; while the 2018 contributions will vest and be expensed ratably over the four or five year vesting period from the date of 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 2019 and 2018 , the director plan purchased 3,769 and 3,889 shares of Company common stock valued at approximately $220,000 and $213,000 , respectively. Common stock valued at approximately $33,000 (and representing 672 shares) and $32,000 (and representing 600 shares) was distributed to past directors during 2019 and 2018 , respectively. The common stock outstanding and the related director deferred compensation liability are offsetting components of the Company’s equity in the amount of $1,030,000 at December 31, 2019 and $831,000 at December 31, 2018 representing 29,202 shares and 26,105 shares, respectively. 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 2019 , 2018 and 2017 , the Company’s 401(k) expense was approximately $2.9 million (including a $1.1 million profit sharing contribution), $1.8 million , and $2.0 million (including a $0.5 million profit sharing contribution), respectively.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The Company may grant stock options and restricted stock under its stock-based compensation plans to certain officers, employees and directors. These plans are administered by a committee of the Board of Directors. The Company's stock-based compensation plans at December 31, 2019 are 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, 2019 , approximately 1.4 million shares were available for grant under this plan. 2002 Stock Incentive Plan : The Company’s 2002 Stock Incentive Plan, as subsequently amended with shareholder approval, reserved a total of 1,175,000 shares of the Company's common stock for potential stock options. This plan became fully utilized in 2012 and no further awards may be granted under this plan. Acquired Equity Incentive Plan : In 2016, the Company assumed sponsorship of an equity incentive plan of an acquired company to allow for that company's already granted awards that became exercisable upon acquisition to be honored. No further awards may be granted under this assumed plan. In general, for stock options granted the exercise price will not be less than the fair value of the Company’s common stock on the date of grant, the options will become exercisable based upon vesting terms determined by the committee, and the options will expire ten years after the date of grant. In general, for restricted stock granted the shares are issued at the fair value of the Company’s common stock 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 options. See Note 1 for the Company’s accounting policy on stock-based compensation. The weighted average assumptions used in the model for valuing stock option grants were as follows. 2019 2018 2017 Dividend yield — % — % — % Expected volatility 25 % 25 % 25 % Risk-free interest rate 1.75 % 2.61 % 2.14 % Expected average life 7 years 7 years 7 years Weighted average per share fair value of options $ 21.30 $ 17.36 $ 15.80 A summary of the Company’s stock option activity is summarized below. Stock Options Option Shares Outstanding Weighted Average Exercise Price Weighted Average Remaining Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding – December 31, 2016 922,026 $ 24.39 Granted 949,500 49.93 Exercise of stock options * (209,371 ) 18.15 Forfeited (18,900 ) 35.36 Outstanding – December 31, 2017 1,643,255 $ 39.82 8.1 $ 24,525 Granted 15,500 52.76 Exercise of stock options * (70,556 ) 21.52 Forfeited (6,500 ) 39.43 Outstanding – December 31, 2018 1,581,699 $ 40.77 7.4 $ 13,825 Granted 203,000 69.69 Exercise of stock options * (337,428 ) 24.15 Forfeited (3,538 ) 27.43 Outstanding – December 31, 2019 1,443,733 $ 48.75 7.4 $ 36,428 Exercisable – December 31, 2019 561,633 $ 42.91 6.7 $ 17,384 *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 142,752 shares, 6,411 shares, and 85,422 shares were surrendered during 2019 , 2018 , and 2017 , respectively. Intrinsic value represents the amount by which the fair market value of the underlying stock exceeds the exercise price of the stock options. The intrinsic value of options exercised in 2019 , 2018 , and 2017 was approximately $13.9 million , $2.2 million , and $7.5 million , respectively. The following options were outstanding at December 31, 2019 . Number of Shares Weighted Average Exercise Price Weighted Average Remaining Life (Years) Outstanding Exercisable Outstanding Exercisable Outstanding Exercisable $13.73 – $30.00 130,436 94,936 $ 22.37 $ 21.85 4.2 4.1 $30.01 – $40.00 155,747 89,747 35.92 35.51 6.4 6.3 $40.01 – $50.00 804,050 319,850 48.86 48.86 7.4 7.4 $50.01 – $60.00 155,500 57,100 56.09 56.23 7.9 7.9 $60.01 – $70.50 198,000 — 70.01 — 9.9 0.0 1,443,733 561,633 $ 48.75 $ 42.91 7.4 6.7 A summary of the Company’s restricted stock activity is summarized below. Restricted Stock Restricted Shares Outstanding Weighted Average Grant Date Fair Value Outstanding – December 31, 2016 42,949 $ 26.80 Granted 9,240 57.75 Vested * (20,514 ) 29.87 Forfeited (755 ) 16.50 Outstanding – December 31, 2017 30,920 $ 34.26 Granted 18,256 52.55 Vested * (19,661 ) 43.58 Forfeited (3 ) 16.50 Outstanding – December 31, 2018 29,512 $ 39.37 Granted 12,498 67.59 Vested * (19,081 ) 51.77 Forfeited (408 ) 16.50 Outstanding – December 31, 2019 22,521 $ 44.94 *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 4,688 shares, 3,948 shares, and 5,266 shares were surrendered during 2019 , 2018 , and 2017 , respectively. The Company recognized $4.8 million , $4.7 million and $3.1 million of stock-based compensation expense (included in personnel on the consolidated statements of income) during the years ended December 31, 2019 , 2018 , and 2017 , respectively, associated with its common stock awards granted to officers and employees. As of December 31, 2019 , there was approximately $13.1 million of unrecognized compensation cost related to equity award grants. The cost is expected to be recognized over the remaining vesting period of approximately three years. The Company recognized a tax benefit of approximately $2.3 million and $0.2 million for the years ended December 31, 2019 and 2018 , respectively, for the tax impact of stock option exercises and vesting of restricted stock. In addition, during 2019 and 2018 , the Company recognized approximately $0.3 million and $0.2 million , respectively, of director expense (included in other expense on the consolidated statements of income) for restricted stock grants with immediate vesting to non-employee directors totaling 4,257 shares in 2019 and 3,510 shares in 2018 .

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY As of December 31, 2019 , the Board of Directors has authorized the use of up to $86 million to repurchase up to 1,975,000 shares of outstanding common stock through our common stock repurchase program. During 2019 , $18.7 million was utilized to repurchase and cancel nearly 310,800 common shares at a weighted average price of $60.17 , bringing the life-to-date cumulative totals to $65.0 million to repurchase and cancel over 1.4 million common shares. As of December 31, 2019 , there remained $21.0 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. See Note 14 , “ Related Party Transactions ” for additional information on common stock repurchases in private transactions with related parties. On November 8, 2019, in connection with its acquisition of Choice, the Company issued 1,184,102 shares of its common stock for consideration of $79.8 million plus cash consideration of $1.7 million for outstanding stock options. Approximately $0.2 million in direct stock issuance costs for the merger were incurred and charged against additional paid-in capital. See Note 2 for additional information on the Company’s acquisitions. On April 28, 2017, in connection with its acquisition of First Menasha, the Company issued 1,309,885 shares of its common stock for consideration of $62.2 million plus cash consideration of $19.3 million . Approximately $0.2 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, 2019
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) 2019 2018 2017 Current $ 15,353 $ 14,967 $ 10,952 Deferred 1,105 (1,521 ) 4,430 Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act — — 885 Income tax expense $ 16,458 $ 13,446 $ 16,267 On December 22, 2017, the Tax Cuts and Jobs Act was signed into law. The new law amended the Internal Revenue Code to reduce corporate tax rates and modify various tax policies, credits, and deductions. The corporate federal tax rate was reduced from a maximum of 35% to a flat 21% rate, which was effective for the Company beginning January 1, 2018. As a result of the corporate tax rate reduction, the Company reduced its net deferred tax asset for the year ended December 31, 2017, by $885,000 , which was recognized as additional income tax expense. The differences between the income tax expense recognized and the amount computed by applying the statutory federal income tax rate (21% for 2019 and 2018 and 35% for 2017) to the income before income taxes, less noncontrolling interest, for the years ended as indicated are included in the following table. Years Ended December 31, (in thousands) 2019 2018 2017 Tax on pretax income, less noncontrolling interest, at statutory rates $ 14,931 $ 11,441 $ 17,296 State income taxes, net of federal effect 3,672 3,308 2,242 Tax-exempt interest income (609 ) (574 ) (1,073 ) Non-deductible interest disallowance 29 30 28 Increase in cash surrender value life insurance (573 ) (508 ) (807 ) Non-deductible business entertainment 189 156 168 Stock-based employee compensation (2,347 ) (232 ) (62 ) Non-deductible compensation 3,122 — — Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act — — 885 Deduction attributable to share-based payments — — (1,854 ) Sale of UFS (2,176 ) — — Other, net 220 (175 ) (556 ) Income tax expense $ 16,458 $ 13,446 $ 16,267 The net deferred tax asset includes the following amounts of deferred tax assets and liabilities. (in thousands) December 31, 2019 December 31, 2018 Deferred tax assets: ALLL $ 4,985 $ 5,240 Net operating loss carryforwards 1,808 2,202 Credit carryforwards 43 43 Compensation 3,477 2,408 Other 2,830 2,549 Other real estate 201 103 Unrealized loss on securities AFS — 1,740 Total deferred tax assets 13,344 14,285 Deferred tax liabilities: Premises and equipment (1,390 ) (821 ) Prepaid expenses (778 ) (693 ) Investment securities (755 ) (1,723 ) Core deposit and other intangibles (2,836 ) (3,563 ) Purchase accounting adjustments to liabilities (2,375 ) (2,011 ) Other (1,391 ) (1,021 ) Unrealized gain on securities AFS (1,879 ) — Total deferred tax liabilities (11,404 ) (9,832 ) Net deferred tax assets $ 1,940 $ 4,453 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, 2019 and 2018 , no valuation allowance was determined to be necessary. At December 31, 2019 , the Company had a federal and state net operating loss carryforward of $3.7 million and $24.7 million , respectively. The entire federal and state net operating loss carryforwards were the result of the Company’s mergers with Mid-Wisconsin, Baylake, First Menasha, and Choice. The federal and state net operating loss carryovers resulting from the mergers have been included in the IRC section 382 limitation calculation and are being limited to the overall amount expected to be realized. The Company’s federal income tax returns are open and subject to examination from the 2015 tax return year and forward. The years open to examination by state and local government authorities varies by jurisdiction.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2019
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. See Note 1 for the Company’s accounting policy on commitments and contingencies. 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. 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, 2019 December 31, 2018 Commitments to extend credit $ 773,555 $ 721,098 Financial standby letters of credit 10,730 8,571 Performance standby letters of credit 8,469 7,094 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 and the contractual amounts were $43.4 million and $16.3 million , respectively, at December 31, 2019 . The fair value of these commitments was not material at December 31, 2019 . 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 74% and 77% of the total year-end commitments for 2019 and 2018 , respectively, 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. At December 31, 2019 and 2018 , no amounts have been recorded as liabilities for the Company’s potential obligations under these guarantees. 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. Total federal funds lines of $175 million were available at both December 31, 2019 and 2018 . In the normal course of business, the Company is involved in various legal proceedings. In the opinion of management, any liability resulting from such proceedings would not have a material adverse effect on the consolidated financial statements.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS The Company conducts transactions, in the normal course of business, with its directors and officers, including companies in which they have a beneficial interest. It is the Company’s policy to comply with federal regulations that require that these transactions with directors and executive officers be made on substantially the same terms as those prevailing at the time made for comparable transactions to other persons. Related party loans totaled approximately $86 million and $84 million at December 31, 2019 and 2018 , respectively. Nicolet has an active common stock repurchase program that allows for the repurchase of common stock in the open market, through block transactions, or in private transactions. During 2019 , Nicolet repurchased common stock in private transactions from two executives under this repurchase program, including 32,415 shares for $2.2 million (or an average cost per share of $69.21 ) from Robert B. Atwell and 33,993 shares for $2.2 million (or an average cost per share of $64.02 ) from Michael E. Daniels. These private transactions were made in conjunction with large stock option exercises by the executives. See Note 10 for additional information on stock option activity and see Note 11 for additional information on the common stock repurchase program. As described in Note 1 , the Company has a 50% ownership in a joint venture with the Firm in connection with the Company’s headquarters facility. The Firm is considered a related party, as one of its principals is a Board member and shareholder of the Company. The Bank incurred approximately $1.2 million in annual rent expense to the joint venture during 2019 , and $1.1 million in annual rent during both 2018 and 2017 . In October 2013, the Company entered into a lease for a branch location in a facility owned by a different member of the Company’s Board and incurred less than $120,000 annually of rent expense on this facility during 2019 , 2018 , and 2017 . During 2019, this same Board member participated in a competitive bid process for and was awarded the contract as general contractor for the 2019 reconstruction of a different existing branch location, payments for which are estimated to total $1.3 million but not yet paid in full. Payments made during 2019 for progress on this branch reconstruction were $0.4 million , of which at least 75% was passed through to various subcontractors. In addition, during 2018, this Board member participated in a competitive bid process for and was awarded the contract as general contractor for the 2018 reconstruction of another branch location. Total payments for the 2018 branch reconstruction were $1.0 million , of which at least 75% of these payments were passed through to various subcontractors. In February 2016, the Company entered into a lease agreement for a non-branch location owned by a relative of a senior management team member and paid approximately $138,000 in both 2018 and 2017 , to the company owned by the relative. This non-branch location was vacated and the lease terminated in first quarter 2019 for a final payment of $47,500 This same relative, who is employed by the Company as a financial advisor, received approximately $650,000 , $657,000 , and $668,000 in 2019 , 2018 , and 2017 , respectively, in compensation. Another relative of the same senior management team member, who is also employed by the Company as a financial advisor, received approximately $287,500 , $284,000 , and $257,000 in 2019 , 2018 , and 2017 , respectively, in compensation.

ASSET GAINS (LOSSES), NET

ASSET GAINS (LOSSES), NET	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [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) 2019 2018 2017 Gains (losses) on sales of securities AFS, net $ (22 ) $ (212 ) $ 1,220 Gains (losses) on equity securities, net 1,115 77 — Gains (losses) on sales of OREO, net (88 ) 1,032 258 Write-downs of OREO (300 ) (120 ) (127 ) Write-down of other investment (100 ) — — Gains (losses) on sales of other investments, net 7,442 187 — Gains (losses) on sales or dispositions of other assets, net (150 ) 205 678 Asset gains (losses), net $ 7,897 $ 1,169 $ 2,029

REGULATORY CAPITAL REQUIREMENTS

REGULATORY CAPITAL REQUIREMENTS	12 Months Ended
	Dec. 31, 2019
Banking and Thrift [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 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. Quantitative measures established by regulation to ensure capital adequacy require the Company and Bank to maintain minimum amounts and ratios of Total, Tier 1 and common equity Tier 1 (“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, 2019 and 2018 . As of December 31, 2019 and 2018 , 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 Company’s and the Bank’s actual regulatory capital amounts and ratios are presented in the following table. Actual For Capital Adequacy Purposes To Be Well Capitalized Under Prompt Corrective Action Provisions (2) (in thousands) Amount Ratio (1) Amount Ratio (1) Amount Ratio (1) December 31, 2019 Company Total risk-based capital $ 404,573 13.4 % $ 241,333 8.0 % Tier 1 risk-based capital 378,608 12.6 181,000 6.0 Common equity Tier 1 capital 348,454 11.6 135,750 4.5 Leverage 378,608 11.9 127,036 4.0 Bank Total risk-based capital $ 323,432 10.8 % $ 240,551 8.0 % $ 300,688 10.0 % Tier 1 risk-based capital 309,460 10.3 180,413 6.0 240,551 8.0 Common equity Tier 1 capital 309,460 10.3 135,310 4.5 195,447 6.5 Leverage 309,460 9.8 126,660 4.0 158,325 5.0 December 31, 2018 Company Total risk-based capital $ 326,235 12.9 % $ 202,836 8.0 % Tier 1 risk-based capital 301,125 11.9 152,127 6.0 Common equity Tier 1 capital 271,435 10.7 114,095 4.5 Leverage 301,125 10.4 115,483 4.0 Bank Total risk-based capital $ 274,492 10.8 % $ 202,800 8.0 % $ 253,501 10.0 % Tier 1 risk-based capital 261,339 10.3 152,100 6.0 202,800 8.0 Common equity Tier 1 capital 261,339 10.3 114,075 4.5 164,775 6.5 Leverage 261,339 9.1 115,280 4.0 144,100 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. 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, 2019 , the Bank could pay dividends of approximately $6 million to the Company without seeking regulatory approval.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2019
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 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. These 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 for the periods presented. (in thousands) Fair Value Measurements Using Measured at Fair Value on a Recurring Basis: Total Level 1 Level 2 Level 3 December 31, 2019 U.S. government agency securities $ 16,460 $ — $ 16,460 $ — State, county and municipals 156,393 — 156,393 — Mortgage-backed securities 195,018 — 195,018 — Corporate debt securities 81,431 — 78,301 3,130 Securities AFS $ 449,302 $ — $ 446,172 $ 3,130 Other investments (equity securities) $ 3,375 $ 3,375 $ — $ — December 31, 2018 U.S. government agency securities $ 21,649 $ — $ 21,649 $ — State, county and municipals 160,526 — 160,460 66 Mortgage-backed securities 131,644 — 131,644 — Corporate debt securities 86,325 — 77,901 8,424 Securities AFS $ 400,144 $ — $ 391,654 $ 8,490 Other investments (equity securities) $ 2,650 $ 2,650 $ — $ — The following is a description of the valuation methodologies used by the Company for the Securities AFS and equity securities measured at fair value on a recurring basis, noted in the tables above. 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. 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 municipal bonds and corporate debt securities, which include trust preferred security investments. At December 31, 2019 and 2018 , it was determined that carrying value was the best approximation of fair value for these Level 3 securities, based primarily on the internal analysis on these securities. 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, 2019 December 31, 2018 Balance at beginning of year $ 8,490 $ 9,151 Acquired balances 300 — Paydowns/Sales/Settlements (5,660 ) (661 ) Balance at end of year $ 3,130 $ 8,490 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, 2019 Impaired loans $ 16,150 $ — $ — $ 16,150 OREO 1,000 — — 1,000 MSR asset 8,420 — — 8,420 December 31, 2018 Impaired loans $ 9,939 $ — $ — $ 9,939 OREO 420 — — 420 MSR asset 6,347 — — 6,347 The following is a description of the valuation methodologies used by the Company for the items noted in the table above. For individually evaluated impaired loans, the amount of impairment 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 for collateral-dependent loans, or the estimated liquidity of the note. For OREO, the fair value is based upon the estimated fair value of the underlying collateral adjusted for the expected costs to sell. 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 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, 2019 (in thousands) Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 182,059 $ 182,059 $ 182,059 $ — $ — Certificates of deposit in other banks 19,305 19,310 — 19,310 — Securities AFS 449,302 449,302 — 446,172 3,130 Other investments 24,072 24,072 3,375 16,759 3,938 Loans held for sale 2,706 2,753 — 2,753 — Loans, net 2,559,779 2,593,110 — — 2,593,110 BOLI 78,140 78,140 78,140 — — MSR asset 5,919 8,420 — — 8,420 Financial liabilities: Deposits $ 2,954,453 $ 2,956,229 $ — $ — $ 2,956,229 Long-term borrowings 67,629 66,816 — 25,075 41,741 December 31, 2018 (in thousands) Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 249,526 $ 249,526 $ 249,526 $ — $ — Certificates of deposit in other banks 993 993 — 993 — Securities AFS 400,144 400,144 — 391,654 8,490 Other investments 17,997 17,997 2,650 13,189 2,158 Loans held for sale 1,639 1,662 — 1,662 — Loans, net 2,153,028 2,139,322 — — 2,139,322 BOLI 66,310 66,310 66,310 — — MSR asset 3,749 6,347 — — 6,347 Financial liabilities: Deposits $ 2,614,138 $ 2,614,995 $ — $ — $ 2,614,995 Long-term borrowings 77,305 75,923 — 34,907 41,016 The carrying value of certain assets and liabilities such as cash and cash equivalents, BOLI, nonmaturing deposits, and short-term borrowings, approximate their estimated fair value. For those financial instruments not previously disclosed, the following is a description of the valuation methodologies used. Certificates of deposits 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. 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, Bankers Bank, Federal Agricultural Mortgage Corporation, 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. Collateral-dependent impaired 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, by definition, 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 : At December 31, 2019 and 2018 , the estimated fair value of 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, 2019
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) 2019 2018 Assets Cash and due from subsidiary $ 70,426 $ 45,279 Investments 6,650 4,500 Investments in subsidiaries 487,644 384,839 Goodwill (3,266 ) (3,266 ) Other assets 396 53 Total assets $ 561,850 $ 431,405 Liabilities and Stockholders’ Equity Junior subordinated debentures $ 30,575 $ 30,096 Subordinated notes 11,993 11,957 Other liabilities 3,020 2,743 Stockholders’ equity 516,262 386,609 Total liabilities and stockholders’ equity $ 561,850 $ 431,405 Statements of Income Years Ended December 31, (in thousands) 2019 2018 2017 Interest income $ 55 $ 52 $ 46 Interest expense 2,936 2,844 2,415 Net interest expense (2,881 ) (2,792 ) (2,369 ) Dividend income from subsidiaries 50,363 40,775 32,000 Operating expense (321 ) (364 ) (369 ) Gain (loss) on investments, net 1,015 265 1,411 Income tax benefit 506 305 1,329 Earnings before equity in undistributed income (loss) of subsidiaries 48,682 38,189 32,002 Equity in undistributed income (loss) of subsidiaries 5,959 2,847 1,148 Net income attributable to Nicolet Bankshares, Inc. $ 54,641 $ 41,036 $ 33,150 Statements of Cash Flows Years Ended December 31, (in thousands) 2019 2018 2017 Cash Flows From Operating Activities: Net income attributable to Nicolet Bankshares, Inc. $ 54,641 $ 41,036 $ 33,150 Adjustments to reconcile net income to net cash provided by operating activities: Accretion of discounts 515 515 501 (Gain) loss on investments, net (1,015 ) (265 ) (1,411 ) Change in other assets and liabilities, net (421 ) (25 ) (1,384 ) Equity in undistributed (income) loss of subsidiaries, net of dividends (5,959 ) (2,847 ) (1,148 ) Net cash provided by operating activities 47,761 38,414 29,708 Cash Flows from Investing Activities: Proceeds from sale of investments — 708 317 Purchases of investments (2,484 ) (920 ) — Net cash paid in business combinations (412 ) — (19,287 ) Net cash used in investing activities (2,896 ) (212 ) (18,970 ) Cash Flows From Financing Activities: Purchase and retirement of common stock (28,460 ) (22,749 ) (15,007 ) Proceeds from issuance of common stock, net 8,742 1,800 4,030 Net cash used in financing activities (19,718 ) (20,949 ) (10,977 ) Net increase (decrease) in cash and due from subsidiary 25,147 17,253 (239 ) Beginning cash and due from subsidiary 45,279 28,026 28,265 Ending cash and due from subsidiary $ 70,426 $ 45,279 $ 28,026

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE See Note 1 for the Company’s accounting policy on earnings per common share. Earnings per common share and related information are summarized as follows. Years Ended December 31, (in thousands, except per share data) 2019 2018 2017 Net income attributable to Nicolet Bankshares, Inc. $ 54,641 $ 41,036 $ 33,150 Weighted average common shares outstanding 9,562 9,640 9,440 Effect of dilutive common stock awards 338 316 518 Diluted weighted average common shares outstanding 9,900 9,956 9,958 Basic earnings per common share $ 5.71 $ 4.26 $ 3.51 Diluted earnings per common share $ 5.52 $ 4.12 $ 3.33 Options to purchase less than 0.1 million shares outstanding for the year ended December 31, 2019 were excluded from the calculation of diluted earnings per common share as the effect of their exercise would have been anti-dilutive. Options to purchase approximately 0.1 million shares outstanding for years ended December 31, 2018 and 2017 were excluded from the calculation of diluted earnings per share as the effect of their exercise would have been anti-dilutive.

