ACNB (ACNB) 10-K 9 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 09, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Entity Registrant Name	ACNB CORP
Entity Central Index Key	715,579
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		7,023,658
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 208,794,290
Entity Voluntary Filers	No

CONSOLIDATED STATEMENTS OF COND

CONSOLIDATED STATEMENTS OF CONDITION - USD ($)	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and due from banks	$ 19,304,000	$ 13,796,000
Interest bearing deposits with banks	15,137,000	5,135,000
Total Cash and Cash Equivalents	34,441,000	18,931,000
Securities available for sale	159,051,000	142,990,000
Securities held to maturity, fair value $44,549; $55,425	44,829,000	55,568,000
Loans held for sale	1,736,000	1,770,000
Loans, net of allowance for loan losses $13,976; $14,194	1,230,194,000	893,716,000
Premises and equipment	26,774,000	18,153,000
Restricted investment in bank stocks	4,773,000	4,349,000
Investment in bank-owned life insurance	44,935,000	40,742,000
Investments in low-income housing partnerships	2,446,000	2,899,000
Goodwill	19,580,000	6,308,000
Intangible assets	2,569,000	688,000
Foreclosed assets held for resale	436,000	256,000
Other assets	23,668,000	19,950,000
Total Assets	1,595,432,000	1,206,320,000
LIABILITIES
Deposits: Non-interest bearing	279,413,000	180,593,000
Deposits: Interest bearing	1,019,079,000	787,028,000
Total Deposits	1,298,492,000	967,621,000
Short-term borrowings	36,908,000	34,590,000
Long-term borrowings	94,600,000	74,250,000
Other liabilities	11,466,000	9,798,000
Total Liabilities	1,441,466,000	1,086,259,000
STOCKHOLDERS' EQUITY
Preferred stock, $2.50 par value; 20,000,000 shares authorized; no shares outstanding	0	0
Common stock, $2.50 par value; 20,000,000 shares authorized; 7,086,258 and 6,126,738 shares issued; 7,023,658 and 6,064,138 shares outstanding	17,716,000	15,317,000
Treasury stock, at cost (62,600 shares)	(728,000)	(728,000)
Additional paid-in capital	37,777,000	10,941,000
Retained earnings	106,293,000	100,555,000
Accumulated other comprehensive loss	(7,092,000)	(6,024,000)
Total Stockholders’ Equity	153,966,000	120,061,000
Total Liabilities and Stockholders’ Equity	$ 1,595,432,000	$ 1,206,320,000

CONSOLIDATED STATEMENTS OF CON3

CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Securities held to maturity, fair value	$ 44,549	$ 55,425
Loans, net allowance for loan losses	$ 13,976	$ 14,194
Preferred stock, par value	$ 2.50	$ 2.50
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	7,086,258	6,126,738
Common stock, shares outstanding	7,023,658	6,064,138
Treasury stock, shares	62,600	62,600

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
INTEREST INCOME
Loans, including fees	$ 47,522,000	$ 36,339,000	$ 35,090,000
Securities:
Taxable	3,389,000	3,179,000	3,127,000
Tax-exempt	428,000	651,000	859,000
Dividends	252,000	212,000	301,000
Other	194,000	119,000	87,000
Total Interest Income	51,785,000	40,500,000	39,464,000
INTEREST EXPENSE
Deposits	3,547,000	2,369,000	2,120,000
Short-term borrowings	83,000	51,000	47,000
Long-term borrowings	1,803,000	1,514,000	1,691,000
Total Interest Expense	5,433,000	3,934,000	3,858,000
Net Interest Income	46,352,000	36,566,000	35,606,000
PROVISION FOR LOAN LOSSES	0	0	0
Net Interest Income after Provision for Loan Losses	46,352,000	36,566,000	35,606,000
OTHER INCOME
Service charges on deposit accounts	2,940,000	2,369,000	2,308,000
Income from fiduciary, investment management and brokerage activities	2,012,000	1,684,000	1,589,000
Earnings on investment in bank-owned life insurance	1,075,000	1,100,000	1,100,000
Gains on sales or calls of securities	0	26,000	261,000
Gain on sales of premises and equipment	0	449,000	0
Service charges on ATM and debit card transactions	1,762,000	1,499,000	1,456,000
Commissions from insurance sales	5,024,000	4,822,000	4,634,000
Other	1,336,000	1,259,000	1,058,000
Total Other Income	14,149,000	13,208,000	12,406,000
OTHER EXPENSES
Salaries and employee benefits	24,654,000	22,200,000	20,932,000
Net occupancy	2,403,000	2,066,000	2,170,000
Equipment	3,757,000	3,046,000	3,007,000
Other tax	791,000	785,000	779,000
Professional services	1,134,000	852,000	844,000
Supplies and postage	731,000	646,000	639,000
Marketing and corporate relations	433,000	574,000	452,000
FDIC and regulatory	644,000	611,000	665,000
Merger related expenses	4,728,000	472,000	0
Intangible assets amortization	537,000	345,000	336,000
Foreclosed real estate expenses	93,000	55,000	119,000
Other operating	4,174,000	3,485,000	3,291,000
Total Other Expenses	44,079,000	35,137,000	33,234,000
Income Before Income Taxes	16,422,000	14,637,000	14,778,000
PROVISION FOR INCOME TAXES	6,634,000	3,768,000	3,761,000
Net Income	$ 9,788,000	$ 10,869,000	$ 11,017,000
PER SHARE DATA
Basic earnings	$ 1.50	$ 1.80	$ 1.83
Cash dividends declared	$ 0.80	$ 0.80	$ 0.80

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
NET INCOME		$ 9,788	$ 10,869	$ 11,017
OTHER COMPREHENSIVE INCOME (LOSS)
SECURITIES: Unrealized losses arising during the period, net of income taxes of $(227), $(728), and $(635), respectively		(609)	(1,413)	(1,234)
SECURITIES: Reclassification adjustment for net gains included in net income, net of income taxes of $0, $(9), and $(89), respectively	[1],[2]	0	(17)	(172)
PENSION: Amortization of pension net loss, transition liability, and prior service cost, net of income taxes of $237, $232, and $172, respectively	[2],[3]	440	451	333
PENSION: Unrecognized net gain (loss), net of income taxes of $(26), $(299), and $(479), respectively	[2]	284	(319)	(930)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)		115	(1,298)	(2,003)
TOTAL COMPREHENSIVE INCOME		$ 9,903	$ 9,571	$ 9,014
[1]	Gross amounts are included in net gains on sales or calls of securities on the Consolidated Statements of Income in total other income.
[2]	Income tax amounts are included in the provision for income taxes on the Consolidated Statements of Income.
[3]	Gross amounts are included in the computation of net periodic benefit cost and are included in salaries and employee benefits on the Consolidated Statements of Income in total other expenses.

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
SECURITIES: Unrealized losses arising during the period, income taxes	$ (227)	$ (728)	$ (635)
SECURITIES: Reclassification adjustment for net gains included in net income, income taxes	0	(9)	(89)
PENSION: Amortization of pension net loss, transition liability, and prior service cost, income taxes	237	232	172
PENSION: Unrecognized net gain (loss), income taxes	$ (26)	$ (299)	$ (479)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2014	$ 110,022,000	$ 15,196,000	$ (728,000)	$ 9,948,000	$ 88,329,000	$ (2,723,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,017,000				11,017,000
Other comprehensive income (loss), net of taxes	(2,003,000)					(2,003,000)
Common stock shares issued	499,000	60,000		439,000
Cash dividends declared	(4,820,000)				(4,820,000)
Ending Balance at Dec. 31, 2015	114,715,000	15,256,000	(728,000)	10,387,000	94,526,000	(4,726,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	10,869,000				10,869,000
Other comprehensive income (loss), net of taxes	(1,298,000)					(1,298,000)
Common stock shares issued	437,000	42,000		395,000
Restricted stock grants	119,000	19,000		100,000
Restricted stock compensation expense	59,000			59,000
Cash dividends declared	(4,840,000)				(4,840,000)
Ending Balance at Dec. 31, 2016	120,061,000	15,317,000	(728,000)	10,941,000	100,555,000	(6,024,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,788,000				9,788,000
Other comprehensive income (loss), net of taxes	115,000					115,000
Reclass of stranded AOCI tax reform adjustment	0				1,183,000	(1,183,000)
Common stock shares issued	28,982,000	2,384,000		26,598,000
Restricted stock grants	120,000	15,000		105,000
Restricted stock compensation expense	133,000			133,000
Cash dividends declared	(5,233,000)				(5,233,000)
Ending Balance at Dec. 31, 2017	$ 153,966,000	$ 17,716,000	$ (728,000)	$ 37,777,000	$ 106,293,000	$ (7,092,000)

CONSOLIDATED STATEMENTS OF CHA8

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Common stock issued, Shares	953,327	16,979	24,074
Restricted stock grants, shares	6,193	7,435

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 9,788,000	$ 10,869,000	$ 11,017,000
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sales of loans originated for sale	(506,000)	(661,000)	(491,000)
Gain on sales of foreclosed assets held for resale, including writedowns	(28,000)	(105,000)	(67,000)
Gain on sale of premises and equipment	0	(449,000)	0
Earnings on investment in bank-owned life insurance	(1,075,000)	(1,100,000)	(1,100,000)
Gain on sales or calls of securities	0	(26,000)	(261,000)
Restricted stock compensation expense	133,000	59,000	0
Depreciation and amortization	2,292,000	1,800,000	1,755,000
Provision for loan losses	0	0	0
Net amortization of investment securities premiums	518,000	554,000	668,000
Increase in accrued interest receivable	(512,000)	(142,000)	(66,000)
Increase in accrued interest payable	326,000	22,000	42,000
Mortgage loans originated for sale	(27,426,000)	(41,195,000)	(32,865,000)
Proceeds from sales of loans originated for sale	27,965,000	41,921,000	33,144,000
Decrease (increase) in other assets	3,014,000	(210,000)	2,904,000
Decrease in deferred tax expense	1,711,000	171,000	392,000
Increase (decrease) in other liabilities	807,000	613,000	(693,000)
Net Cash Provided by Operating Activities	17,007,000	12,121,000	14,379,000
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from maturities of investment securities held to maturity	10,680,000	15,769,000	9,456,000
Proceeds from maturities of investment securities available for sale	34,404,000	30,426,000	23,426,000
Proceeds from sales of investment securities available for sale	0	230,000	3,170,000
Purchase of investment securities available for sale	(30,136,000)	(50,443,000)	(36,434,000)
Purchase of investment securities held to maturity	0	0	(8,044,000)
(Purchase) redemption of restricted investment in bank stocks	(88,000)	65,000	(198,000)
Net increase in loans	(71,830,000)	(56,122,000)	(55,332,000)
Purchase of bank-owned life insurance	0	0	(600,000)
Purchase of book of business	0	0	(173,000)
Purchase of book of business	6,444,000	0	0
Capital expenditures	(1,757,000)	(2,344,000)	(1,738,000)
Proceeds from sale of premises and equipment	6,000	1,929,000	0
Proceeds from sale of foreclosed real estate	324,000	1,048,000	2,323,000
Net Cash (Used in) Provided by Investing Activities	(51,953,000)	(59,442,000)	(64,144,000)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase in demand deposits	18,814,000	14,369,000	21,237,000
Net increase in time certificates of deposits and interest bearing deposits	18,725,000	40,272,000	46,867,000
Net increase (decrease) in short-term borrowings	2,318,000	(612,000)	(10,497,000)
Proceeds from long-term borrowings	29,600,000	16,000,000	18,000,000
Repayments on long-term borrowings	(14,250,000)	(18,250,000)	(22,437,000)
Dividends paid	(5,233,000)	(4,840,000)	(4,820,000)
Common stock issued	482,000	556,000	499,000
Net Cash Provided by (Used in) Financing Activities	50,456,000	47,495,000	48,849,000
Net Increase (Decrease) in Cash and Cash Equivalents	15,510,000	174,000	(916,000)
CASH AND CASH EQUIVALENTS — BEGINNING	18,931,000	18,757,000	19,673,000
CASH AND CASH EQUIVALENTS — ENDING	34,441,000	18,931,000	18,757,000
Supplemental disclosures of cash flow information
Interest paid	5,107,000	3,912,000	3,816,000
Income taxes paid	3,850,000	4,350,000	1,975,000
Loans transferred to foreclosed assets held for resale and other foreclosed transactions	265,000	619,000	1,219,000
Increase in assets and liabilities:
Securities	(21,624,000)	0	0
Loans	(264,913,000)	0	0
Premises and equipment	(8,624,000)	0	0
Investment in bank-owned life insurance	(3,118,000)	0	0
Restricted investments in bank stocks	(336,000)	0	0
Foreclosed assets held for resale	(211,000)	0	0
Goodwill	(13,272,000)	0	0
Core deposit intangible assets	(2,418,000)	0	0
Other assets	(7,463,000)	0	0
Noninterest bearing deposits	80,006,000	0	0
Interest bearing deposits	213,327,000	0	0
Trust preferred subordinated debt	4,688,000	0	0
Other liabilities	$ 1,782,000	$ 0	$ 0

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations ACNB Corporation (the Corporation or ACNB), headquartered in Gettysburg, Pennsylvania, provides banking, insurance, and financial services to businesses and consumers through its wholly-owned subsidiaries, ACNB Bank (Bank) and Russell Insurance Group, Inc. (RIG). The Bank engages in full-service commercial and consumer banking and wealth management services, including trust and retail brokerage, through its twenty-two community banking locations in Adams, Cumberland, Franklin, and York Counties, Pennsylvania. There is also a loan production office situated in York County, Pennsylvania. On July 1, 2017, ACNB completed its acquisition of New Windsor Bancorp, Inc. (New Windsor) of Taneytown, Maryland. At the effective time of the acquisition, New Windsor merged with and into a wholly-owned subsidiary of ACNB, immediately followed by the merger of New Windsor State Bank (NWSB) with and into ACNB Bank. ACNB Bank now operates in the Maryland market as “NWSB Bank, A Division of ACNB Bank” and serves its marketplace with banking and wealth management services via a network of seven community banking offices located in Carroll County, Maryland. RIG is a full-service insurance agency based in Westminster, Maryland with a second location in Germantown, Maryland. The agency offers a broad range of property and casualty, life, and health insurance to both commercial and individual clients. The Corporation’s primary source of revenue is interest income on loans and investment securities and fee income on its products and services. Expenses consist of interest expense on deposits and borrowed funds, provisions for loan losses, and other operating expenses. Basis of Financial Statements The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and include the accounts of the Corporation and its wholly-owned subsidiaries. All significant intercompany transactions have been eliminated. Assets held by the Corporation’s Wealth management Department, including trust and retail brokerage, in an agency, fiduciary or retail brokerage capacity for its customers are excluded from the consolidated financial statements since they do not constitute assets of the Corporation. Assets held by the Wealth Management Department amounted to $327,000,000 and $195,000,000 at December 31, 2017 and 2016 , respectively. Income from fiduciary, investment management and brokerage activities are included in other income. The Corporation has evaluated events and transactions occurring subsequent to the balance sheet date of December 31, 2017 , for items that should potentially be recognized or disclosed in the consolidated financial statements. The evaluation was conducted through the date these consolidated financial statements were issued. Use of Estimates Financial statements prepared in accordance with GAAP require management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingencies at the date of the consolidated financial statements, and revenues and expenses during the reporting period. Actual results could differ from these estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses, the determination of other than temporary impairment on securities, and the potential impairment of goodwill. Significant Group Concentrations of Credit Risk Most of the Corporation’s activities are with customers located within southcentral Pennsylvania and northern Maryland. Note C discusses the types of securities in which the Corporation invests. Note D discusses the types of lending in which the Corporation engages. Included in commercial real estate loans are loans made to lessors of non-residential dwellings that total $269,080,000 , or 21.6% , of total loans at December 31, 2017 . These borrowers are geographically disbursed throughout ACNB’s marketplace and are leasing commercial properties to a varied group of tenants including medical offices, retail space and recreational facilities. Because of the varied nature of the tenants in aggregate, management believes that these loans do not present any greater risk than commercial loans in general. Cash and Cash Equivalents For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash on hand, balances due from banks, and federal funds sold, all of which mature within 90 days. Securities Debt securities that management has the positive intent and ability to hold to maturity are classified as “held to maturity” and recorded at amortized cost. Securities not classified as held to maturity or trading, including equity securities with readily determinable fair values, are classified as “available for sale” and recorded at fair value, with unrealized gains and losses excluded from earnings and reported, net of tax, in other comprehensive income (loss). Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Declines in the fair value of held to maturity and available for sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses. In estimating other-than-temporary impairment losses on debt securities, management considers (1) whether management intends to sell the security, or (2) if it is more likely than not that management will be required to sell the security before recovery, or (3) if management does not expect to recover the entire amortized cost basis. In assessing potential other-than-temporary impairment for equity securities, consideration is given to management’s intention and ability to hold the securities until recovery of unrealized losses. Gains and losses on the sale of securities are recorded on the trade date and are determined using the specific identification method. Loans Held for Sale Loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by aggregate outstanding commitments from investors or current investor yield requirements. Net unrealized losses are recognized through a valuation allowance by charges to income. Mortgage loans held for sale are sold with the mortgage servicing rights released to another financial institution through a correspondent relationship. The correspondent financial institution absorbs all of the risk related to rate lock commitments. Gains or losses on sales of mortgage loans are recognized based on the difference between the selling price and the carrying value of the related mortgage loans sold. Loans The Corporation grants commercial, residential, and consumer loans to customers. A substantial portion of the loan portfolio is represented by mortgage loans throughout southcentral Pennsylvania and northern Maryland. The ability of the Corporation’s debtors to honor their contracts is dependent upon the real estate values and general economic conditions in this area. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off generally are reported at their outstanding unpaid principal balances adjusted for charge-offs, the allowance for loan losses, and any deferred fees or costs on originated loans. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loan yield using the interest method. The loans receivable portfolio is segmented into commercial, residential mortgage, home equity lines of credit, and consumer loans. Commercial loans consist of the following classes: commercial and industrial, commercial real estate, and commercial real estate construction. The accrual of interest on residential mortgage and commercial loans is discontinued at the time the loan is 90 days past due unless the credit is well-secured and in process of collection. Consumer loans (consisting of home equity lines of credit and consumer loan classes) are typically charged off no later than 120 days past due. Past due status is based on the contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal or interest is considered doubtful. All interest accrued, but not collected, for loans that are placed on nonaccrual or charged off is reversed against interest income. The interest on these loans is accounted for on the cash-basis or cost-recovery method, until qualifying for return to accrual status. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Allowance for Credit Losses The allowance for credit losses consists of the allowance for loan losses and the reserve for unfunded lending commitments. The allowance for loan losses (the “allowance”) is established as losses are estimated to occur through a provision for loan losses charged to earnings. Loan losses are charged against the allowance when management believes the uncollectibility of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The reserve for unfunded lending commitments represents management’s estimate of losses inherent in its unfunded loan commitments and is recorded in other liabilities on the consolidated statement of condition. The amount of the reserve for unfunded lending commitments is not material to the consolidated financial statements. The allowance for loan losses is evaluated on a regular basis by management and is based upon management’s periodic review of the collectibility of the loans in light of historical experience, the nature and volume of the loan portfolio, adverse situations that may affect the borrower’s ability to repay, estimated value of any underlying collateral, and prevailing economic conditions. This evaluation is inherently subjective as it requires estimates that are susceptible to significant revision as more information becomes available. The allowance consists of specific, general and unallocated components. The specific component relates to loans that are classified as either doubtful, substandard, or special mention. For such loans that are also classified as impaired, an allowance is established when the discounted cash flows (or collateral value or observable market price) of the impaired loan is lower than the carrying value of that loan. The general component covers pools of loans by loan class including commercial loans not considered impaired, as well as smaller balance homogeneous loans, such as residential real estate, home equity, and other consumer loans. These pools of loans are evaluated for loss exposure based upon historical loss rates for each of these categories of loans, adjusted for qualitative factors. These qualitative risk factors include: • lending policies and procedures, including underwriting standards and collection, charge-off and recovery practices; • national, regional and local economic and business conditions, as well as the condition of various market segments, including the impact on the value of underlying collateral for collateral dependent loans; • the nature and volume of the portfolio and terms of loans; • the experience, ability and depth of lending management and staff; • the volume and severity of past due, classified and nonaccrual loans, as well as other loan modifications; and, • the existence and effect of any concentrations of credit and changes in the level of such concentrations. Each factor is assigned a value to reflect improving, stable or declining conditions based on management’s best judgment using relevant information available at the time of the evaluation. Adjustments to the factors are supported through documentation of changes in conditions in a narrative accompanying the allowance for loan loss calculation. The unallocated component of the allowance is maintained to cover uncertainties that could affect management’s estimate of probable losses. The unallocated component of the allowance reflects the margin of imprecision inherent in the underlying assumptions used in the methodologies for estimating specific and general losses in the portfolio. It covers risks that are inherently difficult to quantify including, but not limited to, collateral risk, information risk, and historical charge-off risk. A loan is considered impaired when, based on current information and events, it is probable that the Corporation will be unable to collect the scheduled payments of principal and/or interest when due according to the contractual terms of the loan agreement. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and/or interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. Impairment is measured on a loan by loan basis for commercial and commercial construction loans by either the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s obtainable market price, or the fair value of the collateral if the loan is collateral dependent. A specific allocation within the allowance for loan losses is established for an impaired loan if its carrying value exceeds its estimated fair value. The estimated fair values of the Corporation’s impaired loans are measured based on the estimated fair value of the loan’s collateral or the discounted cash flows method. It is the policy of the Corporation to order an updated valuation on all real estate secured loans when the loan becomes 90 days past due and there has not been an updated valuation completed within the previous 12 months. In addition, the Corporation orders third-party valuations on all impaired real estate collateralized loans within 30 days of the loan being classified as impaired. Until the valuations are completed, the Corporation utilizes the most recent independent third-party real estate valuation to estimate the need for a specific allocation to be assigned to the loan. These existing valuations are discounted downward to account for such things as the age of the existing collateral valuation, change in the condition of the real estate, change in local market and economic conditions, and other specific factors involving the collateral. Once the updated valuation is completed, the collateral value is updated accordingly. For commercial and industrial loans secured by non-real estate collateral, such as accounts receivable, inventory and equipment, estimated fair values are determined based on the borrower’s financial statements, inventory reports, accounts receivable aging reports, equipment appraisals, or invoices. Indications of value from these sources are generally discounted based on the age of the financial information or the quality of the assets. The Corporation actively monitors the values of collateral as well as the age of the valuation of impaired loans. Management believes that the Corporation’s market area is not as volatile as other areas throughout the United States, therefore valuations are ordered at least every 18 months, or more frequently if management believes that there is an indication that the fair value has declined. For impaired loans secured by collateral other than real estate, the Corporation considers the net book value of the collateral, as recorded in the most recent financial statements of the borrower, and determines fair value based on estimates made by management. Large groups of smaller balance homogeneous loans are collectively evaluated for impairment. Accordingly, the Corporation does not separately identify individual consumer and residential loans for impairment disclosures, unless such loans are the subject of a troubled debt restructure. Loans whose terms are modified are classified as troubled debt restructured loans if the Corporation grants such borrowers concessions that it would not otherwise consider and it is deemed that those borrowers are experiencing financial difficulty. Concessions granted under a troubled debt restructuring generally involve a temporary reduction in interest rate, a below market interest rate given the risk associated with the loan, or an extension of a loan’s stated maturity date. Nonaccrual troubled debt restructurings may be restored to accrual status if principal and interest payments, under the modified terms, are current for a sustained period of time and, based on a well-documented credit evaluation of the borrower’s financial condition, there is reasonable assurance of repayment. Loans classified as troubled debt restructurings are generally designated as impaired. The allowance calculation methodology includes further segregation of loan classes into credit quality rating categories. The borrower’s overall financial condition, repayment sources, guarantors, and value of collateral, if appropriate, are generally evaluated annually for commercial loans or when credit deficiencies arise, such as delinquent loan payments. Credit quality risk ratings include regulatory classifications of special mention, substandard, doubtful and loss. Loans classified special mention have potential weaknesses that deserve management’s close attention. If uncorrected, the potential weaknesses may result in deterioration of the repayment prospects. Loans classified substandard have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They include loans that are inadequately protected by the current sound net worth and paying capacity of the obligor or of the collateral pledged, if any. Loans classified doubtful have all the weaknesses inherent in loans classified substandard with the added characteristic that collection or liquidation in full, on the basis of current conditions and facts, is highly improbable. Loans classified as a loss are considered uncollectible and are charged to the allowance for loan losses. Loans not classified are rated pass. In addition, federal and state regulatory agencies, as an integral part of their examination process, periodically review the Corporation’s allowance for loan losses and may require the Corporation to recognize additions to the allowance based on their judgments about information available to them at the time of their examination, which may not be currently available to management. Based on management’s comprehensive analysis of the loan portfolio and economic conditions, management believes the current level of the allowance for loan losses is adequate. Commercial and Industrial Lending — The Corporation originates commercial and industrial loans primarily to businesses located in its primary market area and surrounding areas. These loans are used for various business purposes which include short-term loans and lines of credit to finance machinery and equipment purchases, inventory, and accounts receivable. Generally, the maximum term for loans extended on machinery and equipment is based on the projected useful life of such machinery and equipment. Most business lines of credit are written on demand and may be renewed annually. Commercial and industrial loans are generally secured with short-term assets; however, in many cases, additional collateral such as real estate is provided as additional security for the loan. Loan-to-value maximum values have been established by the Corporation and are specific to the type of collateral. Collateral values may be determined using invoices, inventory reports, accounts receivable aging reports, collateral appraisals, etc. In underwriting commercial and industrial loans, an analysis is performed to evaluate the borrower’s character and capacity to repay the loan, the adequacy of the borrower’s capital and collateral, as well as the conditions affecting the borrower. Evaluation of the borrower’s past, present and future cash flows is also an important aspect of the Corporation’s analysis. Commercial loans generally present a higher level of risk than other types of loans due primarily to the effect of general economic conditions. Commercial Real Estate Lending — The Corporation engages in commercial real estate lending in its primary market area and surrounding areas. The Corporation’s commercial loan portfolio is secured primarily by commercial retail space, office buildings, and hotels. Generally, commercial real estate loans have terms that do not exceed 20 years, have loan-to-value ratios of up to 80% of the appraised value of the property, and are typically secured by personal guarantees of the borrowers. In underwriting these loans, the Corporation performs a thorough analysis of the financial condition of the borrower, the borrower’s credit history, and the reliability and predictability of the cash flow generated by the property securing the loan. Appraisals on properties securing commercial real estate loans originated by the Corporation are performed by independent appraisers. Commercial real estate loans generally present a higher level of risk than other types of loans due primarily to the effect of general economic conditions and the complexities involved in valuing the underlying collateral. Commercial Real Estate Construction Lending — The Corporation engages in commercial real estate construction lending in its primary market area and surrounding areas. The Corporation’s commercial real estate construction lending consists of commercial and residential site development loans, as well as commercial building construction and residential housing construction loans. The Corporation’s commercial real estate construction loans are generally secured with the subject property. Terms of construction loans depend on the specifics of the project, such as estimated absorption rates, estimated time to complete, etc. In underwriting commercial real estate construction loans, the Corporation performs a thorough analysis of the financial condition of the borrower, the borrower’s credit history, and the reliability and predictability of the cash flow generated by the project using feasibility studies, market data, etc. Appraisals on properties securing commercial real estate construction loans originated by the Corporation are performed by independent appraisers. Commercial real estate construction loans generally present a higher level of risk than other types of loans due primarily to the effect of general economic conditions and the uncertainties surrounding total construction costs. Residential Mortgage Lending — One-to-four family residential mortgage loan originations, including home equity closed-end loans, are generated by the Corporation’s marketing efforts, its present customers, walk-in customers, and referrals. These loans originate primarily within the Corporation’s market area or with customers primarily from the market area. The Corporation offers fixed-rate and adjustable-rate mortgage loans with terms up to a maximum of 30 years for both permanent structures and those under construction. The Corporation’s one-to-four family residential mortgage originations are secured primarily by properties located in its primary market area and surrounding areas. The majority of the Corporation’s residential mortgage loans originate with a loan-to-value of 80% or less. Loans in excess of 80% are required to have private mortgage insurance. In underwriting one-to-four family residential real estate loans, the Corporation evaluates both the borrower’s financial ability to repay the loan as agreed and the value of the property securing the loan. Properties securing real estate loans made by the Corporation are appraised by independent appraisers. The Corporation generally requires borrowers to obtain an attorney’s title opinion or title insurance, as well as fire and property insurance (including flood insurance, if necessary) in an amount not less than the amount of the loan. The Corporation has not engaged in subprime residential mortgage originations. Residential mortgage loans present a moderate level of risk due primarily to general economic conditions, as well as a continued weak housing market. Home Equity Lines of Credit Lending — The Corporation originates home equity lines of credit primarily within the Corporation’s market area or with customers primarily from the market area. Home equity lines of credit are generated by the Corporation’s marketing efforts, its present customers, walk-in customers, and referrals. Home equity lines of credit are secured by the borrower’s primary residence with a maximum loan-to-value of 90% and a maximum term of 20 years. In underwriting home equity lines of credit, the Corporation evaluates both the value of the property securing the loan and the borrower’s financial ability to repay the loan as agreed. The ability to repay is determined by the borrower’s employment history, current financial condition, and credit background. Home equity lines of credit generally present a moderate level of risk due primarily to general economic conditions, as well as a continued weak housing market. Junior liens inherently have more credit risk by virtue of the fact that another financial institution may have a higher security position in the case of foreclosure liquidation of collateral to extinguish the debt. Generally, foreclosure actions could become more prevalent if the real estate market continues to be weak and property values deteriorate. Consumer Lending — The Corporation offers a variety of secured and unsecured consumer loans, including those for vehicles and mobile homes and loans secured by savings deposits. These loans originate primarily within the Corporation’s market area or with customers primarily from the market area. Consumer loan terms vary according to the type and value of collateral and the creditworthiness of the borrower. In underwriting consumer loans, a thorough analysis of the borrower’s financial ability to repay the loan as agreed is performed. The ability to repay is determined by the borrower’s employment history, current financial condition, and credit background. Consumer loans may entail greater credit risk than residential mortgage loans or home equity lines of credit, particularly in the case of consumer loans which are unsecured or are secured by rapidly depreciable assets such as automobiles or recreational equipment. In such cases, any repossessed collateral for a defaulted consumer loan may not provide an adequate source of repayment of the outstanding loan balance as a result of the greater likelihood of damage, loss or depreciation. In addition, consumer loan collections are dependent on the borrower’s continuing financial stability, and thus are more likely to be affected by adverse personal circumstances. Furthermore, the application of various federal and state laws, including bankruptcy and insolvency laws, may limit the amount which can be recovered on such loans. Acquired Loans Acquired Loans (impaired and non-impaired) are initially recorded at their acquisition-date fair values using Level 3 inputs. Fair values are based on a discounted cash flow methodology that involves assumptions and judgments as to credit risk, expected lifetime losses, environmental factors, collateral values, discount rates, expected payments and expected prepayments. Specifically, the Corporation has prepared three separate loan fair value adjustments that it believed a market participant might employ in estimating the entire fair value adjustment necessary under ASC 820-10 for the acquired loan portfolio. The three-separate fair valuation methodology employed are: 1) an interest rate loan fair value adjustment (analysis available at request of the Corporation), 2) a general credit fair value adjustment (analysis available at request of the Corporation) and 3) a specific credit fair value adjustment for purchased credit impaired loans subject to ASC 310-30 procedures. The carryover of allowance for loan losses related to acquired loans is prohibited as any credit losses in the loans are included in the determination of the fair value of the loans at the acquisition date. The allowance for loan losses on acquired loans reflects only those losses incurred after acquisition and represents the present value of cash flows expected at acquisition that is no longer expected to be collected. Acquired loans are marked to fair value on the date of acquisition. In conjunction with the quarterly evaluation of the adequacy of the allowance for loan losses, the Corporation performs an analysis on acquired loans to determine whether or not there has been subsequent deterioration in relation to those loans. If deterioration has occurred, the Corporation will includes these loans in the calculation of the allowance for loan losses after the initial valuation, and provide accordingly. Upon acquisition, in accordance with Generally Accepted Accounting Principles, the Corporation has individually determined whether each acquired loan is within the scope of ASC 310-30. The Corporation’s senior lending management reviewed the accounting seller’s loan portfolio on a loan by loan basis to determine if any loans met the two-part definition of an impaired loan as defined by ASC 310-30: 1) Credit deterioration on the loan from its inception until the acquisition date, and 2) It is probable that not all of the contractual cash flows will be collected on the loan. Any acquired loans that were not individually in the scope of ASC 310-30 because they did not meet the criteria above were pooled into groups of similar loans based on various factors including borrower type, loan purpose, and collateral type. For these pools, we used certain loan information, including outstanding principal balance, estimated expected losses, weighted average maturity, weighted average margin, and weighted average interest rate along with estimated prepayment rates, expected lifetime losses, environment factors to estimate the expected cash flow for each loan pool. With regards to ASC 310-30 loans, for external disclosure purposes, the aggregate contractual cash flows less the aggregate expected cash flows will result in a credit related non-accretable yield amount. The aggregate expected cash flows less the acquisition date fair value will result in an accretable yield amount. The accretable yield reflects the contractual cash flows management expects to collect about the loan’s acquisition date fair value and will be recognized over the life of the loan on a level-yield basis as a component of interest income. Over the life of the acquired ASC 310-30 loan, we continue to estimate cash flows expected to be collected. Decreases in expected cash flows, other than from prepayments or rate adjustments, are recognized as impairments through a charge to the provision for credit losses resulting in an increase in the allowance for credit losses. Subsequent improvements in cash flows result in first, reversal of existing valuation allowances recognized subsequent to acquisition, if any, and next, an increase in the amount of accretable yield to be subsequently recognized on a prospective basis over the loan’s remaining life. Acquired ASC 310-30 loans that met the criteria for non-accrual of interest prior to acquisition are considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if we can reasonably estimate the timing and amount of expected cash flows on such loans. Accordingly, we do not consider acquired contractually delinquent loans to be non-accruing and continue to recognize interest income on these loans using the accretion model. For loans acquired without evidence of credit quality deterioration, ACNB prepared the interest rate loan fair value and credit fair value adjustments. Loans were grouped into homogeneous pools by characteristics such as loan type, term, collateral, and rate. Market rates for

RESTRICTIONS ON CASH AND DUE FR

RESTRICTIONS ON CASH AND DUE FROM BANKS	12 Months Ended
	Dec. 31, 2017
Restricted Cash and Investments [Abstract]
RESTRICTIONS ON CASH AND DUE FROM BANKS	RESTRICTIONS ON CASH AND DUE FROM BANKS In return for services obtained through correspondent banks, the Corporation is required to maintain non-interest bearing cash balances in those correspondent banks. At December 31, 2017 and 2016 , compensating balances approximated $1,769,000 and $1,203,000 , respectively. During 2017 and 2016 , average compensating balances approximated $1,992,000 and $1,337,000 , respectively. All compensating balances are met by vault cash.

