Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2016
Summary of Significant Accounting Policies [Abstract]
Consolidation	Consolidation The accompanying consolidated financial statements include the accounts of NBT Bancorp and its wholly-owned subsidiaries mentioned above. All material intercompany transactions have been eliminated in consolidation. Amounts previously reported in the consolidated financial statements are reclassified whenever necessary to conform to the current year’s presentation. In the “Parent Company Financial Information,” the investment in subsidiaries is recorded using the equity method of accounting. The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting interest entity or a variable interest entity under GAAP. Voting interest entities are entities in which the total equity investment at risk is sufficient to enable the entity to finance itself independently and provides the equity holders with the obligation to absorb losses, the right to receive residual returns and the right to make decisions about the entity’s activities. The Company consolidates voting interest entities in which it has all, or at least a majority of, the voting interest. As defined in applicable accounting standards, variable interest entities (“VIEs”) are entities that lack one or more of the characteristics of a voting interest entity. A controlling financial interest in a VIE is present when the Company has both the power and ability to direct the activities of the VIE that most significantly impact the VIE's economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The Company’s wholly-owned subsidiaries CNBF Capital Trust I, NBT Statutory Trust I, NBT Statutory Trust II, Alliance Financial Capital Trust I and Alliance Financial Capital Trust II are VIEs for which the Company is not the primary beneficiary. Accordingly, the accounts of these entities are not included in the Company’s consolidated financial statements.
Segment Reporting	Segment Reporting The Company’s operations are primarily in the community banking industry and include the provision of traditional banking services. The Company also provides other services through its subsidiaries such as insurance, retirement plan administration, and trust administration. The Company operates solely in the geographical regions of central and upstate New York, northeastern Pennsylvania, western Massachusetts, southern New Hampshire, Vermont, and the greater Portland, Maine area. The Company has no reportable operating segments.
Cash Equivalents	Cash Equivalents The Company considers amounts due from correspondent banks, cash items in process of collection, and institutional money market mutual funds to be cash equivalents for purposes of the consolidated statements of cash flows.
Securities	Securities The Company classifies its securities at date of purchase as either held to maturity ("HTM"), trading or available for sale ("AFS"). HTM debt securities are those that the Company has the ability and intent to hold until maturity. Trading securities are securities purchased with the intent to sell within a short period of time. AFS securities are securities that are not classified as a HTM or trading securities. AFS securities are recorded at fair value. Unrealized holding gains and losses, net of the related tax effect, on AFS securities are excluded from earnings and are reported in the consolidated statements of stockholders’ equity and the consolidated statements of comprehensive income as a component of accumulated other comprehensive income or loss. HTM securities are recorded at amortized cost. Trading securities are recorded at fair value, with net unrealized gains and losses recognized in income. Transfers of securities between categories are recorded at fair value at the date of transfer. Declines in the fair value of HTM and AFS securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses or in other comprehensive income, depending on whether the Company intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If the Company intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If the Company does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the total OTTI impairment related to the credit loss shall be recognized in earnings. The amount of the total OTTI related to other factors shall be recognized in other comprehensive income, net of applicable taxes. In estimating OTTI losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) the historical and implied volatility of the fair value of the security. Non-marketable equity securities are carried at cost. Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the interest method. Dividend and interest income are recognized when earned. Realized gains and losses on securities sold are derived using the specific identification method for determining the cost of securities sold. Investments in Federal Reserve Bank (“FRB”) and Federal Home Loan Bank (“FHLB”) stock are required for membership in those organizations and are carried at cost since there is no market value available. The FHLB New York continues to pay dividends and repurchase stock. As such, the Company has not recognized any impairment on its holdings of FHLB stock.
Loans	Loans Loans are recorded at their current unpaid principal balance, net of unearned income and unamortized loan fees and expenses, which are amortized under the effective interest method over the estimated lives of the loans. Interest income on loans is accrued based on the principal amount outstanding. For all loan classes within the Company’s loan portfolio, loans are placed on nonaccrual status when timely collection of principal and interest in accordance with contractual terms is doubtful. Loans are transferred to nonaccrual status generally when principal or interest payments become ninety days delinquent, unless the loan is well-secured and in the process of collection, or sooner when management concludes circumstances indicate that borrowers may be unable to meet contractual principal or interest payments. When a loan is transferred to a nonaccrual status, all interest previously accrued in the current period but not collected is reversed against interest income in that period. Interest accrued in a prior period and not collected is charged-off against the allowance for loan losses. If ultimate repayment of a nonaccrual loan is expected, any payments received are applied in accordance with contractual terms. If ultimate repayment of principal is not expected, any payment received on a nonaccrual loan is applied to principal until ultimate repayment becomes expected. For all loan classes within the Company’s loan portfolio, nonaccrual loans are returned to accrual status when they become current as to principal and interest and demonstrate a period of performance under the contractual terms and, in the opinion of management, are fully collectible as to principal and interest. For loans in all portfolios, the principal amount is charged off in full or in part as soon as management determines, based on available facts, that the collection of principal in full is improbable. For commercial loans, management considers specific facts and circumstances relative to individual credits in making such a determination. For consumer and residential loan classes, management uses specific guidance and thresholds from the Federal Financial Institutions Examination Council’s Uniform Retail Credit Classification and Account Management Policy. Commercial type loans are considered impaired when it is probable that the borrower will not repay the loan according to the original contractual terms of the loan agreement, and all loan types are considered impaired if the loan is restructured in a troubled debt restructuring (“TDR”). In determining that we will be unable to collect all principal and interest payments due in accordance with the contractual terms of the loan agreements, we consider factors such as payment history and changes in the financial condition of individual borrowers, local economic conditions, historical loss experience and the conditions of the various markets in which the collateral may be liquidated. A loan is considered to be a TDR when the Company grants a concession to the borrower because of the borrower’s financial condition that the Company would not otherwise consider. Such concessions include the reduction of interest rates, forgiveness of all or a portion of principal or interest, or other modifications at interest rates that are less than the current market rate for new obligations with similar risk. TDR loans are nonaccrual loans; however, they can be returned to accrual status after a period of performance, generally evidenced by six months of compliance with their modified terms. When the Company modifies a loan, management evaluates any possible impairment based on the present value of the expected future cash flows, discounted at the contractual interest rate of the original loan agreement, except when the sole (remaining) source of repayment for the loan is the operation or liquidation of the collateral. In these cases, management uses the current fair value of the collateral, less selling costs, instead of discounted cash flows. If management determines that the value of the modified loan is less than the recorded investment in the loan (net of previous charge-offs, deferred loan fees or costs and unamortized premium or discount), impairment is recognized.