REVENUE RECOGNITION

REVENUE RECOGNITION	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION See Note 1 for the Company’s accounting policy on revenue recognition in accordance with Topic 606. This guidance does not apply to revenue associated with financial instruments, including revenue from loans and securities. In addition, certain noninterest income categories such as gains or losses associated with mortgage servicing rights, derivatives, and income from BOLI are not within the scope of the new guidance. The main types of revenue contracts within the scope of Topic 606 include trust services income, brokerage fee income, service charges on deposit accounts, card interchange income, and certain other noninterest income. These contracts 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 is generally terminable 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). Other noninterest income : Other noninterest income includes several items, such as wire transfer income, check cashing fees, check printing fees, safe deposit box rental fees, management fee income, and consulting fees. These fees are generally recognized at the time the service is provided.

SUBSEQUENT EVENT

SUBSEQUENT EVENT	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT On February 17, 2020, Nicolet entered into a definitive merger agreement with Commerce Financial Holdings, Inc. (“Commerce”) pursuant to which Commerce will merge with and into Nicolet, providing entry into Wisconsin's largest MSA. The acquisition will involve stock-for-stock consideration at a fixed exchange ratio, subject to cap and collar provisions provided for in the merger agreement. At December 31, 2019, Commerce had total assets of $713 million , loans of $604 million , deposits of $610 million , and equity of $66 million . Commerce would represent approximately 16% of the combined company's assets at December 31, 2019. The merger is expected to close in the third quarter of 2020 and remains subject to customary closing conditions, including approval by Commerce shareholders and regulatory approvals.

NATURE OF BUSINESS AND SIGNIF_2

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principles of Consolidation	Principles of Consolidation : The consolidated financial statements of the Company include the accounts of the Bank, Brookfield Investments, Nicolet Advisory and the JV. The JV underlies the noncontrolling interest reflected in the consolidated financial statements. 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.
Operating Segment	Operating Segment: The consolidated income of the Company is derived principally from the Bank, which conducts lending (primarily commercial-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 northeastern and central Wisconsin, and Menominee, Michigan, 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. The individual contributions of the JV, Brookfield Investments and Nicolet Advisory were not significant to the consolidated balance sheet or net income for 2019 , 2018 , or 2017 . 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 : Preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying disclosures. These estimates are based on management’s best knowledge of current events and actions the Company may undertake in the future. Estimates are used in accounting for, among other items, the allowance for loan losses, valuation of loans in acquisition transactions, useful lives for depreciation and amortization, fair value of financial instruments, other-than-temporary impairment calculations, valuation of deferred tax assets, uncertain income tax positions, and contingencies. Estimates that are particularly susceptible to significant change for the Company include the determination of the allowance for loan losses, determination and assessment of deferred tax assets and liabilities, and the valuation of loans acquired in acquisition transactions; therefore, these are critical accounting policies. Factors that may cause sensitivity to the aforementioned estimates include but are not limited to: external market factors such as market interest rates and employment rates, changes to operating policies and procedures, changes in applicable banking or tax regulations, and changes to deferred tax estimates. Actual results may ultimately differ from estimates, although management does not generally believe such differences would materially affect the consolidated financial statements in any individual reporting period presented.
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 (“ASC 805”). The Company recognizes the full fair value of the assets acquired and liabilities assumed and immediately expenses transaction costs. There is no separate recognition of the acquired allowance for loan losses on the acquirer’s balance sheet as credit related factors are incorporated directly into the fair value of the net tangible and intangible assets acquired. 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. Additional information regarding recent acquisitions is provided in Note 2 .
Cash and Cash Equivalents	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, if any, 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. The Bank has not experienced any losses in such accounts. The Bank may have restrictions on cash and due from banks as it is required to maintain certain vault cash and reserve balances with the Federal Reserve Bank to meet specific reserve requirements.
Securities Available for Sale	Securities Available for Sale : Securities classified as AFS are those securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity, and includes U.S. government agency securities; state, county and municipal securities; mortgage-backed securities; and corporate debt securities. Effective January 1, 2018, the Company adopted a new accounting standard, which requires equity securities with readily determinable fair values to be measured at fair value with changes in the fair value recognized through net income (see Recent Accounting Pronouncements Adopted within Note 1 for the impact of this new accounting guidance). Such securities are no longer reflected as securities AFS, and are now reflected within other investments on the consolidated balance sheets. Prior periods have not been restated for the impact of this accounting change. 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. Realized gains or losses on sales of securities AFS (using the specific identification method) and declines in value judged to be other-than-temporary 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 life of the related securities using the effective interest method. See Note 3 for additional disclosures on AFS securities. Management evaluates securities AFS for other-than-temporary impairment on a quarterly basis. A decline in the market value of any investment below amortized cost that is deemed other-than-temporary is charged to earnings for the decline in value deemed to be credit related and a new cost basis in the security is established. The decline in value attributed to non-credit related factors considered temporary in nature is recognized in other comprehensive income. In evaluating other-than-temporary impairment, management considers the length of time and extent to which the fair value has been less than cost, and the financial condition and near-term prospects of the issuer for a period sufficient to allow for any anticipated recovery in fair value in the near term.
Other Investments	Other Investments : Other investments include equity securities with readily determinable fair values, “restricted” equity securities, and private company securities. At December 31, 2019 , other investments included $3.4 million of equity securities with readily determinable fair values, $16.8 million of "restricted" equity securities, and $3.9 million of private company securities. As a member of the Federal Reserve Bank System, Federal Agricultural Mortgage Corporation, 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 other-than-temporary 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 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 mortgages. The amount by which cost exceeds market value is recorded as a valuation allowance and charged to earnings. Changes, if any, in the valuation allowance are also included in earnings in the period in which the change occurs. As of December 31, 2019 and 2018 , 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.
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. See Note 13 for additional information and disclosures on credit-related financial instruments.
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 the straight-line method 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. See Note 5 for additional information on 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
Other Real Estate Owned ("OREO")	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 ALLL or to write-down of assets, respectively. OREO properties acquired in conjunction with the 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. At December 31, 2019 and 2018 , OREO was $1.0 million and $0.4 million , respectively.
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 and are amortized on a straight-line basis to expense over their initial weighted average life of approximately 12 years as of acquisition. See Note 6 for additional information on goodwill and other intangibles. 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")	Mortgage Servicing Rights (“MSRs”): If the Company sells originated residential mortgages into the secondary market and retains the right to service the loans sold, then a mortgage servicing right asset (liability) is capitalized upon sale 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. Loan servicing fee income for servicing loans 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). The Company periodically evaluates its MSRs 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 stratifications based on the risk characteristics of the underlying loans (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 carried. An other-than-temporary impairment (i.e., recoverability is considered remote when considering interest rates and loan payoff activity) is recognized as a write-down of the MSRs and the related valuation allowance (to the extent a valuation allowance is available) and then against earnings. A direct write-down permanently reduces the carrying value of the MSRs and valuation allowance, precluding subsequent recoveries. No valuation allowance or impairment charge was recorded for 2019 or 2018 . See Note 6 for additional information on MSRs.
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 noninterest income.
Short-term Borrowings	Short-term Borrowings : Short-term borrowings consist primarily of overnight Federal funds purchased and securities sold under agreements to repurchase (“repos”), or other short-term borrowing arrangements with an original maturity of one year or less. Repos are with commercial deposit customers, and are treated as financing activities carried at the amounts that will be subsequently repurchased as specified in the respective agreements. Repos generally mature within one to four days from the transaction date. The Company may be required to provide additional collateral based on the fair value of the underlying securities.
Stock-based Compensation Plans	Stock-based Compensation: Share-based payments to employees, including grants of restricted stock or stock options, are valued at fair value of the award on the date of grant and expensed on a straight-line basis as compensation expense over the applicable vesting period. A Black-Scholes model is utilized to estimate the fair value of stock options and the quoted market price of the Company’s stock at the date of grant is used to estimate the fair value of restricted stock awards. See Note 10 for additional information on stock-based compensation.
Income Taxes	Income Taxes : The Company files a consolidated federal income tax return and a combined state income tax return (both of which include the Company and its wholly owned subsidiaries). Accordingly, amounts equal to tax benefits of those companies having taxable federal losses or credits are reimbursed by the companies that incur federal 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 market value discounts on PCI loans which resolved in the first twelve months after the acquisition were disallowed under provisions of the tax code. The Company may also recognize a liability for unrecognized tax benefits from uncertainty in income tax positions. Unrecognized tax benefits represent the differences between a tax position taken or expected to be taken in a tax return and the benefit recognized and measured in the consolidated financial statements. At December 31, 2019 , the Company determined it had no significant uncertainty in income tax positions. Interest and penalties related to unrecognized tax benefits are classified as income tax expense. See Note 12 for additional information on income taxes.
Earnings per Common Share	Earnings per Common Share : Basic earnings per common share are calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per common share are calculated by dividing net income available to common shareholders by the weighted average number of common shares adjusted for the dilutive effect of outstanding common stock awards, if any. See Note 19 for additional information on 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, bypass the statement of income and instead are reported in accumulated other comprehensive income, 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. The Company presents comprehensive income in a separate consolidated statement of comprehensive income.
Revenue Recognition	Revenue Recognition : Accounting principles 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. See Note 20 for additional information on Revenue from Contracts with Customers (Topic 606) .
Reclassifications	Reclassifications : Certain amounts in the 2018 and 2017 consolidated financial statements have been reclassified to conform to the 2019 presentation.
Recent Accounting Pronouncements Adopted	Recent Accounting Pronouncements Adopted : In August 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . ASU 2017-12 expands the activities that qualify for hedge accounting and simplifies the rules for reporting hedging transactions. The updated guidance is effective for interim and annual reporting periods beginning after December 15, 2018, with early adoption permitted. The Company adopted the updated guidance effective January 1, 2019 with no material impact on its consolidated financial statements, because the Company does not have any significant derivatives and does not currently apply hedge accounting to derivatives. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , with several subsequent updates. Topic 842 introduced a new accounting model for lessors and lessees. For lessees, almost all leases are now recognized on the balance sheet as a right-of-use ("ROU") asset and lease liability, unlike previous GAAP which required only capital leases to be recognized on the balance sheet. The accounting applied by lessors is largely unchanged from existing guidance. Topic 842 also requires additional disclosures concerning the amount, timing and uncertainty of cash flows arising from leases. The updated guidance is effective for annual reporting periods beginning after December 15, 2018, and provides a modified retrospective transition approach that allows lessees to recognize and measure leases on the balance sheet at the beginning of either the earliest period presented or as of the beginning of the period of adoption (the "effective date" method), with the option to elect certain practical expedients. Nicolet adopted the new guidance prospectively as of January 1, 2019, using the effective date method; thus, prior comparative periods have not been restated. Upon adoption, Nicolet recognized an ROU asset and lease liability of approximately $5 million . There was no impact to its consolidated statements of income or cash flows compared to the prior lease accounting model. The ROU asset and lease liability are recorded in other assets and other liabilities, respectively, in the consolidated balance sheets. As part of the adoption, Nicolet elected the package of practical expedients permitted under the transition guidance of the new standard which allowed the carry forward of the historical lease classification. Nicolet also elected the practical expedient to group lease and non-lease components as a single lease component; thus, the Company's leases include both lease (e.g., fixed payments including rent, taxes, and insurance costs) and non-lease components (e.g., common area or other maintenance costs). See Note 5 for the new disclosures required by Topic 842.
Originated Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Allowance for Loan Losses ("ALLL")	Loans and Allowance for Loan Losses (“ALLL”) – Originated Loans : Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are carried at their principal amount outstanding, net of deferred loan fees and costs. 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. See Note 4 for additional information and disclosures on originated loans. Management considers a loan to be impaired when it is probable the Company will be unable to collect all contractual principal and interest payments due in accordance with the terms of the loan agreement. For determining the appropriateness of the ALLL, management defines impaired loans as nonaccrual credit relationships over $250,000 , all loans determined to be troubled debt restructurings, plus additional loans with impairment risk characteristics. At the time an individual loan goes into nonaccrual status, management evaluates the loan for impairment and possible charge-off regardless of loan size. Typically, impairment amounts for loans under the scope criteria are charged off when the impairment amount is determined. The ALLL represents management’s estimate of probable and inherent credit losses in the Company’s loan portfolio at the balance sheet date. In general, estimating the amount of the ALLL 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 impaired 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 ALLL. Loans are charged off when management believes that the collectability of the principal is unlikely. Subsequent recoveries, if any, are credited to the ALLL. A provision for loan losses, which is a charge against income, is recorded to bring the ALLL to a level that, in management’s judgment, is appropriate to absorb probable losses in the loan portfolio. The allocation methodology applied by the Company is designed to assess the overall appropriateness of the ALLL and includes allocations for specifically identified impaired loans and loss factors for all remaining loans, with a component primarily based on historical loss rates and another component primarily based on other qualitative factors. Impaired loans are individually assessed and are measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate or, as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. Loans that are determined not to be impaired are collectively evaluated for impairment, stratified by type and allocated loss ranges based on the Company’s actual historical loss ratios for each strata, and adjustments are also provided for certain current environmental and qualitative factors. An internal loan review function rates loans using a grading system based on nine different categories. Loans with grades of seven or higher (“classified loans”) represent loans with a greater risk of loss and may be assigned allocations for loss based on specific review of the weaknesses observed in the individual credits if classified as impaired. Classified loans are constantly monitored by the loan review function to ensure early identification of any deterioration. Allocations to the ALLL may be made for specific loans but the entire ALLL 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.
Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Allowance for Loan Losses ("ALLL")	Loans and ALLL – Acquired Loans: The loans purchased in acquisition transactions are acquired loans. Acquired loans are recorded at their estimated fair value at the acquisition date, and are initially classified as either purchase credit impaired (“PCI”) loans (i.e., loans that reflect credit deterioration since origination and it is probable at acquisition that the Company will be unable to collect all contractually required payments) or purchased non-impaired loans (i.e., “performing acquired loans”). See Note 4 for additional information and disclosures on acquired loans. PCI loans are accounted for under the accounting guidance for loans and debt securities acquired with deteriorated credit quality, found in Financial Accounting Standards Board (“FASB”) ASC Topic 310-30, Receivables—Loans and Debt Securities Acquired with Deteriorated Credit Quality . The Company estimates the amount and timing of expected principal, interest and other cash flows for each loan or pool of loans meeting the criteria above, and determines the excess of the loan’s scheduled contractual principal and contractual interest payments over all cash flows expected to be collected at acquisition as an amount that should not be accreted. These credit discounts (“nonaccretable marks”) are included in the determination of the initial fair value for acquired loans; therefore, an allowance for loan losses is not recorded at the acquisition date. Differences between the estimated fair values and expected cash flows of acquired loans at the acquisition date that are not credit-based (“accretable marks”) are subsequently accreted to interest income over the estimated life of the loans using a method that approximates a level yield if the timing and amount of the future cash flows is reasonably estimable. Subsequent to the acquisition date for PCI loans, increases in cash flows over those expected at the acquisition date result in a move of the discount from nonaccretable to accretable. Decreases in expected cash flows after the acquisition date are recognized through the provision for loan losses. All fair value discounts initially recorded on PCI loans were deemed to be credit related. Performing acquired loans are accounted for under FASB ASC Topic 310-20, Receivables—Nonrefundable Fees and Other Costs . Performance of certain loans may be monitored, and based on management’s assessment of the cash flows and other facts available, portions of the accretable difference may be delayed or suspended if management deems appropriate. The Company’s policy for determining when to discontinue accruing interest on performing acquired loans and the subsequent accounting for such loans is essentially the same as the policy for originated loans described above. An ALLL is calculated using a methodology similar to that described for originated loans. Performing acquired loans are subsequently evaluated for any required allowance at each reporting date. Such required allowance for each loan pool is compared to the remaining fair value discount for that pool. If greater, the excess is recognized as an addition to the allowance through a provision for loan losses charge. If less than the discount, no additional allowance is recorded. Charge-offs and losses first reduce any remaining fair value discount for the loan pool and once the discount is depleted, losses are applied against the allowance established for that pool. For PCI loans after acquisition, cash flows expected to be collected are recast for each loan periodically as determined appropriate by management. If the present value of expected cash flows for a loan is less than its carrying value, impairment is reflected by an increase in the ALLL and a charge to the provision for loan losses. If the present value of the expected cash flows for a loan is greater than its carrying value, any previously established ALLL is reversed and any remaining difference increases the accretable yield which will be taken into income over the remaining life of the loan. Loans which were considered troubled debt restructurings prior to the acquisition transaction are not required to be classified as troubled debt restructurings in the Company’s consolidated financial statements unless or until such loans would subsequently meet criteria to be classified as such, since acquired loans were recorded at their estimated fair values at the time of the acquisition.