SECURITIES

SECURITIES	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
SECURITIES	SECURITIES Amortized cost and fair value at December 31, 2017 and 2016 , were as follows: In thousands Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value SECURITIES AVAILABLE FOR SALE December 31, 2017 U.S. Government and agencies $ 105,899 $ 2 $ 1,818 $ 104,083 Mortgage-backed securities, residential 34,473 461 101 34,833 State and municipal 13,227 109 42 13,294 Corporate bonds 5,000 57 — 5,057 CRA mutual fund 1,044 — 9 1,035 Stock in other banks 647 102 — 749 $ 160,290 $ 731 $ 1,970 $ 159,051 December 31, 2016 U.S. Government and agencies $ 81,065 $ 43 $ 1,529 $ 79,579 Mortgage-backed securities, residential 31,272 782 81 31,973 State and municipal 24,514 240 94 24,660 Corporate bonds 5,000 62 — 5,062 CRA mutual fund 1,044 — 9 1,035 Stock in other banks 498 183 — 681 $ 143,393 $ 1,310 $ 1,713 $ 142,990 SECURITIES HELD TO MATURITY December 31, 2017 U.S. Government and agencies $ 19,000 $ 2 $ 99 $ 18,903 Mortgage-backed securities, residential 25,829 55 238 25,646 $ 44,829 $ 57 $ 337 $ 44,549 December 31, 2016 U.S. Government and agencies $ 23,017 $ 26 $ 54 $ 22,989 Mortgage-backed securities, residential 32,551 210 325 32,436 $ 55,568 $ 236 $ 379 $ 55,425 The following table shows the Corporation’s investments’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2017 and 2016 : Less than 12 Months 12 Months or More Total In thousands Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses SECURITIES AVAILABLE FOR SALE December 31, 2017 U.S. Government and agencies $ 42,775 $ 445 $ 58,279 $ 1,373 $ 101,054 $ 1,818 Mortgage-backed securities, residential 7,228 56 2,845 45 10,073 101 State and municipal 1,042 8 1,950 34 2,992 42 CRA Mutual Fund — — 1,035 9 1,035 9 $ 51,045 $ 509 $ 64,109 $ 1,461 $ 115,154 $ 1,970 December 31, 2016 U.S. Government and agencies $ 71,454 $ 1,529 $ — $ — $ 71,454 $ 1,529 Mortgage-backed securities, residential 8,966 81 — — 8,966 81 State and municipal 4,933 94 — — 4,933 94 CRA Mutual Fund 1,035 9 — — 1,035 9 $ 86,388 $ 1,713 $ — $ — $ 86,388 $ 1,713 SECURITIES HELD TO MATURITY December 31, 2017 U.S. Government and agencies $ 4,985 $ 15 $ 10,916 $ 84 $ 15,901 $ 99 Mortgage-backed securities, residential 4,946 29 11,070 209 16,016 238 $ 9,931 $ 44 $ 21,986 $ 293 $ 31,917 $ 337 December 31, 2016 U.S. Government and agencies $ 12,946 $ 54 $ — $ — $ 12,946 $ 54 Mortgage-backed security, residential 12,956 325 — — 12,956 325 $ 25,902 $ 379 $ — $ — $ 25,902 $ 379 All mortgage-backed security investments are government sponsored enterprise (GSE) pass-through instruments issued by the Federal National Mortgage Association (FNMA), Government National Mortgage Association (GNMA) or Federal Home Loan Mortgage Corporation (FHLMC), which guarantee the timely payment of principal on these investments. At December 31, 2017 , sixty-four available for sale U.S. Government and agency securities had unrealized losses that individually did not exceed 5% of amortized cost. Thirty-two of these securities have been in a continuous loss position for 12 months or more. These unrealized losses relate principally to changes in interest rates subsequent to the acquisition of the specific securities. At December 31, 2017 , fifteen available for sale residential mortgage-backed securities had unrealized losses that individually did not exceed 2% of amortized cost. Three of these securities have been in a continuous loss position for 12 months or more. These unrealized losses relate principally to changes in interest rates subsequent to the acquisition of the specific securities. At December 31, 2017 , fourteen available for sale state and municipal securities had unrealized losses that individually did not exceed 3% of amortized cost. Eight of these securities have been in a continuous loss position for 12 months or more. These unrealized losses relate principally to changes in interest rates subsequent to the acquisition of the specific securities. At December 31, 2017 , the CRA Mutual Fund had an unrealized loss that did not exceed 1% of amortized cost. This security has been in a continuous loss position for 12 months or more. This unrealized loss relates principally to changes in interest rates subsequent to the acquisition of the specific security. At December 31, 2017 , nine held to maturity U.S. Government and agency securities had unrealized losses that individually did not exceed 2% of amortized cost. Six of these securities have been in a continuous loss position for 12 months or more. These unrealized losses relate principally to changes in interest rates subsequent to the acquisition of the specific securities. At December 31, 2017 , twenty-one held to maturity residential mortgage-backed securities had unrealized losses that individually did not exceed 3% of amortized cost. Thirteen of these securities have been in a continuous loss position for 12 months or more. These unrealized losses relate principally to changes in interest rates subsequent to the acquisition of the specific securities. In analyzing the issuer’s financial condition, management considers industry analysts’ reports, financial performance, and projected target prices of investment analysts within a one-year time frame. Based on the above information, management has determined that none of these investments are other-than-temporarily impaired. The fair values of securities available for sale (carried at fair value) and held to maturity (carried at amortized cost) are determined by obtaining quoted market prices on nationally recognized securities exchanges (Level 1), or matrix pricing (Level 2), which is a mathematical technique used widely in the industry to value debt securities without relying exclusively on quoted market prices for the specific securities but rather by relying on the security’s relationship to other benchmark quoted prices. The Corporation uses independent service providers to provide matrix pricing. Management routinely sells securities from its available for sale portfolio in an effort to manage and allocate the portfolio. At December 31, 2017 , management had not identified any securities with an unrealized loss that it intends to sell or will be required to sell. In estimating other-than-temporary impairment losses on debt securities, management considers (1) whether management intends to sell the security, or (2) if it is more likely than not that management will be required to sell the security before recovery, or (3) if management does not expect to recover the entire amortized cost basis. In assessing potential other-than-temporary impairment for equity securities, consideration is given to management’s intention and ability to hold the securities until recovery of unrealized losses. Amortized cost and fair value at December 31, 2017 , by contractual maturity, where applicable, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay with or without penalties. Available for Sale Held to Maturity In thousands Amortized Cost Fair Value Amortized Cost Fair Value 1 year or less $ 8,651 $ 8,635 $ 12,000 $ 11,949 Over 1 year through 5 years 102,487 100,911 7,000 6,954 Over 5 years through 10 years 12,917 12,817 — — Over 10 years 71 71 — — Mortgage-backed securities, residential 34,473 34,833 25,829 25,646 CRA mutual fund 1,044 1,035 — — Stock in other banks 647 749 — — $ 160,290 $ 159,051 $ 44,829 $ 44,549 The Corporation realized gross gains of $0 during 2017 , $26,000 during 2016 , and $262,000 during 2015 and gross losses of $0 during 2017 and 2016 , and $1,000 during 2015 on sales of securities available for sale. At December 31, 2017 and 2016 , securities with a carrying value of $157,601,000 and $134,763,000 , respectively, were pledged as collateral as required by law on public and trust deposits, repurchase agreements, and for other purposes.

LOANS AND ALLOWANCE FOR LOAN LO

LOANS AND ALLOWANCE FOR LOAN LOSSES	12 Months Ended
	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
LOANS AND ALLOWANCE FOR LOAN LOSSES	LOANS AND ALLOWANCE FOR LOAN LOSSES The Corporation grants commercial, residential, and consumer loans to customers primarily within southcentral Pennsylvania and northern Maryland and the surrounding area. A large portion of the loan portfolio is secured by real estate. Although the Bank has a diversified loan portfolio, its debtors’ ability to honor their contracts is influenced by the region’s economy. The following tables present the classes of the loan portfolio summarized by the aggregate pass rating and the classified ratings of special mention, substandard and doubtful within the Corporation’s internal risk rating system as of December 31, 2017 and 2016 : In thousands Pass Special Mention Substandard Doubtful Total December 31, 2017 Originated Loans Commercial and industrial $ 154,177 $ 3,466 $ 1,812 $ — $ 159,455 Commercial real estate 325,002 17,666 9,277 — 351,945 Commercial real estate construction 27,413 767 250 — 28,430 Residential mortgage 363,195 3,251 478 — 366,924 Home equity lines of credit 81,976 360 — — 82,336 Consumer 14,454 — — — 14,454 Total Originated Loans 966,217 25,510 11,817 — 1,003,544 Acquired Loans Commercial and industrial 6,120 244 10 — 6,374 Commercial real estate 124,852 12,734 3,228 — 140,814 Commercial real estate construction 6,742 388 — — 7,130 Residential mortgage 52,959 2,762 3,248 — 58,969 Home equity lines of credit 24,990 88 378 — 25,456 Consumer 1,525 358 — — 1,883 Total Acquired Loans 217,188 16,574 6,864 — 240,626 Total Loans Commercial and industrial 160,297 3,710 1,822 — 165,829 Commercial real estate 449,854 30,400 12,505 — 492,759 Commercial real estate construction 34,155 1,155 250 — 35,560 Residential mortgage 416,154 6,013 3,726 — 425,893 Home equity lines of credit 106,966 448 378 — 107,792 Consumer 15,979 358 — — 16,337 Total Loans $ 1,183,405 $ 42,084 $ 18,681 $ — $ 1,244,170 December 31, 2016 Commercial and industrial $ 134,088 $ 2,355 $ 3,901 $ — $ 140,344 Commercial real estate 291,762 17,376 9,842 — 318,980 Commercial real estate construction 13,606 1,202 463 — 15,271 Residential mortgage 344,048 3,617 874 — 348,539 Home equity lines of credit 69,190 756 126 — 70,072 Consumer 14,704 — — — 14,704 Total $ 867,398 $ 25,306 $ 15,206 $ — $ 907,910 The following table provides changes in accretable yield for all acquired loans accounted for under ASC 310-30. Loans accounted for under ASC 310-20 are not included in this table. In thousands Year Ended December 31, 2017 Balance at beginning of period $ — Acquisitions of impaired loans 1,458 Reclassification from non-accretable differences — Accretion to loan interest income (224 ) Balance at end of period $ 1,234 Cash flows expected to be collected on acquired loans are estimated quarterly by incorporating several key assumptions similar to the initial estimate of fair value. These key assumptions include probability of default and the amount of actual prepayments after the acquisition date. Prepayments affect the estimated life of the loans and could change the amount of interest income, and possibly principal expected to be collected. In reforecasting future estimated cash flows, credit loss expectations are adjusted as necessary. Improved cash flow expectations for loans or pools are recorded first as a reversal of previously recorded impairment, if any, and then as an increase in prospective yield when all previously recorded impairment has been recaptured. Decreases in expected cash flows are recognized as impairment through a charge to the provision for loan losses and credit to the allowance for loan losses. The following table summarizes information relative to impaired loans by loan portfolio class as of December 31, 2017 and 2016 : Impaired Loans with Allowance Impaired Loans with No Allowance In thousands Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance December 31, 2017 Commercial and industrial $ 1,311 $ 1,311 $ 792 $ 188 $ 188 Commercial real estate 832 832 60 7,528 7,528 Commercial real estate construction — — — — — Residential mortgage 377 377 377 101 101 Total $ 2,520 $ 2,520 $ 1,229 $ 7,817 $ 7,817 December 31, 2016 Commercial and industrial $ 948 $ 948 $ 599 $ 1,178 $ 1,178 Commercial real estate — — — 8,764 8,965 Commercial real estate construction — — — 300 300 Residential mortgage 376 376 333 379 379 Total $ 1,324 $ 1,324 $ 932 $ 10,621 $ 10,822 The following table summarizes information in regards to average of impaired loans and related interest income by loan portfolio class: Impaired Loans with Allowance Impaired Loans with No Allowance In thousands Average Recorded Investment Interest Income Average Recorded Investment Interest Income December 31, 2017 Commercial and industrial $ 1,184 $ — $ 785 $ — Commercial real estate 499 — 8,030 330 Commercial real estate construction — — 60 25 Residential mortgage 377 — 210 15 Total $ 2,060 $ — $ 9,085 $ 370 December 31, 2016 Commercial and industrial $ 190 $ — $ 1,356 $ 3 Commercial real estate — — 8,377 371 Commercial real estate construction — — 330 — Residential mortgage 224 — 424 17 Total $ 414 $ — $ 10,487 $ 391 December 31, 2015 Commercial and industrial $ — $ — $ 1,591 $ 129 Commercial real estate — — 9,057 449 Commercial real estate construction — — 276 — Residential mortgage 278 — 463 18 Total $ 278 $ — $ 11,387 $ 596 No additional funds are committed to be advanced in connection with impaired loans. If interest on all nonaccrual loans had been accrued at original contract rates, interest income would have increased by $437,000 in 2017 , $369,000 in 2016 , and $456,000 in 2015 . The following table presents nonaccrual loans by loan portfolio class as of December 31, 2017 and 2016 , the table below excludes $6.9 million in purchase credit impaired loans, net of unamortized fair value adjustments: In thousands 2017 2016 Commercial and industrial $ 1,499 $ 2,126 Commercial real estate 4,378 1,593 Commercial real estate construction — 300 Residential mortgage 478 483 Total $ 6,355 $ 4,502 The following table summarizes information relative to troubled debt restructurings by loan portfolio class at December 31, 2017 and 2016 : In thousands Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Recorded Investment at period end December 31, 2017 Nonaccruing troubled debt restructurings: Commercial real estate $ 4,015 $ 4,073 $ 3,405 Total nonaccruing troubled debt restructurings 4,015 4,073 3,405 Accruing troubled debt restructurings: Commercial real estate 4,577 4,577 3,982 Total accruing troubled debt restructurings 4,577 4,577 3,982 Total Troubled Debt Restructurings $ 8,592 $ 8,650 $ 7,387 December 31, 2016 Nonaccruing troubled debt restructurings: Commercial real estate $ 648 $ 648 $ 377 Total nonaccruing troubled debt restructurings 648 648 377 Accruing troubled debt restructurings: Commercial real estate 7,944 8,002 7,171 Residential mortgage 336 336 272 Total accruing troubled debt restructurings 8,280 8,338 7,443 Total Troubled Debt Restructurings $ 8,928 $ 8,986 $ 7,820 All of the Corporation’s troubled debt restructured loans are also impaired loans, of which some have resulted in a specific allocation and, subsequently, a charge-off as appropriate. There were no defaulted troubled debt restructured loans as of December 31, 2017 and 2016 , however two borrowers advised that further payments were unlikely, therefore they were moved to nonaccrual status in the second quarter of 2017. There were no charge-offs on any of the troubled debt restructured loans for the years ended December 31, 2017 and 2016 . One troubled debt restructured loan had a specific allocation in the amount of $60,000 at December 31, 2017. There was no specific allocation on any troubled debt restructured loans for the year ended December 31, 2016. One troubled debt restructured loan paid off during 2017 in the amount of $283,000 . One troubled debt restructured loan paid off during 2016 in the amount of $74,000 . All other troubled debt restructured loans were current with respect to their associated forbearance agreement, except for one loan which has had periodic late payments. As of December 31, 2017 , only one of the loans classified as a troubled debt restructured loan has an active forbearance agreement. The loan was negotiated during 2016. All other forbearance agreements have expired or the loans have paid off. The following table summarizes loans whose terms have been modified resulting in troubled debt restructurings during the years ended December 31, 2017 and 2016 : Dollars in thousands Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Recorded Investment at Period End 2017 Troubled debt restructurings — $ — $ — $ — 2016 Troubled debt restructurings 1 $ 826 $ 832 $ 832 Consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process at December 31, 2017 and 2016 , totaled $848,000 and $471,000 , respectively. The performance and credit quality of the loan portfolio is also monitored by analyzing the age of the loans receivable as determined by the length of time a recorded payment is past due. The following table presents the classes of the loan portfolio summarized by the past due status as of December 31, 2017 and 2016 : In thousands 30-59 Days Past Due 60-89 Days Past Due >90 Days Past Due Total Past Due Current Total Loans Receivable Loans Receivable >90 Days and Accruing December 31, 2017 Originated Loans Commercial and industrial $ 55 $ 76 $ 1,503 $ 1,634 $ 157,821 $ 159,455 $ 4 Commercial real estate 436 317 1,400 2,153 349,792 351,945 88 Commercial real estate construction 252 — — 252 28,178 28,430 — Residential mortgage 3,006 646 1,500 5,152 361,772 366,924 1,022 Home equity lines of credit 254 29 183 466 81,870 82,336 183 Consumer 72 26 3 101 14,353 14,454 3 Total originated loans 4,075 1,094 4,589 9,758 993,786 1,003,544 1,300 Acquired Loans Commercial and industrial 83 — — 83 6,291 6,374 — Commercial real estate 916 — — 916 139,898 140,814 — Commercial real estate construction — — — — 7,130 7,130 — Residential mortgage 930 304 137 1,371 57,598 58,969 137 Home equity lines of credit 83 — 70 153 25,303 25,456 70 Consumer — — — — 1,883 1,883 — Total acquired loans 2,012 304 207 2,523 238,103 240,626 207 Total Loans Commercial and industrial 138 76 1,503 1,717 164,112 165,829 4 Commercial real estate 1,352 317 1,400 3,069 489,690 492,759 88 Commercial real estate construction 252 — — 252 35,308 35,560 — Residential mortgage 3,936 950 1,637 6,523 419,370 425,893 1,159 Home equity lines of credit 337 29 253 619 107,173 107,792 253 Consumer 72 26 3 101 16,236 16,337 3 Total Loans $ 6,087 $ 1,398 $ 4,796 $ 12,281 $ 1,231,889 $ 1,244,170 $ 1,507 December 31, 2016 Commercial and industrial $ 26 $ 1 $ 1,178 $ 1,205 $ 139,139 $ 140,344 $ — Commercial real estate 325 674 — 999 317,981 318,980 — Commercial real estate construction — — 300 300 14,971 15,271 — Residential mortgage 2,866 657 1,413 4,936 343,603 348,539 937 Home equity lines of credit 310 56 408 774 69,298 70,072 408 Consumer 31 47 — 78 14,626 14,704 — Total $ 3,558 $ 1,435 $ 3,299 $ 8,292 $ 899,618 $ 907,910 $ 1,345 The following table summarizes the allowance for loan losses and recorded investment in loans: In thousands Commercial and Industrial Commercial Real Estate Commercial Real Estate Construction Residential Mortgage Home Equity Lines of Credit Consumer Unallocated Total December 31, 2017 Allowance for loan losses Beginning balance- January 1, 2017 $ 3,055 $ 4,968 $ 147 $ 3,478 $ 648 $ 923 $ 975 $ 14,194 Charge-offs (181 ) — — (132 ) (9 ) (139 ) — (461 ) Recoveries 21 61 80 62 — 19 — 243 Provisions 324 199 (101 ) (182 ) (27 ) (54 ) (159 ) — Ending balance- December 31, 2017 $ 3,219 $ 5,228 $ 126 $ 3,226 $ 612 $ 749 $ 816 $ 13,976 Ending balance: individually evaluated for impairment $ 792 $ 60 $ — $ 377 $ — $ — $ — $ 1,229 Ending balance: collectively evaluated for impairment $ 2,427 $ 5,168 $ 126 $ 2,849 $ 612 $ 749 $ 816 $ 12,747 Loans receivables Ending balance $ 165,829 $ 492,759 $ 35,560 $ 425,893 $ 107,792 $ 16,337 $ — $ 1,244,170 Ending balance: individually evaluated for impairment $ 1,499 $ 8,360 $ — $ 478 $ — $ — $ — $ 10,337 Ending balance: collectively evaluated for impairment $ 164,330 $ 484,399 $ 35,560 $ 425,415 $ 107,792 $ 16,337 $ — $ 1,233,833 December 31, 2016 Allowance for loan losses Beginning balance- January 1, 2016 $ 2,508 $ 5,216 $ 112 $ 3,349 $ 619 $ 1,083 $ 1,860 $ 14,747 Charge-offs (318 ) — (135 ) (189 ) (74 ) (50 ) — (766 ) Recoveries 45 — 132 25 — 11 — 213 Provisions 820 (248 ) 38 293 103 (121 ) (885 ) — Ending balance- December 31, 2016 $ 3,055 $ 4,968 $ 147 $ 3,478 $ 648 $ 923 $ 975 $ 14,194 Ending balance: individually evaluated for impairment $ 599 $ — $ — $ 333 $ — $ — $ — $ 932 Ending balance: collectively evaluated for impairment $ 2,456 $ 4,968 $ 147 $ 3,145 $ 648 $ 923 $ 975 $ 13,262 Loans receivables Ending balance $ 140,344 $ 318,980 $ 15,271 $ 348,539 $ 70,072 $ 14,704 $ — $ 907,910 Ending balance: individually evaluated for impairment $ 2,126 $ 8,764 $ 300 $ 755 $ — $ — $ — $ 11,945 Ending balance: collectively evaluated for impairment $ 138,218 $ 310,216 $ 14,971 $ 347,784 $ 70,072 $ 14,704 $ — $ 895,965 In thousands Commercial and Industrial Commercial Real Estate Commercial Real Estate Construction Residential Mortgage Home Equity Lines of Credit Consumer Unallocated Total December 31, 2015 Allowance for loan losses Beginning balance- January 1, 2015 $ 2,048 $ 5,872 $ 194 $ 3,845 $ 557 $ 1,050 $ 1,606 $ 15,172 Charge-offs (150 ) — (39 ) (622 ) (15 ) (111 ) — (937 ) Recoveries 369 — — 136 — 7 — 512 Provisions 241 (656 ) (43 ) (10 ) 77 137 254 — Ending balance- December 31, 2015 $ 2,508 $ 5,216 $ 112 $ 3,349 $ 619 $ 1,083 $ 1,860 $ 14,747 Ending balance: individually evaluated for impairment $ — $ — $ — $ — $ — $ — $ — $ — Ending balance: collectively evaluated for impairment $ 2,508 $ 5,216 $ 112 $ 3,349 $ 619 $ 1,083 $ 1,860 $ 14,747 Loans receivables Ending balance $ 117,692 $ 289,899 $ 13,429 $ 357,228 $ 60,124 $ 14,588 $ — $ 852,960 Ending balance: individually evaluated for impairment $ 1,471 $ 8,185 $ 374 $ 461 $ — $ — $ — $ 10,491 Ending balance: collectively evaluated for impairment $ 116,221 $ 281,714 $ 13,055 $ 356,767 $ 60,124 $ 14,588 $ — $ 842,469 The Bank has granted loans to certain of its executive officers, directors and their related interests. These loans were made on substantially the same basis, including interest rates and collateral as those prevailing for comparable transactions with other borrowers at the same time. The aggregate amount of these loans was $5,703,000 and $4,578,000 at December 31, 2017 and 2016 , respectively. During 2017 , $1,612,000 new loans or advances were extended and repayments totaled $487,000 . None of these loans were past due, in nonaccrual status, or restructured at December 31, 2017 .

PREMISES AND EQUIPMENT

PREMISES AND EQUIPMENT	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
PREMISES AND EQUIPMENT	PREMISES AND EQUIPMENT Premises and equipment at December 31 were as follows: In thousands 2017 2016 Land $ 5,050 $ 2,624 Buildings and improvements 25,881 19,917 Furniture and equipment 14,856 13,273 Construction in process 182 82 45,969 35,896 Accumulated depreciation (19,195 ) (17,743 ) $ 26,774 $ 18,153 Depreciation expense was $1,755,000 , $1,455,000 and $1,419,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.

INVESTMENTS IN LOW-INCOME HOUSI

INVESTMENTS IN LOW-INCOME HOUSING PARTNERSHIPS	12 Months Ended
	Dec. 31, 2017
Real Estate Partnership Investment Subsidiaries, Net Income (Loss) before Tax [Abstract]
INVESTMENTS IN LOW-INCOME HOUSING PARTNERSHIPS	INVESTMENTS IN LOW-INCOME HOUSING PARTNERSHIPS ACNB Corporation is a limited partner in three partnerships, whose purpose is to develop, manage and operate residential low-income properties. At December 31, 2017 and 2016 , the carrying value of these investments was approximately $2,446,000 and $2,899,000 , respectively.

DEPOSITS

DEPOSITS	12 Months Ended
	Dec. 31, 2017
Interest-bearing Deposit Liabilities [Abstract]
DEPOSITS	DEPOSITS Deposits were comprised of the following as of December 31: In thousands 2017 2016 Non-interest bearing demand $ 279,413 $ 180,593 Interest bearing demand 163,278 130,453 Savings 501,710 414,682 Time certificates of deposit of $250,000 or less 295,279 209,805 Time certificates of deposit greater than $250,000 58,812 32,088 $ 1,298,492 $ 967,621 Scheduled maturities of time certificates of deposit at December 31, 2017 , were as follows: Years Ending In thousands 2018 $ 176,525 2019 119,968 2020 29,657 2021 15,766 2022 12,175 $ 354,091

LEASE COMMITMENTS

LEASE COMMITMENTS	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
LEASE COMMITMENTS	LEASE COMMITMENTS Certain branch offices and equipment are leased under agreements which expire at varying dates through 2036. Most leases contain renewal provisions at the Corporation’s option. The total rental expense for all operating leases was $642,000 , $492,000 and $456,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following is a schedule by year of future minimum rental payments required under operating leases that have initial or remaining non-cancelable lease terms in excess of one year as of December 31: Years Ending In thousands 2018 $ 787 2019 579 2020 481 2021 386 2022 328 Later years 1,694 $ 4,255 ACNB leases space at several of its owned offices to other unrelated organizations. Total rental income for these properties was $60,000 , $8,000 and $27,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively.

BORROWINGS

BORROWINGS	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
BORROWINGS	BORROWINGS Short-term borrowings and weighted-average interest rates at December 31 are as follows: 2017 2016 Dollars in thousands Amount Rate Amount Rate FHLB overnight advance $ — — % $ — — % Securities sold under repurchase agreements 36,908 0.12 34,590 0.12 $ 36,908 0.12 % $ 34,590 0.12 % Under an agreement with the FHLB, the Bank has short-term borrowing capacity included within its maximum borrowing capacity. All FHLB advances are collateralized by a security agreement covering qualifying loans and unpledged U.S. Treasury, agency and mortgage-backed securities. In addition, all FHLB advances are secured by the FHLB capital stock owned by the Bank having a par value of $4,194,700 at December 31, 2017 . The Corporation also has lines of credit that total $29,000,000 with correspondent banks for overnight federal funds borrowings. There were no advances on these lines at December 31, 2017 and 2016 . The Corporation enters into agreements under which it sells securities subject to an obligation to repurchase the same or similar securities. Under these arrangements, the Corporation may transfer legal control over the assets but still retain effective control through an agreement that both entitles and obligates the Corporation to repurchase the assets. As a result, these repurchase agreements are accounted for as collateralized financing agreements (i.e., secured borrowings) and not as a sale and subsequent repurchase of securities. The obligation to repurchase the securities is reflected as a liability in the Corporation’s consolidated statements of condition, while the securities underlying the repurchase agreements remain in the respective investment securities asset accounts. In other words, there is no offsetting or netting of the investment securities assets with the repurchase agreement liabilities. In addition, as the Corporation does not enter into reverse repurchase agreements, there is no such offsetting to be done with the repurchase agreements. The right of setoff for a repurchase agreement resembles a secured borrowing, whereby the collateral would be used to settle the fair value of the repurchase agreement should the Corporation be in default (e.g., fails to make an interest payment to the counterparty). For private institution repurchase agreements, if the private institution counterparty were to default (e.g., declare bankruptcy), the Corporation could cancel the repurchase agreement (i.e., cease payment of principal and interest), and attempt collection on the amount of collateral value in excess of the repurchase agreement fair value. The collateral is held by a third-party financial institution in the counterparty’s custodial account. The counterparty has the right to sell or repledge the investment securities. For government entity repurchase agreements, the collateral is held by the Corporation in a segregated custodial account under a tri-party agreement. The following table presents the short-term borrowings subject to an enforceable master netting arrangement or repurchase agreement as of December 31, 2017 and 2016 : Gross Amounts Not Offset in the Statements of Condition Dollars in thousands Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statements of Condition Net Amounts of Liabilities Presented in the Statements of Condition Financial Instruments Cash Collateral Pledged Net Amount December 31, 2017 Repurchase agreements Commercial customers and government entities (a) $ 36,908 $ — $ 36,908 $ (36,908 ) $ — $ — December 31, 2016 Repurchase agreements Commercial customers and government entities (a) $ 34,590 $ — $ 34,590 $ (34,590 ) $ — $ — (a) As of December 31, 2017 and 2016 , the fair value of securities pledged in connection with repurchase agreements was $42,397,000 and $41,406,000 , respectively. A summary of long-term debt as of December 31 is as follows: 2017 2016 Dollars in thousands Amount Rate Amount Rate FHLB fixed-rate advances maturing: 2017 $ — — % $ 14,250 2.30 % 2018 25,500 1.87 % 25,500 1.87 % 2019 23,500 1.73 % 19,500 1.75 % 2020 20,000 1.87 % 12,000 1.84 % 2021 16,000 2.01 % 3,000 1.58 % Loan Payable to local bank 4,600 1.53 % — — % Trust preferred subordinated debt 5,000 6.39 % — — % $ 94,600 2.06 % $ 74,250 1.91 % The FHLB advances are collateralized by the assets defined in security agreement and FHLB capital stock described previously. The Corporation can borrow a maximum of $674,680,200 from the FHLB, of which $567,440,200 was available at December 31, 2017 . The loan payable to a local bank has a one -year draw period in which monthly interest-only payments are due on the outstanding principal amount at 4.5% as of December 31, 2017 . Commencing June 2018, terms include a fixed rate of 4.5% for the first five years and a variable rate of interest with Prime Rate thereafter to final maturity in June 2028. The principal balance of this note may be prepaid at any time without penalty. The trust preferred subordinated debt is comprised of debt securities issued by New Windsor in June 2005 and assumed by ACNB Corporation through the acquisition. New Windsor issued $5,000,000 of 6.39% fixed rate capital securities to institutional investors in a private pooled transaction. The proceeds were transferred to New Windsor as trust preferred subordinated debt under the same terms and conditions. The Corporation then contributed the full amount to the Bank in the form of Tier 1 capital. The Corporation has, through various contractual agreements, fully and unconditionally guaranteed all of the trust obligations with respect to the capital securities.