NATURE OF BUSINESS AND SIGNIF_3

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2019
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

SECURITIES AVAILABLE FOR SALE (

SECURITIES AVAILABLE FOR SALE (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Securities, Available-for-sale [Abstract]
Schedule of amortized costs and fair values of securities AFS	Amortized cost and fair value of securities available for sale are summarized as follows. December 31, 2019 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency securities $ 16,516 $ 4 $ 60 $ 16,460 State, county and municipals 155,501 1,049 157 156,393 Mortgage-backed securities 193,223 2,492 697 195,018 Corporate debt securities 78,009 3,422 — 81,431 $ 443,249 $ 6,967 $ 914 $ 449,302 December 31, 2018 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. government agency securities $ 22,467 $ — $ 818 $ 21,649 State, county and municipals 163,702 76 3,252 160,526 Mortgage-backed securities 134,350 328 3,034 131,644 Corporate debt securities 87,352 66 1,093 86,325 $ 407,871 $ 470 $ 8,197 $ 400,144
Gain (Loss) on Securities	The following table presents gross unrealized losses and the related estimated fair value of investment securities available for sale, aggregated by investment category and the length of time the individual securities have been in a continuous unrealized loss position. December 31, 2019 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Number of Securities U.S. government agency securities $ 1,035 $ 2 $ 11,091 $ 58 $ 12,126 $ 60 6 State, county and municipals 22,451 132 7,605 25 30,056 157 56 Mortgage-backed securities 49,626 245 47,271 452 96,897 697 150 Corporate debt securities — — — — — — — $ 73,112 $ 379 $ 65,967 $ 535 $ 139,079 $ 914 212 December 31, 2018 Less than 12 months 12 months or more Total (in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Number of Securities U.S. government agency securities $ — $ — $ 21,649 $ 818 $ 21,649 $ 818 3 State, county and municipals 16,136 98 130,975 3,154 147,111 3,252 440 Mortgage-backed securities 20,568 132 89,189 2,902 109,757 3,034 204 Corporate debt securities 51,592 677 9,757 416 61,349 1,093 33 $ 88,296 $ 907 $ 251,570 $ 7,290 $ 339,866 $ 8,197 680
Schedule of amortized cost and fair value classified by contractual maturities	The amortized cost and fair value of securities AFS 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. See Note 17 for additional information on the Company’s fair value measurements. December 31, 2019 (in thousands) Amortized Cost Fair Value Due in less than one year $ 18,662 $ 18,679 Due in one year through five years 187,010 190,149 Due after five years through ten years 35,440 35,829 Due after ten years 8,914 9,627 250,026 254,284 Mortgage-backed securities 193,223 195,018 Securities AFS $ 443,249 $ 449,302
Schedule of Proceeds from sales of securities AFS	Proceeds from sales of securities AFS is summarized as follows. Years Ended December 31, (in thousands) 2019 2018 2017 Gross gains $ 152 $ — $ 1,227 Gross losses (174 ) (212 ) (7 ) Gains (losses) on sales of securities AFS, net $ (22 ) $ (212 ) $ 1,220 Proceeds from sales of securities AFS $ 23,405 $ 5,280 $ 10,798

LOANS, ALLOWANCE FOR LOAN LOS_2

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Schedule of loan composition and further breakdown summarized by originated and acquired	The loan composition is summarized as follows. December 31, 2019 December 31, 2018 (in thousands) Amount % of Total Amount % of Total Commercial & industrial $ 806,189 31 % $ 684,920 32 % Owner-occupied commercial real estate (“CRE”) 496,372 19 441,353 20 Agricultural (“AG”) production 35,982 2 35,625 2 AG real estate 59,468 2 53,444 2 CRE investment 443,218 17 343,652 16 Construction & land development 92,970 4 80,599 4 Residential construction 54,403 2 30,926 1 Residential first mortgage 432,167 17 357,841 17 Residential junior mortgage 122,771 5 111,328 5 Retail & other 30,211 1 26,493 1 Loans 2,573,751 100 % 2,166,181 100 % Less ALLL 13,972 13,153 Loans, net $ 2,559,779 $ 2,153,028 ALLL to loans 0.54 % 0.61 % As a further breakdown, loans are summarized by originated and acquired as follows. December 31, 2019 December 31, 2018 (in thousands) Originated Amount % of Total Acquired Amount % of Total Originated Amount % of Total Acquired Amount % of Total Commercial & industrial $ 641,341 39 % $ 164,848 18 % $ 568,100 38 % $ 116,820 17 % Owner-occupied CRE 329,138 20 167,234 18 283,531 19 157,822 23 AG production 11,824 1 24,158 3 11,113 1 24,512 4 AG real estate 38,983 2 20,485 2 31,374 2 22,070 3 CRE investment 183,746 11 259,472 28 171,087 12 172,565 25 Construction & land development 56,086 3 36,884 4 66,478 4 14,121 2 Residential construction 43,460 3 10,943 1 30,926 2 — — Residential first mortgage 232,580 14 199,587 22 220,368 15 137,473 20 Residential junior mortgage 90,284 5 32,487 4 78,379 5 32,949 5 Retail & other 28,373 2 1,838 — 23,809 2 2,684 1 Loans 1,655,815 100 % 917,936 100 % 1,485,165 100 % 681,016 100 % Less ALLL 12,116 1,856 11,448 1,705 Loans, net $ 1,643,699 $ 916,080 $ 1,473,717 $ 679,311 ALLL to loans 0.73 % 0.20 % 0.77 % 0.25 %
Schedule Of Roll Forward Of Allowance For Loan Losses Table	A roll forward of the allowance for loan losses is summarized as follows. Years Ended December 31, (in thousands) 2019 2018 2017 Beginning balance $ 13,153 $ 12,653 $ 11,820 Provision for loan losses 1,200 1,600 2,325 Charge-offs (927 ) (1,213 ) (1,604 ) Recoveries 546 113 112 Net charge-offs (381 ) (1,100 ) (1,492 ) Ending balance $ 13,972 $ 13,153 $ 12,653
Schedule of changes in ALLL by portfolio segment and further breakdown summarized by originated and acquired	The following tables present the balance and activity in the ALLL by portfolio segment and the recorded investment in loans by portfolio segment for the year ended December 31, 2019 . TOTAL – Year Ended December 31, 2019 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 5,271 $ 2,847 $ 121 $ 301 $ 1,470 $ 510 $ 211 $ 1,646 $ 472 $ 304 $ 13,153 Provision (61 ) 254 89 68 130 (96 ) 383 9 86 338 1,200 Charge-offs (159 ) (93 ) — — — — (226 ) (22 ) (80 ) (347 ) (927 ) Recoveries 420 2 — — — — — 36 39 49 546 Net charge-offs 261 (91 ) — — — — (226 ) 14 (41 ) (298 ) (381 ) Ending balance $ 5,471 $ 3,010 $ 210 $ 369 $ 1,600 $ 414 $ 368 $ 1,669 $ 517 $ 344 $ 13,972 As % of ALLL 39 % 22 % 1 % 3 % 11 % 3 % 3 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ 625 $ — $ 116 $ — $ — $ — $ — $ — $ — $ — $ 741 Collectively evaluated 4,846 3,010 94 369 1,600 414 368 1,669 517 344 13,231 Ending balance $ 5,471 $ 3,010 $ 210 $ 369 $ 1,600 $ 414 $ 368 $ 1,669 $ 517 $ 344 $ 13,972 Loans: Individually evaluated $ 5,932 $ 3,430 $ 1,061 $ 1,073 $ 2,426 $ 382 $ — $ 2,357 $ 218 $ 12 $ 16,891 Collectively evaluated 800,257 492,942 34,921 58,395 440,792 92,588 54,403 429,810 122,553 30,199 2,556,860 Total loans $ 806,189 $ 496,372 $ 35,982 $ 59,468 $ 443,218 $ 92,970 $ 54,403 $ 432,167 $ 122,771 $ 30,211 $ 2,573,751 Less ALLL 5,471 3,010 210 369 1,600 414 368 1,669 517 344 13,972 Net loans $ 800,718 $ 493,362 $ 35,772 $ 59,099 $ 441,618 $ 92,556 $ 54,035 $ 430,498 $ 122,254 $ 29,867 $ 2,559,779 As a further breakdown, the ALLL is summarized by originated and acquired as follows. Originated – Year Ended December 31, 2019 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 4,683 $ 2,439 $ 110 $ 255 $ 1,230 $ 431 $ 211 $ 1,400 $ 408 $ 281 $ 11,448 Provision (207 ) 212 85 57 124 (81 ) 340 5 25 335 895 Charge-offs (59 ) (93 ) — — — — (226 ) (22 ) (20 ) (347 ) (767 ) Recoveries 420 2 — — — — — 36 33 49 540 Net charge-offs 361 (91 ) — — — — (226 ) 14 13 (298 ) (227 ) Ending balance $ 4,837 $ 2,560 $ 195 $ 312 $ 1,354 $ 350 $ 325 $ 1,419 $ 446 $ 318 $ 12,116 As % of ALLL 40 % 21 % 2 % 2 % 11 % 3 % 3 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ 625 $ — $ 116 $ — $ — $ — $ — $ — $ — $ — $ 741 Collectively evaluated 4,212 2,560 79 312 1,354 350 325 1,419 446 318 11,375 Ending balance $ 4,837 $ 2,560 $ 195 $ 312 $ 1,354 $ 350 $ 325 $ 1,419 $ 446 $ 318 $ 12,116 Loans: Individually evaluated $ 1,993 $ 1,845 $ 1,008 $ 862 $ — $ — $ — $ — $ — $ — $ 5,708 Collectively evaluated 639,348 327,293 10,816 38,121 183,746 56,086 43,460 232,580 90,284 28,373 1,650,107 Total loans $ 641,341 $ 329,138 $ 11,824 $ 38,983 $ 183,746 $ 56,086 $ 43,460 $ 232,580 $ 90,284 $ 28,373 $ 1,655,815 Less ALLL 4,837 2,560 195 312 1,354 350 325 1,419 446 318 12,116 Net loans $ 636,504 $ 326,578 $ 11,629 $ 38,671 $ 182,392 $ 55,736 $ 43,135 $ 231,161 $ 89,838 $ 28,055 $ 1,643,699 Acquired – Year Ended December 31, 2019 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 588 $ 408 $ 11 $ 46 $ 240 $ 79 $ — $ 246 $ 64 $ 23 $ 1,705 Provision 146 42 4 11 6 (15 ) 43 4 61 3 305 Charge-offs (100 ) — — — — — — — (60 ) — (160 ) Recoveries — — — — — — — — 6 — 6 Net charge-offs (100 ) — — — — — — — (54 ) — (154 ) Ending balance $ 634 $ 450 $ 15 $ 57 $ 246 $ 64 $ 43 $ 250 $ 71 $ 26 $ 1,856 As % of ALLL 34 % 24 % 1 % 3 % 13 % 4 % 2 % 14 % 4 % 1 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 634 450 15 57 246 64 43 250 71 26 1,856 Ending balance $ 634 $ 450 $ 15 $ 57 $ 246 $ 64 $ 43 $ 250 $ 71 $ 26 $ 1,856 Loans: Individually evaluated $ 3,939 $ 1,585 $ 53 $ 211 $ 2,426 $ 382 $ — $ 2,357 $ 218 $ 12 $ 11,183 Collectively evaluated 160,909 165,649 24,105 20,274 257,046 36,502 10,943 197,230 32,269 1,826 906,753 Total loans $ 164,848 $ 167,234 $ 24,158 $ 20,485 $ 259,472 $ 36,884 $ 10,943 $ 199,587 $ 32,487 $ 1,838 $ 917,936 Less ALLL 634 450 15 57 246 64 43 250 71 26 1,856 Net loans $ 164,214 $ 166,784 $ 24,143 $ 20,428 $ 259,226 $ 36,820 $ 10,900 $ 199,337 $ 32,416 $ 1,812 $ 916,080 For comparison, the following tables present the balance and activity in the ALLL by portfolio segment and the recorded investment in loans by portfolio segment for the year ended December 31, 2018 . TOTAL – Year Ended December 31, 2018 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 4,934 $ 2,607 $ 129 $ 296 $ 1,388 $ 726 $ 251 $ 1,609 $ 488 $ 225 $ 12,653 Provision 1,107 300 (8 ) 5 119 (216 ) (40 ) 117 (51 ) 267 1,600 Charge-offs (813 ) (74 ) — — (37 ) — — (85 ) — (204 ) (1,213 ) Recoveries 43 14 — — — — — 5 35 16 113 Net charge-offs (770 ) (60 ) — — (37 ) — — (80 ) 35 (188 ) (1,100 ) Ending balance $ 5,271 $ 2,847 $ 121 $ 301 $ 1,470 $ 510 $ 211 $ 1,646 $ 472 $ 304 $ 13,153 As % of ALLL 40 % 22 % 1 % 2 % 11 % 4 % 2 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 5,271 2,847 121 301 1,470 510 211 1,646 472 304 13,153 Ending balance $ 5,271 $ 2,847 $ 121 $ 301 $ 1,470 $ 510 $ 211 $ 1,646 $ 472 $ 304 $ 13,153 Loans: Individually evaluated $ 2,927 $ 1,506 $ — $ 222 $ 1,686 $ 603 $ — $ 2,750 $ 233 $ 12 $ 9,939 Collectively evaluated 681,993 439,847 35,625 53,222 341,966 79,996 30,926 355,091 111,095 26,481 2,156,242 Total loans $ 684,920 $ 441,353 $ 35,625 $ 53,444 $ 343,652 $ 80,599 $ 30,926 $ 357,841 $ 111,328 $ 26,493 $ 2,166,181 Less ALLL 5,271 2,847 121 301 1,470 510 211 1,646 472 304 13,153 Net loans $ 679,649 $ 438,506 $ 35,504 $ 53,143 $ 342,182 $ 80,089 $ 30,715 $ 356,195 $ 110,856 $ 26,189 $ 2,153,028 As a further breakdown, the December 31, 2018 ALLL is summarized by originated and acquired as follows. Originated – Year Ended December 31, 2018 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 4,192 $ 2,115 $ 112 $ 235 $ 1,154 $ 628 $ 200 $ 1,297 $ 409 $ 200 $ 10,542 Provision 1,262 385 (2 ) 20 113 (197 ) 11 187 (31 ) 266 2,014 Charge-offs (813 ) (64 ) — — (37 ) — — (85 ) — (201 ) (1,200 ) Recoveries 42 3 — — — — — 1 30 16 92 Net charge-offs (771 ) (61 ) — — (37 ) — — (84 ) 30 (185 ) (1,108 ) Ending balance $ 4,683 $ 2,439 $ 110 $ 255 $ 1,230 $ 431 $ 211 $ 1,400 $ 408 $ 281 $ 11,448 As % of ALLL 41 % 21 % 1 % 2 % 11 % 4 % 2 % 12 % 4 % 2 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 4,683 2,439 110 255 1,230 431 211 1,400 408 281 11,448 Ending balance $ 4,683 $ 2,439 $ 110 $ 255 $ 1,230 $ 431 $ 211 $ 1,400 $ 408 $ 281 $ 11,448 Loans: Individually evaluated $ 227 $ 321 $ — $ — $ — $ — $ — $ — $ — $ — $ 548 Collectively evaluated 567,873 283,210 11,113 31,374 171,087 66,478 30,926 220,368 78,379 23,809 1,484,617 Total loans $ 568,100 $ 283,531 $ 11,113 $ 31,374 $ 171,087 $ 66,478 $ 30,926 $ 220,368 $ 78,379 $ 23,809 $ 1,485,165 Less ALLL 4,683 2,439 110 255 1,230 431 211 1,400 408 281 11,448 Net loans $ 563,417 $ 281,092 $ 11,003 $ 31,119 $ 169,857 $ 66,047 $ 30,715 $ 218,968 $ 77,971 $ 23,528 $ 1,473,717 Acquired – Year Ended December 31, 2018 (in thousands) Commercial & industrial Owner- occupied CRE AG production AG real estate CRE investment Construction & land development Residential construction Residential first mortgage Residential junior mortgage Retail & other Total ALLL: Beginning balance $ 742 $ 492 $ 17 $ 61 $ 234 $ 98 $ 51 $ 312 $ 79 $ 25 $ 2,111 Provision (155 ) (85 ) (6 ) (15 ) 6 (19 ) (51 ) (70 ) (20 ) 1 (414 ) Charge-offs — (10 ) — — — — — — — (3 ) (13 ) Recoveries 1 11 — — — — — 4 5 — 21 Net charge-offs 1 1 — — — — — 4 5 (3 ) 8 Ending balance $ 588 $ 408 $ 11 $ 46 $ 240 $ 79 $ — $ 246 $ 64 $ 23 $ 1,705 As % of ALLL 34 % 24 % 1 % 3 % 14 % 5 % — % 14 % 4 % 1 % 100 % ALLL: Individually evaluated $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — $ — Collectively evaluated 588 408 11 46 240 79 — 246 64 23 1,705 Ending balance $ 588 $ 408 $ 11 $ 46 $ 240 $ 79 $ — $ 246 $ 64 $ 23 $ 1,705 Loans: Individually evaluated $ 2,700 $ 1,185 $ — $ 222 $ 1,686 $ 603 $ — $ 2,750 $ 233 $ 12 $ 9,391 Collectively evaluated 114,120 156,637 24,512 21,848 170,879 13,518 — 134,723 32,716 2,672 671,625 Total loans $ 116,820 $ 157,822 $ 24,512 $ 22,070 $ 172,565 $ 14,121 $ — $ 137,473 $ 32,949 $ 2,684 $ 681,016 Less ALLL 588 408 11 46 240 79 — 246 64 23 1,705 Net loans $ 116,232 $ 157,414 $ 24,501 $ 22,024 $ 172,325 $ 14,042 $ — $ 137,227 $ 32,885 $ 2,661 $ 679,311
Schedule of nonaccrual loans by portfolio segment and further breakdown summarized by originated and acquired	The following tables present nonaccrual loans by portfolio segment in total and then as a further breakdown by originated or acquired. Total Nonaccrual Loans (in thousands) December 31, 2019 % to Total December 31, 2018 % to Total Commercial & industrial $ 6,249 44 % $ 2,816 52 % Owner-occupied CRE 3,311 23 673 12 AG production 1,062 8 — — AG real estate 836 6 164 3 CRE investment 1,073 8 210 4 Construction & land development 20 — 80 1 Residential construction — — 1 — Residential first mortgage 1,090 8 1,265 23 Residential junior mortgage 480 3 262 5 Retail & other 1 — — — Nonaccrual loans $ 14,122 100 % $ 5,471 100 % Percent of total loans 0.5 % 0.2 % Originated and Acquired Nonaccrual Loans December 31, 2019 December 31, 2018 (in thousands) Originated Amount % of Total Acquired Amount % of Total Originated Amount % of Total Acquired Amount % of Total Commercial & industrial $ 2,283 36 % $ 3,966 51 % $ 352 25 % $ 2,464 61 % Owner-occupied CRE 1,846 29 1,465 19 362 26 311 8 AG production 1,009 16 53 1 — — — — AG real estate 625 10 211 3 — — 164 4 CRE investment — — 1,073 14 — — 210 5 Construction & land development — — 20 — — — 80 2 Residential construction — — — — 1 — — — Residential first mortgage 434 7 656 8 629 45 636 15 Residential junior mortgage 126 2 354 4 65 4 197 5 Retail & other 1 — — — — — — — Nonaccrual loans $ 6,324 100 % $ 7,798 100 % $ 1,409 100 % $ 4,062 100 % Percent of nonaccrual loans 45 % 55 % 26 % 74 %
Schedule of past due loans by portfolio segment and further breakdown summarized by originated and acquired	The following tables present past due loans by portfolio segment. December 31, 2019 (in thousands) 30-89 Days Past Due (accruing) 90 Days & Over or nonaccrual Current Total Commercial & industrial $ 1,729 $ 6,249 $ 798,211 $ 806,189 Owner-occupied CRE 112 3,311 492,949 496,372 AG production — 1,062 34,920 35,982 AG real estate — 836 58,632 59,468 CRE investment — 1,073 442,145 443,218 Construction & land development 2,063 20 90,887 92,970 Residential construction 302 — 54,101 54,403 Residential first mortgage 2,736 1,090 428,341 432,167 Residential junior mortgage 217 480 122,074 122,771 Retail & other 110 1 30,100 30,211 Total loans $ 7,269 $ 14,122 $ 2,552,360 $ 2,573,751 Percent of total loans 0.3 % 0.5 % 99.2 % 100.0 % December 31, 2018 (in thousands) 30-89 Days Past Due (accruing) 90 Days & Over or nonaccrual Current Total Commercial & industrial $ — $ 2,816 $ 682,104 $ 684,920 Owner-occupied CRE 557 673 440,123 441,353 AG production 19 — 35,606 35,625 AG real estate 35 164 53,245 53,444 CRE investment 180 210 343,262 343,652 Construction & land development — 80 80,519 80,599 Residential construction — 1 30,925 30,926 Residential first mortgage 758 1,265 355,818 357,841 Residential junior mortgage 12 262 111,054 111,328 Retail & other 10 — 26,483 26,493 Total loans $ 1,571 $ 5,471 $ 2,159,139 $ 2,166,181 Percent of total loans 0.1 % 0.2 % 99.7 % 100.0 %
Schedule of total loans by risk categories	The following tables present total loans by risk categories. December 31, 2019 (in thousands) Grades 1-4 Grade 5 Grade 6 Grade 7 Grades 8-9 Total Commercial & industrial $ 765,073 $ 20,199 $ 7,663 $ 13,254 $ — $ 806,189 Owner-occupied CRE 464,661 20,855 953 9,903 — 496,372 AG production 27,521 3,174 1,229 4,058 — 35,982 AG real estate 49,561 3,611 2,046 4,250 — 59,468 CRE investment 430,794 8,085 2,578 1,761 — 443,218 Construction & land development 90,523 2,213 15 219 — 92,970 Residential construction 53,286 1,117 — — — 54,403 Residential first mortgage 424,044 4,677 668 2,778 — 432,167 Residential junior mortgage 122,249 35 — 487 — 122,771 Retail & other 30,210 — — 1 — 30,211 Total loans $ 2,457,922 $ 63,966 $ 15,152 $ 36,711 $ — $ 2,573,751 Percent of total loans 95.5 % 2.5 % 0.6 % 1.4 % — % 100.0 % December 31, 2018 (in thousands) Grades 1-4 Grade 5 Grade 6 Grade 7 Grades 8-9 Total Commercial & industrial $ 649,475 $ 16,145 $ 6,178 $ 13,122 $ — $ 684,920 Owner-occupied CRE 405,198 22,776 6,569 6,810 — 441,353 AG production 29,363 3,302 2,351 609 — 35,625 AG real estate 46,248 3,246 2,983 967 — 53,444 CRE investment 334,080 6,792 — 2,780 — 343,652 Construction & land development 75,365 5,138 16 80 — 80,599 Residential construction 30,926 — — — — 30,926 Residential first mortgage 353,239 1,406 510 2,686 — 357,841 Residential junior mortgage 111,037 17 — 274 — 111,328 Retail & other 26,493 — — — — 26,493 Total loans $ 2,061,424 $ 58,822 $ 18,607 $ 27,328 $ — $ 2,166,181 Percent of total loans 95.1 % 2.7 % 0.9 % 1.3 % — % 100.0 %
Schedule of impaired loans and further breakdown summarized by originated and acquired	The following tables present impaired loans. December 31, 2019 (in thousands) Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized Commercial & industrial $ 5,932 $ 7,950 $ 625 $ 5,405 $ 1,170 Owner-occupied CRE 3,430 4,016 — 3,677 256 AG production 1,061 1,090 116 1,221 28 AG real estate 1,073 1,082 — 1,090 9 CRE investment 2,426 2,790 — 2,497 364 Construction & land development 382 382 — 460 — Residential construction — — — — — Residential first mortgage 2,357 2,629 — 2,412 178 Residential junior mortgage 218 349 — 224 58 Retail & other 12 12 — 12 — Total $ 16,891 $ 20,300 $ 741 $ 16,998 $ 2,063 Originated impaired loans $ 5,708 $ 5,938 $ 741 $ 5,978 $ 230 Acquired impaired loans 11,183 14,362 — 11,020 1,833 Total $ 16,891 $ 20,300 $ 741 $ 16,998 $ 2,063 December 31, 2018 (in thousands) Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized Commercial & industrial $ 2,927 $ 6,736 $ — $ 4,041 $ 660 Owner-occupied CRE 1,506 1,833 — 1,659 137 AG production — — — — — AG real estate 222 281 — 238 26 CRE investment 1,686 2,484 — 1,606 163 Construction & land development 603 1,506 — 603 21 Residential construction — — — — — Residential first mortgage 2,750 2,907 — 2,478 176 Residential junior mortgage 233 262 — 62 15 Retail & other 12 12 — 12 1 Total $ 9,939 $ 16,021 $ — $ 10,699 $ 1,199 Originated impaired loans $ 548 $ 548 $ — $ 899 $ 154 Acquired impaired loans 9,391 15,473 — 9,800 1,045 Total $ 9,939 $ 16,021 $ — $ 10,699 $ 1,199
Schedule of non accretable discount	Nonaccretable discount on PCI loans: Years Ended December 31, (in thousands) 2019 2018 Balance at beginning of period $ 6,408 $ 9,471 Acquired balance, net 911 — Accretion to loan interest income (4,713 ) (1,976 ) Transferred to accretable — (990 ) Disposals of loans (679 ) (97 ) Balance at end of period $ 1,927 $ 6,408

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 December 31, 2018 Land $ 7,418 $ 6,220 Land improvements 3,865 3,842 Building and improvements 50,818 42,238 Leasehold improvements 4,580 4,092 Furniture and equipment 20,262 18,590 86,943 74,982 Less accumulated depreciation and amortization 30,474 26,809 Premises and equipment, net $ 56,469 $ 48,173
Schedule of operating lease	A summary of net lease cost and selected other information related to operating leases was as follows. Year Ended ($ in thousands) December 31, 2019 Net lease cost: Operating lease cost $ 970 Variable lease cost 233 Net lease cost $ 1,203 Selected other operating lease information: Weighted average remaining lease term (years) 4.3 Weighted average discount rate 2.5 %
Schedule of minimum annual rentals under non-cancelable lease agreements	The following table summarizes the maturity of remaining lease liabilities. Years Ending December 31, (in thousands) 2020 $ 1,088 2021 962 2022 851 2023 607 2024 499 Thereafter 16 Total future minimum lease payments 4,023 Less: amount representing interest (100 ) Present value of net future minimum lease payments $ 3,923

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill and other intangibles included in other assets	A summary of goodwill and other intangibles was as follows. (in thousands) December 31, 2019 December 31, 2018 Goodwill $ 151,198 $ 107,366 Core deposit intangibles 10,897 12,562 Customer list intangibles 3,872 4,379 Other intangibles 14,769 16,941 Goodwill and other intangibles, net $ 165,967 $ 124,307
Schedule of goodwill	See Note 1 for the Company’s accounting policy for goodwill and see Note 2 for additional information on the Company’s acquisitions. (in thousands) December 31, 2019 December 31, 2018 Goodwill: Goodwill at beginning of year $ 107,366 $ 107,366 Acquisition 44,594 — Impairment (762 ) — Goodwill at end of year $ 151,198 $ 107,366
Schedule of intangible assets	(in thousands) December 31, 2019 December 31, 2018 Core deposit intangibles: Gross carrying amount $ 30,715 $ 29,015 Accumulated amortization (19,818 ) (16,453 ) Net book value $ 10,897 $ 12,562 Additions during the period $ 1,700 $ — Amortization during the period $ 3,365 $ 3,915 Customer list intangibles: Gross carrying amount $ 5,523 5,523 Accumulated amortization (1,651 ) (1,144 ) Net book value $ 3,872 $ 4,379 Additions during the period $ — $ 290 Amortization during the period $ 507 $ 474
Schedule of mortgage servicing rights	A summary of the changes in the MSR asset was as follows. (in thousands) December 31, 2019 December 31, 2018 MSR asset: MSR asset at beginning of year $ 3,749 $ 3,187 Capitalized MSR 2,876 1,203 MSR asset acquired 160 — Amortization during the period (866 ) (641 ) MSR asset at end of year $ 5,919 $ 3,749 Fair value of MSR asset at end of period $ 8,420 $ 6,347 Residential mortgage loans serviced for others $ 847,756 $ 603,446 Net book value of MSR asset to loans serviced for others 0.70 % 0.62 %
Schedule of estimated future amortization expense for amortizing intangible assets	(in thousands) Core deposit intangibles Customer list intangibles MSR asset Years Ending December 31, 2020 $ 2,993 $ 507 $ 1,048 2021 2,453 507 865 2022 1,987 507 865 2023 1,490 483 835 2024 1,010 449 503 Thereafter 964 1,419 1,803 Total $ 10,897 $ 3,872 $ 5,919

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2019
Deposits [Abstract]
Schedule of maturities of time deposits	At December 31, 2019 , the scheduled maturities of time deposits were as follows. Years Ending December 31, (in thousands) 2020 $ 317,693 2021 114,728 2022 50,949 2023 45,040 2024 19,773 Thereafter 2,374 Total time deposits $ 550,557

SHORT AND LONG-TERM BORROWINGS

SHORT AND LONG-TERM BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of long-term debt instruments	The components of long-term borrowings (borrowing with an original contractual maturity greater than one year) were as follows. (in thousands) December 31, 2019 December 31, 2018 FHLB advances $ 25,061 $ 35,252 Junior subordinated debentures 30,575 30,096 Subordinated notes 11,993 11,957 Total long-term borrowings $ 67,629 $ 77,305
Schedule of maturity of notes payable	The following table shows the maturity schedule of the FHLB advances as of December 31, 2019 . Maturing in: (in thousands) 2020 $ 10,061 2021 10,000 2022 — 2023 — 2024 — 2025 5,000 $ 25,061
Schedule of junior subordinated debentures	All the debentures below are currently callable and may be redeemed in part or in full, at par, plus any accrued but unpaid interest. Junior Subordinated Debentures (in thousands) Maturity Date Par 12/31/2019 Unamortized Discount 12/31/2019 Carrying Value 12/31/2018 Carrying Value 2004 Nicolet Bankshares Statutory Trust (1) 7/15/2034 $ 6,186 $ — $ 6,186 $ 6,186 2005 Mid-Wisconsin Financial Services, Inc. (2) 12/15/2035 10,310 (3,172 ) 7,138 6,939 2006 Baylake Corp. (3) 9/30/2036 16,598 (3,883 ) 12,715 12,478 2004 First Menasha Bancshares, Inc. (4) 3/17/2034 5,155 (619 ) 4,536 4,493 Total $ 38,249 $ (7,674 ) $ 30,575 $ 30,096 (1) The interest rate is 8.00% fixed. (2) The debentures, assumed in April 2013 as the result of an acquisition, have a floating rate of the three-month LIBOR plus 1.43% , adjusted quarterly. The interest rates were 3.32% and 4.22% as of December 31, 2019 and 2018 , respectively. (3) The debentures, assumed in April 2016 as a result of an acquisition, have a floating rate of the three-month LIBOR plus 1.35% , adjusted quarterly. The interest rates were 3.31% and 4.15% as of December 31, 2019 and 2018 , respectively. (4) The debentures, assumed in April 2017 as the result of an acquisition, have a floating rate of the three-month LIBOR plus 2.79% , adjusted quarterly. The interest rate was 4.69% and 5.58% as of December 31, 2019 and 2018 , respectively.

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [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. 2019 2018 2017 Dividend yield — % — % — % Expected volatility 25 % 25 % 25 % Risk-free interest rate 1.75 % 2.61 % 2.14 % Expected average life 7 years 7 years 7 years Weighted average per share fair value of options $ 21.30 $ 17.36 $ 15.80
Schedule of stock incentive plans for options	A summary of the Company’s stock option activity is summarized below. Stock Options Option Shares Outstanding Weighted Average Exercise Price Weighted Average Remaining Life (Years) Aggregate Intrinsic Value (in thousands) Outstanding – December 31, 2016 922,026 $ 24.39 Granted 949,500 49.93 Exercise of stock options * (209,371 ) 18.15 Forfeited (18,900 ) 35.36 Outstanding – December 31, 2017 1,643,255 $ 39.82 8.1 $ 24,525 Granted 15,500 52.76 Exercise of stock options * (70,556 ) 21.52 Forfeited (6,500 ) 39.43 Outstanding – December 31, 2018 1,581,699 $ 40.77 7.4 $ 13,825 Granted 203,000 69.69 Exercise of stock options * (337,428 ) 24.15 Forfeited (3,538 ) 27.43 Outstanding – December 31, 2019 1,443,733 $ 48.75 7.4 $ 36,428 Exercisable – December 31, 2019 561,633 $ 42.91 6.7 $ 17,384 *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 142,752 shares, 6,411 shares, and 85,422 shares were surrendered during 2019 , 2018 , and 2017 , respectively.
Schedule of tax withholding requirements options of outstanding	The following options were outstanding at December 31, 2019 . Number of Shares Weighted Average Exercise Price Weighted Average Remaining Life (Years) Outstanding Exercisable Outstanding Exercisable Outstanding Exercisable $13.73 – $30.00 130,436 94,936 $ 22.37 $ 21.85 4.2 4.1 $30.01 – $40.00 155,747 89,747 35.92 35.51 6.4 6.3 $40.01 – $50.00 804,050 319,850 48.86 48.86 7.4 7.4 $50.01 – $60.00 155,500 57,100 56.09 56.23 7.9 7.9 $60.01 – $70.50 198,000 — 70.01 — 9.9 0.0 1,443,733 561,633 $ 48.75 $ 42.91 7.4 6.7
Schedule of restricted stock	A summary of the Company’s restricted stock activity is summarized below. Restricted Stock Restricted Shares Outstanding Weighted Average Grant Date Fair Value Outstanding – December 31, 2016 42,949 $ 26.80 Granted 9,240 57.75 Vested * (20,514 ) 29.87 Forfeited (755 ) 16.50 Outstanding – December 31, 2017 30,920 $ 34.26 Granted 18,256 52.55 Vested * (19,661 ) 43.58 Forfeited (3 ) 16.50 Outstanding – December 31, 2018 29,512 $ 39.37 Granted 12,498 67.59 Vested * (19,081 ) 51.77 Forfeited (408 ) 16.50 Outstanding – December 31, 2019 22,521 $ 44.94 *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 4,688 shares, 3,948 shares, and 5,266 shares were surrendered during 2019 , 2018 , and 2017 , respectively.

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2019
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) 2019 2018 2017 Current $ 15,353 $ 14,967 $ 10,952 Deferred 1,105 (1,521 ) 4,430 Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act — — 885 Income tax expense $ 16,458 $ 13,446 $ 16,267
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 (21% for 2019 and 2018 and 35% for 2017) to the income before income taxes, less noncontrolling interest, for the years ended as indicated are included in the following table. Years Ended December 31, (in thousands) 2019 2018 2017 Tax on pretax income, less noncontrolling interest, at statutory rates $ 14,931 $ 11,441 $ 17,296 State income taxes, net of federal effect 3,672 3,308 2,242 Tax-exempt interest income (609 ) (574 ) (1,073 ) Non-deductible interest disallowance 29 30 28 Increase in cash surrender value life insurance (573 ) (508 ) (807 ) Non-deductible business entertainment 189 156 168 Stock-based employee compensation (2,347 ) (232 ) (62 ) Non-deductible compensation 3,122 — — Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act — — 885 Deduction attributable to share-based payments — — (1,854 ) Sale of UFS (2,176 ) — — Other, net 220 (175 ) (556 ) Income tax expense $ 16,458 $ 13,446 $ 16,267
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, 2019 December 31, 2018 Deferred tax assets: ALLL $ 4,985 $ 5,240 Net operating loss carryforwards 1,808 2,202 Credit carryforwards 43 43 Compensation 3,477 2,408 Other 2,830 2,549 Other real estate 201 103 Unrealized loss on securities AFS — 1,740 Total deferred tax assets 13,344 14,285 Deferred tax liabilities: Premises and equipment (1,390 ) (821 ) Prepaid expenses (778 ) (693 ) Investment securities (755 ) (1,723 ) Core deposit and other intangibles (2,836 ) (3,563 ) Purchase accounting adjustments to liabilities (2,375 ) (2,011 ) Other (1,391 ) (1,021 ) Unrealized gain on securities AFS (1,879 ) — Total deferred tax liabilities (11,404 ) (9,832 ) Net deferred tax assets $ 1,940 $ 4,453

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2019
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, 2019 December 31, 2018 Commitments to extend credit $ 773,555 $ 721,098 Financial standby letters of credit 10,730 8,571 Performance standby letters of credit 8,469 7,094

ASSETS GAINS (LOSSES), NET (Tab

ASSETS GAINS (LOSSES), NET (Tables)	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Schedule of components of the net gain on sale, disposal or write-down of assets	Components of the net gains (losses) on assets are as follows. Years Ended December 31, (in thousands) 2019 2018 2017 Gains (losses) on sales of securities AFS, net $ (22 ) $ (212 ) $ 1,220 Gains (losses) on equity securities, net 1,115 77 — Gains (losses) on sales of OREO, net (88 ) 1,032 258 Write-downs of OREO (300 ) (120 ) (127 ) Write-down of other investment (100 ) — — Gains (losses) on sales of other investments, net 7,442 187 — Gains (losses) on sales or dispositions of other assets, net (150 ) 205 678 Asset gains (losses), net $ 7,897 $ 1,169 $ 2,029

REGULATORY CAPITAL REQUIREMEN_2

REGULATORY CAPITAL REQUIREMENTS (Tables)	12 Months Ended
	Dec. 31, 2019
Banking and Thrift [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 Purposes To Be Well Capitalized Under Prompt Corrective Action Provisions (2) (in thousands) Amount Ratio (1) Amount Ratio (1) Amount Ratio (1) December 31, 2019 Company Total risk-based capital $ 404,573 13.4 % $ 241,333 8.0 % Tier 1 risk-based capital 378,608 12.6 181,000 6.0 Common equity Tier 1 capital 348,454 11.6 135,750 4.5 Leverage 378,608 11.9 127,036 4.0 Bank Total risk-based capital $ 323,432 10.8 % $ 240,551 8.0 % $ 300,688 10.0 % Tier 1 risk-based capital 309,460 10.3 180,413 6.0 240,551 8.0 Common equity Tier 1 capital 309,460 10.3 135,310 4.5 195,447 6.5 Leverage 309,460 9.8 126,660 4.0 158,325 5.0 December 31, 2018 Company Total risk-based capital $ 326,235 12.9 % $ 202,836 8.0 % Tier 1 risk-based capital 301,125 11.9 152,127 6.0 Common equity Tier 1 capital 271,435 10.7 114,095 4.5 Leverage 301,125 10.4 115,483 4.0 Bank Total risk-based capital $ 274,492 10.8 % $ 202,800 8.0 % $ 253,501 10.0 % Tier 1 risk-based capital 261,339 10.3 152,100 6.0 202,800 8.0 Common equity Tier 1 capital 261,339 10.3 114,075 4.5 164,775 6.5 Leverage 261,339 9.1 115,280 4.0 144,100 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, 2019
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 for the periods presented. (in thousands) Fair Value Measurements Using Measured at Fair Value on a Recurring Basis: Total Level 1 Level 2 Level 3 December 31, 2019 U.S. government agency securities $ 16,460 $ — $ 16,460 $ — State, county and municipals 156,393 — 156,393 — Mortgage-backed securities 195,018 — 195,018 — Corporate debt securities 81,431 — 78,301 3,130 Securities AFS $ 449,302 $ — $ 446,172 $ 3,130 Other investments (equity securities) $ 3,375 $ 3,375 $ — $ — December 31, 2018 U.S. government agency securities $ 21,649 $ — $ 21,649 $ — State, county and municipals 160,526 — 160,460 66 Mortgage-backed securities 131,644 — 131,644 — Corporate debt securities 86,325 — 77,901 8,424 Securities AFS $ 400,144 $ — $ 391,654 $ 8,490 Other investments (equity securities) $ 2,650 $ 2,650 $ — $ —
Schedule of changes in Level 3 assets 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, 2019 December 31, 2018 Balance at beginning of year $ 8,490 $ 9,151 Acquired balances 300 — Paydowns/Sales/Settlements (5,660 ) (661 ) Balance at end of year $ 3,130 $ 8,490
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, 2019 Impaired loans $ 16,150 $ — $ — $ 16,150 OREO 1,000 — — 1,000 MSR asset 8,420 — — 8,420 December 31, 2018 Impaired loans $ 9,939 $ — $ — $ 9,939 OREO 420 — — 420 MSR asset 6,347 — — 6,347
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, 2019 (in thousands) Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 182,059 $ 182,059 $ 182,059 $ — $ — Certificates of deposit in other banks 19,305 19,310 — 19,310 — Securities AFS 449,302 449,302 — 446,172 3,130 Other investments 24,072 24,072 3,375 16,759 3,938 Loans held for sale 2,706 2,753 — 2,753 — Loans, net 2,559,779 2,593,110 — — 2,593,110 BOLI 78,140 78,140 78,140 — — MSR asset 5,919 8,420 — — 8,420 Financial liabilities: Deposits $ 2,954,453 $ 2,956,229 $ — $ — $ 2,956,229 Long-term borrowings 67,629 66,816 — 25,075 41,741 December 31, 2018 (in thousands) Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and cash equivalents $ 249,526 $ 249,526 $ 249,526 $ — $ — Certificates of deposit in other banks 993 993 — 993 — Securities AFS 400,144 400,144 — 391,654 8,490 Other investments 17,997 17,997 2,650 13,189 2,158 Loans held for sale 1,639 1,662 — 1,662 — Loans, net 2,153,028 2,139,322 — — 2,139,322 BOLI 66,310 66,310 66,310 — — MSR asset 3,749 6,347 — — 6,347 Financial liabilities: Deposits $ 2,614,138 $ 2,614,995 $ — $ — $ 2,614,995 Long-term borrowings 77,305 75,923 — 34,907 41,016