REGULATORY RESTRICTIONS ON DIVI

REGULATORY RESTRICTIONS ON DIVIDENDS	12 Months Ended
	Dec. 31, 2017
Disclosure of Restrictions on Dividends, Loans and Advances Disclosure [Abstract]
REGULATORY RESTRICTIONS ON DIVIDENDS	REGULATORY RESTRICTIONS ON DIVIDENDS Dividend payments by the Bank to the Corporation are subject to the Pennsylvania Banking Code, the Federal Deposit Insurance Act, and the regulations of the FDIC, including final rules to implement the Basel III regulatory capital reforms and changes required by the Dodd-Frank Act. Under the Banking Code, no dividends may be paid except from “accumulated net earnings” (generally, retained earnings). The Federal Reserve Board and the FDIC have formal and informal policies which provide that insured banks and bank holding companies should generally pay dividends only out of current operating earnings, with some exceptions. As of December 31, 2017 , $16,066,000 of undistributed earnings of the Bank, included in consolidated retained earnings, was available for distribution to the Corporation as dividends without prior regulatory approval. Additionally, dividends paid by the Bank to the Corporation would be prohibited if the effect thereof would cause the Bank’s capital to be reduced below applicable minimum capital requirements.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The components of income tax expense for the years ended December 31, 2017 , 2016 and 2015 , are as follows: In thousands 2017 2016 2015 Federal: Current $ 4,767 $ 3,530 $ 3,316 Deferred 1,413 171 392 6,180 3,701 3,708 State: Current 156 67 53 Deferred 298 — — 454 67 53 $ 6,634 $ 3,768 $ 3,761 Reconciliations of the statutory federal income tax to the income tax expense reported in the consolidated statements of income for the years ended December 31, 2017 , 2016 and 2015 , are as follows: Percentage of Income before Income Taxes 2017 2016 2015 Federal income tax at statutory rate 35.0 % 34.0 % 34.0 % State income taxes, net of federal benefit 1.8 % 0.3 % 0.2 % Tax-exempt income (5.0 )% (4.8 )% (4.4 )% Earnings on investment in bank-owned life insurance (2.3 )% (2.6 )% (2.5 )% Rehabilitation and low-income housing credits (1.7 )% (2.0 )% (2.0 )% Reduction of federal tax rate 10.2 % — % — % Other 2.4 % 0.8 % 0.2 % 40.4 % 25.7 % 25.5 % The provision for federal income taxes includes $0 , $9,000 and $89,000 of income taxes related to net gains on sales of securities in 2017 , 2016 and 2015 , respectively. Rehabilitation and low-income housing income tax credits were $287,000 , during 2017 , 2016 and 2015 , respectively. Projected credits are $287,000 in 2018 and 2019, and $876,000 thereafter. Components of deferred tax assets and liabilities at December 31 were as follows: In thousands 2017 2016 Deferred tax assets: Allowance for loan losses $ 3,052 $ 4,968 Available for sale securities 282 143 Accrued deferred compensation 852 1,166 Pension 1,789 3,101 Other-than-temporary impairment 43 70 Nonaccrual interest 171 226 Deferred director fees 520 686 Acquisition accounting 1,357 — Other 521 982 8,587 11,342 Deferred tax liabilities: Deferred loan fees 114 79 Available for sale securities — — Prepaid pension benefit cost 4,248 6,632 Prepaid expenses 132 123 Accumulated depreciation 426 372 Goodwill/intangibles 928 1,006 5,848 8,212 Net Deferred Tax Asset included in Other Assets $ 2,739 $ 3,130 The Corporation did not have any uncertain tax positions at December 31, 2017 and 2016 . The Corporation’s policy is to recognize interest and penalties on unrecognized tax benefits in income tax expense in the Consolidated Statements of Income. Years that remain open for potential review by the Internal Revenue Service are 2014 through 2017. On December 22, 2017, the United States government enacted comprehensive tax legislation, known as the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act made broad and complex changes to the U.S. tax code, including a reduction in the base corporate tax rate from the prior existing statutory rate, which was 35% for ACNB, to 21%. Based on estimates and current accounting guidance, the Corporation estimated that the Tax Act resulted in a charge against 2017 net income of approximately $1.7 million, due to the write down of ACNB’s net deferred tax assets due to the Tax Act’s reduction in the base corporate tax rate to 21%. This estimate was based on a review and analysis of the Corporation’s net deferred tax assets at December 31, 2017, as well as adjustments to various deferred tax assets and deferred tax liabilities in the fourth quarter, including those accounted for in accumulated other comprehensive income.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Management uses its best judgment in estimating the fair value of the Corporation’s financial instruments; however, there are inherent weaknesses in any estimation technique. Therefore, for substantially all financial instruments, the fair value estimates herein are not necessarily indicative of the amounts the Corporation could have realized in a sales transaction on the dates indicated. The estimated fair value amounts have been measured as of their respective reporting dates and have not been reevaluated or updated for purposes of these consolidated financial statements subsequent to those respective dates. As such, the estimated fair values of these financial instruments subsequent to the respective reporting dates may be different than the amounts reported at each period end. Fair value measurement and disclosure guidance defines fair value as the price that would be received to sell the asset or transfer the liability in an orderly transaction (that is, not a forced liquidation or distressed sale) between market participants at the measurement date under current market conditions. Fair value measurement and disclosure guidance provides a list of factors that a reporting entity should evaluate to determine whether there has been a significant decrease in the volume and level of activity for the asset or liability in relation to normal market activity for the asset or liability. When the reporting entity concludes there has been a significant decrease in the volume and level of activity for the asset or liability, further analysis of the information from that market is needed and significant adjustments to the related prices may be necessary to estimate fair value in accordance with fair value measurement and disclosure guidance. This guidance further clarifies that when there has been a significant decrease in the volume and level of activity for the asset or liability, some transactions may not be orderly. In those situations, the entity must evaluate the weight of the evidence to determine whether the transaction is orderly. The guidance provides a list of circumstances that may indicate that a transaction is not orderly. A transaction price that is not associated with an orderly transaction is given little, if any, weight when estimating fair value. Fair value measurement and disclosure guidance establishes a fair value hierarchy that prioritizes the inputs to valuation methods used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2: Quoted prices in markets that are not active, or inputs that are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported with little or no market activity). An asset or liability’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. For assets measured at fair value, the fair value measurements by level within the fair value hierarchy, and the basis of measurement used at December 31, 2017 and 2016 , are as follows: Fair Value Measurements at December 31, 2017 In thousands Basis Total Level 1 Level 2 Level 3 U.S. Government and agencies $ 104,083 $ — $ 104,083 $ — Mortgage-backed securities, residential 34,833 — 34,833 — State and municipal 13,294 — 13,294 — Corporate bonds 5,057 — 5,057 — CRA mutual fund 1,035 1,035 — — Stock in other banks 749 749 — — Total securities available for sale Recurring $ 159,051 $ 1,784 $ 157,267 $ — Impaired loans Non-recurring $ 5,426 $ — $ — $ 5,426 Foreclosed assets held for resale Non-recurring $ — $ — $ — $ — Fair Value Measurements at December 31, 2016 In thousands Basis Total Level 1 Level 2 Level 3 U.S. Government and agencies $ 79,579 $ — $ 79,579 $ — Mortgage-backed securities, residential 31,973 — 31,973 — State and municipal 24,660 — 24,660 — Corporate bonds 5,062 — 5,062 — CRA mutual fund 1,035 1,035 — — Stock in other banks 681 681 — — Total securities available for sale Recurring $ 142,990 $ 1,716 $ 141,274 $ — Impaired loans Non-recurring $ 4,406 $ — $ — $ 4,406 Foreclosed assets held for resale Non-recurring $ — $ — $ — $ — The following table presents additional quantitative information about assets measured at fair value on a nonrecurring basis for which the Corporation has utilized Level 3 inputs to determine fair value: Quantitative Information about Level 3 Fair Value Measurements Dollars in thousands Fair Value Estimate Valuation Technique Unobservable Input Range Weighted Average December 31, 2017 Impaired loans $ 5,426 Appraisal of collateral (1) Appraisal adjustments (2) (10) - (50)% (36 )% Foreclosed assets held for resale $ — Appraisal of collateral (1) (3) Appraisal adjustments (2) (10) - (50)% — % December 31, 2016 Impaired loans $ 4,406 Appraisal of collateral (1) Appraisal adjustments (2) (10) - (50)% (39 )% Foreclosed assets held for resale $ — Appraisal of collateral (1) (3) Appraisal adjustments (2) (10) - (50)% — % (1) Fair value is generally determined through management’s estimate or independent third-party appraisals of the underlying collateral, which generally includes various Level 3 inputs which are not observable. (2) Appraisals may be adjusted downward by management for qualitative factors such as economic conditions and estimated liquidation expenses. The range of liquidation expenses and other appraisal adjustments are presented as a percentage of the appraisal. Higher downward adjustments are caused by negative changes to the collateral or conditions in the real estate market, actual offers or sales contracts received, and/or age of the appraisal. (3) Includes qualitative adjustments by management and estimated liquidation expenses. The following information should not be interpreted as an estimate of the fair value of the entire Corporation since a fair value calculation is only provided for a limited portion of the Corporation’s assets and liabilities. Due to a wide range of valuation techniques and the degree of subjectivity used in making the estimates, comparisons between the Corporation’s disclosures and those of other companies may not be meaningful. The following methods and assumptions were used to estimate the fair values of certain Corporation assets and liabilities at December 31, 2017 and 2016 : Cash and Cash Equivalents (Carried at Cost) The carrying amounts reported in the consolidated statement of condition for cash and short-term instruments approximate those assets’ fair value. U.S. currency is Level 1 and cash equivalents are Level 2. Securities The fair values of securities available for sale (carried at fair value) and held to maturity (carried at amortized cost) are determined by obtaining quoted market prices on nationally recognized securities exchanges (Level 1), or matrix pricing (Level 2), which is a mathematical technique used widely in the industry to value debt securities without relying exclusively on quoted market prices for the specific security but rather by relying on the security’s relationship to other benchmark quoted prices. The Corporation uses an independent service provider to provide matrix pricing, and uses the valuation of another provider to compare for reasonableness. Loans Held for Sale (Carried at Lower of Cost or Fair Value) The fair values of mortgage loans held for sale are determined based on amounts to be received at settlement by establishing the respective buyer requirement or market interest rates. Loans (Carried at Cost) The fair values of non-impaired loans are estimated using discounted cash flow analyses, as well as using market rates at the balance sheet date that reflect the credit and interest rate risk inherent in the loans. Projected future cash flows are calculated based upon contractual maturity or call dates, projected repayments, and prepayments of principal. Generally, for variable rate loans that reprice frequently and with no significant change in credit risk, fair values are based on carrying values. Impaired Loans (Generally Carried at Fair Value) Loans for which the Corporation has measured impairment are generally based on the fair value of the loan’s collateral. Fair value is generally determined based upon independent third-party appraisals of the properties, or discounted cash flows based upon the expected proceeds. These assets are included as Level 3 fair values, based upon the lowest level of input that is significant to the fair value measurements. The fair value consists of the loan balances less the valuation allowance and/or charge-offs. Foreclosed Assets Held for Resale The fair value of real estate acquired through foreclosure is based on independent third-party appraisals of the properties. These assets are included as Level 3 fair values, based upon appraisals that consider the sales prices of similar properties in the proximate vicinity. It is the policy of the Corporation to have the initial market value of a foreclosed asset held for resale determined by an independent third-party valuation. If the Corporation already has a valid appraisal on file for the property and that appraisal has been completed within the previous 12 months, another appraisal shall not be required when the Corporation acquires ownership of that real estate. Further, the Corporation shall update the market value of each foreclosed asset with an independent third-party valuation at least every 18 months, or more frequently if management believes that there is an indication that the fair value has declined. These valuations may be adjusted downward to account for specialized use of the property, change in the condition of the real estate, change in local market and economic conditions, and other specific factors involving the collateral. Restricted Investment in Bank Stock (Carried at Cost) The carrying amount of required and restricted investment in correspondent bank stock approximates fair value, and considers the limited marketability of such securities. Accrued Interest Receivable and Payable (Carried at Cost) The carrying amounts of accrued interest receivable and accrued interest payable approximate their fair value. Deposits (Carried at Cost) The fair values disclosed for demand deposits (e.g., interest and non-interest checking, savings, and money market accounts) are, by definition, equal to the amount payable on demand at the reporting date (e.g., their carrying amounts). Fair values for fixed-rate certificates of deposit are estimated using a discounted cash flow calculation that applies market interest rates currently being offered in the market on certificates to a schedule of aggregated expected monthly maturities on time deposits. Short-Term Borrowings (Carried at Cost) The carrying amounts of short-term borrowings approximate their fair values. Long-Term Borrowings (Carried at Cost) The fair values of long-term borrowings are estimated using discounted cash flow analysis, based on quoted prices for new borrowings with similar credit risk characteristics, terms, and remaining maturity. The prices obtained from this active market represent a market value that is deemed to represent the transfer price if the liability were assumed by a third party. The fair value of the trust preferred subordinated debt, included in long-term borrowings, was determined based upon an estimated fair value from an independent brokerage firm. Off-Balance Sheet Credit-Related Instruments The fair values for the Corporation’s off-balance sheet financial instruments (specifically, lending commitments and letters of credit) are based on fees currently charged in the market to enter into similar agreements, taking into account the remaining terms of the agreements and the counterparties’ credit standing. The following presents the carrying amount, fair value, and placement in the fair value hierarchy of the Corporation’s financial instruments at December 31, 2017 and 2016 : December 31, 2017 In thousands Carrying Amount Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and due from banks $ 19,304 $ 19,304 $ 8,313 $ 10,991 $ — Interest-bearing deposits in banks 15,137 15,137 15,137 — — Investment securities available for sale 159,051 159,051 1,784 157,267 — Investment securities held to maturity 44,829 44,549 — 44,549 — Loans held for sale 1,736 1,736 — 1,736 — Loans, less allowance for loan losses 1,230,194 1,213,932 — — 1,213,932 Accrued interest receivable 3,670 3,670 — 3,670 — Restricted investment in bank stocks 4,773 4,773 — 4,773 — Financial liabilities: Deposits 1,298,492 1,295,456 — 1,295,456 — Short-term borrowings 36,908 36,908 — 36,908 — Long-term borrowings 89,600 89,571 — 89,571 — Trust preferred subordinated debt 5,000 4,692 — 4,692 — Accrued interest payable 1,163 1,163 — 1,163 — Off-balance sheet financial instruments — — — — — December 31, 2016 In thousands Carrying Amount Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and due from banks $ 13,796 $ 13,796 $ 6,921 $ 6,875 $ — Interest-bearing deposits in banks 5,135 5,135 5,135 — — Investment securities available for sale 142,990 142,990 1,716 141,274 — Investment securities held to maturity 55,568 55,425 — 55,425 — Loans held for sale 1,770 1,770 — 1,770 — Loans, less allowance for loan losses 893,176 888,169 — — 888,169 Accrued interest receivable 3,158 3,158 — 3,158 — Restricted investment in bank stocks 4,349 4,349 — 4,349 — Financial liabilities: Deposits 967,621 967,236 — 967,236 — Short-term borrowings 34,590 34,590 — 34,590 — Long-term borrowings 74,250 75,029 — 75,029 — Accrued interest payable 837 837 — 837 — Off-balance sheet financial instruments — — — — —

RETIREMENT PLANS

RETIREMENT PLANS	12 Months Ended
	Dec. 31, 2017
Postemployment Benefits [Abstract]
RETIREMENT PLANS	RETIREMENT PLANS The Corporation’s banking subsidiary has a non-contributory, defined benefit pension plan. Retirement benefits are a function of both years of service and compensation. The funding policy is to contribute annually the amount that is sufficient to meet the minimum funding requirements set forth in the Employee Retirement Income Security Act. A measurement date of December 31 has been used for the fiscal years ended December 31, 2017 and 2016 . In thousands 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 28,625 $ 26,670 Service cost 839 795 Interest cost 1,135 1,136 Change in assumptions 2,040 1,059 Benefits paid (1,092 ) (1,035 ) Benefit obligation at end of year 31,547 28,625 Change in plan assets: Fair value of plan assets at beginning of year 38,715 36,880 Actual return on plan assets 4,816 2,870 Employer contribution — — Benefits paid (1,092 ) (1,035 ) Fair value of plan assets at end of year 42,439 38,715 Funded Status, included in other assets $ 10,892 $ 10,090 Amounts recognized in accumulated other comprehensive loss: Total net actuarial loss $ 7,924 $ 8,859 Prior service cost — — Total included in accumulated other comprehensive loss (pretax) $ 7,924 $ 8,859 The estimated costs that will be amortized from accumulated other comprehensive loss into net periodic pension cost during the next fiscal year are as follows: In thousands Net loss $ 515 Prior service cost — $ 515 The accumulated benefit obligation totaled $30,228,000 and $27,508,000 at December 31, 2017 and 2016 , respectively. For the years ended December 31, 2017 and 2016 the mortality assumptions were derived using the mortality rates from RP-2006 (underlying baseline table from SOA RP-2014 study based on experience data for private pension plans of 2006, the central year of experience data 2004-2008). The components of net periodic benefit costs (income) related to the non-contributory, defined benefit pension plan for the years ended December 31 are as follows: In thousands 2017 2016 2015 Components of net periodic benefit cost (income): Service cost $ 839 $ 795 $ 881 Interest cost 1,135 1,136 1,040 Expected return on plan assets (2,518 ) (2,429 ) (2,542 ) Recognized net actuarial loss 676 682 481 Amortization of prior service cost — 1 24 Net Periodic Benefit Cost (Income) 132 185 (116 ) Net loss (259 ) 618 1,409 Amortization of net loss (676 ) (682 ) (481 ) Amortization of prior service cost — (1 ) (24 ) Total recognized in other comprehensive (income) loss $ (935 ) $ (65 ) $ 904 Total recognized in net periodic benefit cost and other comprehensive (income) loss $ (803 ) $ 120 $ 788 For the years ended December 31, 2017 , 2016 and 2015 , the assumptions used to determine the benefit obligation are as follows: 2017 2016 2015 Discount rate 3.55 % 4.05 % 4.35 % Rate of compensation increase 3.50 % 3.50 % 3.50 % For the years ended December 31, 2017 , 2016 and 2015 , the assumptions used to determine the net periodic benefit cost (income) are as follows: 2017 2016 2015 Discount rate 4.05 % 4.35 % 3.90 % Expected long-term rate of return on plan assets 6.75 % 6.75 % 6.75 % Rate of compensation increase 3.50 % 3.50 % 3.75 % The Corporation’s pension plan weighted-average assets’ allocations at December 31, 2017 and 2016 , are as follows: 2017 2016 Equity securities 50 % 48 % Debt securities 44 % 46 % Short-term fixed income — % — % Real estate 6 % 6 % 100 % 100 % The Corporation’s overall investment strategy is to achieve a mix of investments to meet the long-term rate of return assumption and near-term pension obligations with a diversification of assets types, fund strategies and fund managers. The mix of investments is adjusted periodically by retaining an advisory firm to recommend appropriate allocations after reviewing the Corporation’s risk tolerance on contribution levels, funded status and plan expense, and any applicable regulatory requirements. The weighted-average assets’ allocation in the above table represents the Corporation’s conclusion on the appropriate mix of investments. The specific investment vehicles are institutional separate accounts from a variety of fund managers which are regularly reviewed by the Corporation for acceptable performance. Equity securities included Corporation common stock in amounts of $2,114,000 , or 5% of total plan assets, and $2,175,000 , or 6% of total plan assets, at December 31, 2017 and 2016 , respectively. Fair value measurements at December 31, 2017 , are as follows: In thousands Total Level 1 Level 2 Level 3 Equity securities $ 21,423 $ 2,114 $ 19,309 $ — Debt securities 18,668 — 18,668 — Real estate 2,348 — 2,348 — Fair value measurements at December 31, 2016 , are as follows: In thousands Total Level 1 Level 2 Level 3 Equity securities $ 18,687 $ 2,175 $ 16,512 $ — Debt securities 17,888 — 17,888 — Real estate 2,140 — 2,140 — It has not yet been determined the amount that the Bank may contribute to the Plan in 2018 . The Corporation reduced the future benefit accruals for the defined benefit pension plan effective January 1, 2010, in order to manage total benefit expense. The new formula is the earned benefit as of December 31, 2009, plus 0.75% of a participant’s average monthly pay multiplied by years of benefit service earned on and after January 1, 2010, but not more than 25 years. The benefit formula percentage and maximum years of benefit service were both reduced. Effective April 1, 2012, no inactive or former participant in the Plan is eligible to again participate in the plan, and no employee hired after March 31, 2012, is eligible to participate in the Plan. As of the last annual census, ACNB Bank had a combined 353 active, vested terminated, and retired persons in the Plan. Based on current data and assumptions, the following benefit payments, which reflect expected future service, as appropriate, are: Years Ending In thousands 2018 $ 1,320 2019 1,410 2020 1,440 2021 1,650 2022 1,660 2023 - 2027 9,200 The Corporation’s banking subsidiary maintains a 401(k) plan for the benefit of eligible employees. Employees may contribute up to 100% of their compensation subject to certain limits based on federal tax laws. The Bank makes matching contributions up to 100% of the first 4% of an employee’s compensation contributed to the plan. Matching contributions vest immediately to the employee. Bank contributions to and expenses for the plan were $626,000 , $541,000 and $547,000 for 2017 , 2016 and 2015 , respectively. RIG has a similar but separate 401(k) plan with the match of 6% for non-highly compensated employees and 3% match for highly compensated employees. RIG’s contributions to and expenses for the plan were $86,000 , $83,000 and $74,000 for 2017 , 2016 and 2015 , respectively. The Corporation’s banking subsidiary maintains nonqualified compensation plans for selected senior officers. The estimated present value of future benefits is accrued over the period from the effective date of the agreements until the expected retirement dates of the individuals. The balance accrued for these plans included in other liabilities as of December 31, 2017 and 2016 , totaled $2,803,000 and $2,550,000 , respectively. The annual expense included in salaries and benefits expense totaled $279,000 , $383,000 and $360,000 during the years ended December 31, 2017 , 2016 and 2015 , respectively. To fund the benefits under these plans, the Bank is the owner of single premium life insurance policies on participants in the nonqualified retirement plans.

STOCKHOLDERS' EQUITY AND REGULA

STOCKHOLDERS' EQUITY AND REGULATORY MATTERS	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
STOCKHOLDERS' EQUITY AND REGULATORY MATTERS	STOCKHOLDERS’ EQUITY AND REGULATORY MATTERS In January 2011, the Corporation offered stockholders the opportunity to participate in the ACNB Corporation Dividend Reinvestment and Stock Purchase Plan. The plan provides registered holders of ACNB Corporation common stock with a convenient way to purchase additional shares of common stock by permitting participants in the plan to automatically reinvest cash dividends on all or a portion of the shares owned and to make quarterly voluntary cash payments under the terms of the plan. Participation in the plan is voluntary, and there are eligibility requirements to participate in the plan. During 2017, 14,967 shares were issued under this plan with proceeds in the amount of $362,000 . During 2016, 16,979 shares were issued under this plan with proceeds in the amount of $437,000 . During 2015, 18,401 shares were issued under this plan with proceeds in the amount of $499,000 . Proceeds are used for general corporate purposes. On May 5, 2009, stockholders approved and ratified the ACNB Corporation 2009 Restricted Stock Plan, which awards shall not exceed, in the aggregate, 200,000 shares of common stock. The plan is available to employees and directors of the Bank to advance the best interests of ACNB Corporation and its shareholders. The plan provides those persons who have responsibility for its growth with additional incentive by allowing them to acquire an ownership in ACNB Corporation and thereby encouraging them to contribute to the success of the Corporation. To date, 19,301 shares were issued under this plan. The Corporation and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet the 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 Corporation’s consolidated financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Corporation and the 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. Quantitative measures established by regulation to ensure capital adequacy require the Corporation and the Bank to maintain minimum amounts and ratios (set forth below) of total and Tier 1 capital to average assets. The federal banking agencies issued final rules to implement the Basel III regulatory capital reforms and changes required by the Dodd-Frank Act. The phase-in period for community banking organizations began January 1, 2015, while larger institutions (generally those with assets of $250 billion or more) began compliance effective January 1, 2014. The final rules call for the following capital requirements: • a minimum ratio of common Tier 1 capital to risk-weighted assets of 4.5%; • a minimum ratio of Tier 1 capital to risk-weighted assets of 6.0%; • a minimum ratio of total capital to risk-weighted assets of 8.0%; and, • a minimum leverage ratio of 4.0%. In addition, the final rules establish a common equity Tier 1 capital conservation buffer of 2.5% of risk-weighted assets applicable to all banking organizations. If a banking organization fails to hold capital above the minimum capital ratios and the capital conservation buffer, it will be subject to certain restrictions on capital distributions and discretionary bonus payments. The 2.5% at 0.625% per year phase-in period for the capital conservation and countercyclical capital buffers for all banking organizations began on January 1, 2016. Management believes, as of December 31, 2017 , that the Corporation and the Bank meet all capital adequacy requirements to which they are subject. As of December 31, 2017 , the most recent notification from the federal banking regulators categorized the Bank as “well capitalized” under the regulatory framework for prompt corrective action. There are no subsequent conditions or events that management believes have changed the Bank’s category. The actual and required capital amounts and ratios were as follows: Actual For Capital Adequacy Purposes To be Well Capitalized under Prompt Corrective Action Provisions Dollars in thousands Amount Ratio Amount (1) Ratio (1) Amount Ratio CORPORATION As of December 31, 2017 Tier 1 leverage ratio (to average assets) $ 144,376 9.04 % $ ≥63,871 ≥4.0% N/A N/A Common Tier 1 risk-based capital ratio (to risk-weighted assets) 144,376 12.79 ≥50,796 ≥4.5 N/A N/A Tier 1 risk-based capital ratio (to risk-weighted assets) 144,376 12.79 ≥67,728 ≥6.0 N/A N/A Total risk-based capital ratio (to risk-weighted assets) 158,479 14.04 ≥90,304 ≥8.0 N/A N/A As of December 31, 2016 Tier 1 leverage ratio (to average assets) $ 121,650 10.06 % $ ≥48,382 ≥4.0% N/A N/A Common Tier 1 risk-based capital ratio (to risk-weighted assets) 121,650 14.71 ≥37,205 ≥4.5 N/A N/A Tier 1 risk-based capital ratio (to risk-weighted assets) 121,650 14.71 ≥49,606 ≥6.0 N/A N/A Total risk-based capital ratio (to risk-weighted assets) 132,033 15.97 ≥66,142 ≥8.0 N/A N/A BANK As of December 31, 2017 Tier 1 leverage ratio (to average assets) $ 138,811 8.70 % $ ≥68,857 ≥4.0% $ ≥79,822 ≥5.0% Common Tier 1 risk-based capital ratio (to risk-weighted assets) 138,811 12.34 ≥50,639 ≥4.5 ≥73,145 ≥6.5 Tier 1 risk-based capital ratio (to risk-weighted assets) 138,811 12.34 ≥67,519 ≥6.0 ≥90,025 ≥8.0 Total risk-based capital ratio (to risk-weighted assets) 152,868 13.58 ≥90,025 ≥8.0 ≥112,532 ≥10.0 As of December 31, 2016 Tier 1 leverage ratio (to average assets) $ 106,540 8.82 % $ ≥48,316 ≥4.0% $ ≥60,395 ≥5.0% Common Tier 1 risk-based capital ratio (to risk-weighted assets) 106,540 12.96 ≥36,995 ≥4.5 ≥53,438 ≥6.5 Tier 1 risk-based capital ratio (to risk-weighted assets) 106,540 12.96 ≥49,327 ≥6.0 ≥65,770 ≥8.0 Total risk-based capital ratio (to risk-weighted assets) 116,865 14.22 ≥65,770 ≥8.0 ≥82,212 ≥10.0 (1) Amounts and ratios do not include capital conservation buffer.

FINANCIAL INSTRUMENTS WITH OFF-

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK	FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK The Corporation is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments consist primarily of commitments to extend credit (typically mortgages and commercial loans) and, to a lesser extent, standby letters of credit. These instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized on the consolidated balance sheet. The Corporation’s exposure to credit loss in the event of nonperformance by the other party to the financial instrument for commitments to extend credit and standby letters of credit is represented by the contractual amount of those instruments. The Corporation uses the same credit policies in making commitments and conditional obligations as it does for on balance sheet instruments. The Corporation does not anticipate any material losses from these commitments. Commitments to extend credit, including commitments to grant loans and unfunded commitments under lines of credit, are agreements to lend to a customer as long as there is no violation of any condition established in the contract. 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. The Corporation evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Corporation upon extensions of credit, is based on management’s credit evaluation of the customer. Collateral held varies but may include accounts receivable, inventory, property and equipment and income-producing commercial properties. On loans secured by real estate, the Corporation generally requires loan to value ratios of no greater than 80% . Standby letters of credit are conditional commitments issued by the Corporation to guarantee the performance of a customer to a third party. Those guarantees are primarily issued to support public and private borrowing arrangements and similar transactions. The terms of the letters of credit vary and may have renewal features. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loans to customers. The Corporation generally holds collateral and/or personal guarantees supporting those commitments for which collateral is deemed necessary. Management believes that the proceeds obtained through a liquidation of such collateral and the enforcement of guarantees would be sufficient to cover the maximum potential amount of future payments required under the corresponding guarantees. The current amount of the liability as of December 31, 2017 and 2016 , for guarantees under standby letters of credit issued is not material. In 2016, ACNB Corporation executed a guaranty for a note related to a $500,000 commercial line of credit from a local bank, with normal terms and conditions for such a line, for Russell Insurance Group, Inc., the borrower and a wholly-owned subsidiary of ACNB Corporation. The commercial line of credit is for general working capital needs should they arise by the borrower. No liability is recorded for the guarantor’s obligation as the guarantor would have full recourse from all assets of its wholly-owned subsidiary. No draws were taken on this commercial line of credit since its inception. The Corporation has not been required to perform on any financial guarantees, and has not incurred any losses on its commitments, during the past three years. A summary of the Corporation’s commitments at December 31 were as follows: In thousands 2017 2016 Commitments to extend credit $ 264,368 $ 258,631 Standby letters of credit 6,362 6,134

CONTINGENCIES

CONTINGENCIES	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
CONTINGENCIES	CONTINGENCIES The Corporation is subject to claims and lawsuits which arise primarily in the ordinary course of business. Based on information presently available and advice received from legal counsel representing the Corporation in connection with any such claims and lawsuits, it is the opinion of management that the disposition or ultimate determination of any such claims and lawsuits will not have a material adverse effect on the consolidated financial position, consolidated results of operations or liquidity of the Corporation.

ACNB CORPORATION (PARENT COMPAN

ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION	ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION STATEMENTS OF CONDITION December 31, In thousands 2017 2016 ASSETS Cash $ 9,440 $ 8,563 Investment in banking subsidiary 143,288 100,395 Investment in other subsidiaries 8,517 8,768 Investments in low-income housing partnerships 689 1,016 Securities and other assets 1,548 1,232 Receivable from banking subsidiary 118 130 Total Assets $ 163,600 $ 120,104 LIABILITIES AND STOCKHOLDERS’ EQUITY Long-term debt $ 9,600 $ — Other liabilities 34 43 Stockholders’ equity 153,966 120,061 Total Liabilities and Stockholders’ Equity $ 163,600 $ 120,104 STATEMENTS OF INCOME AND COMPREHENSIVE INCOME Years Ended December 31, In thousands 2017 2016 2015 Dividends from banking subsidiary $ 5,233 $ 4,840 $ 4,820 Gain on sale of securities — 26 — Other income 31 35 190 5,264 4,901 5,010 Expenses 1,572 854 431 3,692 4,047 4,579 Income tax benefit 507 490 381 4,199 4,537 4,960 Equity in undistributed earnings of subsidiaries 5,589 6,332 6,057 Net Income $ 9,788 $ 10,869 $ 11,017 Comprehensive Income $ 9,903 $ 9,571 $ 9,014 STATEMENTS OF CASH FLOWS Years Ended December 31, In thousands 2017 2016 2015 CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 9,788 $ 10,869 $ 11,017 Equity in undistributed earnings of subsidiaries (5,589 ) (6,332 ) (6,057 ) Decrease (Increase) in receivable from banking subsidiary 12 2,639 (131 ) Gain on sale of securities — (26 ) — Other 129 540 86 Net Cash Provided by Operating Activities 4,340 7,690 4,915 CASH FLOWS FROM INVESTING ACTIVITIES Return of investment from subsidiary 1,000 650 750 Outlay for business combination (4,445 ) — — Net Cash (Used in) Provided by Investing Activities (3,445 ) 650 750 CASH FLOWS USED IN FINANCING ACTIVITIES Proceeds from long-term debt 4,600 — — Repayments on long-term debt — — (1,437 ) Proceeds from issuance of common stock 615 615 499 Dividends paid (5,233 ) (4,840 ) (4,820 ) Net Cash Used in Financing Activities (18 ) (4,225 ) (5,758 ) Net Increase (Decrease) in Cash and Cash Equivalents 877 4,115 (93 ) CASH AND CASH EQUIVALENTS — BEGINNING 8,563 4,448 4,541 CASH AND CASH EQUIVALENTS — ENDING $ 9,440 $ 8,563 $ 4,448

GOODWILL AND OTHER INTANGIBLES

GOODWILL AND OTHER INTANGIBLES	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	GOODWILL AND OTHER INTANGIBLES On January 5, 2005 , ACNB Corporation completed the acquisition of Russell Insurance Group, Inc. (RIG) and RIG began to operate as a separate subsidiary of ACNB Corporation. In accordance with the terms of the acquisition, there was contingent consideration associated with this transaction of up to $3,000,000 , payable in 2008 subject to performance criteria for the three -year period subsequent to the acquisition. Due to performance at a higher level than the performance criteria, the liability for this consideration was recorded at December 31, 2006, with a related increase in goodwill. Payment was made in the second quarter of 2008 after it was ascertained that the performance criteria had been met for the full three -year period; after which, the total aggregate purchase price was $8,663,000 . On July 1, 2017, ACNB completed its acquisition of New Windsor Bancorp Inc. (New Windsor) of Taneytown, Maryland. The acquisition of New Windsor resulted in goodwill of approximately $13,272,000 and generated $2,418,000 in core deposit intangibles. Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Other intangible assets represent purchased assets that lack physical substance but can be distinguished from goodwill because of contractual or other legal rights. Intangible assets that have finite lives, such as core deposit intangibles, customer relationship intangibles and renewal lists, are amortized over their estimated useful lives and subject to periodic impairment testing. Core deposit intangibles are primarily amortized over ten years using accelerated methods. Customer renewal lists are amortized over their estimated useful lives which range from eight to thirteen years. Combining goodwill resulting from this transaction with existing goodwill from the 2005 RIG purchase of $6,308,000 , total goodwill included in the Corporation’s consolidated statement of condition is $19,580,000 . Goodwill is not deductible for federal income tax purposes. Goodwill, which has an indefinite useful life, is evaluated for impairment annually and is evaluated for impairment more frequently if events and circumstances indicate that the asset might be impaired. The carrying value and accumulated amortization of the intangible assets (RIG customer lists and New Windsor core deposit intangibles) are as follows: 2017 2016 Year Purchased Dollars in thousands Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization 2005 $ 3,282 $ 3,282 $ 3,282 $ 3,282 2007 637 637 637 587 2008 1,165 1,101 1,165 992 2009 1,300 1,170 1,300 1,040 2010 33 26 33 23 2014 77 31 77 23 2015 173 49 173 32 RIG amortized intangible assets 6,667 6,296 6,667 5,979 2017 New Windsor core deposit intangibles 2,418 220 — — $ 9,085 $ 6,516 $ 6,667 $ 5,979 Amortization of the intangible assets for the five years subsequent to December 31, 2017 , is expected to be as follows: Years Ending In thousands 2018 $ 638 2019 400 2020 353 2021 309 2022 265 Thereafter 604

SEGMENT AND RELATED INFORMATION

SEGMENT AND RELATED INFORMATION	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
SEGMENT AND RELATED INFORMATION	SEGMENT AND RELATED INFORMATION The Corporation has two reporting segments, the Bank and RIG. RIG is managed separately from the banking segment, which includes the Bank and related financial services that the Corporation offers through its banking subsidiary. RIG offers a broad range of property and casualty, life and health insurance to both commercial and individual clients. Segment information for 2017 , 2016 and 2015 is as follows: In thousands Banking Insurance Total 2017 Net interest income and other income from external customers $ 55,763 $ 4,738 $ 60,501 Income before income taxes 15,585 837 16,422 Total assets 1,586,064 9,368 1,595,432 Capital expenditures 1,727 30 1,757 2016 Net interest income and other income from external customers $ 45,313 $ 4,461 $ 49,774 Income before income taxes 13,828 809 14,637 Total assets 1,195,857 10,463 1,206,320 Capital expenditures 2,333 11 2,344 2015 Net interest income and other income from external customers $ 43,522 $ 4,490 $ 48,012 Income before income taxes 14,137 641 14,778 Total assets 1,138,106 9,819 1,147,925 Capital expenditures 1,712 26 1,738