PARENT COMPANY ONLY FINANCIAL_2

PARENT COMPANY ONLY FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2019
Condensed Financial Information Disclosure [Abstract]
Schedule of parent company only condensed financial statements	Statements of Cash Flows Years Ended December 31, (in thousands) 2019 2018 2017 Cash Flows From Operating Activities: Net income attributable to Nicolet Bankshares, Inc. $ 54,641 $ 41,036 $ 33,150 Adjustments to reconcile net income to net cash provided by operating activities: Accretion of discounts 515 515 501 (Gain) loss on investments, net (1,015 ) (265 ) (1,411 ) Change in other assets and liabilities, net (421 ) (25 ) (1,384 ) Equity in undistributed (income) loss of subsidiaries, net of dividends (5,959 ) (2,847 ) (1,148 ) Net cash provided by operating activities 47,761 38,414 29,708 Cash Flows from Investing Activities: Proceeds from sale of investments — 708 317 Purchases of investments (2,484 ) (920 ) — Net cash paid in business combinations (412 ) — (19,287 ) Net cash used in investing activities (2,896 ) (212 ) (18,970 ) Cash Flows From Financing Activities: Purchase and retirement of common stock (28,460 ) (22,749 ) (15,007 ) Proceeds from issuance of common stock, net 8,742 1,800 4,030 Net cash used in financing activities (19,718 ) (20,949 ) (10,977 ) Net increase (decrease) in cash and due from subsidiary 25,147 17,253 (239 ) Beginning cash and due from subsidiary 45,279 28,026 28,265 Ending cash and due from subsidiary $ 70,426 $ 45,279 $ 28,026 Condensed Parent Company only financial statements of Nicolet Bankshares, Inc. follow. Balance Sheets December 31, (in thousands) 2019 2018 Assets Cash and due from subsidiary $ 70,426 $ 45,279 Investments 6,650 4,500 Investments in subsidiaries 487,644 384,839 Goodwill (3,266 ) (3,266 ) Other assets 396 53 Total assets $ 561,850 $ 431,405 Liabilities and Stockholders’ Equity Junior subordinated debentures $ 30,575 $ 30,096 Subordinated notes 11,993 11,957 Other liabilities 3,020 2,743 Stockholders’ equity 516,262 386,609 Total liabilities and stockholders’ equity $ 561,850 $ 431,405 Statements of Income Years Ended December 31, (in thousands) 2019 2018 2017 Interest income $ 55 $ 52 $ 46 Interest expense 2,936 2,844 2,415 Net interest expense (2,881 ) (2,792 ) (2,369 ) Dividend income from subsidiaries 50,363 40,775 32,000 Operating expense (321 ) (364 ) (369 ) Gain (loss) on investments, net 1,015 265 1,411 Income tax benefit 506 305 1,329 Earnings before equity in undistributed income (loss) of subsidiaries 48,682 38,189 32,002 Equity in undistributed income (loss) of subsidiaries 5,959 2,847 1,148 Net income attributable to Nicolet Bankshares, Inc. $ 54,641 $ 41,036 $ 33,150

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of earnings per common share	See Note 1 for the Company’s accounting policy on earnings per common share. Earnings per common share and related information are summarized as follows. Years Ended December 31, (in thousands, except per share data) 2019 2018 2017 Net income attributable to Nicolet Bankshares, Inc. $ 54,641 $ 41,036 $ 33,150 Weighted average common shares outstanding 9,562 9,640 9,440 Effect of dilutive common stock awards 338 316 518 Diluted weighted average common shares outstanding 9,900 9,956 9,958 Basic earnings per common share $ 5.71 $ 4.26 $ 3.51 Diluted earnings per common share $ 5.52 $ 4.12 $ 3.33

NATURE OF BUSINESS AND SIGNIF_4

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Detail) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Nature Of Business And Significant Accounting Policies [Line Items]
Operating lease liability		$ 3,923,000
Restricted cash		6,000,000	$ 6,300,000	$ 5,400,000
Other investments		24,072,000	17,997,000
Material loans criteria for ALLL adequacy calculation		250,000
Goodwill, Impairment Loss		762,000	0
Restricted cash pledged as collateral		$ 1,300,000
Core deposit intangibles
Nature Of Business And Significant Accounting Policies [Line Items]
Amortized period of core deposit intangible		10 years
Customer list intangibles:
Nature Of Business And Significant Accounting Policies [Line Items]
Amortized period of core deposit intangible		12 years
Accounting Standards Update 2016-02
Nature Of Business And Significant Accounting Policies [Line Items]
Operating lease liability						$ 5,000,000
Right-of-use asset						$ 5,000,000
Minimum | Securities sold under agreements to repurchase
Nature Of Business And Significant Accounting Policies [Line Items]
Maturity period of repo agreements		1 day
Maximum | Securities sold under agreements to repurchase
Nature Of Business And Significant Accounting Policies [Line Items]
Maturity period of repo agreements		4 days
United Financial Services, Inc. | United Financial Services Llc
Nature Of Business And Significant Accounting Policies [Line Items]
Percentage of indirect interest					49.80%
Percentage of Indirect Interest Sold	80.00%
Equity Method Investment, Realized Gain (Loss) on Disposal	$ 7,400,000
Equity income recognized in business acquisition		$ 900,000	1,800,000	1,300,000
Payment made for acquisition		3,200,000	2,800,000	$ 2,600,000
Carrying value of bank investment		$ 2,800,000	$ 11,500,000

NATURE OF BUSINESS AND SIGNIF_5

NATURE OF BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES - Estimated useful lives of premises and equipment (Details)	12 Months Ended
	Dec. 31, 2019
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 (Detail) $ / shares in Units, $ in Thousands	Nov. 08, 2019USD ($)$ / sharesshares	Apr. 28, 2017USD ($)Branch$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)
Business Acquisition [Line Items]
Amount of addition in goodwill			$ 44,594	$ 0
Customer list intangibles
Business Acquisition [Line Items]
Intangible assets assumed					$ 290
Merger Agreement | Choice Bancorp Inc.
Business Acquisition [Line Items]
Number of common stock issued for consideration | shares	1,184,102
Number of common stock for each outstanding share of common stock	0.00497
Common stock issued amount	$ 79,800
Price per share for stock issued in consideration | $ / shares	$ 67.39
Value of cash consideration	$ 1,700
Direct stock issuance costs for the merger charged against additional paid in capital	200
Amount of addition in assets	457,000
Loans	348,000
Amount of addition in deposit	289,000
Amount of addition in goodwill	45,000
Merger Agreement | Choice Bancorp Inc. | Core deposit intangibles
Business Acquisition [Line Items]
Intangible assets assumed	$ 1,700
Merger Agreement | First Menasha
Business Acquisition [Line Items]
Number of branches | Branch		5
Number of branches closed | Branch		1
Number of common stock issued for consideration | shares		1,309,885
Number of common stock for each outstanding share of common stock		3.126
Common stock issued amount		$ 62,200
Price per share for stock issued in consideration | $ / shares		$ 47.52
Number of trading days		20 days
Value of cash consideration		$ 19,300
Direct stock issuance costs for the merger charged against additional paid in capital		200
Amount of addition in assets		480,000
Loans		351,000
Amount of addition in deposit		375,000
Amount of addition in goodwill		41,000
Merger Agreement | First Menasha | Core deposit intangibles
Business Acquisition [Line Items]
Intangible assets assumed		$ 4,000

SECURITIES AVAILABLE FOR SALE -

SECURITIES AVAILABLE FOR SALE - Narrative (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale Securities
Debt Securities, Available-for-sale [Line Items]
AFS securities pledged as collateral	$ 166	$ 157

SECURITIES AVAILABLE FOR SALE_2

SECURITIES AVAILABLE FOR SALE - Amortized costs and fair values of securities available for sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 443,249	$ 407,871
Gross Unrealized Gains	6,967	470
Gross Unrealized Losses	914	8,197
Securities available for sale (“AFS”), at fair value	449,302	400,144
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,516	22,467
Gross Unrealized Gains	4	0
Gross Unrealized Losses	60	818
Securities available for sale (“AFS”), at fair value	16,460	21,649
State, county and municipals
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	155,501	163,702
Gross Unrealized Gains	1,049	76
Gross Unrealized Losses	157	3,252
Securities available for sale (“AFS”), at fair value	156,393	160,526
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	193,223	134,350
Gross Unrealized Gains	2,492	328
Gross Unrealized Losses	697	3,034
Securities available for sale (“AFS”), at fair value	195,018	131,644
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	78,009	87,352
Gross Unrealized Gains	3,422	66
Gross Unrealized Losses	0	1,093
Securities available for sale (“AFS”), at fair value	$ 81,431	$ 86,325

SECURITIES AVAILABLE FOR SALE_3

SECURITIES AVAILABLE FOR SALE - Gross unrealized losses and the related fair value of securities available for sale (Details) - Accounting Standards Update 2016-01 $ in Thousands	Dec. 31, 2019USD ($)Security	Dec. 31, 2018USD ($)Security
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	$ 73,112	$ 88,296
Less than 12 months, Unrealized Losses	379	907
12 months or more, Fair Value	65,967	251,570
12 months or more, Unrealized Losses	535	7,290
Total, Fair Value	139,079	339,866
Total, Unrealized Losses	$ 914	$ 8,197
Number of Securities | Security	212	680
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	$ 1,035	$ 0
Less than 12 months, Unrealized Losses	2	0
12 months or more, Fair Value	11,091	21,649
12 months or more, Unrealized Losses	58	818
Total, Fair Value	12,126	21,649
Total, Unrealized Losses	$ 60	$ 818
Number of Securities | Security	6	3
US States and Political Subdivisions Debt Securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	$ 22,451	$ 16,136
Less than 12 months, Unrealized Losses	132	98
12 months or more, Fair Value	7,605	130,975
12 months or more, Unrealized Losses	25	3,154
Total, Fair Value	30,056	147,111
Total, Unrealized Losses	$ 157	$ 3,252
Number of Securities | Security	56	440
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	$ 49,626	$ 20,568
Less than 12 months, Unrealized Losses	245	132
12 months or more, Fair Value	47,271	89,189
12 months or more, Unrealized Losses	452	2,902
Total, Fair Value	96,897	109,757
Total, Unrealized Losses	$ 697	$ 3,034
Number of Securities | Security	150	204
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	$ 0	$ 51,592
Less than 12 months, Unrealized Losses	0	677
12 months or more, Fair Value	0	9,757
12 months or more, Unrealized Losses	0	416
Total, Fair Value	0	61,349
Total, Unrealized Losses	$ 0	$ 1,093
Number of Securities | Security	0	33

SECURITIES AVAILABLE FOR SALE_4

SECURITIES AVAILABLE FOR SALE - Amortized cost and fair values of securities available for sale at by contractual maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost, Due in less than one year	$ 18,662
Amortized Cost, Due in one year through five years	187,010
Amortized Cost, Due after five years through ten years	35,440
Amortized Cost, Due after ten years	8,914
Amortized Cost	250,026
Securities AFS, Amortized Cost	443,249	$ 407,871
Fair Value, Due in less than one year	18,679
Fair Value, Due in one year through five years	190,149
Fair Value, Due after five years through ten years	35,829
Fair Value, Due after ten years	9,627
Fair Value	254,284
Securities available for sale (“AFS”), at fair value	449,302	400,144
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Securities AFS, Amortized Cost	193,223	134,350
Securities available for sale (“AFS”), at fair value	$ 195,018	$ 131,644

SECURITIES AVAILABLE FOR SALE_5

SECURITIES AVAILABLE FOR SALE - Proceeds from sales of securities AFS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Abstract]
Gross gains	$ 152	$ 0	$ 1,227
Gross losses	(174)	(212)	(7)
Gains (losses) on sales of securities AFS, net	(22)	(212)	1,220
Proceeds from sales of securities AFS	$ 23,405	$ 5,280	$ 10,798

LOANS, ALLOWANCE FOR LOAN LOS_3

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Narrative (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)Loan	Dec. 31, 2018USD ($)Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans classified as troubled debt restructuring, | Loan	5	4
Postmodification balance	$ 1,100,000	$ 600,000
Premodification balance	1,400,000	$ 2,700,000
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCI loans acquired fair value	45,500,000
Nonaccretable mark	35,300,000
Accretable mark	0
Loans receivables acquired at fair value in acquisition	$ 11,200,000

LOANS, ALLOWANCE FOR LOAN LOS_4

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of loan composition (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 2,573,751	$ 2,166,181
% of Total	100.00%	100.00%
Less ALLL	$ 13,972	$ 13,153	$ 12,653	$ 11,820
Loans, net	$ 2,559,779	$ 2,153,028
ALLL to loans	0.54%	0.61%
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 1,655,815	$ 1,485,165
% of Total	100.00%	100.00%
Less ALLL	$ 12,116	$ 11,448	10,542
Loans, net	$ 1,643,699	$ 1,473,717
ALLL to loans	0.73%	0.77%
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 917,936	$ 681,016
% of Total	100.00%	100.00%
Less ALLL	$ 1,856	$ 1,705	2,111
Loans, net	$ 916,080	$ 679,311
ALLL to loans	0.20%	0.25%
Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 496,372
Owner-occupied commercial real estate (“CRE”) | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount		$ 157,822
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 30,211	$ 26,493
% of Total	1.00%	1.00%
Less ALLL	$ 344	$ 304	225
Loans, net	29,867	26,189
Retail & other | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 28,373	$ 23,809
% of Total	2.00%	2.00%
Less ALLL	$ 318	$ 281	200
Loans, net	28,055	23,528
Retail & other | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 1,838	$ 2,684
% of Total	0.00%	1.00%
Less ALLL	$ 26	$ 23	25
Loans, net	1,812	2,661
Commercial Portfolio Segment | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 806,189	$ 684,920
% of Total	31.00%	32.00%
Less ALLL	$ 5,471	$ 5,271	4,934
Loans, net	800,718	679,649
Commercial Portfolio Segment | Commercial & industrial | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 641,341	$ 568,100
% of Total	39.00%	38.00%
Less ALLL	$ 4,837	$ 4,683	4,192
Loans, net	636,504	563,417
Commercial Portfolio Segment | Commercial & industrial | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 164,848	$ 116,820
% of Total	18.00%	17.00%
Less ALLL	$ 634	$ 588	742
Loans, net	164,214	116,232
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 496,372	$ 441,353
% of Total	19.00%	20.00%
Less ALLL	$ 3,010	$ 2,847	2,607
Loans, net	493,362	438,506
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”) | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 329,138	$ 283,531
% of Total	20.00%	19.00%
Less ALLL	$ 2,560	$ 2,439	2,115
Loans, net	326,578	281,092
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”) | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 167,234	$ 157,822
% of Total	18.00%	23.00%
Less ALLL	$ 450	$ 408	492
Loans, net	166,784	157,414
Commercial Portfolio Segment | Agricultural (“AG”) production
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 35,982	$ 35,625
% of Total	2.00%	2.00%
Less ALLL	$ 210	$ 121	129
Loans, net	35,772	35,504
Commercial Portfolio Segment | Agricultural (“AG”) production | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 11,824	$ 11,113
% of Total	1.00%	1.00%
Less ALLL	$ 195	$ 110	112
Loans, net	11,629	11,003
Commercial Portfolio Segment | Agricultural (“AG”) production | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 24,158	$ 24,512
% of Total	3.00%	4.00%
Less ALLL	$ 15	$ 11	17
Loans, net	24,143	24,501
Commercial Real Estate Portfolio Segment | AG real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 59,468	$ 53,444
% of Total	2.00%	2.00%
Less ALLL	$ 369	$ 301	296
Loans, net	59,099	53,143
Commercial Real Estate Portfolio Segment | AG real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 38,983	$ 31,374
% of Total	2.00%	2.00%
Less ALLL	$ 312	$ 255	235
Loans, net	38,671	31,119
Commercial Real Estate Portfolio Segment | AG real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 20,485	$ 22,070
% of Total	2.00%	3.00%
Less ALLL	$ 57	$ 46	61
Loans, net	20,428	22,024
Commercial Real Estate Portfolio Segment | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 443,218	$ 343,652
% of Total	17.00%	16.00%
Less ALLL	$ 1,600	$ 1,470	1,388
Loans, net	441,618	342,182
Commercial Real Estate Portfolio Segment | CRE investment | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 183,746	$ 171,087
% of Total	11.00%	12.00%
Less ALLL	$ 1,354	$ 1,230	1,154
Loans, net	182,392	169,857
Commercial Real Estate Portfolio Segment | CRE investment | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 259,472	$ 172,565
% of Total	28.00%	25.00%
Less ALLL	$ 246	$ 240	234
Loans, net	259,226	172,325
Commercial Real Estate Portfolio Segment | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 92,970	$ 80,599
% of Total	4.00%	4.00%
Less ALLL	$ 414	$ 510	726
Loans, net	92,556	80,089
Commercial Real Estate Portfolio Segment | Construction & land development | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 56,086	$ 66,478
% of Total	3.00%	4.00%
Less ALLL	$ 350	$ 431	628
Loans, net	55,736	66,047
Commercial Real Estate Portfolio Segment | Construction & land development | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 36,884	$ 14,121
% of Total	4.00%	2.00%
Less ALLL	$ 64	$ 79	98
Loans, net	36,820	14,042
Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 432,167	$ 357,841
% of Total	17.00%	17.00%
Less ALLL	$ 1,669	$ 1,646	1,609
Loans, net	430,498	356,195
Residential | Residential first mortgage | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 232,580	$ 220,368
% of Total	14.00%	15.00%
Less ALLL	$ 1,419	$ 1,400	1,297
Loans, net	231,161	218,968
Residential | Residential first mortgage | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 199,587	$ 137,473
% of Total	22.00%	20.00%
Less ALLL	$ 250	$ 246	312
Loans, net	199,337	137,227
Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 122,771	$ 111,328
% of Total	5.00%	5.00%
Less ALLL	$ 517	$ 472	488
Loans, net	122,254	110,856
Residential | Residential junior mortgage | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 90,284	$ 78,379
% of Total	5.00%	5.00%
Less ALLL	$ 446	$ 408	409
Loans, net	89,838	77,971
Residential | Residential junior mortgage | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 32,487	$ 32,949
% of Total	4.00%	5.00%
Less ALLL	$ 71	$ 64	79
Loans, net	32,416	32,885
Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 54,403	$ 30,926
% of Total	2.00%	1.00%
Less ALLL	$ 368	$ 211	251
Loans, net	54,035	30,715
Residential | Residential construction | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 43,460	$ 30,926
% of Total	3.00%	2.00%
Less ALLL	$ 325	$ 211	200
Loans, net	43,135	30,715
Residential | Residential construction | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 10,943	$ 0
% of Total	1.00%	0.00%
Less ALLL	$ 43	$ 0	$ 51
Loans, net	$ 10,900	$ 0

LOANS, ALLOWANCE FOR LOAN LOS_5

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of allowance for loan losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
ALLL:
Beginning balance	$ 13,153	$ 12,653	$ 11,820
Provision for loan losses	1,200	1,600	2,325
Charge-offs	(927)	(1,213)	(1,604)
Recoveries	546	113	112
Net charge-offs	(381)	(1,100)	(1,492)
Ending balance	$ 13,972	$ 13,153	$ 12,653

LOANS, ALLOWANCE FOR LOAN LOS_6

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of changes in ALLL by portfolio segment for periods - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses
Beginning balance	$ 13,153	$ 12,653	$ 11,820
Provision for loan losses	1,200	1,600	2,325
Charge-offs	(927)	(1,213)	(1,604)
Recoveries	546	113	112
Net charge-offs	(381)	(1,100)	(1,492)
Ending balance	$ 13,972	$ 13,153	12,653
As percent of ALLL	100.00%	100.00%
ALLL:
Individually evaluated	$ 741	$ 0
Collectively evaluated	13,231	13,153
Loans:
Individually evaluated	16,891	9,939
Collectively evaluated	2,556,860	2,156,242
Total loans	2,573,751	2,166,181
Loans, net	2,559,779	2,153,028
Owner-occupied commercial real estate (“CRE”)
Loans:
Total loans	496,372
Retail & other
Financing Receivable, Allowance for Credit Losses
Beginning balance	304	225
Provision for loan losses	338	267
Charge-offs	(347)	(204)
Recoveries	49	16
Net charge-offs	(298)	(188)
Ending balance	$ 344	$ 304	225
As percent of ALLL	2.00%	2.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	344	304
Loans:
Individually evaluated	12	12
Collectively evaluated	30,199	26,481
Total loans	30,211	26,493
Loans, net	29,867	26,189
Commercial Portfolio Segment | Commercial & industrial
Financing Receivable, Allowance for Credit Losses
Beginning balance	5,271	4,934
Provision for loan losses	(61)	1,107
Charge-offs	(159)	(813)
Recoveries	420	43
Net charge-offs	261	(770)
Ending balance	$ 5,471	$ 5,271	4,934
As percent of ALLL	39.00%	40.00%
ALLL:
Individually evaluated	$ 625	$ 0
Collectively evaluated	4,846	5,271
Loans:
Individually evaluated	5,932	2,927
Collectively evaluated	800,257	681,993
Total loans	806,189	684,920
Loans, net	800,718	679,649
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Allowance for Credit Losses
Beginning balance	2,847	2,607
Provision for loan losses	254	300
Charge-offs	(93)	(74)
Recoveries	2	14
Net charge-offs	(91)	(60)
Ending balance	$ 3,010	$ 2,847	2,607
As percent of ALLL	22.00%	22.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	3,010	2,847
Loans:
Individually evaluated	3,430	1,506
Collectively evaluated	492,942	439,847
Total loans	496,372	441,353
Loans, net	493,362	438,506
Commercial Portfolio Segment | Agricultural (“AG”) production
Financing Receivable, Allowance for Credit Losses
Beginning balance	121	129
Provision for loan losses	89	(8)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 210	$ 121	129
As percent of ALLL	1.00%	1.00%
ALLL:
Individually evaluated	$ 116	$ 0
Collectively evaluated	94	121
Loans:
Individually evaluated	1,061	0
Collectively evaluated	34,921	35,625
Total loans	35,982	35,625
Loans, net	35,772	35,504
Commercial Real Estate Portfolio Segment | AG real estate
Financing Receivable, Allowance for Credit Losses
Beginning balance	301	296
Provision for loan losses	68	5
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 369	$ 301	296
As percent of ALLL	3.00%	2.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	369	301
Loans:
Individually evaluated	1,073	222
Collectively evaluated	58,395	53,222
Total loans	59,468	53,444
Loans, net	59,099	53,143
Commercial Real Estate Portfolio Segment | CRE investment
Financing Receivable, Allowance for Credit Losses
Beginning balance	1,470	1,388
Provision for loan losses	130	119
Charge-offs	0	(37)
Recoveries	0	0
Net charge-offs	0	(37)
Ending balance	$ 1,600	$ 1,470	1,388
As percent of ALLL	11.00%	11.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	1,600	1,470
Loans:
Individually evaluated	2,426	1,686
Collectively evaluated	440,792	341,966
Total loans	443,218	343,652
Loans, net	441,618	342,182
Commercial Real Estate Portfolio Segment | Construction & land development
Financing Receivable, Allowance for Credit Losses
Beginning balance	510	726
Provision for loan losses	(96)	(216)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 414	$ 510	726
As percent of ALLL	3.00%	4.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	414	510
Loans:
Individually evaluated	382	603
Collectively evaluated	92,588	79,996
Total loans	92,970	80,599
Loans, net	92,556	80,089
Residential | Residential first mortgage
Financing Receivable, Allowance for Credit Losses
Beginning balance	1,646	1,609
Provision for loan losses	9	117
Charge-offs	(22)	(85)
Recoveries	36	5
Net charge-offs	14	(80)
Ending balance	$ 1,669	$ 1,646	1,609
As percent of ALLL	12.00%	12.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	1,669	1,646
Loans:
Individually evaluated	2,357	2,750
Collectively evaluated	429,810	355,091
Total loans	432,167	357,841
Loans, net	430,498	356,195
Residential | Residential junior mortgage
Financing Receivable, Allowance for Credit Losses
Beginning balance	472	488
Provision for loan losses	86	(51)
Charge-offs	(80)	0
Recoveries	39	35
Net charge-offs	(41)	35
Ending balance	$ 517	$ 472	488
As percent of ALLL	4.00%	4.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	517	472
Loans:
Individually evaluated	218	233
Collectively evaluated	122,553	111,095
Total loans	122,771	111,328
Loans, net	122,254	110,856
Residential | Residential construction
Financing Receivable, Allowance for Credit Losses
Beginning balance	211	251
Provision for loan losses	383	(40)
Charge-offs	(226)	0
Recoveries	0	0
Net charge-offs	(226)	0
Ending balance	$ 368	$ 211	251
As percent of ALLL	3.00%	2.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	368	211
Loans:
Individually evaluated	0	0
Collectively evaluated	54,403	30,926
Total loans	54,403	30,926
Loans, net	54,035	30,715
Originated
Financing Receivable, Allowance for Credit Losses
Beginning balance	11,448	10,542
Provision for loan losses	895	2,014
Charge-offs	(767)	(1,200)
Recoveries	540	92
Net charge-offs	(227)	(1,108)
Ending balance	$ 12,116	$ 11,448	10,542
As percent of ALLL	100.00%	100.00%
ALLL:
Individually evaluated	$ 741	$ 0
Collectively evaluated	11,375	11,448
Loans:
Individually evaluated	5,708	548
Collectively evaluated	1,650,107	1,484,617
Total loans	1,655,815	1,485,165
Loans, net	1,643,699	1,473,717
Originated | Retail & other
Financing Receivable, Allowance for Credit Losses
Beginning balance	281	200
Provision for loan losses	335	266
Charge-offs	(347)	(201)
Recoveries	49	16
Net charge-offs	(298)	(185)
Ending balance	$ 318	$ 281	200
As percent of ALLL	2.00%	2.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	318	281
Loans:
Individually evaluated	0	0
Collectively evaluated	28,373	23,809
Total loans	28,373	23,809
Loans, net	28,055	23,528
Originated | Commercial Portfolio Segment | Commercial & industrial
Financing Receivable, Allowance for Credit Losses
Beginning balance	4,683	4,192
Provision for loan losses	(207)	1,262
Charge-offs	(59)	(813)
Recoveries	420	42
Net charge-offs	361	(771)
Ending balance	$ 4,837	$ 4,683	4,192
As percent of ALLL	40.00%	41.00%
ALLL:
Individually evaluated	$ 625	$ 0
Collectively evaluated	4,212	4,683
Loans:
Individually evaluated	1,993	227
Collectively evaluated	639,348	567,873
Total loans	641,341	568,100
Loans, net	636,504	563,417
Originated | Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Allowance for Credit Losses
Beginning balance	2,439	2,115
Provision for loan losses	212	385
Charge-offs	(93)	(64)
Recoveries	2	3
Net charge-offs	(91)	(61)
Ending balance	$ 2,560	$ 2,439	2,115
As percent of ALLL	21.00%	21.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	2,560	2,439
Loans:
Individually evaluated	1,845	321
Collectively evaluated	327,293	283,210
Total loans	329,138	283,531
Loans, net	326,578	281,092
Originated | Commercial Portfolio Segment | Agricultural (“AG”) production
Financing Receivable, Allowance for Credit Losses
Beginning balance	110	112
Provision for loan losses	85	(2)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 195	$ 110	112
As percent of ALLL	2.00%	1.00%
ALLL:
Individually evaluated	$ 116	$ 0
Collectively evaluated	79	110
Loans:
Individually evaluated	1,008	0
Collectively evaluated	10,816	11,113
Total loans	11,824	11,113
Loans, net	11,629	11,003
Originated | Commercial Real Estate Portfolio Segment | AG real estate
Financing Receivable, Allowance for Credit Losses
Beginning balance	255	235
Provision for loan losses	57	20
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 312	$ 255	235
As percent of ALLL	2.00%	2.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	312	255
Loans:
Individually evaluated	862	0
Collectively evaluated	38,121	31,374
Total loans	38,983	31,374
Loans, net	38,671	31,119
Originated | Commercial Real Estate Portfolio Segment | CRE investment
Financing Receivable, Allowance for Credit Losses
Beginning balance	1,230	1,154
Provision for loan losses	124	113
Charge-offs	0	(37)
Recoveries	0	0
Net charge-offs	0	(37)
Ending balance	$ 1,354	$ 1,230	1,154
As percent of ALLL	11.00%	11.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	1,354	1,230
Loans:
Individually evaluated	0	0
Collectively evaluated	183,746	171,087
Total loans	183,746	171,087
Loans, net	182,392	169,857
Originated | Commercial Real Estate Portfolio Segment | Construction & land development
Financing Receivable, Allowance for Credit Losses
Beginning balance	431	628
Provision for loan losses	(81)	(197)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 350	$ 431	628
As percent of ALLL	3.00%	4.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	350	431
Loans:
Individually evaluated	0	0
Collectively evaluated	56,086	66,478
Total loans	56,086	66,478
Loans, net	55,736	66,047
Originated | Residential | Residential first mortgage
Financing Receivable, Allowance for Credit Losses
Beginning balance	1,400	1,297
Provision for loan losses	5	187
Charge-offs	(22)	(85)
Recoveries	36	1
Net charge-offs	14	(84)
Ending balance	$ 1,419	$ 1,400	1,297
As percent of ALLL	12.00%	12.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	1,419	1,400
Loans:
Individually evaluated	0	0
Collectively evaluated	232,580	220,368
Total loans	232,580	220,368
Loans, net	231,161	218,968
Originated | Residential | Residential junior mortgage
Financing Receivable, Allowance for Credit Losses
Beginning balance	408	409
Provision for loan losses	25	(31)
Charge-offs	(20)	0
Recoveries	33	30
Net charge-offs	13	30
Ending balance	$ 446	$ 408	409
As percent of ALLL	4.00%	4.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	446	408
Loans:
Individually evaluated	0	0
Collectively evaluated	90,284	78,379
Total loans	90,284	78,379
Loans, net	89,838	77,971
Originated | Residential | Residential construction
Financing Receivable, Allowance for Credit Losses
Beginning balance	211	200
Provision for loan losses	340	11
Charge-offs	(226)	0
Recoveries	0	0
Net charge-offs	(226)	0
Ending balance	$ 325	$ 211	200
As percent of ALLL	3.00%	2.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	325	211
Loans:
Individually evaluated	0	0
Collectively evaluated	43,460	30,926
Total loans	43,460	30,926
Loans, net	43,135	30,715
Acquired
Financing Receivable, Allowance for Credit Losses
Beginning balance	1,705	2,111
Provision for loan losses	305	(414)
Charge-offs	(160)	(13)
Recoveries	6	21
Net charge-offs	(154)	8
Ending balance	$ 1,856	$ 1,705	2,111
As percent of ALLL	100.00%	100.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	1,856	1,705
Loans:
Individually evaluated	11,183	9,391
Collectively evaluated	906,753	671,625
Total loans	917,936	681,016
Loans, net	916,080	679,311
Acquired | Owner-occupied commercial real estate (“CRE”)
Loans:
Total loans		157,822
Acquired | Retail & other
Financing Receivable, Allowance for Credit Losses
Beginning balance	23	25
Provision for loan losses	3	1
Charge-offs	0	(3)
Recoveries	0	0
Net charge-offs	0	(3)
Ending balance	$ 26	$ 23	25
As percent of ALLL	1.00%	1.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	26	23
Loans:
Individually evaluated	12	12
Collectively evaluated	1,826	2,672
Total loans	1,838	2,684
Loans, net	1,812	2,661
Acquired | Commercial Portfolio Segment | Commercial & industrial
Financing Receivable, Allowance for Credit Losses
Beginning balance	588	742
Provision for loan losses	146	(155)
Charge-offs	(100)	0
Recoveries	0	1
Net charge-offs	(100)	1
Ending balance	$ 634	$ 588	742
As percent of ALLL	34.00%	34.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	634	588
Loans:
Individually evaluated	3,939	2,700
Collectively evaluated	160,909	114,120
Total loans	164,848	116,820
Loans, net	164,214	116,232
Acquired | Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Allowance for Credit Losses
Beginning balance	408	492
Provision for loan losses	42	(85)
Charge-offs	0	(10)
Recoveries	0	11
Net charge-offs	0	1
Ending balance	$ 450	$ 408	492
As percent of ALLL	24.00%	24.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	450	408
Loans:
Individually evaluated	1,585	1,185
Collectively evaluated	165,649	156,637
Total loans	167,234	157,822
Loans, net	166,784	157,414
Acquired | Commercial Portfolio Segment | Agricultural (“AG”) production
Financing Receivable, Allowance for Credit Losses
Beginning balance	11	17
Provision for loan losses	4	(6)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 15	$ 11	17
As percent of ALLL	1.00%	1.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	15	11
Loans:
Individually evaluated	53	0
Collectively evaluated	24,105	24,512
Total loans	24,158	24,512
Loans, net	24,143	24,501
Acquired | Commercial Real Estate Portfolio Segment | AG real estate
Financing Receivable, Allowance for Credit Losses
Beginning balance	46	61
Provision for loan losses	11	(15)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 57	$ 46	61
As percent of ALLL	3.00%	3.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	57	46
Loans:
Individually evaluated	211	222
Collectively evaluated	20,274	21,848
Total loans	20,485	22,070
Loans, net	20,428	22,024
Acquired | Commercial Real Estate Portfolio Segment | CRE investment
Financing Receivable, Allowance for Credit Losses
Beginning balance	240	234
Provision for loan losses	6	6
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 246	$ 240	234
As percent of ALLL	13.00%	14.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	246	240
Loans:
Individually evaluated	2,426	1,686
Collectively evaluated	257,046	170,879
Total loans	259,472	172,565
Loans, net	259,226	172,325
Acquired | Commercial Real Estate Portfolio Segment | Construction & land development
Financing Receivable, Allowance for Credit Losses
Beginning balance	79	98
Provision for loan losses	(15)	(19)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 64	$ 79	98
As percent of ALLL	4.00%	5.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	64	79
Loans:
Individually evaluated	382	603
Collectively evaluated	36,502	13,518
Total loans	36,884	14,121
Loans, net	36,820	14,042
Acquired | Residential | Residential first mortgage
Financing Receivable, Allowance for Credit Losses
Beginning balance	246	312
Provision for loan losses	4	(70)
Charge-offs	0	0
Recoveries	0	4
Net charge-offs	0	4
Ending balance	$ 250	$ 246	312
As percent of ALLL	14.00%	14.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	250	246
Loans:
Individually evaluated	2,357	2,750
Collectively evaluated	197,230	134,723
Total loans	199,587	137,473
Loans, net	199,337	137,227
Acquired | Residential | Residential junior mortgage
Financing Receivable, Allowance for Credit Losses
Beginning balance	64	79
Provision for loan losses	61	(20)
Charge-offs	(60)	0
Recoveries	6	5
Net charge-offs	(54)	5
Ending balance	$ 71	$ 64	79
As percent of ALLL	4.00%	4.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	71	64
Loans:
Individually evaluated	218	233
Collectively evaluated	32,269	32,716
Total loans	32,487	32,949
Loans, net	32,416	32,885
Acquired | Residential | Residential construction
Financing Receivable, Allowance for Credit Losses
Beginning balance	0	51
Provision for loan losses	43	(51)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	$ 43	$ 0	$ 51
As percent of ALLL	2.00%	0.00%
ALLL:
Individually evaluated	$ 0	$ 0
Collectively evaluated	43	0
Loans:
Individually evaluated	0	0
Collectively evaluated	10,943	0
Total loans	10,943	0
Loans, net	$ 10,900	$ 0

LOANS, ALLOWANCE FOR LOAN LOS_7

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Nonaccrual loans by portfolio segment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 14,122	$ 5,471
% of Total	100.00%	100.00%
Percent of nonaccrual loans	0.50%	0.20%
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1	$ 0
% of Total	0.00%	0.00%
Commercial Portfolio Segment | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 6,249	$ 2,816
% of Total	44.00%	52.00%
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 3,311	$ 673
% of Total	23.00%	12.00%
Commercial Portfolio Segment | Agricultural (“AG”) production
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,062	$ 0
% of Total	8.00%	0.00%
Commercial Real Estate Portfolio Segment | AG real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 836	$ 164
% of Total	6.00%	3.00%
Commercial Real Estate Portfolio Segment | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,073	$ 210
% of Total	8.00%	4.00%
Commercial Real Estate Portfolio Segment | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 20	$ 80
% of Total	0.00%	1.00%
Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,090	$ 1,265
% of Total	8.00%	23.00%
Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 480	$ 262
% of Total	3.00%	5.00%
Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 0	$ 1
% of Total	0.00%	0.00%
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 6,324	$ 1,409
% of Total	100.00%	100.00%
Percent of nonaccrual loans	45.00%	26.00%
Originated | Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1	$ 0
% of Total	0.00%	0.00%
Originated | Commercial Portfolio Segment | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 2,283	$ 352
% of Total	36.00%	25.00%
Originated | Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,846	$ 362
% of Total	29.00%	26.00%
Originated | Commercial Portfolio Segment | Agricultural (“AG”) production
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,009	$ 0
% of Total	16.00%	0.00%
Originated | Commercial Real Estate Portfolio Segment | AG real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 625	$ 0
% of Total	10.00%	0.00%
Originated | Commercial Real Estate Portfolio Segment | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 0	$ 0
% of Total	0.00%	0.00%
Originated | Commercial Real Estate Portfolio Segment | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 0	$ 0
% of Total	0.00%	0.00%
Originated | Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 434	$ 629
% of Total	7.00%	45.00%
Originated | Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 126	$ 65
% of Total	2.00%	4.00%
Originated | Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 0	$ 1
% of Total	0.00%	0.00%
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 7,798	$ 4,062
% of Total	100.00%	100.00%
Percent of nonaccrual loans	55.00%	74.00%
Acquired | Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 0	$ 0
% of Total	0.00%	0.00%
Acquired | Commercial Portfolio Segment | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 3,966	$ 2,464
% of Total	51.00%	61.00%
Acquired | Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,465	$ 311
% of Total	19.00%	8.00%
Acquired | Commercial Portfolio Segment | Agricultural (“AG”) production
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 53	$ 0
% of Total	1.00%	0.00%
Acquired | Commercial Real Estate Portfolio Segment | AG real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 211	$ 164
% of Total	3.00%	4.00%
Acquired | Commercial Real Estate Portfolio Segment | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 1,073	$ 210
% of Total	14.00%	5.00%
Acquired | Commercial Real Estate Portfolio Segment | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 20	$ 80
% of Total	0.00%	2.00%
Acquired | Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 656	$ 636
% of Total	8.00%	15.00%
Acquired | Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 354	$ 197
% of Total	4.00%	5.00%
Acquired | Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 0	$ 0
% of Total	0.00%	0.00%

LOANS, ALLOWANCE FOR LOAN LOS_8

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of loans by past due status (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 2,552,360	$ 2,159,139
Amount	$ 2,573,751	$ 2,166,181
Current - As a percent of total loans	99.20%	99.70%
As a percent of total loans	100.00%	100.00%
30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	$ 7,269	$ 1,571
Percent of total loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Percent Past Due	0.30%	0.10%
90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	$ 14,122	$ 5,471
Financing Receivable, Percent Past Due	0.50%	0.20%
Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 496,372
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	30,100	$ 26,483
Amount	30,211	26,493
Retail & other | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	110	10
Retail & other | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	1	0
Commercial Portfolio Segment | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	798,211	682,104
Amount	806,189	684,920
Commercial Portfolio Segment | Commercial & industrial | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	1,729	0
Commercial Portfolio Segment | Commercial & industrial | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	6,249	2,816
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	492,949	440,123
Amount	496,372	441,353
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”) | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	112	557
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”) | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	3,311	673
Commercial Portfolio Segment | Agricultural (“AG”) production
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	34,920	35,606
Amount	35,982	35,625
Commercial Portfolio Segment | Agricultural (“AG”) production | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	0	19
Commercial Portfolio Segment | Agricultural (“AG”) production | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	1,062	0
Commercial Real Estate Portfolio Segment | AG real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	58,632	53,245
Amount	59,468	53,444
Commercial Real Estate Portfolio Segment | AG real estate | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	0	35
Commercial Real Estate Portfolio Segment | AG real estate | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	836	164
Commercial Real Estate Portfolio Segment | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	442,145	343,262
Amount	443,218	343,652
Commercial Real Estate Portfolio Segment | CRE investment | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	0	180
Commercial Real Estate Portfolio Segment | CRE investment | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	1,073	210
Commercial Real Estate Portfolio Segment | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	90,887	80,519
Amount	92,970	80,599
Commercial Real Estate Portfolio Segment | Construction & land development | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	2,063	0
Commercial Real Estate Portfolio Segment | Construction & land development | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	20	80
Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	428,341	355,818
Amount	432,167	357,841
Residential | Residential first mortgage | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	2,736	758
Residential | Residential first mortgage | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	1,090	1,265
Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	122,074	111,054
Amount	122,771	111,328
Residential | Residential junior mortgage | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	217	12
Residential | Residential junior mortgage | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	480	262
Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	54,101	30,925
Amount	54,403	30,926
Residential | Residential construction | 30-89 Days Past Due (accruing)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	302	0
Residential | Residential construction | 90 Days & Over or nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due	$ 0	$ 1

LOANS, ALLOWANCE FOR LOAN LOS_9

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of loans by credit quality indicator based on internally assigned credit grade (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 2,573,751	$ 2,166,181
Percent of total	100.00%	100.00%
Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 2,457,922	$ 2,061,424
Percent of total	95.50%	95.10%
Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 63,966	$ 58,822
Percent of total	2.50%	2.70%
Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 15,152	$ 18,607
Percent of total	0.60%	0.90%
Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 36,711	$ 27,328
Percent of total	1.40%	1.30%
Retail & other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 30,211	$ 26,493
Retail & other | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	30,210	26,493
Retail & other | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	0	0
Retail & other | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	0	0
Retail & other | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	1	0
Commercial Portfolio Segment | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	806,189	684,920
Commercial Portfolio Segment | Commercial & industrial | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	765,073	649,475
Commercial Portfolio Segment | Commercial & industrial | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	20,199	16,145
Commercial Portfolio Segment | Commercial & industrial | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	7,663	6,178
Commercial Portfolio Segment | Commercial & industrial | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	13,254	13,122
Commercial Portfolio Segment | Owner-occupied CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	496,372	441,353
Commercial Portfolio Segment | Owner-occupied CRE | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	464,661	405,198
Commercial Portfolio Segment | Owner-occupied CRE | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	20,855	22,776
Commercial Portfolio Segment | Owner-occupied CRE | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	953	6,569
Commercial Portfolio Segment | Owner-occupied CRE | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	9,903	6,810
Commercial Portfolio Segment | Agricultural (“AG”) production
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	35,982	35,625
Commercial Portfolio Segment | Agricultural (“AG”) production | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	27,521	29,363
Commercial Portfolio Segment | Agricultural (“AG”) production | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	3,174	3,302
Commercial Portfolio Segment | Agricultural (“AG”) production | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	1,229	2,351
Commercial Portfolio Segment | Agricultural (“AG”) production | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	4,058	609
Commercial Real Estate Portfolio Segment | AG real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	59,468	53,444
Commercial Real Estate Portfolio Segment | AG real estate | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	49,561	46,248
Commercial Real Estate Portfolio Segment | AG real estate | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	3,611	3,246
Commercial Real Estate Portfolio Segment | AG real estate | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	2,046	2,983
Commercial Real Estate Portfolio Segment | AG real estate | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	4,250	967
Commercial Real Estate Portfolio Segment | CRE investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	443,218	343,652
Commercial Real Estate Portfolio Segment | CRE investment | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	430,794	334,080
Commercial Real Estate Portfolio Segment | CRE investment | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	8,085	6,792
Commercial Real Estate Portfolio Segment | CRE investment | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	2,578	0
Commercial Real Estate Portfolio Segment | CRE investment | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	1,761	2,780
Commercial Real Estate Portfolio Segment | Construction & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	92,970	80,599
Commercial Real Estate Portfolio Segment | Construction & land development | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	90,523	75,365
Commercial Real Estate Portfolio Segment | Construction & land development | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	2,213	5,138
Commercial Real Estate Portfolio Segment | Construction & land development | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	15	16
Commercial Real Estate Portfolio Segment | Construction & land development | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	219	80
Residential | Residential first mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	432,167	357,841
Residential | Residential first mortgage | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	424,044	353,239
Residential | Residential first mortgage | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	4,677	1,406
Residential | Residential first mortgage | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	668	510
Residential | Residential first mortgage | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	2,778	2,686
Residential | Residential junior mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	122,771	111,328
Residential | Residential junior mortgage | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	122,249	111,037
Residential | Residential junior mortgage | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	35	17
Residential | Residential junior mortgage | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	0	0
Residential | Residential junior mortgage | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	487	274
Residential | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	54,403	30,926
Residential | Residential construction | Grades 1-4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	53,286	30,926
Residential | Residential construction | Grade 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	1,117	0
Residential | Residential construction | Grade 6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	0	0
Residential | Residential construction | Grade 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount	$ 0	$ 0