NEW WINDSOR ACQUISITION

NEW WINDSOR ACQUISITION	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
NEW WINDSOR ACQUISITION	NEW WINDSOR ACQUISITION On July 1, 2017, ACNB completed its acquisition of New Windsor Bancorp Inc. (New Windsor) of Taneytown, Maryland. New Windsor was a locally owned and managed institution with seven locations in north central Maryland that complemented, enhanced and expanded ACNB’s physical presence in north central Maryland. ACNB transacted the acquisition to enhance its competitive strategic position, potential prospective business opportunities, operations, management, prospective financial condition, future earnings and business prospects. Specifically, ACNB believes that the acquisition will enhance its business opportunities in Northern Maryland due to the combined company having a greater market share, market presence and the ability to offer more diverse (i.e. Trust Services) and more profitable products, as well as a broader based and geographically diversified branch system to enhance deposit collection and potentially improve funding costs. The fair value of total assets acquired as a result of the acquisition totaled $319.8 million, loans totaled $263.5 million and deposits totaled $293.3 million. Goodwill recorded in the acquisition was $13.3 million. In accordance with the terms of the Reorganization Agreement, dated November 21, 2016, as amended, New Windsor shareholders received, in aggregate, $4.5 million in cash and 938,360 shares or approximately 13% of the post transaction outstanding shares of the Corporation’s common stock. The transaction was valued at $33.3 million based on the Corporation’s June 30, 2017 closing price of $30.50 as quoted on NASDAQ. The results of the combined entity’s operations are included in the Corporation’s Consolidated Financial Statements from the date of acquisition. The acquisition of New Windsor is being accounted for as a business combination using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed, and consideration paid were recorded at estimated fair values on the acquisition date. Fair values are preliminary and subject to refinement for up to one year after the closing date of the acquisition. The following table summarizes the consideration paid for New Windsor and the fair value of assets acquired and liabilities assumed as of the acquisition date: Purchase Price Consideration in Common Stock New Windsor shares outstanding 1,003,703 Shares paid cash consideration 150,555 Cash consideration (per New Windsor share) $ 30.00 Cash portion of purchase price $ 4,519,995 New Windsor shares outstanding 1,003,703 Shares paid stock consideration 853,148 Exchange ratio 1.10 Total ACNB shares issued 938,360 ACNB’s share price for purposes of calculation $ 30.50 Equity portion of purchase price $ 28,619,980 Cost of shares owned by buyer $ 150,000 Total consideration paid $ 33,289,975 Allocation of Purchase Price In thousands Total Purchase Price $ 33,290 Fair Value of Assets Acquired Cash and cash equivalents 10,964 Investment securities 21,624 Loans held for sale 1,463 Loans 263,450 Restricted stock 486 Premises and equipment 8,624 Core deposit intangible asset 2,418 Other assets 10,792 Total assets 319,821 Fair Value of Liabilities Assumed Non-interest bearing deposits 80,006 Interest bearing deposits 213,327 Subordinated debt 4,688 Other liabilities 1,782 Total liabilities 299,803 Net Assets Acquired 20,018 Goodwill Recorded in Acquisition $ 13,272 Pursuant to the accounting requirements, the Corporation assigned a fair value to the assets acquired and liabilities assumed of New Windsor. ASC 820 defines fair value as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The calculation of goodwill is subject to change for up to one year after the date of acquisition as additional information relative to the closing date estimates and uncertainties become available. Goodwill and core deposit intangibles are allocated to the banking business segment. Fair values of the major categories of assets acquired and liabilities assumed were determined as follows: Investment securities available-for-sale The estimated fair values of the investment securities available for sale, primarily comprised of U.S. Government agency mortgage-backed securities, U.S. government agencies and municipal bonds, were determined using Level 2 inputs in the fair value hierarchy. The fair values were determined using independent pricing services. The Corporation’s independent pricing service utilized matrix pricing, which is a mathematical technique used widely in the industry to value debt securities without relying exclusively on quoted market prices for the specific security but rather relying on the security’s relationship to other benchmark quoted prices. Management reviewed the data and assumptions used in pricing the securities. A fair value premium of $361,000 was recorded and will be amortized over the estimated life of the investments using the interest rate method. Loans Acquired loans (impaired and non-impaired) are initially recorded at their acquisition-date fair values using Level 3 inputs. Fair values are based on a discounted cash flow methodology that involves assumptions and judgments as to credit risk, expected life time losses, environmental factors, collateral values, discount rates, expected payments and expected prepayments. Specifically, the Corporation has prepared three separate loan fair value adjustments that it believed a market participant might employ in estimating the entire fair value adjustment necessary under ASC 820-10 for the acquired loan portfolio. The three-separate fair valuation methodology employed are: 1) an interest rate loan fair value adjustment (analysis available at request of the Corporation), 2) a general credit fair value adjustment (analysis available at request of the Corporation), and 3) a specific credit fair value adjustment for purchased credit impaired loans subject to ASC 310-30 procedures. The acquired loans were recorded at fair value at the acquisition date without carryover of New Windsor’s previously established allowance for loan losses. The fair value of the financial assets acquired included loans receivable with a gross amortized cost basis of $272,646,000 . The table below illustrates the fair value adjustments made to the amortized cost basis in order to present a fair value of the loans acquired. The credit adjustment on purchased credit impaired loans is derived in accordance with ASC 310-30 and represents the portion of the loan balances that has been deemed uncollectible based on the Corporation’s expectations of future cash flows for each respective loan. In thousands Gross amortized cost basis at July 1, 2017 $ 272,646 Interest rate fair value adjustment on pools of homogeneous loans (731 ) Credit fair value adjustment on pools of homogeneous loans (4,501 ) Credit fair value adjustment on purchased credit impaired loans (3,964 ) Fair value of acquired loans at July 1, 2017 $ 263,450 For loans acquired without evidence of credit quality deterioration, ACNB prepared the interest rate loan fair value and credit fair value adjustments. Loans were grouped into homogeneous pools by characteristics such as loan type, term, collateral and rate. Market rates for similar loans were obtained from various internal and external data sources and reviewed by management for reasonableness. The average of these rates was used as the fair value interest rate a market participant would utilize. A present value approach was utilized to calculate the interest rate fair value discount of $731,000 . Additionally for loans acquired without credit deterioration, a credit fair value adjustment was calculated using a two-part credit fair value analysis: 1) expected lifetime credit migration losses; and 2) estimated fair value adjustment for certain qualitative factors. The expected lifetime losses were calculated using historical losses observed at the Bank, NWSB and peer banks. ACNB also estimated an environmental factor to apply to each loan type. The environmental factor represents potential discount which may arise due to general credit and economic factors. A credit fair value discount of $4.5 million was determined. Both the interest rate and credit fair value adjustments relate to loans acquired with evidence of credit quality deterioration will be substantially recognized as interest income on a level yield amortization method over the expected life of the loans. The following table presents the acquired purchased credit impaired loans receivable at the Acquisition Date: In thousands Contractual principal and interest at acquisition $ 13,439 Nonaccretable difference (5,651 ) Expected cash flows at acquisition 7,788 Accretable yield (1,458 ) Fair value of purchased impaired loans $ 6,330 Premises and Equipment The Corporation acquired seven branches from New Windsor. The fair value of New Windsor’s premises, including land, buildings, and improvements, was determined based upon independent third-party appraisals and other data in the market in which the premises are located. The Corporation prepared an internal analysis to compare the lease contract obligations to comparable market rental rates. The Corporation believed that the leased contract rates were in a reasonable range of market rental rates and concluded that no fair market value adjustment related to leasehold interest was necessary. Core Deposit Intangible The fair value of the core deposit intangible was determined based on a discounted cash flow analysis using a discount rate commensurate with market participants. To calculate cash flows, deposit account servicing costs (net of deposit fee income) and interest expense on deposits were compared to the cost of alternative funding sources available through national brokered CD offering rates. The projected cash flows were developed using projected deposit attrition rates. The core deposit intangible will be amortized over ten years using the sum-of-years digits method. Time Deposits The fair value adjustment for time deposits represents a discount from the value of the contractual repayments of fixed-maturity deposits using prevailing market interest rates for similar-term time deposits. The time deposit discount of approximately $847,500 is being amortized into income on a level yield amortization method over the contractual life of the deposits. Long-term Borrowings The Corporation assumed a trust preferred subordinated debt in connection with the acquisition. The fair value of the trust preferred subordinated debt was determined based upon an estimated fair value from an independent brokerage firm. The trust preferred capital note was valued at discount of $312,500 , which is being amortized into income on a level yield amortization method based upon the assumed market rate, and the term of the trust preferred subordinated debt instrument. The following table presents certain pro forma information as if New Windsor had been acquired on December 31, 2016. These results combine the historical results of the Corporation in the Corporation’s Consolidated Statements of Income and, while certain adjustments were made for the estimated impact of certain fair value adjustments and other acquisition-related activity, they are not indicative of what would have occurred had the acquisition taken place on December 31, 2016. In particular, no adjustments have been made to eliminate the amount of New Windor’s provision for loan losses that would not have been necessary had the acquired loans been recorded at fair value as of December 31, 2016. The Corporation expects to achieve further operating cost savings and other business synergies as a result of the acquisition which are not reflected in the pro forma amounts below: In thousands For the Year Ended December 31, 2016 Total revenues (net interest income plus noninterest income) $ 102,891 Net Income 13,591 Acquisition-related expenses associated with the acquisition of New Windsor were $4,728,000 and $472,000 for the year ended December 31, 2017 and 2016, respectively. Such costs include legal and accounting fees, lease and contract termination expenses, system conversion, operations integration, and employee severances, which have been expensed as incurred.

QUARTERLY RESULTS OF OPERATIONS

QUARTERLY RESULTS OF OPERATIONS	12 Months Ended
	Dec. 31, 2017
Quarterly Results of Operations [Abstract]
QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)	QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) Selected quarterly information for the years ended December 31, 2017 and 2016 , is as follows: Dollars in thousands, except per share data First Quarter Second Quarter Third Quarter Fourth Quarter 2017 Interest income $ 10,533 $ 10,962 $ 15,109 $ 15,181 Interest expense 1,067 1,131 1,547 1,688 Net interest income 9,466 9,831 13,562 13,493 Provision for loan losses — — — — Net interest income after provision for loan losses 9,466 9,831 13,562 13,493 Net gains on sales of securities — — — — Gain on sales of premises and equipment — — — — Other income 3,082 3,528 3,930 3,609 Merger related expenses 162 208 4,305 53 Other expenses and provision for income taxes 9,749 10,429 11,275 14,532 Net income $ 2,637 $ 2,722 $ 1,912 $ 2,517 Basic earnings per share $ 0.43 $ 0.45 $ 0.27 $ 0.35 Dividends per share $ 0.20 $ 0.20 $ 0.20 $ 0.20 2016 Interest income $ 9,964 $ 10,010 $ 10,181 $ 10,345 Interest expense 957 980 996 1,001 Net interest income 9,007 9,030 9,185 9,344 Provision for loan losses — — — — Net interest income after provision for loan losses 9,007 9,030 9,185 9,344 Net gains on sales of securities — — — 26 Gain on sales of premises and equipment — 449 — — Other income 2,872 3,362 3,301 3,198 Proposed merger expenses — — — 472 Other expenses and provision for income taxes 9,332 9,859 9,718 9,524 Net income $ 2,547 $ 2,982 $ 2,768 $ 2,572 Basic earnings per share $ 0.42 $ 0.49 $ 0.46 $ 0.43 Dividends per share $ 0.20 $ 0.20 $ 0.20 $ 0.20

SUMMARY OF SIGNIFICANT ACCOUN31

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policy)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations ACNB Corporation (the Corporation or ACNB), headquartered in Gettysburg, Pennsylvania, provides banking, insurance, and financial services to businesses and consumers through its wholly-owned subsidiaries, ACNB Bank (Bank) and Russell Insurance Group, Inc. (RIG). The Bank engages in full-service commercial and consumer banking and wealth management services, including trust and retail brokerage, through its twenty-two community banking locations in Adams, Cumberland, Franklin, and York Counties, Pennsylvania. There is also a loan production office situated in York County, Pennsylvania. On July 1, 2017, ACNB completed its acquisition of New Windsor Bancorp, Inc. (New Windsor) of Taneytown, Maryland. At the effective time of the acquisition, New Windsor merged with and into a wholly-owned subsidiary of ACNB, immediately followed by the merger of New Windsor State Bank (NWSB) with and into ACNB Bank. ACNB Bank now operates in the Maryland market as “NWSB Bank, A Division of ACNB Bank” and serves its marketplace with banking and wealth management services via a network of seven community banking offices located in Carroll County, Maryland. RIG is a full-service insurance agency based in Westminster, Maryland with a second location in Germantown, Maryland. The agency offers a broad range of property and casualty, life, and health insurance to both commercial and individual clients. The Corporation’s primary source of revenue is interest income on loans and investment securities and fee income on its products and services. Expenses consist of interest expense on deposits and borrowed funds, provisions for loan losses, and other operating expenses.
Basis of Financial Statements	Basis of Financial Statements The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and include the accounts of the Corporation and its wholly-owned subsidiaries. All significant intercompany transactions have been eliminated. Assets held by the Corporation’s Wealth management Department, including trust and retail brokerage, in an agency, fiduciary or retail brokerage capacity for its customers are excluded from the consolidated financial statements since they do not constitute assets of the Corporation. Assets held by the Wealth Management Department amounted to $327,000,000 and $195,000,000 at December 31, 2017 and 2016 , respectively. Income from fiduciary, investment management and brokerage activities are included in other income. The Corporation has evaluated events and transactions occurring subsequent to the balance sheet date of December 31, 2017 , for items that should potentially be recognized or disclosed in the consolidated financial statements. The evaluation was conducted through the date these consolidated financial statements were issued.
Use of Estimates	Use of Estimates Financial statements prepared in accordance with GAAP require management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingencies at the date of the consolidated financial statements, and revenues and expenses during the reporting period. Actual results could differ from these estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses, the determination of other than temporary impairment on securities, and the potential impairment of goodwill.
Significant Group Concentrations of Credit Risk	Significant Group Concentrations of Credit Risk Most of the Corporation’s activities are with customers located within southcentral Pennsylvania and northern Maryland. Note C discusses the types of securities in which the Corporation invests. Note D discusses the types of lending in which the Corporation engages. Included in commercial real estate loans are loans made to lessors of non-residential dwellings that total $269,080,000 , or 21.6% , of total loans at December 31, 2017 . These borrowers are geographically disbursed throughout ACNB’s marketplace and are leasing commercial properties to a varied group of tenants including medical offices, retail space and recreational facilities. Because of the varied nature of the tenants in aggregate, management believes that these loans do not present any greater risk than commercial loans in general.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash on hand, balances due from banks, and federal funds sold, all of which mature within 90 days.
Securities	Securities Debt securities that management has the positive intent and ability to hold to maturity are classified as “held to maturity” and recorded at amortized cost. Securities not classified as held to maturity or trading, including equity securities with readily determinable fair values, are classified as “available for sale” and recorded at fair value, with unrealized gains and losses excluded from earnings and reported, net of tax, in other comprehensive income (loss). Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Declines in the fair value of held to maturity and available for sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses. In estimating other-than-temporary impairment losses on debt securities, management considers (1) whether management intends to sell the security, or (2) if it is more likely than not that management will be required to sell the security before recovery, or (3) if management does not expect to recover the entire amortized cost basis. In assessing potential other-than-temporary impairment for equity securities, consideration is given to management’s intention and ability to hold the securities until recovery of unrealized losses. Gains and losses on the sale of securities are recorded on the trade date and are determined using the specific identification method.
Loans Held for Sale	Loans Held for Sale Loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by aggregate outstanding commitments from investors or current investor yield requirements. Net unrealized losses are recognized through a valuation allowance by charges to income. Mortgage loans held for sale are sold with the mortgage servicing rights released to another financial institution through a correspondent relationship. The correspondent financial institution absorbs all of the risk related to rate lock commitments. Gains or losses on sales of mortgage loans are recognized based on the difference between the selling price and the carrying value of the related mortgage loans sold.
Loans	Loans The Corporation grants commercial, residential, and consumer loans to customers. A substantial portion of the loan portfolio is represented by mortgage loans throughout southcentral Pennsylvania and northern Maryland. The ability of the Corporation’s debtors to honor their contracts is dependent upon the real estate values and general economic conditions in this area. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off generally are reported at their outstanding unpaid principal balances adjusted for charge-offs, the allowance for loan losses, and any deferred fees or costs on originated loans. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loan yield using the interest method. The loans receivable portfolio is segmented into commercial, residential mortgage, home equity lines of credit, and consumer loans. Commercial loans consist of the following classes: commercial and industrial, commercial real estate, and commercial real estate construction. The accrual of interest on residential mortgage and commercial loans is discontinued at the time the loan is 90 days past due unless the credit is well-secured and in process of collection. Consumer loans (consisting of home equity lines of credit and consumer loan classes) are typically charged off no later than 120 days past due. Past due status is based on the contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal or interest is considered doubtful. All interest accrued, but not collected, for loans that are placed on nonaccrual or charged off is reversed against interest income. The interest on these loans is accounted for on the cash-basis or cost-recovery method, until qualifying for return to accrual status. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured.
Allowance for Credit Losses	Allowance for Credit Losses The allowance for credit losses consists of the allowance for loan losses and the reserve for unfunded lending commitments. The allowance for loan losses (the “allowance”) is established as losses are estimated to occur through a provision for loan losses charged to earnings. Loan losses are charged against the allowance when management believes the uncollectibility of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The reserve for unfunded lending commitments represents management’s estimate of losses inherent in its unfunded loan commitments and is recorded in other liabilities on the consolidated statement of condition. The amount of the reserve for unfunded lending commitments is not material to the consolidated financial statements. The allowance for loan losses is evaluated on a regular basis by management and is based upon management’s periodic review of the collectibility of the loans in light of historical experience, the nature and volume of the loan portfolio, adverse situations that may affect the borrower’s ability to repay, estimated value of any underlying collateral, and prevailing economic conditions. This evaluation is inherently subjective as it requires estimates that are susceptible to significant revision as more information becomes available. The allowance consists of specific, general and unallocated components. The specific component relates to loans that are classified as either doubtful, substandard, or special mention. For such loans that are also classified as impaired, an allowance is established when the discounted cash flows (or collateral value or observable market price) of the impaired loan is lower than the carrying value of that loan. The general component covers pools of loans by loan class including commercial loans not considered impaired, as well as smaller balance homogeneous loans, such as residential real estate, home equity, and other consumer loans. These pools of loans are evaluated for loss exposure based upon historical loss rates for each of these categories of loans, adjusted for qualitative factors. These qualitative risk factors include: • lending policies and procedures, including underwriting standards and collection, charge-off and recovery practices; • national, regional and local economic and business conditions, as well as the condition of various market segments, including the impact on the value of underlying collateral for collateral dependent loans; • the nature and volume of the portfolio and terms of loans; • the experience, ability and depth of lending management and staff; • the volume and severity of past due, classified and nonaccrual loans, as well as other loan modifications; and, • the existence and effect of any concentrations of credit and changes in the level of such concentrations. Each factor is assigned a value to reflect improving, stable or declining conditions based on management’s best judgment using relevant information available at the time of the evaluation. Adjustments to the factors are supported through documentation of changes in conditions in a narrative accompanying the allowance for loan loss calculation. The unallocated component of the allowance is maintained to cover uncertainties that could affect management’s estimate of probable losses. The unallocated component of the allowance reflects the margin of imprecision inherent in the underlying assumptions used in the methodologies for estimating specific and general losses in the portfolio. It covers risks that are inherently difficult to quantify including, but not limited to, collateral risk, information risk, and historical charge-off risk. A loan is considered impaired when, based on current information and events, it is probable that the Corporation will be unable to collect the scheduled payments of principal and/or interest when due according to the contractual terms of the loan agreement. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and/or interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. Impairment is measured on a loan by loan basis for commercial and commercial construction loans by either the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s obtainable market price, or the fair value of the collateral if the loan is collateral dependent. A specific allocation within the allowance for loan losses is established for an impaired loan if its carrying value exceeds its estimated fair value. The estimated fair values of the Corporation’s impaired loans are measured based on the estimated fair value of the loan’s collateral or the discounted cash flows method. It is the policy of the Corporation to order an updated valuation on all real estate secured loans when the loan becomes 90 days past due and there has not been an updated valuation completed within the previous 12 months. In addition, the Corporation orders third-party valuations on all impaired real estate collateralized loans within 30 days of the loan being classified as impaired. Until the valuations are completed, the Corporation utilizes the most recent independent third-party real estate valuation to estimate the need for a specific allocation to be assigned to the loan. These existing valuations are discounted downward to account for such things as the age of the existing collateral valuation, change in the condition of the real estate, change in local market and economic conditions, and other specific factors involving the collateral. Once the updated valuation is completed, the collateral value is updated accordingly. For commercial and industrial loans secured by non-real estate collateral, such as accounts receivable, inventory and equipment, estimated fair values are determined based on the borrower’s financial statements, inventory reports, accounts receivable aging reports, equipment appraisals, or invoices. Indications of value from these sources are generally discounted based on the age of the financial information or the quality of the assets. The Corporation actively monitors the values of collateral as well as the age of the valuation of impaired loans. Management believes that the Corporation’s market area is not as volatile as other areas throughout the United States, therefore valuations are ordered at least every 18 months, or more frequently if management believes that there is an indication that the fair value has declined. For impaired loans secured by collateral other than real estate, the Corporation considers the net book value of the collateral, as recorded in the most recent financial statements of the borrower, and determines fair value based on estimates made by management. Large groups of smaller balance homogeneous loans are collectively evaluated for impairment. Accordingly, the Corporation does not separately identify individual consumer and residential loans for impairment disclosures, unless such loans are the subject of a troubled debt restructure. Loans whose terms are modified are classified as troubled debt restructured loans if the Corporation grants such borrowers concessions that it would not otherwise consider and it is deemed that those borrowers are experiencing financial difficulty. Concessions granted under a troubled debt restructuring generally involve a temporary reduction in interest rate, a below market interest rate given the risk associated with the loan, or an extension of a loan’s stated maturity date. Nonaccrual troubled debt restructurings may be restored to accrual status if principal and interest payments, under the modified terms, are current for a sustained period of time and, based on a well-documented credit evaluation of the borrower’s financial condition, there is reasonable assurance of repayment. Loans classified as troubled debt restructurings are generally designated as impaired. The allowance calculation methodology includes further segregation of loan classes into credit quality rating categories. The borrower’s overall financial condition, repayment sources, guarantors, and value of collateral, if appropriate, are generally evaluated annually for commercial loans or when credit deficiencies arise, such as delinquent loan payments. Credit quality risk ratings include regulatory classifications of special mention, substandard, doubtful and loss. Loans classified special mention have potential weaknesses that deserve management’s close attention. If uncorrected, the potential weaknesses may result in deterioration of the repayment prospects. Loans classified substandard have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They include loans that are inadequately protected by the current sound net worth and paying capacity of the obligor or of the collateral pledged, if any. Loans classified doubtful have all the weaknesses inherent in loans classified substandard with the added characteristic that collection or liquidation in full, on the basis of current conditions and facts, is highly improbable. Loans classified as a loss are considered uncollectible and are charged to the allowance for loan losses. Loans not classified are rated pass. In addition, federal and state regulatory agencies, as an integral part of their examination process, periodically review the Corporation’s allowance for loan losses and may require the Corporation to recognize additions to the allowance based on their judgments about information available to them at the time of their examination, which may not be currently available to management. Based on management’s comprehensive analysis of the loan portfolio and economic conditions, management believes the current level of the allowance for loan losses is adequate. Commercial and Industrial Lending — The Corporation originates commercial and industrial loans primarily to businesses located in its primary market area and surrounding areas. These loans are used for various business purposes which include short-term loans and lines of credit to finance machinery and equipment purchases, inventory, and accounts receivable. Generally, the maximum term for loans extended on machinery and equipment is based on the projected useful life of such machinery and equipment. Most business lines of credit are written on demand and may be renewed annually. Commercial and industrial loans are generally secured with short-term assets; however, in many cases, additional collateral such as real estate is provided as additional security for the loan. Loan-to-value maximum values have been established by the Corporation and are specific to the type of collateral. Collateral values may be determined using invoices, inventory reports, accounts receivable aging reports, collateral appraisals, etc. In underwriting commercial and industrial loans, an analysis is performed to evaluate the borrower’s character and capacity to repay the loan, the adequacy of the borrower’s capital and collateral, as well as the conditions affecting the borrower. Evaluation of the borrower’s past, present and future cash flows is also an important aspect of the Corporation’s analysis. Commercial loans generally present a higher level of risk than other types of loans due primarily to the effect of general economic conditions. Commercial Real Estate Lending — The Corporation engages in commercial real estate lending in its primary market area and surrounding areas. The Corporation’s commercial loan portfolio is secured primarily by commercial retail space, office buildings, and hotels. Generally, commercial real estate loans have terms that do not exceed 20 years, have loan-to-value ratios of up to 80% of the appraised value of the property, and are typically secured by personal guarantees of the borrowers. In underwriting these loans, the Corporation performs a thorough analysis of the financial condition of the borrower, the borrower’s credit history, and the reliability and predictability of the cash flow generated by the property securing the loan. Appraisals on properties securing commercial real estate loans originated by the Corporation are performed by independent appraisers. Commercial real estate loans generally present a higher level of risk than other types of loans due primarily to the effect of general economic conditions and the complexities involved in valuing the underlying collateral. Commercial Real Estate Construction Lending — The Corporation engages in commercial real estate construction lending in its primary market area and surrounding areas. The Corporation’s commercial real estate construction lending consists of commercial and residential site development loans, as well as commercial building construction and residential housing construction loans. The Corporation’s commercial real estate construction loans are generally secured with the subject property. Terms of construction loans depend on the specifics of the project, such as estimated absorption rates, estimated time to complete, etc. In underwriting commercial real estate construction loans, the Corporation performs a thorough analysis of the financial condition of the borrower, the borrower’s credit history, and the reliability and predictability of the cash flow generated by the project using feasibility studies, market data, etc. Appraisals on properties securing commercial real estate construction loans originated by the Corporation are performed by independent appraisers. Commercial real estate construction loans generally present a higher level of risk than other types of loans due primarily to the effect of general economic conditions and the uncertainties surrounding total construction costs. Residential Mortgage Lending — One-to-four family residential mortgage loan originations, including home equity closed-end loans, are generated by the Corporation’s marketing efforts, its present customers, walk-in customers, and referrals. These loans originate primarily within the Corporation’s market area or with customers primarily from the market area. The Corporation offers fixed-rate and adjustable-rate mortgage loans with terms up to a maximum of 30 years for both permanent structures and those under construction. The Corporation’s one-to-four family residential mortgage originations are secured primarily by properties located in its primary market area and surrounding areas. The majority of the Corporation’s residential mortgage loans originate with a loan-to-value of 80% or less. Loans in excess of 80% are required to have private mortgage insurance. In underwriting one-to-four family residential real estate loans, the Corporation evaluates both the borrower’s financial ability to repay the loan as agreed and the value of the property securing the loan. Properties securing real estate loans made by the Corporation are appraised by independent appraisers. The Corporation generally requires borrowers to obtain an attorney’s title opinion or title insurance, as well as fire and property insurance (including flood insurance, if necessary) in an amount not less than the amount of the loan. The Corporation has not engaged in subprime residential mortgage originations. Residential mortgage loans present a moderate level of risk due primarily to general economic conditions, as well as a continued weak housing market. Home Equity Lines of Credit Lending — The Corporation originates home equity lines of credit primarily within the Corporation’s market area or with customers primarily from the market area. Home equity lines of credit are generated by the Corporation’s marketing efforts, its present customers, walk-in customers, and referrals. Home equity lines of credit are secured by the borrower’s primary residence with a maximum loan-to-value of 90% and a maximum term of 20 years. In underwriting home equity lines of credit, the Corporation evaluates both the value of the property securing the loan and the borrower’s financial ability to repay the loan as agreed. The ability to repay is determined by the borrower’s employment history, current financial condition, and credit background. Home equity lines of credit generally present a moderate level of risk due primarily to general economic conditions, as well as a continued weak housing market. Junior liens inherently have more credit risk by virtue of the fact that another financial institution may have a higher security position in the case of foreclosure liquidation of collateral to extinguish the debt. Generally, foreclosure actions could become more prevalent if the real estate market continues to be weak and property values deteriorate. Consumer Lending — The Corporation offers a variety of secured and unsecured consumer loans, including those for vehicles and mobile homes and loans secured by savings deposits. These loans originate primarily within the Corporation’s market area or with customers primarily from the market area. Consumer loan terms vary according to the type and value of collateral and the creditworthiness of the borrower. In underwriting consumer loans, a thorough analysis of the borrower’s financial ability to repay the loan as agreed is performed. The ability to repay is determined by the borrower’s employment history, current financial condition, and credit background. Consumer loans may entail greater credit risk than residential mortgage loans or home equity lines of credit, particularly in the case of consumer loans which are unsecured or are secured by rapidly depreciable assets such as automobiles or recreational equipment. In such cases, any repossessed collateral for a defaulted consumer loan may not provide an adequate source of repayment of the outstanding loan balance as a result of the greater likelihood of damage, loss or depreciation. In addition, consumer loan collections are dependent on the borrower’s continuing financial stability, and thus are more likely to be affected by adverse personal circumstances. Furthermore, the application of various federal and state laws, including bankruptcy and insolvency laws, may limit the amount which can be recovered on such loans.
Acquired Loans	Acquired Loans Acquired Loans (impaired and non-impaired) are initially recorded at their acquisition-date fair values using Level 3 inputs. Fair values are based on a discounted cash flow methodology that involves assumptions and judgments as to credit risk, expected lifetime losses, environmental factors, collateral values, discount rates, expected payments and expected prepayments. Specifically, the Corporation has prepared three separate loan fair value adjustments that it believed a market participant might employ in estimating the entire fair value adjustment necessary under ASC 820-10 for the acquired loan portfolio. The three-separate fair valuation methodology employed are: 1) an interest rate loan fair value adjustment (analysis available at request of the Corporation), 2) a general credit fair value adjustment (analysis available at request of the Corporation) and 3) a specific credit fair value adjustment for purchased credit impaired loans subject to ASC 310-30 procedures. The carryover of allowance for loan losses related to acquired loans is prohibited as any credit losses in the loans are included in the determination of the fair value of the loans at the acquisition date. The allowance for loan losses on acquired loans reflects only those losses incurred after acquisition and represents the present value of cash flows expected at acquisition that is no longer expected to be collected. Acquired loans are marked to fair value on the date of acquisition. In conjunction with the quarterly evaluation of the adequacy of the allowance for loan losses, the Corporation performs an analysis on acquired loans to determine whether or not there has been subsequent deterioration in relation to those loans. If deterioration has occurred, the Corporation will includes these loans in the calculation of the allowance for loan losses after the initial valuation, and provide accordingly. Upon acquisition, in accordance with Generally Accepted Accounting Principles, the Corporation has individually determined whether each acquired loan is within the scope of ASC 310-30. The Corporation’s senior lending management reviewed the accounting seller’s loan portfolio on a loan by loan basis to determine if any loans met the two-part definition of an impaired loan as defined by ASC 310-30: 1) Credit deterioration on the loan from its inception until the acquisition date, and 2) It is probable that not all of the contractual cash flows will be collected on the loan. Any acquired loans that were not individually in the scope of ASC 310-30 because they did not meet the criteria above were pooled into groups of similar loans based on various factors including borrower type, loan purpose, and collateral type. For these pools, we used certain loan information, including outstanding principal balance, estimated expected losses, weighted average maturity, weighted average margin, and weighted average interest rate along with estimated prepayment rates, expected lifetime losses, environment factors to estimate the expected cash flow for each loan pool. With regards to ASC 310-30 loans, for external disclosure purposes, the aggregate contractual cash flows less the aggregate expected cash flows will result in a credit related non-accretable yield amount. The aggregate expected cash flows less the acquisition date fair value will result in an accretable yield amount. The accretable yield reflects the contractual cash flows management expects to collect about the loan’s acquisition date fair value and will be recognized over the life of the loan on a level-yield basis as a component of interest income. Over the life of the acquired ASC 310-30 loan, we continue to estimate cash flows expected to be collected. Decreases in expected cash flows, other than from prepayments or rate adjustments, are recognized as impairments through a charge to the provision for credit losses resulting in an increase in the allowance for credit losses. Subsequent improvements in cash flows result in first, reversal of existing valuation allowances recognized subsequent to acquisition, if any, and next, an increase in the amount of accretable yield to be subsequently recognized on a prospective basis over the loan’s remaining life. Acquired ASC 310-30 loans that met the criteria for non-accrual of interest prior to acquisition are considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if we can reasonably estimate the timing and amount of expected cash flows on such loans. Accordingly, we do not consider acquired contractually delinquent loans to be non-accruing and continue to recognize interest income on these loans using the accretion model. For loans acquired without evidence of credit quality deterioration, ACNB prepared the interest rate loan fair value and credit fair value adjustments. Loans were grouped into homogeneous pools by characteristics such as loan type, term, collateral, and rate. Market rates for similar loans were obtained from various internal and external data sources and reviewed by management for reasonableness. The average of these rates was used as the fair value interest rate a market participant would utilize. A present value approach was utilized to calculate the interest rate fair value discount of $731,000 . Additionally, for loans acquired without credit quality deterioration, a credit fair value adjustment was calculated using a two-part credit fair value analysis: 1) expected lifetime credit migration losses; and 2) estimated fair value adjustment for certain qualitative factors. The expected lifetime losses were calculated using historical losses observed at the Bank, NWSB and peer banks. ACNB also estimated an environmental factor to apply to each loan type. The environmental factor represents potential discount which may arise due to general credit and economic factors. A credit fair value discount of $4.5 million was determined. Both the interest rate and credit fair value adjustments relate to loans acquired with evidence of credit quality deterioration will be substantially recognized as interest income on a level yield amortization method over the expected life of the loans.
Premises and Equipment	Premises and Equipment Land is carried at cost. Buildings, furniture, fixtures, equipment and leasehold improvements are carried at cost, less accumulated depreciation. Depreciation is computed principally by the straight-line method over the assets’ estimated useful lives. Normally, a buildings useful life is 40 years, except for building remodels and additions, which are depreciated over fifteen years. Bank equipment, including furniture and fixtures, is normally depreciated over five - fifteen years depending upon the nature of the purchase. Maintenance and normal repairs are charged to expense when incurred while major additions and improvements are capitalized. Gains and losses on disposals are reflected in current operations. Amortization of leasehold improvements is computed by straight line over the shorter of the assets’ useful life or the related lease term.
Restricted Investment in Bank Stocks	Restricted Investment in Bank Stocks Restricted investment in bank stocks, which represents required investments in the common stock of correspondent banks, is carried at cost as of December 31, 2017 and 2016 , and consists of common stock in the Atlantic Central Bankers Bank, Maryland Financial Bank, Community Bankers Bank and Federal Home Loan Bank (FHLB). Management evaluates the restricted investment in bank stocks for impairment in accordance with Accounting Standard Codification (ASC) Topic 942, Financial Services—Depository and Lending. Management’s determination of whether these investments are impaired is based on their assessment of the ultimate recoverability of their cost rather than by recognizing temporary declines in value. The determination of whether a decline affects the ultimate recoverability of their cost is influenced by criteria such as (1) the significance of the decline in net assets of the correspondent bank as compared to the capital stock amount for the correspondent bank and the length of time this situation has persisted, (2) commitments by the correspondent bank to make payments required by law or regulation and the level of such payments in relation to the operating performance of the correspondent bank, (3) the impact of legislative and regulatory changes on institutions and, accordingly, on the customer base of the correspondent bank, and (4) the liquidity position of the correspondent bank. Management believes no impairment charge was necessary related to the restricted investment in bank stocks during 2017 , 2016 or 2015 . However, security impairment analysis is completed quarterly, and the determination that no impairment has occurred during those years is no assurance that impairment may not occur in future periods.
Bank-Owned Life Insurance	Bank-Owned Life Insurance The Corporation’s banking subsidiary maintains nonqualified compensation plans for selected senior officers. To fund the benefits under these plans, the Bank is the owner of single premium life insurance policies on participants in the nonqualified retirement plans. Investment in bank-owned life insurance policies was used to finance the nonqualified compensation plans and provide tax-exempt income to the Corporation. ASC Topic 715, Compensation—Retirement Benefits , requires a liability to be recorded during the service period when a split-dollar life insurance agreement continues after participants’ employment or retirement. The required accrued liability is based on either the post-employment benefit cost for continuing life insurance or based on the future death benefit depending on the contractual terms of the underlying agreement. The Corporation’s liability is based on the post-employment benefit cost for continuing life insurance. The Corporation incurred approximately $96,000 , $96,000 , and $46,000 of expense in 2017 , 2016 , and 2015 , respectively, related to these benefits
Investments in Low-Income Housing Partnerships	Investments in Low-Income Housing Partnerships The Corporation’s investments in low-income housing partnerships are accounted for using the “equity method” prescribed by ASC Topic 323, Investments — Equity Method . In accordance with ASC Topic 740, Income Taxes , tax credits are recognized as they become available. Any residual loss is amortized as the tax credits are received.
Goodwill and Intangible Assets	Goodwill and Intangible Assets The Corporation accounts for its acquisitions using the acquisition accounting method required by ASC Topic 805, Business Combinations. Acquisition accounting requires the total purchase price to be allocated to the estimated fair values of assets and liabilities acquired, including certain intangible assets that must be recognized. Generally, this results in a residual amount in excess of the net fair values, which is recorded as goodwill. ASC Topic 350, Intangibles—Goodwill and Other, requires that goodwill is not amortized to expense, but rather that it be assessed for impairment at least annually. If certain events occur which might indicate goodwill has been impaired, the goodwill is tested for impairment when such events occur. Impairment write-downs are charged to results of operations in the period in which the impairment is determined. The Corporation did not identify any impairment on RIG’s outstanding goodwill from its most recent testing, which was performed as of October 1, 2017 . The Corporation has not identified any such events, and, accordingly, has not tested goodwill resulting from the acquisition of New Windsor for impairment during the year ended December 31, 2017. ACNB plans on testing New Windsor goodwill during 2018. Other acquired intangible assets with finite lives, such as customer lists, are required to be amortized over the estimated lives. These intangibles are generally amortized using the straight line method over estimated useful lives of five to fifteen years.
Foreclosed Assets	Foreclosed Assets Assets acquired through, or in lieu of, loan foreclosure are held for sale and are initially recorded at fair value, less costs to sell at the date of foreclosure, establishing a new cost basis. Subsequent to foreclosure, valuations are periodically performed by management and the assets are adjusted to the fair value, less costs to sell as necessary. Revenue and expenses from operations and changes in the valuation allowance are included in net expenses from foreclosed assets.
Income Taxes	Income Taxes The Corporation accounts for income taxes in accordance with income tax accounting guidance ASC Topic 740, Income Taxes . Current income tax accounting guidance results in two components of income tax expense: current and deferred. Current income tax expense reflects taxes to be paid or refunded for the current period by applying the provisions of the enacted tax law to the taxable income or excess of deductions over revenues. The Corporation determines deferred income taxes using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is based on the tax effects of the differences between the book and tax bases of assets and liabilities, and enacted changes in tax rates and laws are recognized in the period in which they occur. Deferred income tax expense results from changes in deferred tax assets and liabilities between periods. Deferred tax assets are reduced by a valuation allowance if, based on the weight of the evidence available, it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Corporation accounts for uncertain tax positions if it is more likely than not, based on the technical merits, that the tax position will be realized or sustained upon examination. The term more-likely-than-not means a likelihood of more than 50%; the terms examined and upon examination also include resolution of the related appeals or litigation processes, if any. A tax position that meets the more-likely-than-not recognition threshold is initially and subsequently measured as the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position has met the more-likely-than-not recognition threshold considers the facts, circumstances, and information available at the reporting date and is subject to management’s judgment. The Corporation recognizes interest and penalties on income taxes, if any, as a component of income tax expense.
Retirement Plan	Retirement Plan The compensation cost of an employee’s pension benefit is recognized on the projected unit credit method over the employee’s approximate service period. The aggregate cost method is utilized for funding purposes.
Stock-based Compensation	Stock-based Compensation ACNB Corporation has a Restricted Stock plan available to selected officers and employees of the Bank, to advance the best interest of ACNB Corporation and its shareholders. The plan provides those persons who have responsibility for its growth with additional incentive by allowing them to acquire an ownership in ACNB Corporation and thereby encouraging them to contribute to the success of the Corporation. Plan expense is recognized over the vesting period of the stock issued under the plan. To date, 19,301 shares were issued under this plan, which resulted in $133,000 and $59,000 of compensation expense for the year ended December 31, 2017 and 2016, respectively. Of the 19,301 shares issued under the plan, 13,235 shares are fully vested and 6,066 will vest over the next two years.
Net Income per Share	Net Income per Share The Corporation has a simple capital structure. Basic earnings per share of common stock is computed based on 6,543,756 , 6,051,579 and 6,026,224 weighted average shares of common stock outstanding for 2017 , 2016 and 2015 , respectively. All outstanding unvested restricted stock awards that contain rights to nonforfeitable dividends are considered participating for this calculation.
Advertising Costs	Advertising Costs Costs of advertising, which are included in marketing expenses, are expensed when incurred.
Off-Balance Sheet Credit-Related Financial Instruments	Off-Balance Sheet Credit-Related Financial Instruments In the ordinary course of business, the Corporation has entered into commitments to extend credit, including commitments under commercial lines of credit, and standby letters of credit. Such financial instruments are recorded when they are funded.
Transfers of Financial Assets	Transfers of Financial Assets Transfers of financial assets are accounted for as sales 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 Corporation, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3) the Corporation 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 specific assets.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The components of the accumulated other comprehensive loss, net of taxes, are as follows: In thousands Unrealized Losses on Securities Pension Liability Accumulated Other Comprehensive Loss BALANCE — DECEMBER 31, 2017 $ (957 ) $ (6,135 ) $ (7,092 ) BALANCE — DECEMBER 31, 2016 $ (266 ) $ (5,758 ) $ (6,024 )
Segment Reporting	Segment Reporting The Bank acts as an independent community financial services provider, which offers traditional banking and related financial services to individual, business, and government customers. Through its branch and automated teller machine networks, the Bank offers a full array of commercial and community financial services, including the taking of time, savings, and demand deposits; the making of commercial, consumer, and mortgage loans; and the providing of other financial services. Management does not separately allocate expenses, including the cost of funding loan demand, between the commercial, community and mortgage banking operations of the Bank. As such, discrete financial information for commercial, community and mortgage banking operations is not available and segment reporting would not be meaningful. Please refer to Note S — “Segment and Related Information” for a discussion of insurance operations.
New Accounting Pronouncements	New Accounting Pronouncements ASU 2014-09, 2015-14, 2016-08, 2016-12, 2016-20, and 2017-10 In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), superseding the revenue recognition requirements in ASC 605 . This ASU requires an entity to recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The amendment includes a five-step process to assist an entity in achieving the main principle(s) of revenue recognition under ASC 605. In March 2016, the FASB also issued ASU 2016-08, an amendment to the guidance in ASU 2014-09, which reframed the structure of the indicators of when an entity is acting as an agent and focused on evidence that an entity is acting as the principal or agent in a revenue transaction. ASU 2016-08 also eliminated two of the indicators (the entity’s consideration is in the form of a commission, and the entity is not exposed to credit risk) in making that determination. This amendment also clarifies that each indicator may be more or less relevant to the assessment depending on the terms and conditions of the contract. In May 2016, the FASB issued ASU 2016-12, and amendment to ASU 2014-09, which provided practical expedients related to disclosures of remaining performance obligations, as well as other amendments to guidance on transition, collectability, non-cash consideration and presentation of sales and other similar taxes. The amendments, collectively, should be applied retrospectively to each prior reporting period presented or as a cumulative effect adjustment as of the date of adoption (modified retrospective approach). The Corporation’s revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. With respect to non-interest income, the Corporation has identified revenue streams within the scope of the guidance, and has performed an evaluation of the underlying revenue contracts. The Corporation’s overall assessment indicates that adoption of this ASU will not materially change its current method and timing of recognizing revenue for the identified revenue streams. The Corporation, however, is still in process of developing additional quantitative and qualitative disclosures that are required upon the adoption of the new revenue recognition standard as well as evaluating certain revenue streams for principal versus agent treatment of the related revenue (i.e., reporting revenues on a gross basis or net of related expenses). The Corporation adopted this ASU on January 1, 2018, on a cumulative effect approach. The adoption of this ASU, as discussed above, did not have a significant impact on the Corporation’s financial condition, results of operations and consolidated financial statements. ASU 2016-01 In January 2016, the FASB issued ASU 2016-01, Financial Instruments—Overall (Topic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 amends the guidance on the classification and measurement of financial instruments. Some of the amendments in ASU 2016-01 include the following among others: (i) requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; (iii) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; and, (iv) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value. For public business entities, the amendments of ASU 2016-01 are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Corporation had determined this ASU will not have a material effect on its consolidated financial condition or results of operations when adopted on January 1, 2018. ASU 2016-02 In February 2016, the FASB issued ASU 2016-02, Leases . From the lessee’s perspective, the new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement for a lessee. From the lessor’s perspective, the new standard requires a lessor to classify leases as either sales-type, finance or operating. A lease will be treated as a sale if it transfers all of the risks and rewards, as well as control of the underlying asset, to the lessee. If risks and rewards are conveyed without the transfer of control, the lease is treated as a financing lease. If the lessor doesn’t convey risks and rewards or control, an operating lease results. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. A modified retrospective transition approach is required for lessors for sales-type, direct financing, and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. While the Corporation is currently evaluating the timing and impact of adopting ASU 2016-02, the ultimate impact of adopting ASU 2016-02 will depend on the Corporation’s lease portfolio as of the adoption date and interest rates at that time. The Corporation expects to recognize right-of-use assets and lease liabilities for substantially all of its operating lease commitments based on the present value of committed lease payments as of the date of adoption. The effect on operations and capital adequacy is not expected to be material. ASU 2016-13 In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires credit losses on most financial assets measured at amortized cost and certain other instruments to be measured using an expected credit loss model (referred to as the current expected credit loss (CECL) model). Under this model, entities will estimate credit losses over the entire contractual term of the instrument (considering estimated prepayments, but not expected extensions or modifications unless reasonable expectation of a troubled debt restructuring exists) from the date of initial recognition of that instrument. The ASU also replaces the current accounting model for purchased credit impaired loans and debt securities. The allowance for credit losses for purchased financial assets with a more-than insignificant amount of credit deterioration since origination (“PCD assets”), should be determined in a similar manner to other financial assets measured on an amortized cost basis. However, upon initial recognition, the allowance for credit losses is added to the purchase price (“gross up approach”) to determine the initial amortized cost basis. The subsequent accounting for PCD financial assets is the same expected loss model described above. Further, the ASU made certain targeted amendments to the existing impairment model for available-for-sale (AFS) debt securities. For an AFS debt security for which there is neither the intent nor a more-likely-than-not requirement to sell, an entity will record credit losses as an allowance rather than a write-down of the amortized cost basis. Certain incremental disclosures are required. The new standard is effective for fiscal years beginning after December 15, 2019, including interim periods within the fiscal year. For public business entities that are SEC filers, the amendments are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with early adoption permitted. The Corporation is currently evaluating the impact this ASU will have on its consolidated financial condition or results of operations. Management has developed a committee to address CECL and the committee is currently evaluating options to comply with the ASU in a timely manner. ASU 2017-08 In March 2017, the FASB issued ASU 2017-08, Premium Amortization on Purchased Callable Debt Securities . ASU 2017-08 shortens the amortization period for premiums on purchased callable debt securities to the earliest call date (i.e., yield-to-earliest call amortization), rather than amortizing over the full contractual term. The ASU does not change the accounting for securities held at a discount. The amendments apply to callable debt securities with explicit, noncontingent call features that are callable at fixed prices and on preset dates. If a security may be prepaid based upon prepayments of the underlying loans, not because the issuer exercised a date specific call option, it is excluded from the scope of the new standard. However, for instruments with contingent call features, once the contingency is resolved and the security is callable at a fixed price and preset date, the security is within the scope of the amendments. Further, the amendments apply to all premiums on callable debt securities, regardless of how they were generated. The amendments require companies to reset the effective yield using the payment terms of the debt security if the call option is not exercised on the earliest call date. If the security has additional future call dates, any excess of the amortized cost basis over the amount repayable by the issuer at the next call date should be amortized to the next call date. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, including interim periods within those years. Early adoption is permitted, including adoption in an interim period. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. The Corporation has evaluated the provision of ASU 2017-08 to determine the potential impact of the new standard and has determined that it is not expected to have a significant impact on its consolidated financial condition or results of operations, as the Corporation holds one security that this ASU would impact. ASU 2017-04 In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment. ASU 2017-04 eliminates Step 2 of the goodwill impairment test. As such, an entity will perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize a goodwill impairment charge for the amount by which the reporting unit’s carrying amount exceeds its fair value. If fair value exceeds the carrying amount, no impairment should be recorded. Any loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Impairment losses on goodwill cannot be reversed once recognized. An entity may still perform the optional qualitative assessment for a reporting unit to determine if it is more likely than not that goodwill is impaired. However, the ASU eliminates the requirement to perform a qualitative assessment for any reporting unit with a zero or negative carrying amount. Therefore, the same one-step impairment assessment will apply to all reporting units. However, for a reporting unit with a zero or negative carrying amount, the ASU adds a requirement to disclose the amount of goodwill allocated to it and the reportable segment in which it is included. For public business entities that are SEC filers, the amendments are effective with their annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Corporation has evaluated the provision of ASU 2017-04 to determine the potential impact of the new standard and has determined that it is not expected to have an impact on its consolidated financial condition or results of operations based on the current circumstances. ASU 2017-07 In March 2017, the FASB issued ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. ASU 2017-07 requires that an employer disaggregate the service cost component from the other components of net benefit cost, as follows: • Service cost must be presented in the same line item(s) as other employee compensation costs. These costs are generally included within income from continuing operations, but in some cases may be eligible for capitalization, if certain criteria are met. • All other components of net benefit cost must be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. These generally include interest cost, actual return on plan assets, amortization of prior service cost included in accumulated other comprehensive income, and gains or losses from changes in the value of the projected benefit obligation or plan assets. If a separate line item is used to present the other components of net benefit cost, it must be appropriately described. If a separate line item is not used, an entity must disclose the line item(s) in the income statement that includes the other components of net benefit cost. The ASU clarifies that these costs are not eligible for capitalization. The amendments are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those years. Early adoption is permitted as of the beginning of an annual period. The Corporation adopted this ASU on January 1, 2018. The adoption of this ASU did not have an impact on its consolidated financial condition or results of operations based on the current circumstances. ASU 2017-13 In September 2017, the FASB issued ASU 2017-13, Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842) . ASU 2017-13 adds SEC paragraphs pursuant to an SEC Staff Announcement made at the July 20, 2017 Emerging Issues Task Force (EITF) meeting. The SEC staff announced that it will not object if an entity that qualifies as a public business entity solely because its financial statements or financial information is included in another entity’s filing with the SEC adopts ASU 2014-09, Revenue from Contracts with Customers (Topic 606) and ASU 2016-02, Leases (Topic 842) using the effective dates applicable to private entities. The amendments represent guidance related to the effective dates of the standards noted above, therefore, the amendments themselves do not have an effective date. ASU 2018-02 In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018-02 allows a reclassification from accumulated other comprehensive income (loss) to retained earnings for stranded tax effects resulting from the 2017 Tax Cuts and Jobs Act. Consequently, the amendments eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act and will improve the usefulness of information reported to financial statement users. However, because the amendments only relate to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. The amendments in this ASU also require certain disclosures about stranded tax effects. The amendments are effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period, for public business entities for reporting periods for which financial statements have not yet been issued. The amendments should be applied in either the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. The Corporation early adopted this ASU. The total adjustment of $1,183,000 is reclassified from Accumulated Other Comprehensive Income (Loss) to Retained Earnings in the Corporation’s consolidated statement of condition, as well as, reflected in the consolidated statement of changes in stockholders’ equity for the period ended December 31, 2017.