LOANS, ALLOWANCE FOR LOAN LO_10

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of information pertaining to impaired loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	$ 16,891	$ 9,939
Unpaid Principal Balance	20,300	16,021
Related Allowance	741	0
Average Recorded Investment	16,998	10,699
Interest Income Recognized	2,063	1,199
Impaired Financing Receivable
Recorded Investment	16,891	9,939
Unpaid Principal Balance	20,300	16,021
Related Allowance	741	0
Average Recorded Investment	16,998	10,699
Interest Income Recognized	2,063	1,199
Retail & other
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	12	12
Unpaid Principal Balance	12	12
Related Allowance	0	0
Average Recorded Investment	12	12
Interest Income Recognized	0	1
Commercial Portfolio Segment | Commercial & industrial
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	5,932	2,927
Unpaid Principal Balance	7,950	6,736
Related Allowance	625	0
Average Recorded Investment	5,405	4,041
Interest Income Recognized	1,170	660
Commercial Portfolio Segment | Owner-occupied commercial real estate (“CRE”)
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	3,430	1,506
Unpaid Principal Balance	4,016	1,833
Related Allowance	0	0
Average Recorded Investment	3,677	1,659
Interest Income Recognized	256	137
Commercial Portfolio Segment | Agricultural (“AG”) production
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	1,061	0
Unpaid Principal Balance	1,090	0
Related Allowance	116	0
Average Recorded Investment	1,221	0
Interest Income Recognized	28	0
Commercial Real Estate Portfolio Segment | AG real estate
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	1,073	222
Unpaid Principal Balance	1,082	281
Related Allowance	0	0
Average Recorded Investment	1,090	238
Interest Income Recognized	9	26
Commercial Real Estate Portfolio Segment | CRE investment
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	2,426	1,686
Unpaid Principal Balance	2,790	2,484
Related Allowance	0	0
Average Recorded Investment	2,497	1,606
Interest Income Recognized	364	163
Commercial Real Estate Portfolio Segment | Construction & land development
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	382	603
Unpaid Principal Balance	382	1,506
Related Allowance	0	0
Average Recorded Investment	460	603
Interest Income Recognized	0	21
Residential | Residential first mortgage
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	2,357	2,750
Unpaid Principal Balance	2,629	2,907
Related Allowance	0	0
Average Recorded Investment	2,412	2,478
Interest Income Recognized	178	176
Residential | Residential junior mortgage
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	218	233
Unpaid Principal Balance	349	262
Related Allowance	0	0
Average Recorded Investment	224	62
Interest Income Recognized	58	15
Residential | Residential construction
Impaired Financing Receivable, with No Realted Allowance
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Originated
Impaired Financing Receivable
Recorded Investment	5,708	548
Unpaid Principal Balance	5,938	548
Related Allowance	741	0
Average Recorded Investment	5,978	899
Interest Income Recognized	230	154
Acquired
Impaired Financing Receivable
Recorded Investment	11,183	9,391
Unpaid Principal Balance	14,362	15,473
Related Allowance	0	0
Average Recorded Investment	11,020	9,800
Interest Income Recognized	$ 1,833	$ 1,045

LOANS, ALLOWANCE FOR LOAN LO_11

LOANS, ALLOWANCE FOR LOAN LOSSES, AND CREDIT QUALITY - Summary of Non-accretable discount on purchase credit impaired ("PCI") loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accretion Discount [Roll Forward]
Balance at beginning of period	$ 6,408	$ 9,471
Acquired balance, net	911	0
Accretion To Loan Interest Income	(4,713)	(1,976)
Transferred to accretable	0	(990)
Disposals of loans	(679)	(97)
Balance at end of period	$ 1,927	$ 6,408

PREMISES AND EQUIPMENT - Narrat

PREMISES AND EQUIPMENT - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation expense		$ 3.8	$ 4.4	$ 4.2
Rent expense		$ 1.2	$ 1.4	$ 1.1
Lease termination liability	$ 0.7
Minimum
Property, Plant and Equipment [Line Items]
Renewal term on operating leases	5 years	5 years
Maximum
Property, Plant and Equipment [Line Items]
Renewal term on operating leases	10 years	10 years
Land and Building | Minimum
Property, Plant and Equipment [Line Items]
Remaining lease term on operating leases		2 years
Land and Building | Maximum
Property, Plant and Equipment [Line Items]
Remaining lease term on operating leases		6 years

PREMISES AND EQUIPMENT - Summar

PREMISES AND EQUIPMENT - Summary of premises and equipment, less accumulated depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 86,943	$ 74,982
Less accumulated depreciation and amortization	30,474	26,809
Premises and equipment, net	56,469	48,173
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	7,418	6,220
Land improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	3,865	3,842
Building and improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	50,818	42,238
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	4,580	4,092
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 20,262	$ 18,590

PREMISES AND EQUIPMENT - Other

PREMISES AND EQUIPMENT - Other Information Related To Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Property, Plant and Equipment [Abstract]
Operating lease cost	$ 970
Variable lease cost	233
Net lease cost	$ 1,203
Weighted average remaining lease term (years)	4 years 4 months 2 days
Weighted average discount rate	2.50%

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, 2019USD ($)
Property, Plant and Equipment [Abstract]
2020	$ 1,088
2021	962
2022	851
2023	607
2024	499
Thereafter	16
Lessee, Operating Lease, Liability, Payments, Due	4,023
Less: amount representing interest	(100)
Present value of net future minimum lease payments	$ 3,923

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS Other Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill:
Goodwill at beginning of year	$ 107,366	$ 107,366
Acquisition	44,594	0
Impairment	(762)	0
Goodwill at end of year	$ 151,198	$ 107,366

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS - Summary of Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets And Mortgage Servicing Rights [Line Items]
Goodwill	$ 151,198	$ 107,366	$ 107,366
Goodwill and other intangibles, net	165,967	124,307
Core deposit intangibles
Goodwill And Intangible Assets And Mortgage Servicing Rights [Line Items]
Other intangibles	10,897	12,562
Customer list intangibles:
Goodwill And Intangible Assets And Mortgage Servicing Rights [Line Items]
Other intangibles	3,872	4,379
Other intangibles
Goodwill And Intangible Assets And Mortgage Servicing Rights [Line Items]
Other intangibles	$ 14,769	$ 16,941

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS - Other Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization during the period	$ 3,872	$ 4,389	$ 4,695
Core deposit intangibles:
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	30,715	29,015
Accumulated amortization	(19,818)	(16,453)
Net book value	10,897	12,562
Additions during the period	1,700	0
Amortization during the period	3,365	3,915
Customer list intangibles:
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	5,523	5,523
Accumulated amortization	(1,651)	(1,144)
Net book value	3,872	4,379
Additions during the period	0	290
Amortization during the period	$ 507	$ 474

GOODWILL AND OTHER INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS (Details 2) - Mortgage Servicing Rights - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
MSR Asset
MSR asset at beginning of year	$ 3,749	$ 3,187
Capitalized MSR	2,876	1,203
MSR asset acquired	160	0
Amortization during the period	(866)	(641)
MSR asset at end of year	5,919	3,749
Fair value of MSR asset at end of period	8,420	6,347
Residential mortgage loans serviced for others	$ 847,756	$ 603,446
Net Book Value Of Msr Asset To Loans Serviced For Others	0.70%	0.62%

GOODWILL AND OTHER INTANGIBLE_7

GOODWILL AND OTHER INTANGIBLES AND MORTGAGE SERVICING RIGHTS (Details 3) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Core deposit intangibles
Core Deposit and Customer List Intangibles
2020	$ 2,993
2021	2,453
2022	1,987
2023	1,490
2024	1,010
Thereafter	964
Net book value	10,897	$ 12,562
Customer list intangibles:
Core Deposit and Customer List Intangibles
2020	507
2021	507
2022	507
2023	483
2024	449
Thereafter	1,419
Net book value	3,872	$ 4,379
Mortgage Servicing Rights [Member]
Core Deposit and Customer List Intangibles
2020	1,048
2021	865
2022	865
2023	835
2024	503
Thereafter	1,803
Net book value	$ 5,919

DEPOSITS - Narrative (Details)

DEPOSITS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Aggregate amount of time deposits with minimum denomination of $250,000	$ 91.2	$ 77.6

DEPOSITS - Maturities of time d

DEPOSITS - Maturities of time deposits (Details) $ in Thousands	Dec. 31, 2019USD ($)
Deposits [Abstract]
2020	$ 317,693
2021	114,728
2022	50,949
2023	45,040
2024	19,773
Thereafter	2,374
Total time deposits	$ 550,557

SHORT AND LONG-TERM BORROWING_2

SHORT AND LONG-TERM BORROWINGS - Narrative (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2015	Dec. 31, 2018
Debt Type [Line Items]
Trust preferred securities qualify as Tier 1 capital	$ 29,400,000		$ 28,900,000
Par	$ 38,249,000
FHLB advances
Debt Type [Line Items]
Weighted average rate of FHLB advances	1.57%		1.72%
FHLB advances collateralized pledged	$ 273,500,000		$ 295,300,000
Subordinated Notes
Debt Type [Line Items]
Par		$ 12,000,000
Subordinated notes, maturity period		10 years
Subordinated Borrowing, Interest Rate		5.00%
Nicolet Bankshares, Inc | Line of Credit
Debt Type [Line Items]
Line of credit with third party bank	$ 10,000,000
Basis spread rate	2.25%
Floor rate	3.25%
Long-term line of credit outstanding	$ 0		$ 0

SHORT AND LONG-TERM BORROWING_3

SHORT AND LONG-TERM BORROWINGS - Long-term debt instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term borrowings	$ 67,629	$ 77,305
FHLB advances
Debt Instrument [Line Items]
Long-term borrowings	25,061	35,252
Junior subordinated debentures
Debt Instrument [Line Items]
Subordinated notes	30,575	30,096
Subordinated notes
Debt Instrument [Line Items]
Subordinated notes	$ 11,993	$ 11,957

SHORT AND LONG-TERM BORROWING_4

SHORT AND LONG-TERM BORROWINGS - Summary of maturity of notes payable (Details) - FHLB advances $ in Thousands	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
2020	$ 10,061
2021	10,000
2022	0
2023	0
2024	0
2025	5,000
Advances from Federal Home Loan Banks	$ 25,061

SHORT AND LONG-TERM BORROWING_5

SHORT AND LONG-TERM BORROWINGS - Junior Subordinated Debentures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Par	$ 38,249
Unamortized discount	(7,674)
Carrying Value	30,575	$ 30,096
2005 Mid-Wisconsin Financial Services, Inc.
Debt Instrument [Line Items]
Par	10,310
Unamortized discount	(3,172)
Carrying Value	$ 7,138	$ 6,939
Interest rate at period end	3.32%	4.22%
2006 Baylake Corp.
Debt Instrument [Line Items]
Par	$ 16,598
Unamortized discount	(3,883)
Carrying Value	$ 12,715	$ 12,478
Interest rate at period end	3.31%	4.15%
2004 First Menasha Bancshares, Inc.
Debt Instrument [Line Items]
Par	$ 5,155
Unamortized discount	(619)
Carrying Value	$ 4,536	$ 4,493
Interest rate at period end	4.69%	5.58%
2004 Nicolet Bankshares Statutory Trust
Debt Instrument [Line Items]
Par	$ 6,186
Unamortized discount	0
Carrying Value	$ 6,186	$ 6,186
Interest rate at period end	8.00%
London Interbank Offered Rate (LIBOR) | 2005 Mid-Wisconsin Financial Services, Inc.
Debt Instrument [Line Items]
Basis spread rate	1.43%
London Interbank Offered Rate (LIBOR) | 2006 Baylake Corp.
Debt Instrument [Line Items]
Basis spread rate	1.35%
London Interbank Offered Rate (LIBOR) | 2004 First Menasha Bancshares, Inc.
Debt Instrument [Line Items]
Basis spread rate	2.79%

EMPLOYEE AND DIRECTOR BENEFIT_2

EMPLOYEE AND DIRECTOR BENEFIT PLANS - Narrative (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)Planshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of deferred compensation plans | Plan	2
Employees contribution	100.00%
Employer contribution matching percent	100.00%
Percentage of employee's gross pay	6.00%
Vesting period	5 years
Company 401k expense	$ 2,900	$ 1,800	$ 2,000
Profit sharing contribution	1,100		$ 500
Deferred compensation plan | Key Management Employees | Other liabilities
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Liability for cumulative employee contributions and earnings	906	527
Non elective contributions to selected recipients	$ 1,800	$ 175
Deferred compensation plan | Director
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Maximum percentage to defer the compensation under the plan	100.00%
Number of shares purchased under deferred compensation plan | shares	3,769	3,889
Value of shares purchased under deferred compensation plan	$ 220	$ 213
Value of shares distributed under director plan	$ 33	$ 32
Number of shares distributed under director plan | shares	672	600
Deferred compensation liability offsetting equity component	$ 1,030	$ 831
Deferred compensation liability offsetting equity component (in shares) | shares	29,202	26,105
Minimum | Deferred compensation plan | Key Management Employees | Other liabilities
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period from date of grant	4 years
Maximum | Deferred compensation plan | Key Management Employees | Other liabilities
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period from date of grant	5 years

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of options	10 years
Number of shares surrendered (in shares)	142,752	6,411	85,422
Numbers of shares surrendered (in shares)	4,688	3,948	5,266
Stock based compensation expense	$ 4.8	$ 4.7	$ 3.1
Unrecognized compensation cost	$ 13.1
Remaining vesting period over which cost expected to be recognized	3 years
Stock based compensation tax benefit	$ 2.3	0.2
2011 Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares initially covered under the plan	3,000,000
Number of shares were available for grant	1,400,000
2002 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares initially covered under the plan	1,175,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised	$ 13.9	2.2	$ 7.5
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	$ 0.3	$ 0.2
Restricted stock grant	4,257	3,510

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summery weighted average assumptions (Details) - Stock Incentive Plan - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Expected volatility	25.00%	25.00%	25.00%
Risk-free interest rate	1.75%	2.61%	2.14%
Expected average life	7 years	7 years	7 years
Weighted average per share fair value of options (in dollars per share)	$ 21.30	$ 17.36	$ 15.80

STOCK-BASED COMPENSATION- Activ

STOCK-BASED COMPENSATION- Activity of stock incentive plans for options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Options Shares Outstanding
Forfeited	(142,752)	(6,411)	(85,422)
Stock Incentive Plan | Stock Options
Options Shares Outstanding
Outstanding, beginning of period	1,581,699	1,643,255	922,026
Granted	203,000	15,500	949,500
Exercise of stock options	(337,428)	(70,556)	(209,371)
Forfeited	(3,538)	(6,500)	(18,900)
Outstanding, ending of period	1,443,733	1,581,699	1,643,255
Exercisable	561,633
Weighted-Average Exercise Price
Outstanding	$ 40.77	$ 39.82	$ 24.39
Granted	69.69	52.76	49.93
Exercise of stock options	24.15	21.52	18.15
Forfeited	27.43	39.43	35.36
Outstanding	48.75	$ 40.77	$ 39.82
Exercisable Shares	$ 42.91
Outstanding Shares, Weighted Average Remaining Life (in years)	7 years 4 months 20 days	7 years 4 months 17 days	8 years 1 month 6 days
Exercisable Shares, Weighted Average Remaining Life (in years)	6 years 8 months 15 days
Outstanding Shares, Aggregate Intrinsic Value	$ 36,428	$ 13,825	$ 24,525
Exercisable Shares, Aggregate Intrinsic Value	$ 17,384

STOCK-BASED COMPENSATION - Sche

STOCK-BASED COMPENSATION - Schedule of options outstanding (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding | shares	1,443,733
Number of shares exercisable | shares	561,633
Weighted average exercise price outstanding	$ 48.75
Weighted average exercise price exercisable	$ 42.91
Weighted average remaining life (years) outstanding	7 years 4 months 20 days
Weighted average remaining life (years) exercisable	6 years 8 months 15 days
Exercise Price $13.73 - $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding | shares	130,436
Number of shares exercisable | shares	94,936
Weighted average exercise price outstanding	$ 22.37
Weighted average exercise price exercisable	$ 21.85
Weighted average remaining life (years) outstanding	4 years 2 months 12 days
Weighted average remaining life (years) exercisable	4 years 1 month 9 days
Exercise Price $30.01 - $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding | shares	155,747
Number of shares exercisable | shares	89,747
Weighted average exercise price outstanding	$ 35.92
Weighted average exercise price exercisable	$ 35.51
Weighted average remaining life (years) outstanding	6 years 5 months 4 days
Weighted average remaining life (years) exercisable	6 years 4 months 6 days
Exercise Price $40.01 - $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding | shares	804,050
Number of shares exercisable | shares	319,850
Weighted average exercise price outstanding	$ 48.86
Weighted average exercise price exercisable	$ 48.86
Weighted average remaining life (years) outstanding	7 years 4 months 17 days
Weighted average remaining life (years) exercisable	7 years 4 months 17 days
Exercise Price $50.01 - $60.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding | shares	155,500
Number of shares exercisable | shares	57,100
Weighted average exercise price outstanding	$ 56.09
Weighted average exercise price exercisable	$ 56.23
Weighted average remaining life (years) outstanding	7 years 11 months 8 days
Weighted average remaining life (years) exercisable	7 years 10 months 13 days
Exercise Price $60.01- $70.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares outstanding | shares	198,000
Number of shares exercisable | shares	0
Weighted average exercise price outstanding	$ 70.01
Weighted average exercise price exercisable	$ 0
Weighted average remaining life (years) outstanding	9 years 10 months 13 days
Weighted average remaining life (years) exercisable	0 days
Minimum | Exercise Price $13.73 - $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	$ 13.73
Weighted average exercise price exercisable	13.73
Minimum | Exercise Price $30.01 - $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	30.01
Weighted average exercise price exercisable	30.01
Minimum | Exercise Price $40.01 - $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	40.01
Weighted average exercise price exercisable	40.01
Minimum | Exercise Price $50.01 - $60.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	50.01
Weighted average exercise price exercisable	50.01
Minimum | Exercise Price $60.01- $70.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	60.01
Weighted average exercise price exercisable	60.01
Maximum | Exercise Price $13.73 - $30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	30
Weighted average exercise price exercisable	30
Maximum | Exercise Price $30.01 - $40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	40
Weighted average exercise price exercisable	40
Maximum | Exercise Price $40.01 - $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	50
Weighted average exercise price exercisable	50
Maximum | Exercise Price $50.01 - $60.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	60
Weighted average exercise price exercisable	60
Maximum | Exercise Price $60.01- $70.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average exercise price outstanding	70.50
Weighted average exercise price exercisable	$ 70.50

STOCK-BASED COMPENSATION - Acti

STOCK-BASED COMPENSATION - Activity of restricted stock awards (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-Average Grant Date Fair Value
Outstanding, beginning of period	$ 39.37	$ 34.26	$ 26.80
Granted	67.59	52.55	57.75
Vested	51.77	43.58	29.87
Forfeited	16.50	16.50	16.50
Outstanding, end of period	$ 44.94	$ 39.37	$ 34.26
Stock Incentive Plan
Restricted Shares Outstanding
Outstanding, beginning of period	22,521	29,512	30,920	42,949
Granted	12,498	18,256	9,240
Vested	(19,081)	(19,661)	(20,514)
Forfeited	(408)	(3)	(755)
Outstanding, end of period	22,521	29,512	30,920

STOCKHOLDERS' EQUITY (Details)