SUMMARY OF SIGNIFICANT ACCOUN32

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule Of Components Of The Accumulated Other Comprehensive Loss, Net Of Taxes	The components of the accumulated other comprehensive loss, net of taxes, are as follows: In thousands Unrealized Losses on Securities Pension Liability Accumulated Other Comprehensive Loss BALANCE — DECEMBER 31, 2017 $ (957 ) $ (6,135 ) $ (7,092 ) BALANCE — DECEMBER 31, 2016 $ (266 ) $ (5,758 ) $ (6,024 )

SECURITIES (Tables)

SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Unrealized Gain (Loss) on Investments	Amortized cost and fair value at December 31, 2017 and 2016 , were as follows: In thousands Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value SECURITIES AVAILABLE FOR SALE December 31, 2017 U.S. Government and agencies $ 105,899 $ 2 $ 1,818 $ 104,083 Mortgage-backed securities, residential 34,473 461 101 34,833 State and municipal 13,227 109 42 13,294 Corporate bonds 5,000 57 — 5,057 CRA mutual fund 1,044 — 9 1,035 Stock in other banks 647 102 — 749 $ 160,290 $ 731 $ 1,970 $ 159,051 December 31, 2016 U.S. Government and agencies $ 81,065 $ 43 $ 1,529 $ 79,579 Mortgage-backed securities, residential 31,272 782 81 31,973 State and municipal 24,514 240 94 24,660 Corporate bonds 5,000 62 — 5,062 CRA mutual fund 1,044 — 9 1,035 Stock in other banks 498 183 — 681 $ 143,393 $ 1,310 $ 1,713 $ 142,990 SECURITIES HELD TO MATURITY December 31, 2017 U.S. Government and agencies $ 19,000 $ 2 $ 99 $ 18,903 Mortgage-backed securities, residential 25,829 55 238 25,646 $ 44,829 $ 57 $ 337 $ 44,549 December 31, 2016 U.S. Government and agencies $ 23,017 $ 26 $ 54 $ 22,989 Mortgage-backed securities, residential 32,551 210 325 32,436 $ 55,568 $ 236 $ 379 $ 55,425
Schedule of Unrealized Loss on Investments	The following table shows the Corporation’s investments’ gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at December 31, 2017 and 2016 : Less than 12 Months 12 Months or More Total In thousands Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses SECURITIES AVAILABLE FOR SALE December 31, 2017 U.S. Government and agencies $ 42,775 $ 445 $ 58,279 $ 1,373 $ 101,054 $ 1,818 Mortgage-backed securities, residential 7,228 56 2,845 45 10,073 101 State and municipal 1,042 8 1,950 34 2,992 42 CRA Mutual Fund — — 1,035 9 1,035 9 $ 51,045 $ 509 $ 64,109 $ 1,461 $ 115,154 $ 1,970 December 31, 2016 U.S. Government and agencies $ 71,454 $ 1,529 $ — $ — $ 71,454 $ 1,529 Mortgage-backed securities, residential 8,966 81 — — 8,966 81 State and municipal 4,933 94 — — 4,933 94 CRA Mutual Fund 1,035 9 — — 1,035 9 $ 86,388 $ 1,713 $ — $ — $ 86,388 $ 1,713 SECURITIES HELD TO MATURITY December 31, 2017 U.S. Government and agencies $ 4,985 $ 15 $ 10,916 $ 84 $ 15,901 $ 99 Mortgage-backed securities, residential 4,946 29 11,070 209 16,016 238 $ 9,931 $ 44 $ 21,986 $ 293 $ 31,917 $ 337 December 31, 2016 U.S. Government and agencies $ 12,946 $ 54 $ — $ — $ 12,946 $ 54 Mortgage-backed security, residential 12,956 325 — — 12,956 325 $ 25,902 $ 379 $ — $ — $ 25,902 $ 379
Investments Classified by Contractual Maturity Date	Amortized cost and fair value at December 31, 2017 , by contractual maturity, where applicable, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay with or without penalties. Available for Sale Held to Maturity In thousands Amortized Cost Fair Value Amortized Cost Fair Value 1 year or less $ 8,651 $ 8,635 $ 12,000 $ 11,949 Over 1 year through 5 years 102,487 100,911 7,000 6,954 Over 5 years through 10 years 12,917 12,817 — — Over 10 years 71 71 — — Mortgage-backed securities, residential 34,473 34,833 25,829 25,646 CRA mutual fund 1,044 1,035 — — Stock in other banks 647 749 — — $ 160,290 $ 159,051 $ 44,829 $ 44,549

LOANS AND ALLOWANCE FOR LOAN 34

LOANS AND ALLOWANCE FOR LOAN LOSSES (Tables)	12 Months Ended
	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Classes Of The Loan Portfolio Summarized By The Aggregate Risk Rating	The following tables present the classes of the loan portfolio summarized by the aggregate pass rating and the classified ratings of special mention, substandard and doubtful within the Corporation’s internal risk rating system as of December 31, 2017 and 2016 : In thousands Pass Special Mention Substandard Doubtful Total December 31, 2017 Originated Loans Commercial and industrial $ 154,177 $ 3,466 $ 1,812 $ — $ 159,455 Commercial real estate 325,002 17,666 9,277 — 351,945 Commercial real estate construction 27,413 767 250 — 28,430 Residential mortgage 363,195 3,251 478 — 366,924 Home equity lines of credit 81,976 360 — — 82,336 Consumer 14,454 — — — 14,454 Total Originated Loans 966,217 25,510 11,817 — 1,003,544 Acquired Loans Commercial and industrial 6,120 244 10 — 6,374 Commercial real estate 124,852 12,734 3,228 — 140,814 Commercial real estate construction 6,742 388 — — 7,130 Residential mortgage 52,959 2,762 3,248 — 58,969 Home equity lines of credit 24,990 88 378 — 25,456 Consumer 1,525 358 — — 1,883 Total Acquired Loans 217,188 16,574 6,864 — 240,626 Total Loans Commercial and industrial 160,297 3,710 1,822 — 165,829 Commercial real estate 449,854 30,400 12,505 — 492,759 Commercial real estate construction 34,155 1,155 250 — 35,560 Residential mortgage 416,154 6,013 3,726 — 425,893 Home equity lines of credit 106,966 448 378 — 107,792 Consumer 15,979 358 — — 16,337 Total Loans $ 1,183,405 $ 42,084 $ 18,681 $ — $ 1,244,170 December 31, 2016 Commercial and industrial $ 134,088 $ 2,355 $ 3,901 $ — $ 140,344 Commercial real estate 291,762 17,376 9,842 — 318,980 Commercial real estate construction 13,606 1,202 463 — 15,271 Residential mortgage 344,048 3,617 874 — 348,539 Home equity lines of credit 69,190 756 126 — 70,072 Consumer 14,704 — — — 14,704 Total $ 867,398 $ 25,306 $ 15,206 $ — $ 907,910
Schedule Of Changes In Accretable Yields Of Acquired Loans [Table Text Block]	The following table provides changes in accretable yield for all acquired loans accounted for under ASC 310-30. Loans accounted for under ASC 310-20 are not included in this table. In thousands Year Ended December 31, 2017 Balance at beginning of period $ — Acquisitions of impaired loans 1,458 Reclassification from non-accretable differences — Accretion to loan interest income (224 ) Balance at end of period $ 1,234
Impaired Loans By Loan Portfolio Class	The following table summarizes information relative to impaired loans by loan portfolio class as of December 31, 2017 and 2016 : Impaired Loans with Allowance Impaired Loans with No Allowance In thousands Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance December 31, 2017 Commercial and industrial $ 1,311 $ 1,311 $ 792 $ 188 $ 188 Commercial real estate 832 832 60 7,528 7,528 Commercial real estate construction — — — — — Residential mortgage 377 377 377 101 101 Total $ 2,520 $ 2,520 $ 1,229 $ 7,817 $ 7,817 December 31, 2016 Commercial and industrial $ 948 $ 948 $ 599 $ 1,178 $ 1,178 Commercial real estate — — — 8,764 8,965 Commercial real estate construction — — — 300 300 Residential mortgage 376 376 333 379 379 Total $ 1,324 $ 1,324 $ 932 $ 10,621 $ 10,822
Average Of Impaired Loans And Related Interest Income By Loan Portfolio Class	The following table summarizes information in regards to average of impaired loans and related interest income by loan portfolio class: Impaired Loans with Allowance Impaired Loans with No Allowance In thousands Average Recorded Investment Interest Income Average Recorded Investment Interest Income December 31, 2017 Commercial and industrial $ 1,184 $ — $ 785 $ — Commercial real estate 499 — 8,030 330 Commercial real estate construction — — 60 25 Residential mortgage 377 — 210 15 Total $ 2,060 $ — $ 9,085 $ 370 December 31, 2016 Commercial and industrial $ 190 $ — $ 1,356 $ 3 Commercial real estate — — 8,377 371 Commercial real estate construction — — 330 — Residential mortgage 224 — 424 17 Total $ 414 $ — $ 10,487 $ 391 December 31, 2015 Commercial and industrial $ — $ — $ 1,591 $ 129 Commercial real estate — — 9,057 449 Commercial real estate construction — — 276 — Residential mortgage 278 — 463 18 Total $ 278 $ — $ 11,387 $ 596
Nonaccrual Loans By Classes Of The Loan Portfolio	The following table presents nonaccrual loans by loan portfolio class as of December 31, 2017 and 2016 , the table below excludes $6.9 million in purchase credit impaired loans, net of unamortized fair value adjustments: In thousands 2017 2016 Commercial and industrial $ 1,499 $ 2,126 Commercial real estate 4,378 1,593 Commercial real estate construction — 300 Residential mortgage 478 483 Total $ 6,355 $ 4,502
Troubled Debt Restructurings	The following table summarizes information relative to troubled debt restructurings by loan portfolio class at December 31, 2017 and 2016 : In thousands Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Recorded Investment at period end December 31, 2017 Nonaccruing troubled debt restructurings: Commercial real estate $ 4,015 $ 4,073 $ 3,405 Total nonaccruing troubled debt restructurings 4,015 4,073 3,405 Accruing troubled debt restructurings: Commercial real estate 4,577 4,577 3,982 Total accruing troubled debt restructurings 4,577 4,577 3,982 Total Troubled Debt Restructurings $ 8,592 $ 8,650 $ 7,387 December 31, 2016 Nonaccruing troubled debt restructurings: Commercial real estate $ 648 $ 648 $ 377 Total nonaccruing troubled debt restructurings 648 648 377 Accruing troubled debt restructurings: Commercial real estate 7,944 8,002 7,171 Residential mortgage 336 336 272 Total accruing troubled debt restructurings 8,280 8,338 7,443 Total Troubled Debt Restructurings $ 8,928 $ 8,986 $ 7,820 The following table summarizes loans whose terms have been modified resulting in troubled debt restructurings during the years ended December 31, 2017 and 2016 : Dollars in thousands Number of Contracts Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Recorded Investment at Period End 2017 Troubled debt restructurings — $ — $ — $ — 2016 Troubled debt restructurings 1 $ 826 $ 832 $ 832
Loan Portfolio Summarized By The Past Due Status	The following table presents the classes of the loan portfolio summarized by the past due status as of December 31, 2017 and 2016 : In thousands 30-59 Days Past Due 60-89 Days Past Due >90 Days Past Due Total Past Due Current Total Loans Receivable Loans Receivable >90 Days and Accruing December 31, 2017 Originated Loans Commercial and industrial $ 55 $ 76 $ 1,503 $ 1,634 $ 157,821 $ 159,455 $ 4 Commercial real estate 436 317 1,400 2,153 349,792 351,945 88 Commercial real estate construction 252 — — 252 28,178 28,430 — Residential mortgage 3,006 646 1,500 5,152 361,772 366,924 1,022 Home equity lines of credit 254 29 183 466 81,870 82,336 183 Consumer 72 26 3 101 14,353 14,454 3 Total originated loans 4,075 1,094 4,589 9,758 993,786 1,003,544 1,300 Acquired Loans Commercial and industrial 83 — — 83 6,291 6,374 — Commercial real estate 916 — — 916 139,898 140,814 — Commercial real estate construction — — — — 7,130 7,130 — Residential mortgage 930 304 137 1,371 57,598 58,969 137 Home equity lines of credit 83 — 70 153 25,303 25,456 70 Consumer — — — — 1,883 1,883 — Total acquired loans 2,012 304 207 2,523 238,103 240,626 207 Total Loans Commercial and industrial 138 76 1,503 1,717 164,112 165,829 4 Commercial real estate 1,352 317 1,400 3,069 489,690 492,759 88 Commercial real estate construction 252 — — 252 35,308 35,560 — Residential mortgage 3,936 950 1,637 6,523 419,370 425,893 1,159 Home equity lines of credit 337 29 253 619 107,173 107,792 253 Consumer 72 26 3 101 16,236 16,337 3 Total Loans $ 6,087 $ 1,398 $ 4,796 $ 12,281 $ 1,231,889 $ 1,244,170 $ 1,507 December 31, 2016 Commercial and industrial $ 26 $ 1 $ 1,178 $ 1,205 $ 139,139 $ 140,344 $ — Commercial real estate 325 674 — 999 317,981 318,980 — Commercial real estate construction — — 300 300 14,971 15,271 — Residential mortgage 2,866 657 1,413 4,936 343,603 348,539 937 Home equity lines of credit 310 56 408 774 69,298 70,072 408 Consumer 31 47 — 78 14,626 14,704 — Total $ 3,558 $ 1,435 $ 3,299 $ 8,292 $ 899,618 $ 907,910 $ 1,345
Allowance For Loan Losses And Recorded Investment In Financing Receivables	The following table summarizes the allowance for loan losses and recorded investment in loans: In thousands Commercial and Industrial Commercial Real Estate Commercial Real Estate Construction Residential Mortgage Home Equity Lines of Credit Consumer Unallocated Total December 31, 2017 Allowance for loan losses Beginning balance- January 1, 2017 $ 3,055 $ 4,968 $ 147 $ 3,478 $ 648 $ 923 $ 975 $ 14,194 Charge-offs (181 ) — — (132 ) (9 ) (139 ) — (461 ) Recoveries 21 61 80 62 — 19 — 243 Provisions 324 199 (101 ) (182 ) (27 ) (54 ) (159 ) — Ending balance- December 31, 2017 $ 3,219 $ 5,228 $ 126 $ 3,226 $ 612 $ 749 $ 816 $ 13,976 Ending balance: individually evaluated for impairment $ 792 $ 60 $ — $ 377 $ — $ — $ — $ 1,229 Ending balance: collectively evaluated for impairment $ 2,427 $ 5,168 $ 126 $ 2,849 $ 612 $ 749 $ 816 $ 12,747 Loans receivables Ending balance $ 165,829 $ 492,759 $ 35,560 $ 425,893 $ 107,792 $ 16,337 $ — $ 1,244,170 Ending balance: individually evaluated for impairment $ 1,499 $ 8,360 $ — $ 478 $ — $ — $ — $ 10,337 Ending balance: collectively evaluated for impairment $ 164,330 $ 484,399 $ 35,560 $ 425,415 $ 107,792 $ 16,337 $ — $ 1,233,833 December 31, 2016 Allowance for loan losses Beginning balance- January 1, 2016 $ 2,508 $ 5,216 $ 112 $ 3,349 $ 619 $ 1,083 $ 1,860 $ 14,747 Charge-offs (318 ) — (135 ) (189 ) (74 ) (50 ) — (766 ) Recoveries 45 — 132 25 — 11 — 213 Provisions 820 (248 ) 38 293 103 (121 ) (885 ) — Ending balance- December 31, 2016 $ 3,055 $ 4,968 $ 147 $ 3,478 $ 648 $ 923 $ 975 $ 14,194 Ending balance: individually evaluated for impairment $ 599 $ — $ — $ 333 $ — $ — $ — $ 932 Ending balance: collectively evaluated for impairment $ 2,456 $ 4,968 $ 147 $ 3,145 $ 648 $ 923 $ 975 $ 13,262 Loans receivables Ending balance $ 140,344 $ 318,980 $ 15,271 $ 348,539 $ 70,072 $ 14,704 $ — $ 907,910 Ending balance: individually evaluated for impairment $ 2,126 $ 8,764 $ 300 $ 755 $ — $ — $ — $ 11,945 Ending balance: collectively evaluated for impairment $ 138,218 $ 310,216 $ 14,971 $ 347,784 $ 70,072 $ 14,704 $ — $ 895,965 In thousands Commercial and Industrial Commercial Real Estate Commercial Real Estate Construction Residential Mortgage Home Equity Lines of Credit Consumer Unallocated Total December 31, 2015 Allowance for loan losses Beginning balance- January 1, 2015 $ 2,048 $ 5,872 $ 194 $ 3,845 $ 557 $ 1,050 $ 1,606 $ 15,172 Charge-offs (150 ) — (39 ) (622 ) (15 ) (111 ) — (937 ) Recoveries 369 — — 136 — 7 — 512 Provisions 241 (656 ) (43 ) (10 ) 77 137 254 — Ending balance- December 31, 2015 $ 2,508 $ 5,216 $ 112 $ 3,349 $ 619 $ 1,083 $ 1,860 $ 14,747 Ending balance: individually evaluated for impairment $ — $ — $ — $ — $ — $ — $ — $ — Ending balance: collectively evaluated for impairment $ 2,508 $ 5,216 $ 112 $ 3,349 $ 619 $ 1,083 $ 1,860 $ 14,747 Loans receivables Ending balance $ 117,692 $ 289,899 $ 13,429 $ 357,228 $ 60,124 $ 14,588 $ — $ 852,960 Ending balance: individually evaluated for impairment $ 1,471 $ 8,185 $ 374 $ 461 $ — $ — $ — $ 10,491 Ending balance: collectively evaluated for impairment $ 116,221 $ 281,714 $ 13,055 $ 356,767 $ 60,124 $ 14,588 $ — $ 842,469

PREMISES AND EQUIPMENT (Tables)

PREMISES AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and equipment	Premises and equipment at December 31 were as follows: In thousands 2017 2016 Land $ 5,050 $ 2,624 Buildings and improvements 25,881 19,917 Furniture and equipment 14,856 13,273 Construction in process 182 82 45,969 35,896 Accumulated depreciation (19,195 ) (17,743 ) $ 26,774 $ 18,153

DEPOSITS (Tables)

DEPOSITS (Tables)	12 Months Ended
	Dec. 31, 2017
Interest-bearing Deposit Liabilities [Abstract]
Schedule Of Deposits	Deposits were comprised of the following as of December 31: In thousands 2017 2016 Non-interest bearing demand $ 279,413 $ 180,593 Interest bearing demand 163,278 130,453 Savings 501,710 414,682 Time certificates of deposit of $250,000 or less 295,279 209,805 Time certificates of deposit greater than $250,000 58,812 32,088 $ 1,298,492 $ 967,621
Schedule Of Maturities Of Time Certificates Of Deposits	Scheduled maturities of time certificates of deposit at December 31, 2017 , were as follows: Years Ending In thousands 2018 $ 176,525 2019 119,968 2020 29,657 2021 15,766 2022 12,175 $ 354,091

LEASE COMMITMENTS (Tables)

LEASE COMMITMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Future Minimum Rental Payments	The following is a schedule by year of future minimum rental payments required under operating leases that have initial or remaining non-cancelable lease terms in excess of one year as of December 31: Years Ending In thousands 2018 $ 787 2019 579 2020 481 2021 386 2022 328 Later years 1,694 $ 4,255

BORROWINGS (Tables)

BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Short-term Debt	Short-term borrowings and weighted-average interest rates at December 31 are as follows: 2017 2016 Dollars in thousands Amount Rate Amount Rate FHLB overnight advance $ — — % $ — — % Securities sold under repurchase agreements 36,908 0.12 34,590 0.12 $ 36,908 0.12 % $ 34,590 0.12 %
Offsetting Liabilities	The following table presents the short-term borrowings subject to an enforceable master netting arrangement or repurchase agreement as of December 31, 2017 and 2016 : Gross Amounts Not Offset in the Statements of Condition Dollars in thousands Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Statements of Condition Net Amounts of Liabilities Presented in the Statements of Condition Financial Instruments Cash Collateral Pledged Net Amount December 31, 2017 Repurchase agreements Commercial customers and government entities (a) $ 36,908 $ — $ 36,908 $ (36,908 ) $ — $ — December 31, 2016 Repurchase agreements Commercial customers and government entities (a) $ 34,590 $ — $ 34,590 $ (34,590 ) $ — $ — (a) As of December 31, 2017 and 2016 , the fair value of securities pledged in connection with repurchase agreements was $42,397,000 and $41,406,000 , respectively.
Schedule of Maturities of Long-term Debt	A summary of long-term debt as of December 31 is as follows: 2017 2016 Dollars in thousands Amount Rate Amount Rate FHLB fixed-rate advances maturing: 2017 $ — — % $ 14,250 2.30 % 2018 25,500 1.87 % 25,500 1.87 % 2019 23,500 1.73 % 19,500 1.75 % 2020 20,000 1.87 % 12,000 1.84 % 2021 16,000 2.01 % 3,000 1.58 % Loan Payable to local bank 4,600 1.53 % — — % Trust preferred subordinated debt 5,000 6.39 % — — % $ 94,600 2.06 % $ 74,250 1.91 %

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The components of income tax expense for the years ended December 31, 2017 , 2016 and 2015 , are as follows: In thousands 2017 2016 2015 Federal: Current $ 4,767 $ 3,530 $ 3,316 Deferred 1,413 171 392 6,180 3,701 3,708 State: Current 156 67 53 Deferred 298 — — 454 67 53 $ 6,634 $ 3,768 $ 3,761
Schedule of Reconciliations of the Statutory Federal Income Tax	Reconciliations of the statutory federal income tax to the income tax expense reported in the consolidated statements of income for the years ended December 31, 2017 , 2016 and 2015 , are as follows: Percentage of Income before Income Taxes 2017 2016 2015 Federal income tax at statutory rate 35.0 % 34.0 % 34.0 % State income taxes, net of federal benefit 1.8 % 0.3 % 0.2 % Tax-exempt income (5.0 )% (4.8 )% (4.4 )% Earnings on investment in bank-owned life insurance (2.3 )% (2.6 )% (2.5 )% Rehabilitation and low-income housing credits (1.7 )% (2.0 )% (2.0 )% Reduction of federal tax rate 10.2 % — % — % Other 2.4 % 0.8 % 0.2 % 40.4 % 25.7 % 25.5 %
Components of Deferred Tax Assets and Liabilities	Components of deferred tax assets and liabilities at December 31 were as follows: In thousands 2017 2016 Deferred tax assets: Allowance for loan losses $ 3,052 $ 4,968 Available for sale securities 282 143 Accrued deferred compensation 852 1,166 Pension 1,789 3,101 Other-than-temporary impairment 43 70 Nonaccrual interest 171 226 Deferred director fees 520 686 Acquisition accounting 1,357 — Other 521 982 8,587 11,342 Deferred tax liabilities: Deferred loan fees 114 79 Available for sale securities — — Prepaid pension benefit cost 4,248 6,632 Prepaid expenses 132 123 Accumulated depreciation 426 372 Goodwill/intangibles 928 1,006 5,848 8,212 Net Deferred Tax Asset included in Other Assets $ 2,739 $ 3,130

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	For assets measured at fair value, the fair value measurements by level within the fair value hierarchy, and the basis of measurement used at December 31, 2017 and 2016 , are as follows: Fair Value Measurements at December 31, 2017 In thousands Basis Total Level 1 Level 2 Level 3 U.S. Government and agencies $ 104,083 $ — $ 104,083 $ — Mortgage-backed securities, residential 34,833 — 34,833 — State and municipal 13,294 — 13,294 — Corporate bonds 5,057 — 5,057 — CRA mutual fund 1,035 1,035 — — Stock in other banks 749 749 — — Total securities available for sale Recurring $ 159,051 $ 1,784 $ 157,267 $ — Impaired loans Non-recurring $ 5,426 $ — $ — $ 5,426 Foreclosed assets held for resale Non-recurring $ — $ — $ — $ — Fair Value Measurements at December 31, 2016 In thousands Basis Total Level 1 Level 2 Level 3 U.S. Government and agencies $ 79,579 $ — $ 79,579 $ — Mortgage-backed securities, residential 31,973 — 31,973 — State and municipal 24,660 — 24,660 — Corporate bonds 5,062 — 5,062 — CRA mutual fund 1,035 1,035 — — Stock in other banks 681 681 — — Total securities available for sale Recurring $ 142,990 $ 1,716 $ 141,274 $ — Impaired loans Non-recurring $ 4,406 $ — $ — $ 4,406 Foreclosed assets held for resale Non-recurring $ — $ — $ — $ —
Fair Value Inputs, Assets, Quantitative Information	The following table presents additional quantitative information about assets measured at fair value on a nonrecurring basis for which the Corporation has utilized Level 3 inputs to determine fair value: Quantitative Information about Level 3 Fair Value Measurements Dollars in thousands Fair Value Estimate Valuation Technique Unobservable Input Range Weighted Average December 31, 2017 Impaired loans $ 5,426 Appraisal of collateral (1) Appraisal adjustments (2) (10) - (50)% (36 )% Foreclosed assets held for resale $ — Appraisal of collateral (1) (3) Appraisal adjustments (2) (10) - (50)% — % December 31, 2016 Impaired loans $ 4,406 Appraisal of collateral (1) Appraisal adjustments (2) (10) - (50)% (39 )% Foreclosed assets held for resale $ — Appraisal of collateral (1) (3) Appraisal adjustments (2) (10) - (50)% — % (1) Fair value is generally determined through management’s estimate or independent third-party appraisals of the underlying collateral, which generally includes various Level 3 inputs which are not observable. (2) Appraisals may be adjusted downward by management for qualitative factors such as economic conditions and estimated liquidation expenses. The range of liquidation expenses and other appraisal adjustments are presented as a percentage of the appraisal. Higher downward adjustments are caused by negative changes to the collateral or conditions in the real estate market, actual offers or sales contracts received, and/or age of the appraisal. (3) Includes qualitative adjustments by management and estimated liquidation expenses.
Fair Value, by Balance Sheet Grouping	The following presents the carrying amount, fair value, and placement in the fair value hierarchy of the Corporation’s financial instruments at December 31, 2017 and 2016 : December 31, 2017 In thousands Carrying Amount Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and due from banks $ 19,304 $ 19,304 $ 8,313 $ 10,991 $ — Interest-bearing deposits in banks 15,137 15,137 15,137 — — Investment securities available for sale 159,051 159,051 1,784 157,267 — Investment securities held to maturity 44,829 44,549 — 44,549 — Loans held for sale 1,736 1,736 — 1,736 — Loans, less allowance for loan losses 1,230,194 1,213,932 — — 1,213,932 Accrued interest receivable 3,670 3,670 — 3,670 — Restricted investment in bank stocks 4,773 4,773 — 4,773 — Financial liabilities: Deposits 1,298,492 1,295,456 — 1,295,456 — Short-term borrowings 36,908 36,908 — 36,908 — Long-term borrowings 89,600 89,571 — 89,571 — Trust preferred subordinated debt 5,000 4,692 — 4,692 — Accrued interest payable 1,163 1,163 — 1,163 — Off-balance sheet financial instruments — — — — — December 31, 2016 In thousands Carrying Amount Fair Value Level 1 Level 2 Level 3 Financial assets: Cash and due from banks $ 13,796 $ 13,796 $ 6,921 $ 6,875 $ — Interest-bearing deposits in banks 5,135 5,135 5,135 — — Investment securities available for sale 142,990 142,990 1,716 141,274 — Investment securities held to maturity 55,568 55,425 — 55,425 — Loans held for sale 1,770 1,770 — 1,770 — Loans, less allowance for loan losses 893,176 888,169 — — 888,169 Accrued interest receivable 3,158 3,158 — 3,158 — Restricted investment in bank stocks 4,349 4,349 — 4,349 — Financial liabilities: Deposits 967,621 967,236 — 967,236 — Short-term borrowings 34,590 34,590 — 34,590 — Long-term borrowings 74,250 75,029 — 75,029 — Accrued interest payable 837 837 — 837 — Off-balance sheet financial instruments — — — — —

RETIREMENT PLANS (Tables)

RETIREMENT PLANS (Tables)	12 Months Ended
	Dec. 31, 2017
Postemployment Benefits [Abstract]
Schedule of Benefit Plan Funded Status	A measurement date of December 31 has been used for the fiscal years ended December 31, 2017 and 2016 . In thousands 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 28,625 $ 26,670 Service cost 839 795 Interest cost 1,135 1,136 Change in assumptions 2,040 1,059 Benefits paid (1,092 ) (1,035 ) Benefit obligation at end of year 31,547 28,625 Change in plan assets: Fair value of plan assets at beginning of year 38,715 36,880 Actual return on plan assets 4,816 2,870 Employer contribution — — Benefits paid (1,092 ) (1,035 ) Fair value of plan assets at end of year 42,439 38,715 Funded Status, included in other assets $ 10,892 $ 10,090 Amounts recognized in accumulated other comprehensive loss: Total net actuarial loss $ 7,924 $ 8,859 Prior service cost — — Total included in accumulated other comprehensive loss (pretax) $ 7,924 $ 8,859
Estimated Costs To Be Amortized From AOCI Into Net Periodic Pension Cost During The Next Fiscal Year	The estimated costs that will be amortized from accumulated other comprehensive loss into net periodic pension cost during the next fiscal year are as follows: In thousands Net loss $ 515 Prior service cost — $ 515
Components Of Net Periodic Benefit Costs (Income)	The components of net periodic benefit costs (income) related to the non-contributory, defined benefit pension plan for the years ended December 31 are as follows: In thousands 2017 2016 2015 Components of net periodic benefit cost (income): Service cost $ 839 $ 795 $ 881 Interest cost 1,135 1,136 1,040 Expected return on plan assets (2,518 ) (2,429 ) (2,542 ) Recognized net actuarial loss 676 682 481 Amortization of prior service cost — 1 24 Net Periodic Benefit Cost (Income) 132 185 (116 ) Net loss (259 ) 618 1,409 Amortization of net loss (676 ) (682 ) (481 ) Amortization of prior service cost — (1 ) (24 ) Total recognized in other comprehensive (income) loss $ (935 ) $ (65 ) $ 904 Total recognized in net periodic benefit cost and other comprehensive (income) loss $ (803 ) $ 120 $ 788
Assumptions Used To Determine The Benefit Obligation and Net Periodic Benefit Cost (Income)	For the years ended December 31, 2017 , 2016 and 2015 , the assumptions used to determine the benefit obligation are as follows: 2017 2016 2015 Discount rate 3.55 % 4.05 % 4.35 % Rate of compensation increase 3.50 % 3.50 % 3.50 % For the years ended December 31, 2017 , 2016 and 2015 , the assumptions used to determine the net periodic benefit cost (income) are as follows: 2017 2016 2015 Discount rate 4.05 % 4.35 % 3.90 % Expected long-term rate of return on plan assets 6.75 % 6.75 % 6.75 % Rate of compensation increase 3.50 % 3.50 % 3.75 %
Pension Plan Weighted-Average Assets' Allocations	The Corporation’s pension plan weighted-average assets’ allocations at December 31, 2017 and 2016 , are as follows: 2017 2016 Equity securities 50 % 48 % Debt securities 44 % 46 % Short-term fixed income — % — % Real estate 6 % 6 % 100 % 100 %
Fair Value Measurements	Fair value measurements at December 31, 2017 , are as follows: In thousands Total Level 1 Level 2 Level 3 Equity securities $ 21,423 $ 2,114 $ 19,309 $ — Debt securities 18,668 — 18,668 — Real estate 2,348 — 2,348 — Fair value measurements at December 31, 2016 , are as follows: In thousands Total Level 1 Level 2 Level 3 Equity securities $ 18,687 $ 2,175 $ 16,512 $ — Debt securities 17,888 — 17,888 — Real estate 2,140 — 2,140 —
Future Benefit Payments	Based on current data and assumptions, the following benefit payments, which reflect expected future service, as appropriate, are: Years Ending In thousands 2018 $ 1,320 2019 1,410 2020 1,440 2021 1,650 2022 1,660 2023 - 2027 9,200

STOCKHOLDERS' EQUITY AND REGU42

STOCKHOLDERS' EQUITY AND REGULATORY MATTERS (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Capital Requirements [Abstract]
The Actual and Required Capital Amounts and Ratios	The actual and required capital amounts and ratios were as follows: Actual For Capital Adequacy Purposes To be Well Capitalized under Prompt Corrective Action Provisions Dollars in thousands Amount Ratio Amount (1) Ratio (1) Amount Ratio CORPORATION As of December 31, 2017 Tier 1 leverage ratio (to average assets) $ 144,376 9.04 % $ ≥63,871 ≥4.0% N/A N/A Common Tier 1 risk-based capital ratio (to risk-weighted assets) 144,376 12.79 ≥50,796 ≥4.5 N/A N/A Tier 1 risk-based capital ratio (to risk-weighted assets) 144,376 12.79 ≥67,728 ≥6.0 N/A N/A Total risk-based capital ratio (to risk-weighted assets) 158,479 14.04 ≥90,304 ≥8.0 N/A N/A As of December 31, 2016 Tier 1 leverage ratio (to average assets) $ 121,650 10.06 % $ ≥48,382 ≥4.0% N/A N/A Common Tier 1 risk-based capital ratio (to risk-weighted assets) 121,650 14.71 ≥37,205 ≥4.5 N/A N/A Tier 1 risk-based capital ratio (to risk-weighted assets) 121,650 14.71 ≥49,606 ≥6.0 N/A N/A Total risk-based capital ratio (to risk-weighted assets) 132,033 15.97 ≥66,142 ≥8.0 N/A N/A BANK As of December 31, 2017 Tier 1 leverage ratio (to average assets) $ 138,811 8.70 % $ ≥68,857 ≥4.0% $ ≥79,822 ≥5.0% Common Tier 1 risk-based capital ratio (to risk-weighted assets) 138,811 12.34 ≥50,639 ≥4.5 ≥73,145 ≥6.5 Tier 1 risk-based capital ratio (to risk-weighted assets) 138,811 12.34 ≥67,519 ≥6.0 ≥90,025 ≥8.0 Total risk-based capital ratio (to risk-weighted assets) 152,868 13.58 ≥90,025 ≥8.0 ≥112,532 ≥10.0 As of December 31, 2016 Tier 1 leverage ratio (to average assets) $ 106,540 8.82 % $ ≥48,316 ≥4.0% $ ≥60,395 ≥5.0% Common Tier 1 risk-based capital ratio (to risk-weighted assets) 106,540 12.96 ≥36,995 ≥4.5 ≥53,438 ≥6.5 Tier 1 risk-based capital ratio (to risk-weighted assets) 106,540 12.96 ≥49,327 ≥6.0 ≥65,770 ≥8.0 Total risk-based capital ratio (to risk-weighted assets) 116,865 14.22 ≥65,770 ≥8.0 ≥82,212 ≥10.0 (1) Amounts and ratios do not include capital conservation buffer.

FINANCIAL INSTRUMENTS WITH OF43

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK (Tables)	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Schedule of Fair Value, Off-balance Sheet Risks	A summary of the Corporation’s commitments at December 31 were as follows: In thousands 2017 2016 Commitments to extend credit $ 264,368 $ 258,631 Standby letters of credit 6,362 6,134

ACNB CORPORATION (PARENT COMP44

ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Statements of Condition	December 31, In thousands 2017 2016 ASSETS Cash $ 9,440 $ 8,563 Investment in banking subsidiary 143,288 100,395 Investment in other subsidiaries 8,517 8,768 Investments in low-income housing partnerships 689 1,016 Securities and other assets 1,548 1,232 Receivable from banking subsidiary 118 130 Total Assets $ 163,600 $ 120,104 LIABILITIES AND STOCKHOLDERS’ EQUITY Long-term debt $ 9,600 $ — Other liabilities 34 43 Stockholders’ equity 153,966 120,061 Total Liabilities and Stockholders’ Equity $ 163,600 $ 120,104
Statements of Income	Years Ended December 31, In thousands 2017 2016 2015 Dividends from banking subsidiary $ 5,233 $ 4,840 $ 4,820 Gain on sale of securities — 26 — Other income 31 35 190 5,264 4,901 5,010 Expenses 1,572 854 431 3,692 4,047 4,579 Income tax benefit 507 490 381 4,199 4,537 4,960 Equity in undistributed earnings of subsidiaries 5,589 6,332 6,057 Net Income $ 9,788 $ 10,869 $ 11,017 Comprehensive Income $ 9,903 $ 9,571 $ 9,014
Statements of Cash Flows	Years Ended December 31, In thousands 2017 2016 2015 CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 9,788 $ 10,869 $ 11,017 Equity in undistributed earnings of subsidiaries (5,589 ) (6,332 ) (6,057 ) Decrease (Increase) in receivable from banking subsidiary 12 2,639 (131 ) Gain on sale of securities — (26 ) — Other 129 540 86 Net Cash Provided by Operating Activities 4,340 7,690 4,915 CASH FLOWS FROM INVESTING ACTIVITIES Return of investment from subsidiary 1,000 650 750 Outlay for business combination (4,445 ) — — Net Cash (Used in) Provided by Investing Activities (3,445 ) 650 750 CASH FLOWS USED IN FINANCING ACTIVITIES Proceeds from long-term debt 4,600 — — Repayments on long-term debt — — (1,437 ) Proceeds from issuance of common stock 615 615 499 Dividends paid (5,233 ) (4,840 ) (4,820 ) Net Cash Used in Financing Activities (18 ) (4,225 ) (5,758 ) Net Increase (Decrease) in Cash and Cash Equivalents 877 4,115 (93 ) CASH AND CASH EQUIVALENTS — BEGINNING 8,563 4,448 4,541 CASH AND CASH EQUIVALENTS — ENDING $ 9,440 $ 8,563 $ 4,448

GOODWILL AND OTHER INTANGIBLES

GOODWILL AND OTHER INTANGIBLES (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Carrying Value And Accumulated Amortization Of The Intangible Assets (RIG Customer Lists and New Windsor Core Deposit Intangibles)	The carrying value and accumulated amortization of the intangible assets (RIG customer lists and New Windsor core deposit intangibles) are as follows: 2017 2016 Year Purchased Dollars in thousands Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization 2005 $ 3,282 $ 3,282 $ 3,282 $ 3,282 2007 637 637 637 587 2008 1,165 1,101 1,165 992 2009 1,300 1,170 1,300 1,040 2010 33 26 33 23 2014 77 31 77 23 2015 173 49 173 32 RIG amortized intangible assets 6,667 6,296 6,667 5,979 2017 New Windsor core deposit intangibles 2,418 220 — — $ 9,085 $ 6,516 $ 6,667 $ 5,979
Expected Amortization Expense	Amortization of the intangible assets for the five years subsequent to December 31, 2017 , is expected to be as follows: Years Ending In thousands 2018 $ 638 2019 400 2020 353 2021 309 2022 265 Thereafter 604

SEGMENT AND RELATED INFORMATI46

SEGMENT AND RELATED INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment information for 2017 , 2016 and 2015 is as follows: In thousands Banking Insurance Total 2017 Net interest income and other income from external customers $ 55,763 $ 4,738 $ 60,501 Income before income taxes 15,585 837 16,422 Total assets 1,586,064 9,368 1,595,432 Capital expenditures 1,727 30 1,757 2016 Net interest income and other income from external customers $ 45,313 $ 4,461 $ 49,774 Income before income taxes 13,828 809 14,637 Total assets 1,195,857 10,463 1,206,320 Capital expenditures 2,333 11 2,344 2015 Net interest income and other income from external customers $ 43,522 $ 4,490 $ 48,012 Income before income taxes 14,137 641 14,778 Total assets 1,138,106 9,819 1,147,925 Capital expenditures 1,712 26 1,738

NEW WINDSOR ACQUISITION (Tables

NEW WINDSOR ACQUISITION (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Purchase Price Consideration in Common Stock	The following table summarizes the consideration paid for New Windsor and the fair value of assets acquired and liabilities assumed as of the acquisition date: Purchase Price Consideration in Common Stock New Windsor shares outstanding 1,003,703 Shares paid cash consideration 150,555 Cash consideration (per New Windsor share) $ 30.00 Cash portion of purchase price $ 4,519,995 New Windsor shares outstanding 1,003,703 Shares paid stock consideration 853,148 Exchange ratio 1.10 Total ACNB shares issued 938,360 ACNB’s share price for purposes of calculation $ 30.50 Equity portion of purchase price $ 28,619,980 Cost of shares owned by buyer $ 150,000 Total consideration paid $ 33,289,975 Allocation of Purchase Price In thousands Total Purchase Price $ 33,290 Fair Value of Assets Acquired Cash and cash equivalents 10,964 Investment securities 21,624 Loans held for sale 1,463 Loans 263,450 Restricted stock 486 Premises and equipment 8,624 Core deposit intangible asset 2,418 Other assets 10,792 Total assets 319,821 Fair Value of Liabilities Assumed Non-interest bearing deposits 80,006 Interest bearing deposits 213,327 Subordinated debt 4,688 Other liabilities 1,782 Total liabilities 299,803 Net Assets Acquired 20,018 Goodwill Recorded in Acquisition $ 13,272
Fair Value Adjustments	The table below illustrates the fair value adjustments made to the amortized cost basis in order to present a fair value of the loans acquired. The credit adjustment on purchased credit impaired loans is derived in accordance with ASC 310-30 and represents the portion of the loan balances that has been deemed uncollectible based on the Corporation’s expectations of future cash flows for each respective loan. In thousands Gross amortized cost basis at July 1, 2017 $ 272,646 Interest rate fair value adjustment on pools of homogeneous loans (731 ) Credit fair value adjustment on pools of homogeneous loans (4,501 ) Credit fair value adjustment on purchased credit impaired loans (3,964 ) Fair value of acquired loans at July 1, 2017 $ 263,450
Acquired Purchased Credit Impaired Loans Receivable	The following table presents the acquired purchased credit impaired loans receivable at the Acquisition Date: In thousands Contractual principal and interest at acquisition $ 13,439 Nonaccretable difference (5,651 ) Expected cash flows at acquisition 7,788 Accretable yield (1,458 ) Fair value of purchased impaired loans $ 6,330
Pro Forma Information	The following table presents certain pro forma information as if New Windsor had been acquired on December 31, 2016. These results combine the historical results of the Corporation in the Corporation’s Consolidated Statements of Income and, while certain adjustments were made for the estimated impact of certain fair value adjustments and other acquisition-related activity, they are not indicative of what would have occurred had the acquisition taken place on December 31, 2016. In particular, no adjustments have been made to eliminate the amount of New Windor’s provision for loan losses that would not have been necessary had the acquired loans been recorded at fair value as of December 31, 2016. The Corporation expects to achieve further operating cost savings and other business synergies as a result of the acquisition which are not reflected in the pro forma amounts below: In thousands For the Year Ended December 31, 2016 Total revenues (net interest income plus noninterest income) $ 102,891 Net Income 13,591

QUARTERLY RESULTS OF OPERATIO48

QUARTERLY RESULTS OF OPERATIONS (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Results of Operations [Abstract]
Selected Quarterly Information	Selected quarterly information for the years ended December 31, 2017 and 2016 , is as follows: Dollars in thousands, except per share data First Quarter Second Quarter Third Quarter Fourth Quarter 2017 Interest income $ 10,533 $ 10,962 $ 15,109 $ 15,181 Interest expense 1,067 1,131 1,547 1,688 Net interest income 9,466 9,831 13,562 13,493 Provision for loan losses — — — — Net interest income after provision for loan losses 9,466 9,831 13,562 13,493 Net gains on sales of securities — — — — Gain on sales of premises and equipment — — — — Other income 3,082 3,528 3,930 3,609 Merger related expenses 162 208 4,305 53 Other expenses and provision for income taxes 9,749 10,429 11,275 14,532 Net income $ 2,637 $ 2,722 $ 1,912 $ 2,517 Basic earnings per share $ 0.43 $ 0.45 $ 0.27 $ 0.35 Dividends per share $ 0.20 $ 0.20 $ 0.20 $ 0.20 2016 Interest income $ 9,964 $ 10,010 $ 10,181 $ 10,345 Interest expense 957 980 996 1,001 Net interest income 9,007 9,030 9,185 9,344 Provision for loan losses — — — — Net interest income after provision for loan losses 9,007 9,030 9,185 9,344 Net gains on sales of securities — — — 26 Gain on sales of premises and equipment — 449 — — Other income 2,872 3,362 3,301 3,198 Proposed merger expenses — — — 472 Other expenses and provision for income taxes 9,332 9,859 9,718 9,524 Net income $ 2,547 $ 2,982 $ 2,768 $ 2,572 Basic earnings per share $ 0.42 $ 0.49 $ 0.46 $ 0.43 Dividends per share $ 0.20 $ 0.20 $ 0.20 $ 0.20

SUMMARY OF SIGNIFICANT ACCOUN49

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details)	Jul. 01, 2017USD ($)bank	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Summary of Significant Accounting Policies [Line Items]
Number of community banking office locations, ACNB		22
Number of community banking office locations, NWSB		7
Assets Held-in-trust		$ 327,000,000	$ 195,000,000
Total Loans Receivable		$ 1,244,170,000	907,910,000	$ 852,960,000
Number of minimum months for corporation to order updated valuation		18 months
Post-employment benefit cost for continuing life insurance		$ 96,000	96,000	$ 46,000
Foreclosed assets held for resale		$ 436,000	$ 256,000
Weighted average number of shares outstanding, basic | shares		6,543,756	6,051,579	6,026,224
ASU 2018-02 adjustment		$ 0
Restricted Stock
Summary of Significant Accounting Policies [Line Items]
Cumulative amount of shares issued under the plan | shares		19,301
Compensation expense		$ 133,000	$ 59,000
Shares vested | shares		13,235
Shares expected to vest over next two years | shares		6,066
Weighted average remaining contractual term		2 years
Credit Concentration Risk
Summary of Significant Accounting Policies [Line Items]
Total Loans Receivable		$ 269,080,000
Concentration Risk, Percentage		21.60%
Minimum
Summary of Significant Accounting Policies [Line Items]
Intangible asset amortization life		5 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Intangible asset amortization life		15 years
Residential Mortgage and Commercial Loans
Summary of Significant Accounting Policies [Line Items]
Threshold period past due to discontinue accrual interest on financing receivable		90 days
Consumer
Summary of Significant Accounting Policies [Line Items]
Total Loans Receivable		$ 16,337,000	14,704,000	$ 14,588,000
Threshold period past due for charge off of financing receivable		120 days
Commercial real estate
Summary of Significant Accounting Policies [Line Items]
Total Loans Receivable		$ 492,759,000	$ 318,980,000	$ 289,899,000
Threshold period past due for Corporation to order updated valuation on financing receivable		90 days
Number of previous months with no updated valuation completed for Corporation to update validation		12 months
Number of maximum days of loan being classified as impaired for Corporation to order third party valuation		30 days
Commercial real estate | Maximum
Summary of Significant Accounting Policies [Line Items]
Financing receivable term		20 years
Loan-to-value ratio (no greater than)		80.00%
Residential Mortgage
Summary of Significant Accounting Policies [Line Items]
Loan-to-value ratio that requires private mortgage insurance (in excess of)		80.00%
Foreclosed assets held for resale		$ 264,000
Residential Mortgage | Maximum
Summary of Significant Accounting Policies [Line Items]
Financing receivable term		30 years
Loan-to-value ratio (no greater than)		80.00%
Home Equity Line of Credit | Maximum
Summary of Significant Accounting Policies [Line Items]
Financing receivable term		20 years
Loan-to-value ratio (no greater than)		90.00%
Buildings
Summary of Significant Accounting Policies [Line Items]
Useful life		40 years
Building Remodels and Additions
Summary of Significant Accounting Policies [Line Items]
Useful life		15 years
Bank Equipment | Minimum
Summary of Significant Accounting Policies [Line Items]
Useful life		5 years
Bank Equipment | Maximum
Summary of Significant Accounting Policies [Line Items]
Useful life		15 years
Retained Earnings
Summary of Significant Accounting Policies [Line Items]
ASU 2018-02 adjustment		$ 1,183,000
New Windsor
Summary of Significant Accounting Policies [Line Items]
Number of community banking office locations, NWSB | bank	7
Interest rate fair value discount	$ 731,000
Credit fair value discount	$ 4,501,000

SUMMARY OF SIGNIFICANT ACCOUN50

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Schedule Of Components Of The Accumulated Other Comprehensive Income, Net Of Taxes) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Loss [Line Items]
Components of accumulated other comprehensive loss	$ 153,966	$ 120,061	$ 114,715	$ 110,022
Unrealized Losses on Securities
Accumulated Other Comprehensive Loss [Line Items]
Components of accumulated other comprehensive loss	(957)	(266)
Pension Liability
Accumulated Other Comprehensive Loss [Line Items]
Components of accumulated other comprehensive loss	(6,135)	(5,758)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss [Line Items]
Components of accumulated other comprehensive loss	$ (7,092)	$ (6,024)	$ (4,726)	$ (2,723)

RESTRICTIONS ON CASH AND DUE 51

RESTRICTIONS ON CASH AND DUE FROM BANKS (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Restricted Cash and Investments [Abstract]
Compensating Balance Amount	$ 1,769	$ 1,203
Average Compensating Balance Amount	$ 1,992	$ 1,337

SECURITIES (Unrealized Gain (Lo

SECURITIES (Unrealized Gain (Loss) on Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	$ 160,290	$ 143,393
Securities Available for sale, Gross Unrealized Gains	731	1,310
Securities Available for sale, Gross Unrealized Losses	1,970	1,713
Securities available for sale	159,051	142,990
Securities Held to maturity, Amortized Cost	44,829	55,568
Securities Held to maturity, Gross Unrealized Gains	57	236
Securities Held to maturity, Gross Unrealized Losses	337	379
Securities held to maturity, fair value	44,549	55,425
U.S. Government and agencies
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	105,899	81,065
Securities Available for sale, Gross Unrealized Gains	2	43
Securities Available for sale, Gross Unrealized Losses	1,818	1,529
Securities available for sale	104,083	79,579
Securities Held to maturity, Amortized Cost	19,000	23,017
Securities Held to maturity, Gross Unrealized Gains	2	26
Securities Held to maturity, Gross Unrealized Losses	99	54
Securities held to maturity, fair value	18,903	22,989
Residential Mortgage Backed Securities
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	34,473	31,272
Securities Available for sale, Gross Unrealized Gains	461	782
Securities Available for sale, Gross Unrealized Losses	101	81
Securities available for sale	34,833	31,973
Securities Held to maturity, Amortized Cost	25,829	32,551
Securities Held to maturity, Gross Unrealized Gains	55	210
Securities Held to maturity, Gross Unrealized Losses	238	325
Securities held to maturity, fair value	25,646	32,436
State and municipal
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	13,227	24,514
Securities Available for sale, Gross Unrealized Gains	109	240
Securities Available for sale, Gross Unrealized Losses	42	94
Securities available for sale	13,294	24,660
Corporate bonds
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	5,000	5,000
Securities Available for sale, Gross Unrealized Gains	57	62
Securities Available for sale, Gross Unrealized Losses	0	0
Securities available for sale	5,057	5,062
CRA mutual fund
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	1,044	1,044
Securities Available for sale, Gross Unrealized Gains	0	0
Securities Available for sale, Gross Unrealized Losses	9	9
Securities available for sale	1,035	1,035
Stock In Other Banks
Schedule of Investments [Line Items]
Securities Available for sale, Amortized Cost	647	498
Securities Available for sale, Gross Unrealized Gains	102	183
Securities Available for sale, Gross Unrealized Losses	0	0
Securities available for sale	$ 749	$ 681

SECURITIES (Schedule of Unreali

SECURITIES (Schedule of Unrealized Loss on Investments) (Details) $ in Thousands	Dec. 31, 2017USD ($)Security	Dec. 31, 2016USD ($)
Schedule of Investments [Line Items]
Securities Available for sale, Less than 12 Months: Fair Value	$ 51,045	$ 86,388
Securities Available for sale, Less than 12 Months: Unrealized Losses	509	1,713
Securities Available for sale, 12 Months or More: Fair Value	64,109	0
Securities Available for sale, 12 Months or More: Unrealized Losses	1,461	0
Securities Available for sale, Total: Fair Value	115,154	86,388
Securities Available for sale, Total Unrealized Loss	1,970	1,713
Securities Held to maturity, Less than 12 Months: Fair Value	9,931	25,902
Securities Held to maturity, Less than 12 Months: Unrealized Losses	44	379
Securities Held to maturity, 12 Months or More, Fair Value	21,986	0
Securities Held to maturity, 12 Months or More, Unrealized Losses	293	0
Securities Held to maturity, Total: Fair Value	31,917	25,902
Securities Held to maturity, Total Unrealized Losses	337	379
U.S. Government and agencies
Schedule of Investments [Line Items]
Securities Available for sale, Less than 12 Months: Fair Value	42,775	71,454
Securities Available for sale, Less than 12 Months: Unrealized Losses	445	1,529
Securities Available for sale, 12 Months or More: Fair Value	58,279	0
Securities Available for sale, 12 Months or More: Unrealized Losses	1,373	0
Securities Available for sale, Total: Fair Value	101,054	71,454
Securities Available for sale, Total Unrealized Loss	1,818	1,529
Securities Held to maturity, Less than 12 Months: Fair Value	4,985	12,946
Securities Held to maturity, Less than 12 Months: Unrealized Losses	15	54
Securities Held to maturity, 12 Months or More, Fair Value	10,916	0
Securities Held to maturity, 12 Months or More, Unrealized Losses	84	0
Securities Held to maturity, Total: Fair Value	15,901	12,946
Securities Held to maturity, Total Unrealized Losses	$ 99	54
Available for sale securities in unrealized loss positions | Security	64
Available for sale securities in unrealized loss positions, percentage of amortized cost (individually did not exceed)	5.00%
Available for sale securities in unrealized loss positions for 12 months or more | Security	32
Held to maturity securities in unrealized loss positions | Security	9
Held to maturity securities in unrealized loss positions, percentage of amortized cost (individually did not exceed)	2.00%
Held to maturity securities in unrealized loss positions for 12 months or more | Security	6
Residential Mortgage Backed Securities
Schedule of Investments [Line Items]
Securities Available for sale, Less than 12 Months: Fair Value	$ 7,228	8,966
Securities Available for sale, Less than 12 Months: Unrealized Losses	56	81
Securities Available for sale, 12 Months or More: Fair Value	2,845	0
Securities Available for sale, 12 Months or More: Unrealized Losses	45	0
Securities Available for sale, Total: Fair Value	10,073	8,966
Securities Available for sale, Total Unrealized Loss	101	81
Securities Held to maturity, Less than 12 Months: Fair Value	4,946	12,956
Securities Held to maturity, Less than 12 Months: Unrealized Losses	29	325
Securities Held to maturity, 12 Months or More, Fair Value	11,070	0
Securities Held to maturity, 12 Months or More, Unrealized Losses	209	0
Securities Held to maturity, Total: Fair Value	16,016	12,956
Securities Held to maturity, Total Unrealized Losses	$ 238	325
Available for sale securities in unrealized loss positions | Security	15
Available for sale securities in unrealized loss positions, percentage of amortized cost (individually did not exceed)	2.00%
Available for sale securities in unrealized loss positions for 12 months or more | Security	3
Held to maturity securities in unrealized loss positions | Security	21
Held to maturity securities in unrealized loss positions, percentage of amortized cost (individually did not exceed)	3.00%
Held to maturity securities in unrealized loss positions for 12 months or more | Security	13
State and municipal
Schedule of Investments [Line Items]
Securities Available for sale, Less than 12 Months: Fair Value	$ 1,042	4,933
Securities Available for sale, Less than 12 Months: Unrealized Losses	8	94
Securities Available for sale, 12 Months or More: Fair Value	1,950	0
Securities Available for sale, 12 Months or More: Unrealized Losses	34	0
Securities Available for sale, Total: Fair Value	2,992	4,933
Securities Available for sale, Total Unrealized Loss	$ 42	94
Available for sale securities in unrealized loss positions | Security	14
Available for sale securities in unrealized loss positions, percentage of amortized cost (individually did not exceed)	3.00%
Available for sale securities in unrealized loss positions for 12 months or more | Security	8
Corporate bonds
Schedule of Investments [Line Items]
Securities Available for sale, Total Unrealized Loss	$ 0	0
CRA mutual fund
Schedule of Investments [Line Items]
Securities Available for sale, Less than 12 Months: Fair Value	0	1,035
Securities Available for sale, Less than 12 Months: Unrealized Losses	0	9
Securities Available for sale, 12 Months or More: Fair Value	1,035	0
Securities Available for sale, 12 Months or More: Unrealized Losses	9	0
Securities Available for sale, Total: Fair Value	1,035	1,035
Securities Available for sale, Total Unrealized Loss	$ 9	9
Available for sale securities in unrealized loss positions, percentage of amortized cost (individually did not exceed)	1.00%
Stock In Other Banks
Schedule of Investments [Line Items]
Securities Available for sale, Total Unrealized Loss	$ 0	$ 0