STOCKHOLDERS' EQUITY (Details) - USD ($)	Nov. 08, 2019	Apr. 28, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Transaction [Line Items]
Cumulative amount repurchased			$ 65,000,000
Cumulative shares repurchased (in shares)			1,400,000
Stock repurchase amount			$ 21,000,000
Common stock issued in acquisitions			79,797,000	$ 0	$ 62,246,000
Merger Agreement | Choice Bancorp Inc.
Stock Transaction [Line Items]
Number of common stock issued for consideration	1,184,102
Common stock issued in acquisitions	$ 79,800,000
Value of cash consideration	1,700,000
Costs incurred related to stock issuance	$ 200,000
Merger Agreement | First Menasha
Stock Transaction [Line Items]
Number of common stock issued for consideration		1,309,885
Common stock issued in acquisitions		$ 62,200,000
Value of cash consideration		19,300,000
Costs incurred related to stock issuance		$ 200,000
Common stock repurchase program
Stock Transaction [Line Items]
Value of shares authorized to repurchased			$ 86,000,000
Shares authorized to repurchased			1,975,000
Stock repurchased under plan			$ 18,700,000
Number of shares cancelled under plan (in shares)			310,800
Weighted average price of share cancelled			$ 60.17

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Additional Tax information [Line Items]
Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act	$ 0	$ 0	$ 885,000
Valuation allowance	0	$ 0
Federal
Additional Tax information [Line Items]
Operating loss carryforwards	3,700,000
State
Additional Tax information [Line Items]
Operating loss carryforwards	$ 24,700,000

INCOME TAXES - Current and defe

INCOME TAXES - Current and deferred amounts of income tax expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current	$ 15,353	$ 14,967	$ 10,952
Deferred	1,105	(1,521)	4,430
Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act	0	0	885
Income tax expense	$ 16,458	$ 13,446	$ 16,267

INCOME TAXES - Differences betw

INCOME TAXES - Differences between income tax expense recognized and amount computed by applying statutory federal income tax rate to earnings before income taxes, less noncontrolling interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax on pretax income, less noncontrolling interest, at statutory rates	$ 14,931	$ 11,441	$ 17,296
State income taxes, net of federal effect	3,672	3,308	2,242
Tax-exempt interest income	(609)	(574)	(1,073)
Non-deductible interest disallowance	29	30	28
Increase in cash surrender value life insurance	(573)	(508)	(807)
Non-deductible business entertainment	189	156	168
Stock-based employee compensation	(2,347)	(232)	(62)
Non-deductible compensation	3,122	0	0
Stock-based employee compensation	0	0	(1,854)
Adjustment to the net deferred tax asset for the Tax Cuts and Jobs Act	0	0	885
Sale of UFS	(2,176)	0	0
Other, net	220	(175)	(556)
Income tax expense	$ 16,458	$ 13,446	$ 16,267

INCOME TAXES - Net deferred tax

INCOME TAXES - Net deferred tax asset includes amounts of deferred tax assets and liabilities (Details 2) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
ALLL	$ 4,985	$ 5,240
Net operating loss carryforwards	1,808	2,202
Credit carryforwards	43	43
Compensation	3,477	2,408
Other	2,830	2,549
Other real estate	201	103
Unrealized loss on securities AFS	0	1,740
Total deferred tax assets	13,344	14,285
Deferred tax liabilities:
Premises and equipment	(1,390)	(821)
Prepaid expenses	(778)	(693)
Investment securities	(755)	(1,723)
Core deposit and other intangibles	(2,836)	(3,563)
Purchase accounting adjustments to liabilities	(2,375)	(2,011)
Other	(1,391)	(1,021)
Unrealized gain on securities AFS	1,879	0
Total deferred tax liabilities	(11,404)	(9,832)
Net deferred tax assets	$ 1,940	$ 4,453

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Commercial-related commitments to extend credit	74.00%	77.00%
Federal funds accommodations	$ 175	$ 175
Interest Rate Lock Commitments
Derivative [Line Items]
Commitments to sell residential mortgage loans held for sale considered derivative instruments	43.4
Forward Commitments
Derivative [Line Items]
Commitments to sell residential mortgage loans held for sale considered derivative instruments	$ 16.3

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Contract or notional amount of exposure to off-balance-sheet risk (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commitments to extend credit
Other Commitments [Line Items]
Contract and notional amounts of commitments	$ 773,555	$ 721,098
Financial standby letters of credit
Other Commitments [Line Items]
Contract and notional amounts of commitments	10,730	8,571
Performance standby letters of credit
Other Commitments [Line Items]
Contract and notional amounts of commitments	$ 8,469	$ 7,094

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Detail Textuals) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Related party loans, total	$ 86,000,000	$ 84,000,000
Cumulative amount repurchased	65,000,000
Rent expense	$ 1,200,000	1,400,000	$ 1,100,000
Nicolet Joint Ventures, LLC (the "JV")
Related Party Transaction [Line Items]
Percentage of Nicolet National Bank	50.00%
Director
Related Party Transaction [Line Items]
Stock repurchased	33,993
Cumulative amount repurchased	$ 2,200,000
Average cost per share	64.02
Director | New branch location in facility opened in October 2013
Related Party Transaction [Line Items]
Estimated, but not paid in full, total payments for capital improvements	$ 1,300,000
Payments for branch reconstruction	$ 400,000	$ 1,000,000
Percentage payments for branch reconstruction paid to subcontractor	75.00%	75.00%
Director | New branch location in facility opened in October 2013 | Maximum
Related Party Transaction [Line Items]
Rent expense	$ 120,000	$ 120,000	120,000
Management
Related Party Transaction [Line Items]
Stock repurchased	32,415
Cumulative amount repurchased	$ 2,200,000
Average cost per share	69.21
Management | Lease agreement for a non-branch location owned by a relative of a senior management team member and paid approximately
Related Party Transaction [Line Items]
Rent expense		138,000	138,000,000
Rent expense	$ 47,500
Relative of the management
Related Party Transaction [Line Items]
Payment for services	650,000	657,000	668,000
Relative of the senior management team member
Related Party Transaction [Line Items]
Payment for services	288,000	284,000	257,000
Nicolet national bank | Nicolet Joint Ventures, LLC (the "JV")
Related Party Transaction [Line Items]
Rent expense	$ 1,200,000	$ 1,100,000	$ 1,100,000

ASSETS GAINS (LOSSES), NET - Co

ASSETS GAINS (LOSSES), NET - Components of gain (loss) on sale, disposals and writedown of assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Gains (losses) on sales of securities AFS, net	$ (22)	$ (212)	$ 1,220
Gains (losses) on equity securities, net	1,115	77	0
Gains (losses) on sales of OREO, net	(88)	1,032	258
Write-downs of OREO	(300)	(120)	(127)
Write-down of other investment	(100)	0	0
Gains (losses) on sales of other investments, net	7,442	187	0
Gains (losses) on sales or dispositions of other assets, net	(150)	205	678
Asset gains (losses), net	$ 7,897	$ 1,169	$ 2,029

REGULATORY CAPITAL REQUIREMEN_3

REGULATORY CAPITAL REQUIREMENTS - Company's and Bank's actual regulatory capital amounts and ratios (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Allowable amount of dividends before regulatory approval required	$ 6,000
Nicolet Bankshares, Inc
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, Actual amount	$ 404,573	$ 326,235
Total risk-based capital, Actual ratio	13.40%	12.90%
Total risk-based capital, For capital adequacy purposes, Actual Amount	$ 241,333	$ 202,836
Total risk-based capital, For capital adequacy purposes, Actual Ratio	8.00%	8.00%
Tier I risk-based capital, Actual amount	$ 378,608	$ 301,125
Tier I risk-based capital, Actual ratio	12.60%	11.90%
Tier I risk-based capital, For capital adequacy purposes, Actual Amount	$ 181,000	$ 152,127
Tier I risk-based capital, For capital adequacy purposes, Actual Ratio	6.00%	6.00%
Common equity Tier 1 capital, Actual Amount	$ 348,454	$ 271,435
Common equity Tier 1 capital, Actual Ratio	11.60%	10.70%
Common equity Tier 1 capital, For Capital Adequacy Purposes, Actual Amount	$ 135,750	$ 114,095
Common equity Tier 1 capital, For Capital Adequacy Purposes, Actual Ratio	4.50%	4.50%
Leverage, Actual amount	$ 378,608	$ 301,125
Leverage, Actual ratio	11.90%	10.40%
Leverage, For capital adequacy purposes, Actual Amount	$ 127,036	$ 115,483
Leverage, For capital adequacy purposes, Actual Ratio	4.00%	4.00%
Nicolet national bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, Actual amount	$ 323,432	$ 274,492
Total risk-based capital, Actual ratio	10.80%	10.80%
Total risk-based capital, For capital adequacy purposes, Actual Amount	$ 240,551	$ 202,800
Total risk-based capital, For capital adequacy purposes, Actual Ratio	8.00%	8.00%
Total risk-based capital, To be well capitalized under prompt corrective action provisions, Actual Amount	$ 300,688	$ 253,501
Total risk-based capital, To be well capitalized under prompt corrective action provisions, Actual Ratio	10.00%	10.00%
Tier I risk-based capital, Actual amount	$ 309,460	$ 261,339
Tier I risk-based capital, Actual ratio	10.30%	10.30%
Tier I risk-based capital, For capital adequacy purposes, Actual Amount	$ 180,413	$ 152,100
Tier I risk-based capital, For capital adequacy purposes, Actual Ratio	6.00%	6.00%
Tier I risk-based capital, To be well capitalized under prompt corrective action provisions, Actual Amount	$ 240,551	$ 202,800
Tier I risk-based capital, To be well capitalized under prompt corrective action provisions, Actual Ratio	8.00%	8.00%
Common equity Tier 1 capital, Actual Amount	$ 309,460	$ 261,339
Common equity Tier 1 capital, Actual Ratio	10.30%	10.30%
Common equity Tier 1 capital, For Capital Adequacy Purposes, Actual Amount	$ 135,310	$ 114,075
Common equity Tier 1 capital, For Capital Adequacy Purposes, Actual Ratio	4.50%	4.50%
Common equity Tier 1 capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Actual Amount	$ 195,447	$ 164,775
Common equity Tier 1 capital, To be well capitalized under prompt corrective action provisions ratio, Actual Ratio	6.50%	6.50%
Leverage, Actual amount	$ 309,460	$ 261,339
Leverage, Actual ratio	9.80%	9.10%
Leverage, For capital adequacy purposes, Actual Amount	$ 126,660	$ 115,280
Leverage, For capital adequacy purposes, Actual Ratio	4.00%	4.00%
Leverage, To be well capitalized under prompt corrective action provisions, Actual Amount	$ 158,325	$ 144,100
Leverage, To be well capitalized under prompt corrective action provisions, Actual Ratio	5.00%	5.00%

FAIR VALUE MEASUREMENTS - Measu

FAIR VALUE MEASUREMENTS - Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	$ 449,302	$ 400,144
Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	449,302	400,144
Level 1 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Level 2 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	446,172	391,654
Level 3 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	3,130	8,490
Measured at Fair Value on a Recurring Basis | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	449,302	400,144
Measured at Fair Value on a Recurring Basis | Total | U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	16,460	21,649
Measured at Fair Value on a Recurring Basis | Total | State, county and municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	156,393	160,526
Measured at Fair Value on a Recurring Basis | Total | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	195,018	131,644
Measured at Fair Value on a Recurring Basis | Total | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	81,431	86,325
Measured at Fair Value on a Recurring Basis | Level 1 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 1 | Total | U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 1 | Total | State, county and municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 1 | Total | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 1 | Total | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 2 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	446,172	391,654
Measured at Fair Value on a Recurring Basis | Level 2 | Total | U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	16,460	21,649
Measured at Fair Value on a Recurring Basis | Level 2 | Total | State, county and municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	156,393	160,460
Measured at Fair Value on a Recurring Basis | Level 2 | Total | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	195,018	131,644
Measured at Fair Value on a Recurring Basis | Level 2 | Total | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	78,301	77,901
Measured at Fair Value on a Recurring Basis | Level 3 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	3,130	8,490
Measured at Fair Value on a Recurring Basis | Level 3 | Total | U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 3 | Total | State, county and municipals
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	66
Measured at Fair Value on a Recurring Basis | Level 3 | Total | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	0	0
Measured at Fair Value on a Recurring Basis | Level 3 | Total | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale (“AFS”), at fair value	3,130	8,424
Equity securities | Measured at Fair Value on a Recurring Basis | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, FV-NI	3,375	2,650
Equity securities | Measured at Fair Value on a Recurring Basis | Level 1 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, FV-NI	3,375	2,650
Equity securities | Measured at Fair Value on a Recurring Basis | Level 2 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, FV-NI	0	0
Equity securities | Measured at Fair Value on a Recurring Basis | Level 3 | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, FV-NI	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Chang

FAIR VALUE MEASUREMENTS - Changes in Level 3 assets (Details) - Level 3 - Fair Value, Measurements, Recurring - Securities AFS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Level 3 Fair Value Measurements:
Balance at beginning of year	$ 8,490	$ 9,151
Acquired balances	300	0
Paydowns/Sales/Settlements	(5,660)	(661)
Balance at end of year	$ 3,130	$ 8,490

FAIR VALUE MEASUREMENTS - Fair

FAIR VALUE MEASUREMENTS - Fair value on a nonrecurring basis (Details) - Measured at Fair Value on a Nonrecurring Basis - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 16,150	$ 9,939
OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	1,000	420
MSR asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	8,420	6,347
Level 1 | Impaired 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 | Impaired 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 | Impaired loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	16,150	9,939
Level 3 | OREO
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	1,000	420
Level 3 | MSR asset
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 8,420	$ 6,347

FAIR VALUE MEASUREMENTS - Finan

FAIR VALUE MEASUREMENTS - Financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial assets:
Securities available for sale (“AFS”), at fair value	$ 449,302	$ 400,144
Carrying Amount
Financial assets:
Cash and cash equivalents	182,059	249,526
Certificates of deposit in other banks	19,305	993
Securities available for sale (“AFS”), at fair value	449,302	400,144
Other investments	24,072	17,997
Loans held for sale	2,706	1,639
Loans, net	2,559,779	2,153,028
BOLI	78,140	66,310
MSR asset	5,919	3,749
Financial liabilities:
Deposits	2,954,453	2,614,138
Long-term Debt, Fair Value	67,629	77,305
Estimated Fair Value
Financial assets:
Cash and cash equivalents	182,059	249,526
Certificates of deposit in other banks	19,310	993
Securities available for sale (“AFS”), at fair value	449,302	400,144
Other investments	24,072	17,997
Loans held for sale	2,753	1,662
Loans, net	2,593,110	2,139,322
BOLI	78,140	66,310
MSR asset	8,420	6,347
Financial liabilities:
Deposits	2,956,229	2,614,995
Long-term Debt, Fair Value	66,816	75,923
Level 1 | Estimated Fair Value
Financial assets:
Cash and cash equivalents	182,059	249,526
Certificates of deposit in other banks	0	0
Securities available for sale (“AFS”), at fair value	0	0
Other investments	3,375	2,650
Loans held for sale	0	0
Loans, net	0	0
BOLI	78,140	66,310
MSR asset	0	0
Financial liabilities:
Deposits	0	0
Long-term Debt, Fair Value	0	0
Level 2 | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Certificates of deposit in other banks	19,310	993
Securities available for sale (“AFS”), at fair value	446,172	391,654
Other investments	16,759	13,189
Loans held for sale	2,753	1,662
Loans, net	0	0
BOLI	0	0
MSR asset	0	0
Financial liabilities:
Deposits	0	0
Long-term Debt, Fair Value	25,075	34,907
Level 3 | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Certificates of deposit in other banks	0	0
Securities available for sale (“AFS”), at fair value	3,130	8,490
Other investments	3,938	2,158
Loans held for sale	0	0
Loans, net	2,593,110	2,139,322
BOLI	0	0
MSR asset	8,420	6,347
Financial liabilities:
Deposits	2,956,229	2,614,995
Long-term Debt, Fair Value	$ 41,741	$ 41,016

PARENT COMPANY ONLY FINANCIAL_3

PARENT COMPANY ONLY FINANCIAL INFORMATION - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and due from subsidiary	$ 75,433	$ 85,896
Goodwill	151,198	107,366	$ 107,366
Total assets	3,577,260	3,096,535
Liabilities and Stockholders’ Equity
Junior subordinated debentures	30,575	30,096
Other liabilities	38,188	17,740
Stockholders’ equity	516,262	386,609
Total liabilities, noncontrolling interest and stockholders’ equity	3,577,260	3,096,535
Nicolet Bankshares, Inc
Assets
Cash and due from subsidiary	70,426	45,279
Investments	6,650	4,500
Investments in subsidiaries	487,644	384,839
Goodwill	(3,266)	(3,266)
Other assets	396	53
Total assets	561,850	431,405
Liabilities and Stockholders’ Equity
Junior subordinated debentures	30,575	30,096
Subordinated notes	11,993	11,957
Other liabilities	3,020	2,743
Stockholders’ equity	516,262	386,609
Total liabilities, noncontrolling interest and stockholders’ equity	$ 561,850	$ 431,405

PARENT COMPANY ONLY FINANCIAL_4

PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Income (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Interest income	$ 138,588	$ 125,537	$ 109,253
Interest expense	22,510	18,889	10,511
Net interest income	116,078	106,648	98,742
Income tax benefit	(16,458)	(13,446)	(16,267)
Net income	54,988	41,353	33,433
Nicolet Bankshares, Inc
Condensed Financial Statements, Captions [Line Items]
Interest income	55	52	46
Interest expense	2,936	2,844	2,415
Net interest income	(2,881)	(2,792)	(2,369)
Dividend income from subsidiaries	50,363	40,775	32,000
Operating expense	(321)	(364)	(369)
Gain (loss) on investments, net	1,015	265	1,411
Income tax benefit	506	305	1,329
Earnings before equity in undistributed income (loss) of subsidiaries	48,682	38,189	32,002
Equity in undistributed income (loss) of subsidiaries	5,959	2,847	1,148
Net income	$ 54,641	$ 41,036	$ 33,150

PARENT COMPANY ONLY FINANCIAL_5

PARENT COMPANY ONLY FINANCIAL INFORMATION - Statements of Cash Flows (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows From Operating Activities:
Net income attributable to Nicolet Bankshares, Inc.	$ 54,988	$ 41,353	$ 33,433
Cash Flows From Financing Activities:
Purchase and retirement of common stock	(28,460)	(22,749)	(15,007)
Proceeds from issuance of common stock, net	8,742	1,800	4,030
Nicolet Bankshares, Inc
Cash Flows From Operating Activities:
Net income attributable to Nicolet Bankshares, Inc.	54,641	41,036	33,150
Adjustments to reconcile net income to net cash provided by operating activities:
Accretion of discounts	515	515	501
(Gain) loss on investments, net	(1,015)	(265)	(1,411)
Change in other assets and liabilities, net	(421)	(25)	(1,384)
Equity in undistributed (income) loss of subsidiaries, net of dividends	(5,959)	(2,847)	(1,148)
Net cash provided by operating activities	47,761	38,414	29,708
Cash Flows From Investing Activities:
Proceeds from sale of investments	0	708	317
Purchases of investments	(2,484)	(920)	0
Net cash paid in business combinations	(412)	0	(19,287)
Net cash used in investing activities	(2,896)	(212)	(18,970)
Cash Flows From Financing Activities:
Purchase and retirement of common stock	(28,460)	(22,749)	(15,007)
Proceeds from issuance of common stock, net	8,742	1,800	4,030
Net cash used in financing activities	(19,718)	(20,949)	(10,977)
Net increase (decrease) in cash and due from subsidiary	25,147	17,253	(239)
Beginning cash and due from subsidiary	45,279	28,026	28,265
Ending cash and due from subsidiary	$ 70,426	$ 45,279	$ 28,026

EARNINGS PER COMMON SHARE (Deta

EARNINGS PER COMMON SHARE (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Shares excluded from calculation of earnings per common share	0.1	0.1	0.1

EARNINGS PER COMMON SHARE (De_2

EARNINGS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income attributable to Nicolet Bankshares, Inc.	$ 54,641	$ 41,036	$ 33,150
Weighted average common shares outstanding (in shares)	9,561,978	9,640,258	9,439,951
Effect of dilutive common stock awards (in shares)	338,000	316,000	518,000
Diluted weighted average common shares outstanding (in shares)	9,900,319	9,956,353	9,958,160
Basic earnings per common share (in dollars per share)	$ 5.71	$ 4.26	$ 3.51
Diluted earnings per common share (in dollars per share)	$ 5.52	$ 4.12	$ 3.33

SUBSEQUENT EVENT (Details)

SUBSEQUENT EVENT (Details) $ in Thousands	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Subsequent Event [Line Items]
Assets	$ 3,577,260	$ 3,096,535
Deposits	2,954,453	2,614,138
Equity	516,990	$ 387,352	$ 364,879	$ 276,365
Commerce Financial Holdings, Inc.
Subsequent Event [Line Items]
Assets	713,000
Loans	604,000
Deposits	610,000
Equity	$ 66,000
Percentage of assets represented by acquiree	0.16

Uncategorized Items - ncbs-2019

Label	Element	Value
Accounting Standards Update 2016-01 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(937,000)
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 937,000