SECURITIES (Investments Classif

SECURITIES (Investments Classified by Contractual Maturity Date) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Available for sale Securities, Amortized Cost, 1 year or less	$ 8,651
Available for sale Securities, Fair Value, 1 year or less	8,635
Available for sale Securities, Amortized Cost, Over 1 year through 5 years	102,487
Available for sale Securities, Fair Value, Over 1 year through 5 years	100,911
Available for sale Securities, Amortized Cost, Over 5 years through 10 years	12,917
Available for sale Securities, Fair Value, Over 5 years through 10 years	12,817
Available for sale Securities, Amortized Cost, Over 10 years	71
Available for sale Securities, Fair Value, Over 10 years	71
Available for sale Securities, Amortized Cost	160,290	$ 143,393
Available for sale Securities, Fair Value	159,051	142,990
Held to maturity Securities, Amortized Cost, 1 year or less	12,000
Held to maturity Securities, Fair Value, 1 year or less	11,949
Held to maturity Securities, Amortized Cost, Over 1 year through 5 years	7,000
Held to maturity Securities, Fair Value, Over 1 year through 5 years	6,954
Held to maturity Securities, Amortized Cost, Over 5 years through 10 years	0
Held to maturity Securities, Fair Value, Over 5 years through 10 years	0
Held to maturity Securities, Amortized Cost, Over 10 years	0
Held to maturity Securities, Fair Value, Over 10 years	0
Held to maturity Securities, Amortized Cost	44,829	55,568
Investment securities held to maturity	$ 44,549	55,425
Available For Sale Securities Debt Maturities Within One Year Amortized Cost and Fair Value Period	1 year
Available For Sale Securities and Held-to-Maturity Securities Debt Maturities After Ten Years Amortized Cost Period	10 years
Minimum
Schedule of Investments [Line Items]
Available For Sale Securities and Held-to-Maturity Securities Debt Maturities After One Through Five Years Amortized Cost Period	1 year
Available For Sale Securities and Held-to-Maturity Securities Debt Maturities After Five Through Ten Years Amortized Cost Period	5 years
Maximum
Schedule of Investments [Line Items]
Available For Sale Securities and Held-to-Maturity Securities Debt Maturities After One Through Five Years Amortized Cost Period	5 years
Available For Sale Securities and Held-to-Maturity Securities Debt Maturities After Five Through Ten Years Amortized Cost Period	10 years
Residential Mortgage Backed Securities
Schedule of Investments [Line Items]
Available for sale Securities, Amortized Cost, without a Single Maturity Date	$ 34,473
Available for sale Securities, Fair Value, without a Single Maturity Date	34,833
Available for sale Securities, Amortized Cost	34,473	31,272
Available for sale Securities, Fair Value	34,833	31,973
Held to maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount	25,829
Held to maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value	25,646
Held to maturity Securities, Amortized Cost	25,829	32,551
Investment securities held to maturity	25,646	32,436
CRA mutual fund
Schedule of Investments [Line Items]
Available for sale Securities, Amortized Cost, without a Single Maturity Date	1,044
Available for sale Securities, Fair Value, without a Single Maturity Date	1,035
Available for sale Securities, Amortized Cost	1,044	1,044
Available for sale Securities, Fair Value	1,035	1,035
Held to maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount	0
Held to maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value	0
Stock In Other Banks
Schedule of Investments [Line Items]
Available for sale Securities, Amortized Cost, without a Single Maturity Date	647
Available for sale Securities, Fair Value, without a Single Maturity Date	749
Available for sale Securities, Amortized Cost	647	498
Available for sale Securities, Fair Value	749	$ 681
Held to maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount	0
Held to maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value	$ 0

SECURITIES (Narrative) (Details

SECURITIES (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Available for sale Securities, Gross Realized Gains	$ 0	$ 26,000	$ 262,000
Available for sale Securities, Gross Realized Losses	0	0	$ 1,000
Available for sale Securities Pledged as Collateral	$ 157,601,000	$ 134,763,000

LOANS AND ALLOWANCE FOR LOAN 56

LOANS AND ALLOWANCE FOR LOAN LOSSES (Classes Of The Loan Portfolio Summarized By The Aggregate Risk Rating) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	$ 1,244,170	$ 907,910	$ 852,960
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	165,829	140,344	117,692
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	492,759	318,980	289,899
Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	35,560	15,271	13,429
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	425,893	348,539	357,228
Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	107,792	70,072	60,124
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	16,337	14,704	$ 14,588
Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,183,405	867,398
Pass | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	160,297	134,088
Pass | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	449,854	291,762
Pass | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	34,155	13,606
Pass | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	416,154	344,048
Pass | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	106,966	69,190
Pass | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	15,979	14,704
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	42,084	25,306
Special Mention | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,710	2,355
Special Mention | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	30,400	17,376
Special Mention | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,155	1,202
Special Mention | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	6,013	3,617
Special Mention | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	448	756
Special Mention | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	358	0
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	18,681	15,206
Substandard | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,822	3,901
Substandard | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	12,505	9,842
Substandard | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	250	463
Substandard | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,726	874
Substandard | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	378	126
Substandard | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	0
Doubtful | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0	$ 0
Originated Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,003,544
Originated Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	159,455
Originated Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	351,945
Originated Loans | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	28,430
Originated Loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	366,924
Originated Loans | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	82,336
Originated Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	14,454
Originated Loans | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	966,217
Originated Loans | Pass | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	154,177
Originated Loans | Pass | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	325,002
Originated Loans | Pass | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	27,413
Originated Loans | Pass | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	363,195
Originated Loans | Pass | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	81,976
Originated Loans | Pass | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	14,454
Originated Loans | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	25,510
Originated Loans | Special Mention | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,466
Originated Loans | Special Mention | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	17,666
Originated Loans | Special Mention | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	767
Originated Loans | Special Mention | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,251
Originated Loans | Special Mention | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	360
Originated Loans | Special Mention | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	11,817
Originated Loans | Substandard | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,812
Originated Loans | Substandard | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	9,277
Originated Loans | Substandard | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	250
Originated Loans | Substandard | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	478
Originated Loans | Substandard | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Substandard | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Originated Loans | Doubtful | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	240,626
Acquired Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	6,374
Acquired Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	140,814
Acquired Loans | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	7,130
Acquired Loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	58,969
Acquired Loans | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	25,456
Acquired Loans | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,883
Acquired Loans | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	217,188
Acquired Loans | Pass | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	6,120
Acquired Loans | Pass | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	124,852
Acquired Loans | Pass | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	6,742
Acquired Loans | Pass | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	52,959
Acquired Loans | Pass | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	24,990
Acquired Loans | Pass | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	1,525
Acquired Loans | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	16,574
Acquired Loans | Special Mention | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	244
Acquired Loans | Special Mention | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	12,734
Acquired Loans | Special Mention | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	388
Acquired Loans | Special Mention | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	2,762
Acquired Loans | Special Mention | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	88
Acquired Loans | Special Mention | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	358
Acquired Loans | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	6,864
Acquired Loans | Substandard | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	10
Acquired Loans | Substandard | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,228
Acquired Loans | Substandard | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Substandard | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,248
Acquired Loans | Substandard | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	378
Acquired Loans | Substandard | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful | Commercial real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	0
Acquired Loans | Doubtful | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	$ 0

LOANS AND ALLOWANCE FOR LOAN 57

LOANS AND ALLOWANCE FOR LOAN LOSSES (Schedule of Change in Accretable Yields of Acquired Loans) (Details) - Acquired Loans Accounted For Under ASC 310-30 $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Certain Loans Acquired in Transfer Accounted for as Debt Securities Accretable Yield Movement Schedule [Line Items]
Balance at beginning of period	$ 0
Acquisitions of impaired loans	1,458
Reclassification from non-accretable differences	0
Accretion to loan interest income	(224)
Balance at end of period	$ 1,234

LOANS AND ALLOWANCE FOR LOAN 58

LOANS AND ALLOWANCE FOR LOAN LOSSES (Impaired Loans By Loan Portfolio Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Recorded Investment	$ 2,520	$ 1,324
Impaired Loans with Allowance, Unpaid Principal Balance	2,520	1,324
Impaired Loans with Allowance, Related Allowance	1,229	932
Impaired Loans with No Allowance, Recorded Investment	7,817	10,621
Impaired Loans with No Allowance, Unpaid Principal Balance	7,817	10,822
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Recorded Investment	1,311	948
Impaired Loans with Allowance, Unpaid Principal Balance	1,311	948
Impaired Loans with Allowance, Related Allowance	792	599
Impaired Loans with No Allowance, Recorded Investment	188	1,178
Impaired Loans with No Allowance, Unpaid Principal Balance	188	1,178
Commercial real estate
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Recorded Investment	832	0
Impaired Loans with Allowance, Unpaid Principal Balance	832	0
Impaired Loans with Allowance, Related Allowance	60	0
Impaired Loans with No Allowance, Recorded Investment	7,528	8,764
Impaired Loans with No Allowance, Unpaid Principal Balance	7,528	8,965
Commercial real estate construction
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Recorded Investment	0	0
Impaired Loans with Allowance, Unpaid Principal Balance	0	0
Impaired Loans with Allowance, Related Allowance	0	0
Impaired Loans with No Allowance, Recorded Investment	0	300
Impaired Loans with No Allowance, Unpaid Principal Balance	0	300
Residential mortgage
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Recorded Investment	377	376
Impaired Loans with Allowance, Unpaid Principal Balance	377	376
Impaired Loans with Allowance, Related Allowance	377	333
Impaired Loans with No Allowance, Recorded Investment	101	379
Impaired Loans with No Allowance, Unpaid Principal Balance	$ 101	$ 379

LOANS AND ALLOWANCE FOR LOAN 59

LOANS AND ALLOWANCE FOR LOAN LOSSES (Average Of Impaired Loans And Related Interest Income By Loan Portfolio Class) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Average Recorded Investment	$ 2,060	$ 414	$ 278
Impaired Loans with Allowance, Interest Income	0	0	0
Impaired Loans with No Allowance, Average Recorded Investment	9,085	10,487	11,387
Impaired Loans with No Allowance, Interest Income	370	391	596
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Average Recorded Investment	1,184	190	0
Impaired Loans with Allowance, Interest Income	0	0	0
Impaired Loans with No Allowance, Average Recorded Investment	785	1,356	1,591
Impaired Loans with No Allowance, Interest Income	0	3	129
Commercial real estate
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Average Recorded Investment	499	0	0
Impaired Loans with Allowance, Interest Income	0	0	0
Impaired Loans with No Allowance, Average Recorded Investment	8,030	8,377	9,057
Impaired Loans with No Allowance, Interest Income	330	371	449
Commercial real estate construction
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Average Recorded Investment	0	0	0
Impaired Loans with Allowance, Interest Income	0	0	0
Impaired Loans with No Allowance, Average Recorded Investment	60	330	276
Impaired Loans with No Allowance, Interest Income	25	0	0
Residential mortgage
Financing Receivable, Impaired [Line Items]
Impaired Loans with Allowance, Average Recorded Investment	377	224	278
Impaired Loans with Allowance, Interest Income	0	0	0
Impaired Loans with No Allowance, Average Recorded Investment	210	424	463
Impaired Loans with No Allowance, Interest Income	$ 15	$ 17	$ 18

LOANS AND ALLOWANCE FOR LOAN 60

LOANS AND ALLOWANCE FOR LOAN LOSSES (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Interest lost on nonaccrual loans	$ 437	$ 369	$ 456
Aggregate amount of loans with related parties	5,703	$ 4,578
New loans or advances extended to related parties	1,612
Repayments on loans or advances to related parties	$ 487

LOANS AND ALLOWANCE FOR LOAN 61

LOANS AND ALLOWANCE FOR LOAN LOSSES (Nonaccrual Loans By Classes Of The Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Purchase credit impaired loans, net of unamortized fair value adjustments	$ 6,900
Total nonaccrual loans	6,355	$ 4,502
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccrual loans	1,499	2,126
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccrual loans	4,378	1,593
Commercial real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccrual loans	0	300
Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccrual loans	$ 478	$ 483

LOANS AND ALLOWANCE FOR LOAN 62

LOANS AND ALLOWANCE FOR LOAN LOSSES (Troubled Debt Restructurings Modified On Financing Receivables) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Modifications [Line Items]
Pre-Modification Outstanding Recorded Investment	$ 8,592	$ 8,928
Post-Modification Outstanding Recorded Investment	8,650	8,986
Recorded Investment at period end	7,387	7,820
Nonaccrual
Financing Receivable, Modifications [Line Items]
Pre-Modification Outstanding Recorded Investment	4,015	648
Post-Modification Outstanding Recorded Investment	4,073	648
Recorded Investment at period end	3,405	377
Nonaccrual | Commercial real estate
Financing Receivable, Modifications [Line Items]
Pre-Modification Outstanding Recorded Investment	4,015	648
Post-Modification Outstanding Recorded Investment	4,073	648
Recorded Investment at period end	3,405	377
Accrual
Financing Receivable, Modifications [Line Items]
Pre-Modification Outstanding Recorded Investment	4,577	8,280
Post-Modification Outstanding Recorded Investment	4,577	8,338
Recorded Investment at period end	3,982	7,443
Accrual | Commercial real estate
Financing Receivable, Modifications [Line Items]
Pre-Modification Outstanding Recorded Investment	4,577	7,944
Post-Modification Outstanding Recorded Investment	4,577	8,002
Recorded Investment at period end	$ 3,982	7,171
Accrual | Residential mortgage
Financing Receivable, Modifications [Line Items]
Pre-Modification Outstanding Recorded Investment		336
Post-Modification Outstanding Recorded Investment		336
Recorded Investment at period end		$ 272

LOANS AND ALLOWANCE FOR LOAN 63

LOANS AND ALLOWANCE FOR LOAN LOSSES (Troubled Debt Restructurings) (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 2017Contract	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)Contract
Financing Receivable, Modifications [Line Items]
Number of loans moved to nonaccrual status	2
Number of troubled debt restructured loans with a specific allocation		1
Amount of specific allocation | $		$ 60,000
Number of troubled debt restructured loan paid off		1	1
Number of loans which has periodic payments		1
Number of loans classified as troubled debt restructured loans with active forbearance agreements		1
Mortgage loans in process of foreclosure | $		$ 848,000	$ 471,000
Entity Loan Modification Program
Financing Receivable, Modifications [Line Items]
Proceeds from paid off troubled debt restructured loans | $		$ 283,000	$ 74,000

LOANS AND ALLOWANCE FOR LOAN 64

LOANS AND ALLOWANCE FOR LOAN LOSSES (Summary of Modified Loans Resulting in Troubled Debt Restructurings) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Contract	Dec. 31, 2016USD ($)Contract
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]
Number of Contracts | Contract	0	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 826
Post-Modification Outstanding Recorded Investment	0	832
Recorded Investment at Period End	$ 0	$ 832

LOANS AND ALLOWANCE FOR LOAN 65

LOANS AND ALLOWANCE FOR LOAN LOSSES (Loan Portfolio Summarized By The Past Due Status) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 12,281	$ 8,292
Current	1,231,889	899,618
Total Loans Receivable	1,244,170	907,910	$ 852,960
Loans Receivable Greater than 90 Days and Accruing	1,507	1,345
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,087	3,558
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,398	1,435
Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,796	3,299
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,717	1,205
Current	164,112	139,139
Total Loans Receivable	165,829	140,344	117,692
Loans Receivable Greater than 90 Days and Accruing	4	0
Commercial and industrial | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	138	26
Commercial and industrial | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	76	1
Commercial and industrial | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,503	1,178
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,069	999
Current	489,690	317,981
Total Loans Receivable	492,759	318,980	289,899
Loans Receivable Greater than 90 Days and Accruing	88	0
Commercial real estate | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,352	325
Commercial real estate | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	317	674
Commercial real estate | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,400	0
Commercial real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	252	300
Current	35,308	14,971
Total Loans Receivable	35,560	15,271	13,429
Loans Receivable Greater than 90 Days and Accruing	0	0
Commercial real estate construction | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	252	0
Commercial real estate construction | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate construction | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	300
Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,523	4,936
Current	419,370	343,603
Total Loans Receivable	425,893	348,539	357,228
Loans Receivable Greater than 90 Days and Accruing	1,159	937
Residential mortgage | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,936	2,866
Residential mortgage | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	950	657
Residential mortgage | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,637	1,413
Home equity lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	619	774
Current	107,173	69,298
Total Loans Receivable	107,792	70,072	60,124
Loans Receivable Greater than 90 Days and Accruing	253	408
Home equity lines of credit | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	337	310
Home equity lines of credit | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	29	56
Home equity lines of credit | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	253	408
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	101	78
Current	16,236	14,626
Total Loans Receivable	16,337	14,704	$ 14,588
Loans Receivable Greater than 90 Days and Accruing	3	0
Consumer | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	72	31
Consumer | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	26	47
Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3	$ 0
Originated Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,758
Current	993,786
Total Loans Receivable	1,003,544
Loans Receivable Greater than 90 Days and Accruing	1,300
Originated Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,075
Originated Loans | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,094
Originated Loans | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,589
Originated Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,634
Current	157,821
Total Loans Receivable	159,455
Loans Receivable Greater than 90 Days and Accruing	4
Originated Loans | Commercial and industrial | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	55
Originated Loans | Commercial and industrial | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	76
Originated Loans | Commercial and industrial | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,503
Originated Loans | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,153
Current	349,792
Total Loans Receivable	351,945
Loans Receivable Greater than 90 Days and Accruing	88
Originated Loans | Commercial real estate | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	436
Originated Loans | Commercial real estate | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	317
Originated Loans | Commercial real estate | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,400
Originated Loans | Commercial real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	252
Current	28,178
Total Loans Receivable	28,430
Loans Receivable Greater than 90 Days and Accruing	0
Originated Loans | Commercial real estate construction | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	252
Originated Loans | Commercial real estate construction | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Originated Loans | Commercial real estate construction | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Originated Loans | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,152
Current	361,772
Total Loans Receivable	366,924
Loans Receivable Greater than 90 Days and Accruing	1,022
Originated Loans | Residential mortgage | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,006
Originated Loans | Residential mortgage | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	646
Originated Loans | Residential mortgage | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,500
Originated Loans | Home equity lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	466
Current	81,870
Total Loans Receivable	82,336
Loans Receivable Greater than 90 Days and Accruing	183
Originated Loans | Home equity lines of credit | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	254
Originated Loans | Home equity lines of credit | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	29
Originated Loans | Home equity lines of credit | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	183
Originated Loans | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	101
Current	14,353
Total Loans Receivable	14,454
Loans Receivable Greater than 90 Days and Accruing	3
Originated Loans | Consumer | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	72
Originated Loans | Consumer | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	26
Originated Loans | Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3
Acquired Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,523
Current	238,103
Total Loans Receivable	240,626
Loans Receivable Greater than 90 Days and Accruing	207
Acquired Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,012
Acquired Loans | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	304
Acquired Loans | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	207
Acquired Loans | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	83
Current	6,291
Total Loans Receivable	6,374
Loans Receivable Greater than 90 Days and Accruing	0
Acquired Loans | Commercial and industrial | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	83
Acquired Loans | Commercial and industrial | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial and industrial | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	916
Current	139,898
Total Loans Receivable	140,814
Loans Receivable Greater than 90 Days and Accruing	0
Acquired Loans | Commercial real estate | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	916
Acquired Loans | Commercial real estate | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial real estate | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Current	7,130
Total Loans Receivable	7,130
Loans Receivable Greater than 90 Days and Accruing	0
Acquired Loans | Commercial real estate construction | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial real estate construction | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Commercial real estate construction | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,371
Current	57,598
Total Loans Receivable	58,969
Loans Receivable Greater than 90 Days and Accruing	137
Acquired Loans | Residential mortgage | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	930
Acquired Loans | Residential mortgage | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	304
Acquired Loans | Residential mortgage | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	137
Acquired Loans | Home equity lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	153
Current	25,303
Total Loans Receivable	25,456
Loans Receivable Greater than 90 Days and Accruing	70
Acquired Loans | Home equity lines of credit | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	83
Acquired Loans | Home equity lines of credit | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Home equity lines of credit | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	70
Acquired Loans | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Current	1,883
Total Loans Receivable	1,883
Loans Receivable Greater than 90 Days and Accruing	0
Acquired Loans | Consumer | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0
Acquired Loans | Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 0

LOANS AND ALLOWANCE FOR LOAN 66

LOANS AND ALLOWANCE FOR LOAN LOSSES (Allowance For Loan Losses And Recorded Investment In Financing Receivables) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				$ 14,194,000				$ 14,747,000	$ 14,194,000	$ 14,747,000	$ 15,172,000
Charge-offs									(461,000)	(766,000)	(937,000)
Recoveries									243,000	213,000	512,000
Provisions	$ 0	$ 0	$ 0	0	$ 0	$ 0	$ 0	0	0	0	0
Allowance for Loan Losses, Ending Balance	13,976,000				14,194,000				13,976,000	14,194,000	14,747,000
Ending balance: individually evaluated for impairment	1,229,000				932,000				1,229,000	932,000	0
Ending balance: collectively evaluated for impairment	12,747,000				13,262,000				12,747,000	13,262,000	14,747,000
Loans receivables, Ending Balance	1,244,170,000				907,910,000				1,244,170,000	907,910,000	852,960,000
Loans receivables: Ending balance: individually evaluated for impairment	10,337,000				11,945,000				10,337,000	11,945,000	10,491,000
Loans receivables: Ending balance: collectively evaluated for impairment	1,233,833,000				895,965,000				1,233,833,000	895,965,000	842,469,000
Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				3,055,000				2,508,000	3,055,000	2,508,000	2,048,000
Charge-offs									(181,000)	(318,000)	(150,000)
Recoveries									21,000	45,000	369,000
Provisions									324,000	820,000	241,000
Allowance for Loan Losses, Ending Balance	3,219,000				3,055,000				3,219,000	3,055,000	2,508,000
Ending balance: individually evaluated for impairment	792,000				599,000				792,000	599,000	0
Ending balance: collectively evaluated for impairment	2,427,000				2,456,000				2,427,000	2,456,000	2,508,000
Loans receivables, Ending Balance	165,829,000				140,344,000				165,829,000	140,344,000	117,692,000
Loans receivables: Ending balance: individually evaluated for impairment	1,499,000				2,126,000				1,499,000	2,126,000	1,471,000
Loans receivables: Ending balance: collectively evaluated for impairment	164,330,000				138,218,000				164,330,000	138,218,000	116,221,000
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				4,968,000				5,216,000	4,968,000	5,216,000	5,872,000
Charge-offs									0	0	0
Recoveries									61,000	0	0
Provisions									199,000	(248,000)	(656,000)
Allowance for Loan Losses, Ending Balance	5,228,000				4,968,000				5,228,000	4,968,000	5,216,000
Ending balance: individually evaluated for impairment	60,000				0				60,000	0	0
Ending balance: collectively evaluated for impairment	5,168,000				4,968,000				5,168,000	4,968,000	5,216,000
Loans receivables, Ending Balance	492,759,000				318,980,000				492,759,000	318,980,000	289,899,000
Loans receivables: Ending balance: individually evaluated for impairment	8,360,000				8,764,000				8,360,000	8,764,000	8,185,000
Loans receivables: Ending balance: collectively evaluated for impairment	484,399,000				310,216,000				484,399,000	310,216,000	281,714,000
Commercial real estate construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				147,000				112,000	147,000	112,000	194,000
Charge-offs									0	(135,000)	(39,000)
Recoveries									80,000	132,000	0
Provisions									(101,000)	38,000	(43,000)
Allowance for Loan Losses, Ending Balance	126,000				147,000				126,000	147,000	112,000
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	126,000				147,000				126,000	147,000	112,000
Loans receivables, Ending Balance	35,560,000				15,271,000				35,560,000	15,271,000	13,429,000
Loans receivables: Ending balance: individually evaluated for impairment	0				300,000				0	300,000	374,000
Loans receivables: Ending balance: collectively evaluated for impairment	35,560,000				14,971,000				35,560,000	14,971,000	13,055,000
Residential mortgage
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				3,478,000				3,349,000	3,478,000	3,349,000	3,845,000
Charge-offs									(132,000)	(189,000)	(622,000)
Recoveries									62,000	25,000	136,000
Provisions									(182,000)	293,000	(10,000)
Allowance for Loan Losses, Ending Balance	3,226,000				3,478,000				3,226,000	3,478,000	3,349,000
Ending balance: individually evaluated for impairment	377,000				333,000				377,000	333,000	0
Ending balance: collectively evaluated for impairment	2,849,000				3,145,000				2,849,000	3,145,000	3,349,000
Loans receivables, Ending Balance	425,893,000				348,539,000				425,893,000	348,539,000	357,228,000
Loans receivables: Ending balance: individually evaluated for impairment	478,000				755,000				478,000	755,000	461,000
Loans receivables: Ending balance: collectively evaluated for impairment	425,415,000				347,784,000				425,415,000	347,784,000	356,767,000
Home equity lines of credit
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				648,000				619,000	648,000	619,000	557,000
Charge-offs									(9,000)	(74,000)	(15,000)
Recoveries									0	0	0
Provisions									(27,000)	103,000	77,000
Allowance for Loan Losses, Ending Balance	612,000				648,000				612,000	648,000	619,000
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	612,000				648,000				612,000	648,000	619,000
Loans receivables, Ending Balance	107,792,000				70,072,000				107,792,000	70,072,000	60,124,000
Loans receivables: Ending balance: individually evaluated for impairment	0				0				0	0	0
Loans receivables: Ending balance: collectively evaluated for impairment	107,792,000				70,072,000				107,792,000	70,072,000	60,124,000
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				923,000				1,083,000	923,000	1,083,000	1,050,000
Charge-offs									(139,000)	(50,000)	(111,000)
Recoveries									19,000	11,000	7,000
Provisions									(54,000)	(121,000)	137,000
Allowance for Loan Losses, Ending Balance	749,000				923,000				749,000	923,000	1,083,000
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	749,000				923,000				749,000	923,000	1,083,000
Loans receivables, Ending Balance	16,337,000				14,704,000				16,337,000	14,704,000	14,588,000
Loans receivables: Ending balance: individually evaluated for impairment	0				0				0	0	0
Loans receivables: Ending balance: collectively evaluated for impairment	16,337,000				14,704,000				16,337,000	14,704,000	14,588,000
Unallocated
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Loan Losses, Beginning Balance				$ 975,000				$ 1,860,000	975,000	1,860,000	1,606,000
Charge-offs									0	0	0
Recoveries									0	0	0
Provisions									(159,000)	(885,000)	254,000
Allowance for Loan Losses, Ending Balance	816,000				975,000				816,000	975,000	1,860,000
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	816,000				975,000				816,000	975,000	1,860,000
Loans receivables, Ending Balance	0				0				0	0	0
Loans receivables: Ending balance: individually evaluated for impairment	0				0				0	0	0
Loans receivables: Ending balance: collectively evaluated for impairment	$ 0				$ 0				$ 0	$ 0	$ 0

PREMISES AND EQUIPMENT (Table)

PREMISES AND EQUIPMENT (Table) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 45,969	$ 35,896
Accumulated depreciation	(19,195)	(17,743)
Premises and equipment, net	26,774	18,153
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	5,050	2,624
Buildings and improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	25,881	19,917
Furniture and equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	14,856	13,273
Construction in process
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 182	$ 82

PREMISES AND EQUIPMENT (Narrati

PREMISES AND EQUIPMENT (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation	$ 1,755	$ 1,455	$ 1,419

INVESTMENTS IN LOW-INCOME HOU69

INVESTMENTS IN LOW-INCOME HOUSING PARTNERSHIPS (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Partnership	Dec. 31, 2016USD ($)
Real Estate Partnership Investment Subsidiaries, Net Income (Loss) before Tax [Abstract]
Number of limited partnerships in low-income properties | Partnership	3
Investments in low-income housing partnerships | $	$ 2,446	$ 2,899

DEPOSITS (Schedule Of Deposits)

DEPOSITS (Schedule Of Deposits) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Interest-bearing Deposit Liabilities [Abstract]
Non-interest bearing demand	$ 279,413	$ 180,593
Interest bearing demand	163,278	130,453
Savings	501,710	414,682
Time certificates of deposit of $250,000 or less	295,279	209,805
Time certificates of deposit greater than $250,000	58,812	32,088
Total Deposits	1,298,492	$ 967,621
Time certificate of deposits, threshold amount	$ 250,000

DEPOSITS (Schedule Of Maturitie

DEPOSITS (Schedule Of Maturities Of Time Certificates Of Deposits) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Interest-bearing Deposit Liabilities [Abstract]
2,018	$ 176,525
2,019	119,968
2,020	29,657
2,021	15,766
2,022	12,175
Time Deposits	$ 354,091

LEASE COMMITMENTS (Narrative) (

LEASE COMMITMENTS (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Leases [Abstract]
Rental expense	$ 642	$ 492	$ 456
Description of lessee leasing arrangement, operating leases	ACNB leases space at several of its owned offices to other unrelated organizations.
Total rental income	$ 60	$ 8	$ 27

LEASE COMMITMENTS (Table) (Deta

LEASE COMMITMENTS (Table) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Leases [Abstract]
2,018	$ 787
2,019	579
2,020	481
2,021	386
2,022	328
Later years	1,694
Total future minimum rental payments	$ 4,255

BORROWINGS (Schedule of Short-t

BORROWINGS (Schedule of Short-term Debt) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Amount	$ 36,908,000	$ 34,590,000
Rate	0.12%	0.12%
Federal Home Loan Bank Stock	$ 4,194,700
Line of Credit Facility, Current Borrowing Capacity	29,000,000
FHLB overnight advance
Short-term Debt [Line Items]
Amount	$ 0	$ 0
Rate	0.00%	0.00%
Securities Sold under Agreements to Repurchase
Short-term Debt [Line Items]
Amount	$ 36,908,000	$ 34,590,000
Rate	0.12%	0.12%

BORROWINGS (Offsetting Liabilit

BORROWINGS (Offsetting Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting Liabilities [Line Items]
Fair value of securities pledged in connection with repurchase agreements	$ 42,397	$ 41,406
Commercial Customers and Government Entities
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	36,908	34,590
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Liabilities Presented in the Statements of Condition	36,908	34,590
Gross Amounts Not Offset in the Statements of Condition, Financial Instruments	(36,908)	(34,590)
Gross Amounts Not Offset in the Statements of Condition, Cash Collateral Pledged	0	0
Net Amount	$ 0	$ 0

BORROWINGS (Schedule of Maturit

BORROWINGS (Schedule of Maturities of Long-term Debt) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
FHLB fixed-rate advances maturing in 2017, Amount	$ 0	$ 14,250,000
FHLB fixed-rate advances maturing in 2017, Rate	0.00%	2.30%
FHLB fixed-rate advances maturing in 2018, Amount	$ 25,500,000	$ 25,500,000
FHLB fixed-rate advances maturing in 2018, Rate	1.87%	1.87%
FHLB fixed-rate advances maturing in 2019, Amount	$ 23,500,000	$ 19,500,000
FHLB fixed-rate advances maturing in 2019, Rate	1.73%	1.75%
FHLB fixed-rate advances maturing in 2020, Amount	$ 20,000,000	$ 12,000,000
FHLB fixed-rate advances maturing in 2020, Rate	1.87%	1.84%
FHLB fixed-rate advances maturing in 2021, Amount	$ 16,000,000	$ 3,000,000
FHLB fixed-rate advances maturing in 2021, Rate	2.01%	1.58%
Loan Payable to local bank	$ 4,600,000	$ 0
Trust preferred subordinated debt	5,000,000	0
Long-term debt, Amount	$ 94,600,000	$ 74,250,000
Long-term debt, Rate	2.06%	1.91%
Maximum borrowings from FHLB	$ 674,680,200
Available borrowings from FHLB	$ 567,440,200
Loan payable to local bank
Debt Instrument [Line Items]
Fixed rate percentage	4.50%
Long-term debt, Rate	1.53%	0.00%
Loan payable to local bank draw period	1 year
Period of fixed interest rate	5 years
Trust preferred subordinated debt
Debt Instrument [Line Items]
Fixed rate percentage	6.39%	0.00%
Trust preferred subordinated debt issued	$ 5,000,000

REGULATORY RESTRICTIONS ON DI77

REGULATORY RESTRICTIONS ON DIVIDENDS (Narrative) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Disclosure of Restrictions on Dividends, Loans and Advances Disclosure [Abstract]
Undistributed earnings of the Bank available for distribution as dividends without prior regulatory approval	$ 16,066

INCOME TAXES (Schedule of Compo

INCOME TAXES (Schedule of Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal:
Current	$ 4,767	$ 3,530	$ 3,316
Deferred	1,413	171	392
Federal Income Tax Expense, Total	6,180	3,701	3,708
State:
Current	156	67	53
Deferred	298	0	0
State Income Tax Expense, Total	454	67	53
Income Tax Expense, Total	$ 6,634	$ 3,768	$ 3,761

INCOME TAXES (Schedule of Recon

INCOME TAXES (Schedule of Reconciliations of the Statutory Federal Income Tax) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal income tax at statutory rate	35.00%	34.00%	34.00%
State income taxes, net of federal benefit	1.80%	0.30%	0.20%
Tax-exempt income	(5.00%)	(4.80%)	(4.40%)
Earnings on investment in bank-owned life insurance	(2.30%)	(2.60%)	(2.50%)
Rehabilitation and low-income housing credits	(1.70%)	(2.00%)	(2.00%)
Reduction of federal tax rate	10.20%	0.00%	0.00%
Other	2.40%	0.80%	0.20%
Effective Income Tax Rate, Total	40.40%	25.70%	25.50%

INCOME TAXES (Narrative) (Detai

INCOME TAXES (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes Related To Net Gains On Sales Of Securities	$ 0	$ 9,000	$ 89,000
Rehabilitation and Low-Income Housing Income Tax Credits	287,000	$ 287,000	$ 287,000
Projected Tax Credit, 2018	287,000
Projected Tax Credit, 2019	287,000
Projected Tax Credit, Thereafter	$ 876,000
Federal income tax at statutory rate	35.00%	34.00%	34.00%
Increase in income tax expense as a result of the Tax Cuts and Jobs Act	$ 1,700,000

INCOME TAXES (Components of Def

INCOME TAXES (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Net [Abstract]
Allowance for loan losses	$ 3,052	$ 4,968
Available for sale securities	282	143
Accrued deferred compensation	852	1,166
Pension	1,789	3,101
Other-than-temporary impairment	43	70
Nonaccrual interest	171	226
Deferred director fees	520	686
Acquisition accounting	1,357	0
Other	521	982
Deferred tax assets: Total	8,587	11,342
Deferred Tax Liabilities, Net [Abstract]
Deferred loan fees	114	79
Available for sale securities	0	0
Prepaid pension benefit cost	4,248	6,632
Prepaid expenses	132	123
Accumulated depreciation	426	372
Goodwill/intangibles	928	1,006
Deferred tax liabilities: Total	5,848	8,212
Net Deferred Tax Asset included in Other Assets	$ 2,739	$ 3,130

FAIR VALUE MEASUREMENTS (Fair V

FAIR VALUE MEASUREMENTS (Fair Value Measurements, Recurring and Nonrecurring) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	$ 159,051	$ 142,990
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	159,051	142,990
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	1,784	1,716
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	157,267	141,274
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
U.S. Government and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	104,083	79,579
Residential Mortgage Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	34,833	31,973
State and municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	13,294	24,660
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	5,057	5,062
CRA mutual fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	1,035	1,035
Stock In Other Banks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	749	681
Fair Value, Measurements, Recurring | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	159,051	142,990
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	1,784	1,716
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	157,267	141,274
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | U.S. Government and agencies | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	104,083	79,579
Fair Value, Measurements, Recurring | U.S. Government and agencies | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | U.S. Government and agencies | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	104,083	79,579
Fair Value, Measurements, Recurring | U.S. Government and agencies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	34,833	31,973
Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	34,833	31,973
Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | State and municipal | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	13,294	24,660
Fair Value, Measurements, Recurring | State and municipal | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | State and municipal | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	13,294	24,660
Fair Value, Measurements, Recurring | State and municipal | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | Corporate bonds | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	5,057	5,062
Fair Value, Measurements, Recurring | Corporate bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | Corporate bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	5,057	5,062
Fair Value, Measurements, Recurring | Corporate bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | CRA mutual fund | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	1,035	1,035
Fair Value, Measurements, Recurring | CRA mutual fund | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	1,035	1,035
Fair Value, Measurements, Recurring | CRA mutual fund | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | CRA mutual fund | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | Stock In Other Banks | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	749	681
Fair Value, Measurements, Recurring | Stock In Other Banks | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	749	681
Fair Value, Measurements, Recurring | Stock In Other Banks | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Fair Value, Measurements, Recurring | Stock In Other Banks | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale Securities, Fair Value	0	0
Impaired Loan | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	5,426	4,406
Impaired Loan | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Impaired Loan | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Impaired Loan | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	5,426	4,406
Foreclosed Assets Held For Resale | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Foreclosed Assets Held For Resale | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Foreclosed Assets Held For Resale | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Foreclosed Assets Held For Resale | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Fair83

FAIR VALUE MEASUREMENTS (Fair Value Inputs, Assets, Quantitative Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Impaired Loan
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average	(36.00%)	(39.00%)
Impaired Loan | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average	(10.00%)	(10.00%)
Impaired Loan | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average	(50.00%)	(50.00%)
Foreclosed Assets Held For Resale
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average	(0.00%)	(0.00%)
Foreclosed Assets Held For Resale | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average	(10.00%)	(10.00%)
Foreclosed Assets Held For Resale | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Weighted average	(50.00%)	(50.00%)
Fair Value Estimate | Impaired Loan
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$ 5,426	$ 4,406
Fair Value Estimate | Foreclosed Assets Held For Resale
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Fair84

FAIR VALUE MEASUREMENTS (Fair Value, by Balance Sheet Grouping) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Assets [Abstract]
Interest-bearing deposits in banks	$ 15,137	$ 5,135
Investment securities available for sale	159,051	142,990
Investment securities held to maturity	44,549	55,425
Restricted investment in bank stocks	4,773	4,349
Carrying Amount
Financial Assets [Abstract]
Cash and due from banks	19,304	13,796
Interest-bearing deposits in banks	15,137	5,135
Investment securities available for sale	159,051	142,990
Investment securities held to maturity	44,829	55,568
Loans held for sale	1,736	1,770
Loans, less allowance for loan losses	1,230,194	893,176
Accrued interest receivable	3,670	3,158
Restricted investment in bank stocks	4,773	4,349
Financial Liabilities [Abstract]
Deposits	1,298,492	967,621
Short-term borrowings	36,908	34,590
Long-term borrowings	89,600	74,250
Trust preferred subordinated debt	5,000
Accrued interest payable	1,163	837
Off-balance sheet financial instruments	0	0
Fair Value
Financial Assets [Abstract]
Cash and due from banks	19,304	13,796
Interest-bearing deposits in banks	15,137	5,135
Investment securities available for sale	159,051	142,990
Investment securities held to maturity	44,549	55,425
Loans held for sale	1,736	1,770
Loans, less allowance for loan losses	1,213,932	888,169
Accrued interest receivable	3,670	3,158
Restricted investment in bank stocks	4,773	4,349
Financial Liabilities [Abstract]
Deposits	1,295,456	967,236
Short-term borrowings	36,908	34,590
Long-term borrowings	89,571	75,029
Trust preferred subordinated debt	4,692
Accrued interest payable	1,163	837
Off-balance sheet financial instruments	0	0
Level 1
Financial Assets [Abstract]
Cash and due from banks	8,313	6,921
Interest-bearing deposits in banks	15,137	5,135
Investment securities available for sale	1,784	1,716
Investment securities held to maturity	0	0
Loans held for sale	0	0
Loans, less allowance for loan losses	0	0
Accrued interest receivable	0	0
Restricted investment in bank stocks	0	0
Financial Liabilities [Abstract]
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Trust preferred subordinated debt	0
Accrued interest payable	0	0
Off-balance sheet financial instruments	0	0
Level 2
Financial Assets [Abstract]
Cash and due from banks	10,991	6,875
Interest-bearing deposits in banks	0	0
Investment securities available for sale	157,267	141,274
Investment securities held to maturity	44,549	55,425
Loans held for sale	1,736	1,770
Loans, less allowance for loan losses	0	0
Accrued interest receivable	3,670	3,158
Restricted investment in bank stocks	4,773	4,349
Financial Liabilities [Abstract]
Deposits	1,295,456	967,236
Short-term borrowings	36,908	34,590
Long-term borrowings	89,571	75,029
Trust preferred subordinated debt	4,692
Accrued interest payable	1,163	837
Off-balance sheet financial instruments	0	0
Level 3
Financial Assets [Abstract]
Cash and due from banks	0	0
Interest-bearing deposits in banks	0	0
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans held for sale	0	0
Loans, less allowance for loan losses	1,213,932	888,169
Accrued interest receivable	0	0
Restricted investment in bank stocks	0	0
Financial Liabilities [Abstract]
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Trust preferred subordinated debt	0
Accrued interest payable	0	0
Off-balance sheet financial instruments	$ 0	$ 0

RETIREMENT PLANS (Schedule of B

RETIREMENT PLANS (Schedule of Benefit Plan Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 28,625	$ 26,670
Service cost	839	795	$ 881
Interest cost	1,135	1,136	1,040
Change in assumptions	2,040	1,059
Benefits paid	(1,092)	(1,035)
Benefit obligation at end of year	31,547	28,625	26,670
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	38,715	36,880
Actual return on plan assets	4,816	2,870
Employer contribution	0	0
Benefits paid	(1,092)	(1,035)
Fair value of plan assets at end of year	42,439	38,715	$ 36,880
Funded Status, included in other assets	10,892	10,090
Amounts recognized in accumulated other comprehensive income: Total net actuarial loss	7,924	8,859
Amounts recognized in accumulated other comprehensive income: Prior service cost	0	0
Total included in accumulated other comprehensive loss (pretax)	$ 7,924	$ 8,859

RETIREMENT PLANS (Estimated Cos

RETIREMENT PLANS (Estimated Costs To Be Amortized From AOCI Into Net Periodic Pension Cost) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Postemployment Benefits [Abstract]
Net loss	$ 515
Prior service cost	0
Total costs to be amortized from AOCI into Net Periodic Pension Cost	$ 515

RETIREMENT PLANS (Narrative) (D

RETIREMENT PLANS (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)person	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated Benefit Obligation	$ 30,228	$ 27,508
Corporation Common Stock Included in Equity Securities	$ 2,114	$ 2,175
Corporation Common Stock Included in Equity Securities, Percentage of Total Plan Assets	5.00%	6.00%
Percentage of participants average monthly pay used to calculate benefit accruals	0.75%
Maximum years of benefit used to calculate benefit accruals	25 years
Number of active, vested terminated, and retired persons in the Plan | person	353
Employee contribution percentage, maximum	100.00%
Balance accrued included in other liabilities	$ 2,803	$ 2,550
Annual expense included in salaries and benefits expense	$ 279	383	$ 360
Banking Subsidiary
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer Match Percentage of Income	4.00%
Employer Contributions to and Expenses for the Plan	$ 626	541	547
Insurance Subsidiary
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer Contributions to and Expenses for the Plan	$ 86	$ 83	$ 74
Non highly compensated employees | Insurance Subsidiary
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer Match Percentage of Income	6.00%
Highly Compensated Employees | Insurance Subsidiary
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer Match Percentage of Income	3.00%

RETIREMENT PLANS (Components Of

RETIREMENT PLANS (Components Of Net Periodic Benefit Costs (Income)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postemployment Benefits [Abstract]
Service cost	$ 839	$ 795	$ 881
Interest cost	1,135	1,136	1,040
Expected return on plan assets	(2,518)	(2,429)	(2,542)
Recognized net actuarial loss	676	682	481
Amortization of prior service cost	0	1	24
Net Periodic Benefit Cost (Income)	132	185	(116)
Net loss	(259)	618	1,409
Amortization of net loss	(676)	(682)	(481)
Amortization of prior service cost	0	(1)	(24)
Total recognized in other comprehensive (income) loss	(935)	(65)	904
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ (803)	$ 120	$ 788

RETIREMENT PLANS (Assumptions U

RETIREMENT PLANS (Assumptions Used To Determine The Benefit Obligation and Net Periodic Benefit) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postemployment Benefits [Abstract]
Assumptions Used Calculating Benefit Obligation: Discount rate	3.55%	4.05%	4.35%
Assumptions Used Calculating Benefit Obligation: Rate of compensation increase	3.50%	3.50%	3.50%
Assumptions Used Calculating Net Periodic Benefit Cost: Discount rate	4.05%	4.35%	3.90%
Assumptions Used Calculating Net Periodic Benefit Cost: Expected long-term rate of return on plan assets	6.75%	6.75%	6.75%
Assumptions Used Calculating Net Periodic Benefit Cost: Rate of compensation increase	3.50%	3.50%	3.75%

RETIREMENT PLANS (Pension Plan

RETIREMENT PLANS (Pension Plan Weighted-Average Assets' Allocations) (Details)	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Weighted-Average Asset Allocation	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-Average Asset Allocation	50.00%	48.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-Average Asset Allocation	44.00%	46.00%
Short-term fixed income
Defined Benefit Plan Disclosure [Line Items]
Weighted-Average Asset Allocation	0.00%	0.00%
Real estate
Defined Benefit Plan Disclosure [Line Items]
Weighted-Average Asset Allocation	6.00%	6.00%

RETIREMENT PLANS (Fair Value Me

RETIREMENT PLANS (Fair Value Measurements) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 42,439	$ 38,715	$ 36,880
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,423	18,687
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,668	17,888
Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,348	2,140
Level 1 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,114	2,175
Level 1 | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 1 | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19,309	16,512
Level 2 | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,668	17,888
Level 2 | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,348	2,140
Level 3 | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 3 | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0

RETIREMENT PLANS (Future Benefi

RETIREMENT PLANS (Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Postemployment Benefits [Abstract]
2,018	$ 1,320
2,019	1,410
2,020	1,440
2,021	1,650
2,022	1,660
2023 - 2027	$ 9,200

STOCKHOLDERS' EQUITY AND REGU93

STOCKHOLDERS' EQUITY AND REGULATORY MATTERS (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 05, 2009
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Shares issued, Dividend Reinvestment and Stock Repurchase Plan (in shares)	14,967	16,979	18,401
Proceeds from issuance of common stock, Dividend Reinvestment and Stock Purchase Plan	$ 362	$ 437	$ 499
Restricted Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cumulative amount of shares issued under the plan	19,301
Maximum | Restricted Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Awards authorized (in shares)				200,000

STOCKHOLDERS' EQUITY AND REGU94

STOCKHOLDERS' EQUITY AND REGULATORY MATTERS (The Actual and Required Capital Amounts and Ratios) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual, Tier 1 leverage ratio (to average assets), Amount	$ 144,376	$ 121,650
Actual, Tier 1 leverage ratio (to average assets), Ratio	9.04%	10.06%
For Capital Adequacy Purposes, Tier 1 leverage ratio (to average assets), Amount (greater than or equal to)	$ 63,871	$ 48,382
For Capital Adequacy Purposes, Tier 1 leverage ratio (to average assets), Ratio (greater than or equal to)	4.00%	4.00%
Actual, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Amount	$ 144,376	$ 121,650
Actual, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio	12.79%	14.71%
For Capital Adequacy Purposes, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 50,796	$ 37,205
For Capital Adequacy Purposes, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	4.50%	4.50%
Actual, Tier 1 risk-based capital ratio (to risk-weighted assets), Amount	$ 144,376	$ 121,650
Actual, Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio	12.79%	14.71%
For Capital Adequacy Purposes, Tier 1 risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 67,728	$ 49,606
For Capital Adequacy Purposes, Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	6.00%	6.00%
Actual, Total risk-based capital ratio (to risk-weighted assets), Amount	$ 158,479	$ 132,033
Actual, Total risk-based capital ratio (to risk-weighted assets), Ratio	14.04%	15.97%
For Capital Adequacy Purposes, Total risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 90,304	$ 66,142
For Capital Adequacy Purposes, Total risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	8.00%	8.00%
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual, Tier 1 leverage ratio (to average assets), Amount	$ 138,811	$ 106,540
Actual, Tier 1 leverage ratio (to average assets), Ratio	8.70%	8.82%
For Capital Adequacy Purposes, Tier 1 leverage ratio (to average assets), Amount (greater than or equal to)	$ 68,857	$ 48,316
For Capital Adequacy Purposes, Tier 1 leverage ratio (to average assets), Ratio (greater than or equal to)	4.00%	4.00%
To be Well Capitalized under Prompt Corrective Action Provisions, Tier 1 leverage ratio (to average assets), Amount (greater than or equal to)	$ 79,822	$ 60,395
To be Well Capitalized under Prompt Corrective Action Provisions, Tier 1 leverage ratio (to average assets), Ratio (greater than or equal to)	5.00%	5.00%
Actual, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Amount	$ 138,811	$ 106,540
Actual, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio	12.34%	12.96%
For Capital Adequacy Purposes, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 50,639	$ 36,995
For Capital Adequacy Purposes, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	4.50%	4.50%
To be Well Capitalized under Prompt Corrective Action Provisions, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 73,145	$ 53,438
To be Well Capitalized under Prompt Corrective Action Provisions, Common Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	6.50%	6.50%
Actual, Tier 1 risk-based capital ratio (to risk-weighted assets), Amount	$ 138,811	$ 106,540
Actual, Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio	12.34%	12.96%
For Capital Adequacy Purposes, Tier 1 risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 67,519	$ 49,327
For Capital Adequacy Purposes, Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	6.00%	6.00%
To be Well Capitalized under Prompt Corrective Action Provisions, Tier 1 risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 90,025	$ 65,770
To be Well Capitalized under Prompt Corrective Action Provisions, Tier 1 risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	8.00%	8.00%
Actual, Total risk-based capital ratio (to risk-weighted assets), Amount	$ 152,868	$ 116,865
Actual, Total risk-based capital ratio (to risk-weighted assets), Ratio	13.58%	14.22%
For Capital Adequacy Purposes, Total risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 90,025	$ 65,770
For Capital Adequacy Purposes, Total risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	8.00%	8.00%
To be Well Capitalized under Prompt Corrective Action Provisions, Total risk-based capital ratio (to risk-weighted assets), Amount (greater than or equal to)	$ 112,532	$ 82,212
To be Well Capitalized under Prompt Corrective Action Provisions, Total risk-based capital ratio (to risk-weighted assets), Ratio (greater than or equal to)	10.00%	10.00%

FINANCIAL INSTRUMENTS WITH OF95

FINANCIAL INSTRUMENTS WITH OFF-BALANCE SHEET RISK (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loan to value ratio requirement (no greater than)	80.00%
Commercial line of credit borrowing capacity		$ 500,000
Commitments to Extend Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet financial instruments	$ 264,368,000	258,631,000
Standby Letters of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance sheet financial instruments	$ 6,362,000	$ 6,134,000

ACNB CORPORATION (PARENT COMP96

ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Statements of Condition) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Cash	$ 19,304	$ 13,796
Investments in low-income housing partnerships	2,446	2,899
Securities and other assets	23,668	19,950
Total assets	1,595,432	1,206,320	$ 1,147,925
LIABILITIES AND STOCKHOLDERS’ EQUITY
Long-term debt	94,600	74,250
Other liabilities	11,466	9,798
Stockholders’ equity	153,966	120,061
Total Liabilities and Stockholders’ Equity	1,595,432	1,206,320
Parent Company
ASSETS
Cash	9,440	8,563
Investments in low-income housing partnerships	689	1,016
Securities and other assets	1,548	1,232
Receivable from banking subsidiary	118	130
Total assets	163,600	120,104
LIABILITIES AND STOCKHOLDERS’ EQUITY
Long-term debt	9,600	0
Other liabilities	34	43
Stockholders’ equity	153,966	120,061
Total Liabilities and Stockholders’ Equity	163,600	120,104
Banking Subsidiary | Parent Company
ASSETS
Investment	143,288	100,395
Other Subsidiary | Parent Company
ASSETS
Investment	$ 8,517	$ 8,768

ACNB CORPORATION (PARENT COMP97

ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Statements of Income) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Gain on sale of securities	$ 0	$ 0	$ 0	$ 0	$ 26,000	$ 0	$ 0	$ 0	$ 0	$ 26,000	$ 261,000
Other income									14,149,000	13,208,000	12,406,000
Income tax benefit									(6,634,000)	(3,768,000)	(3,761,000)
Net Income	$ 2,517,000	$ 1,912,000	$ 2,722,000	$ 2,637,000	$ 2,572,000	$ 2,768,000	$ 2,982,000	$ 2,547,000	9,788,000	10,869,000	11,017,000
Comprehensive Income									9,903,000	9,571,000	9,014,000
Parent Company
Condensed Financial Statements, Captions [Line Items]
Dividends from banking subsidiary									5,233,000	4,840,000	4,820,000
Gain on sale of securities									0	26,000	0
Other income									31,000	35,000	190,000
Total Revenues									5,264,000	4,901,000	5,010,000
Expenses									1,572,000	854,000	431,000
Net income before taxes and equity in undistributed earnings of subsidiaries									3,692,000	4,047,000	4,579,000
Income tax benefit									507,000	490,000	381,000
Net income before equity in undistributed earnings of subsidiaries									4,199,000	4,537,000	4,960,000
Equity in undistributed earnings of subsidiaries									5,589,000	6,332,000	6,057,000
Net Income									9,788,000	10,869,000	11,017,000
Comprehensive Income									$ 9,903,000	$ 9,571,000	$ 9,014,000

ACNB CORPORATION (PARENT COMP98

ACNB CORPORATION (PARENT COMPANY ONLY) FINANCIAL INFORMATION (Statements of Cash Flows) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 2,517,000	$ 1,912,000	$ 2,722,000	$ 2,637,000	$ 2,572,000	$ 2,768,000	$ 2,982,000	$ 2,547,000	$ 9,788,000	$ 10,869,000	$ 11,017,000
Gain on sale of securities	0	$ 0	$ 0	0	(26,000)	$ 0	$ 0	0	0	(26,000)	(261,000)
Net Cash Provided by Operating Activities									17,007,000	12,121,000	14,379,000
CASH FLOWS FROM INVESTING ACTIVITIES
Net Cash (Used in) Provided by Investing Activities									(51,953,000)	(59,442,000)	(64,144,000)
CASH FLOWS USED IN FINANCING ACTIVITIES
Proceeds from long-term debt									29,600,000	16,000,000	18,000,000
Repayments on long-term debt									(14,250,000)	(18,250,000)	(22,437,000)
Proceeds from issuance of common stock									482,000	556,000	499,000
Dividends paid									(5,233,000)	(4,840,000)	(4,820,000)
Net Cash Provided by (Used in) Financing Activities									50,456,000	47,495,000	48,849,000
Net Increase (Decrease) in Cash and Cash Equivalents									15,510,000	174,000	(916,000)
CASH AND CASH EQUIVALENTS — BEGINNING				18,931,000				18,757,000	18,931,000	18,757,000	19,673,000
CASH AND CASH EQUIVALENTS — ENDING	34,441,000				18,931,000				34,441,000	18,931,000	18,757,000
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net income									9,788,000	10,869,000	11,017,000
Equity in undistributed earnings of subsidiaries									(5,589,000)	(6,332,000)	(6,057,000)
Decrease (Increase) in receivable from banking subsidiary									12,000	2,639,000	(131,000)
Gain on sale of securities									0	(26,000)	0
Other									129,000	540,000	86,000
Net Cash Provided by Operating Activities									4,340,000	7,690,000	4,915,000
CASH FLOWS FROM INVESTING ACTIVITIES
Return of investment from subsidiary									1,000,000	650,000	750,000
Outlay for business combination									(4,445,000)	0	0
Net Cash (Used in) Provided by Investing Activities									(3,445,000)	650,000	750,000
CASH FLOWS USED IN FINANCING ACTIVITIES
Proceeds from long-term debt									4,600,000	0	0
Repayments on long-term debt									0	0	(1,437,000)
Proceeds from issuance of common stock									615,000	615,000	499,000
Dividends paid									(5,233,000)	(4,840,000)	(4,820,000)
Net Cash Provided by (Used in) Financing Activities									(18,000)	(4,225,000)	(5,758,000)
Net Increase (Decrease) in Cash and Cash Equivalents									877,000	4,115,000	(93,000)
CASH AND CASH EQUIVALENTS — BEGINNING				$ 8,563,000				$ 4,448,000	8,563,000	4,448,000	4,541,000
CASH AND CASH EQUIVALENTS — ENDING	$ 9,440,000				$ 8,563,000				$ 9,440,000	$ 8,563,000	$ 4,448,000

GOODWILL AND OTHER INTANGIBLE99

GOODWILL AND OTHER INTANGIBLES (Carrying Value And Accumulated Amortization Of The Intangible Assets) (Details) - USD ($)	Jul. 01, 2017	Jan. 05, 2005	Jan. 05, 2005	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Date of Acquisition, Russell Insurance Group, Inc.				Jan. 5, 2005
Contingent Consideration, Russell Insurance Group, Inc.		$ 3,000,000	$ 3,000,000
Length of Period Subsequent to Acquisition Subject to Performance Criteria to Determine Contingent Consideration			3 years
Total consideration paid		$ 8,663,000
Goodwill				$ 19,580,000	$ 6,308,000
Gross Carrying Amount of Intangible Asset				9,085,000	6,667,000
Accumulated Amortization of Intangible Asset				6,516,000	5,979,000
RIG Customer Lists, Purchased in 2005
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				3,282,000	3,282,000
Accumulated Amortization of Intangible Asset				3,282,000	3,282,000
RIG Customer Lists, Purchased in 2007
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				637,000	637,000
Accumulated Amortization of Intangible Asset				637,000	587,000
RIG Customer Lists, Purchased in 2008
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				1,165,000	1,165,000
Accumulated Amortization of Intangible Asset				1,101,000	992,000
RIG Customer Lists, Purchased in 2009
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				1,300,000	1,300,000
Accumulated Amortization of Intangible Asset				1,170,000	1,040,000
RIG Customer Lists, Purchased in 2010
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				33,000	33,000
Accumulated Amortization of Intangible Asset				26,000	23,000
RIG Customer Lists, Purchased in 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				77,000	77,000
Accumulated Amortization of Intangible Asset				31,000	23,000
RIG Customer Lists, Purchased in 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				173,000	173,000
Accumulated Amortization of Intangible Asset				$ 49,000	32,000
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization life				10 years
RIG
Finite-Lived Intangible Assets [Line Items]
Goodwill				$ 6,308,000
RIG | Customer Lists
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount of Intangible Asset				6,667,000	6,667,000
Accumulated Amortization of Intangible Asset				6,296,000	5,979,000
New Windsor
Finite-Lived Intangible Assets [Line Items]
Total consideration paid	$ 33,289,975
Goodwill	$ 13,272,000			13,300,000
New Windsor | Core Deposits
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization life	10 years
Gross Carrying Amount of Intangible Asset				2,418,000	0
Accumulated Amortization of Intangible Asset				$ 220,000	$ 0
Minimum
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization life				5 years
Minimum | Customer Lists
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization life				8 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization life				15 years
Maximum | Customer Lists
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization life				13 years

GOODWILL AND OTHER INTANGIBL100

GOODWILL AND OTHER INTANGIBLES (Expected Amortization Expense) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Business Combinations [Abstract]
2,018	$ 638
2,019	400
2,020	353
2,021	309
2,022	265
Thereafter	$ 604

SEGMENT AND RELATED INFORMAT101

SEGMENT AND RELATED INFORMATION (Segment Information) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments	2
Net interest income and other income from external customers	$ 60,501	$ 49,774	$ 48,012
Income before income taxes	16,422	14,637	14,778
Total assets	1,595,432	1,206,320	1,147,925
Capital expenditures	1,757	2,344	1,738
Banking
Segment Reporting Information [Line Items]
Net interest income and other income from external customers	55,763	45,313	43,522
Income before income taxes	15,585	13,828	14,137
Total assets	1,586,064	1,195,857	1,138,106
Capital expenditures	1,727	2,333	1,712
Insurance
Segment Reporting Information [Line Items]
Net interest income and other income from external customers	4,738	4,461	4,490
Income before income taxes	837	809	641
Total assets	9,368	10,463	9,819
Capital expenditures	$ 30	$ 11	$ 26

NEW WINDSOR ACQUISITION (Narrat

NEW WINDSOR ACQUISITION (Narrative) (Details)	Jul. 01, 2017USD ($)bank$ / sharesshares	Jan. 05, 2005USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)$ / shares	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Number of community banking office locations, NWSB							7
Goodwill			$ 19,580,000				$ 19,580,000	$ 6,308,000
Total consideration paid		$ 8,663,000
Merger related expenses			53,000	$ 4,305,000	$ 208,000	$ 162,000	4,728,000	$ 472,000	$ 0
New Windsor
Business Acquisition [Line Items]
Number of community banking office locations, NWSB | bank	7
Fair Value of total assets acquired	$ 319,821,000
Fair Value of total loans acquired	263,450,000
Fair Value of total deposits acquired	293,300,000
Goodwill	13,272,000		$ 13,300,000				$ 13,300,000
Cash portion of purchase price	$ 4,519,995
Percent of post transaction outstanding shares of the Corporation's common stock issued in merger	13.00%
Total consideration paid	$ 33,289,975
ACNB’s share price for purposes of calculation (in dollars per share) | $ / shares	$ 30.50				$ 30.50
Loans receivable, gross amortized cost bases	$ 272,646,000
Interest rate fair value discount	731,000
Credit fair value discount	$ 4,501,000
Common Stock | New Windsor
Business Acquisition [Line Items]
Shares of common stock issued in merger (in shares) | shares	938,360
Investment Securities Available-for-sale | New Windsor
Business Acquisition [Line Items]
Assets, fair value premium (discount)	$ 361,000
Time Deposits | New Windsor
Business Acquisition [Line Items]
Assets, fair value premium (discount)	$ (847,500)
Core Deposit Intangible
Business Acquisition [Line Items]
Amortization period							10 years
Core Deposit Intangible | New Windsor
Business Acquisition [Line Items]
Amortization period	10 years
Long-term Borrowings | New Windsor
Business Acquisition [Line Items]
Liabilities, fair value discount	$ 312,500

NEW WINDSOR ACQUISITION (Purcha

NEW WINDSOR ACQUISITION (Purchase Price Consideration in Common Stock) (Details) - USD ($)	Jul. 01, 2017	Jan. 05, 2005	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
New Windsor shares outstanding			7,023,658		6,064,138
Total consideration paid		$ 8,663,000
Fair Value of Liabilities Assumed
Goodwill Recorded in Acquisition			$ 19,580,000		$ 6,308,000
New Windsor
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Cash consideration (per New Windsor share)	$ 30
Cash portion of purchase price	$ 4,519,995
ACNB’s share price for purposes of calculation	$ 30.50			$ 30.50
Equity portion of purchase price	$ 28,619,980
Cost of shares owned by buyer	150,000
Total consideration paid	33,289,975
Fair Value of Assets Acquired
Cash and cash equivalents	10,964,000
Investment securities	21,624,000
Loans held for sale	1,463,000
Loans	263,450,000
Restricted stock	486,000
Premises and equipment	8,624,000
Core deposit intangible asset	2,418,000
Other assets	10,792,000
Total assets	319,821,000
Fair Value of Liabilities Assumed
Non-interest bearing deposits	80,006,000
Interest bearing deposits	213,327,000
Subordinated debt	4,688,000
Other liabilities	1,782,000
Total liabilities	299,803,000
Net Assets Acquired	20,018,000
Goodwill Recorded in Acquisition	$ 13,272,000		$ 13,300,000
New Windsor | Common Stock
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Exchange ratio	1.10
Total ACNB shares issued	938,360
NW Bancorp | New Windsor
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
New Windsor shares outstanding	1,003,703
Shares paid cash consideration	150,555
Shares paid stock consideration	853,148

NEW WINDSOR ACQUISITION (Fair V

NEW WINDSOR ACQUISITION (Fair Value Adjustments) (Details) - New Windsor $ in Thousands	Jul. 01, 2017USD ($)
Business Acquisition [Line Items]
Gross amortized cost basis at July 1, 2017	$ 272,646
Interest rate fair value adjustment on pools of homogeneous loans	(731)
Credit fair value adjustment	(4,501)
Fair value of acquired loans at July 1, 2017	263,450
Purchased credit impaired loans
Business Acquisition [Line Items]
Credit fair value adjustment	$ (3,964)

NEW WINDSOR ACQUISITION (Acquir

NEW WINDSOR ACQUISITION (Acquired Purchased Credit Impaired Loans Receivable) (Details) - New Windsor $ in Thousands	Jul. 01, 2017USD ($)
Business Acquisition [Line Items]
Contractual principal and interest at acquisition	$ 13,439
Nonaccretable difference	(5,651)
Expected cash flows at acquisition	7,788
Accretable yield	(1,458)
Fair value of purchased impaired loans	$ 6,330

NEW WINDSOR ACQUISITION (Pro Fo

NEW WINDSOR ACQUISITION (Pro Forma Information) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Business Combinations [Abstract]
Total revenues (net interest income plus noninterest income)	$ 102,891
Net Income	$ 13,591

QUARTERLY RESULTS OF OPERATI107

QUARTERLY RESULTS OF OPERATIONS (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Results of Operations [Abstract]
Interest income	$ 15,181,000	$ 15,109,000	$ 10,962,000	$ 10,533,000	$ 10,345,000	$ 10,181,000	$ 10,010,000	$ 9,964,000	$ 51,785,000	$ 40,500,000	$ 39,464,000
Interest expense	1,688,000	1,547,000	1,131,000	1,067,000	1,001,000	996,000	980,000	957,000	5,433,000	3,934,000	3,858,000
Net interest income	13,493,000	13,562,000	9,831,000	9,466,000	9,344,000	9,185,000	9,030,000	9,007,000	46,352,000	36,566,000	35,606,000
Provision for loan losses	0	0	0	0	0	0	0	0	0	0	0
Net interest income after provision for loan losses	13,493,000	13,562,000	9,831,000	9,466,000	9,344,000	9,185,000	9,030,000	9,007,000	46,352,000	36,566,000	35,606,000
Net gains on sales of securities	0	0	0	0	26,000	0	0	0	0	26,000	261,000
Gain on sales of premises and equipment	0	0	0	0	0	0	449,000	0	0	449,000	0
Other income	3,609,000	3,930,000	3,528,000	3,082,000	3,198,000	3,301,000	3,362,000	2,872,000
Merger related expenses	53,000	4,305,000	208,000	162,000					4,728,000	472,000	0
Merger related expenses					472,000	0	0	0
Other expenses and provision for income taxes	14,532,000	11,275,000	10,429,000	9,749,000	9,524,000	9,718,000	9,859,000	9,332,000
Net income	$ 2,517,000	$ 1,912,000	$ 2,722,000	$ 2,637,000	$ 2,572,000	$ 2,768,000	$ 2,982,000	$ 2,547,000	$ 9,788,000	$ 10,869,000	$ 11,017,000
Basic earnings per share	$ 0.35	$ 0.27	$ 0.45	$ 0.43	$ 0.43	$ 0.46	$ 0.49	$ 0.42	$ 1.50	$ 1.80	$ 1.83
Dividends per share	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.80	$ 0.80	$ 0.80