Acquired Loans	Acquired Loans Acquired loans are initially measured at fair value as of the acquisition date without carryover of historical allowance for loan losses. For loans that meet the criteria stipulated in ASC 310-30 - Receivables - Loans and Debt Securities Acquired with Deteriorated Credit Quality, the Company shall recognize the accretable yield, which is defined as the excess of all cash flows expected at acquisition over the initial fair value of the loan, as interest income on a level-yield basis over the expected remaining life of the loan. The excess of the loan's contractually required payments over the cash flows expected to be collected is the nonaccretable difference. The nonaccretable difference shall not be recognized as an adjustment of yield, a loss accrual, or a valuation allowance. Decreases in the expected cash flows in subsequent periods require the establishment of an allowance for loan losses. Improvements in expected cash flows in future periods result in a reduction of the nonaccretable discount, with such amount reclassified as part of the accretable yield and subsequently recognized in interest income over the remaining lives of the acquired loans on a level-yield basis if the amount and timing of future cash flows is reasonably estimable. Acquired loans that met the criteria for nonaccrual of interest prior to the acquisition are considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if the Company can reasonably estimate the timing and amount of the expected cash flows on such loans and if the Company expects to fully collect the new carrying value of the loans. As such, the Company may no longer consider the loan to be nonaccrual or nonperforming and may accrue interest on these loans, including the impact of any accretable yield. As such, charge-offs on acquired loans are first applied to the nonaccretable difference and then to any allowance for loan losses recognized subsequent to acquisition. For loans that meet the criteria stipulated in ASC 310-20 - Receivables - Nonrefundable Fees and Other Costs ("ASC 310-20"), the Company shall amortize/accrete into interest income the premium/discount determined at the date of purchase on a level-yield basis over the life of the loan. Subsequent to the acquisition date, the methods utilized to estimate the required allowance for loan losses are similar to originated loans. Loans accounted for under ASC 310-20 are placed on nonaccrual status when past due in accordance with the Company's nonaccrual policy. An acquired loan may be resolved either through receipt of payment (in full or in part) from the borrower, the sale of the loan to a third party, or foreclosure of the collateral. In the event of a sale of the loan, a gain or loss on sale is recognized and reported within noninterest income based on the difference between the sales proceeds and the carrying amount of the loan. In other cases, individual loans are removed from the pool based on comparing the amount received from its resolution (fair value of the underlying collateral less costs to sell in the case of a foreclosure) with its outstanding balance. Any difference between these amounts is recorded as a charge-off through the allowance for loan losses. Acquired loans subject to modification are not removed from the pool even if those loans would otherwise be deemed TDRs as the pool, and not the individual loan, represents the unit of account.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses is the amount which, in the opinion of management, is necessary to absorb probable losses inherent in the loan portfolio. The allowance is determined based upon numerous considerations, including local and regional conditions, the growth and composition of the loan portfolio with respect to the mix between the various types of loans and their related risk characteristics, a review of the value of collateral supporting the loans, comprehensive reviews of the loan portfolio by the independent loan review staff and management, as well as consideration of volume and trends of delinquencies, nonperforming loans, and loan charge-offs. Loan losses are charged off against the allowance, while recoveries of amounts previously charged off are credited to the allowance. As a result of tests of adequacy, required additions to the allowance for loan losses are made periodically by charges to the provision for loan losses. The allowance for loan losses related to impaired loans specifically allocated for impairment is based on discounted expected cash flows using the loan’s initial effective interest rate or the fair value of the collateral for certain loans where repayment of the loan is expected to be provided solely by the underlying collateral ("collateral dependent"). The Company’s impaired loans are generally collateral dependent. The Company considers the estimated cost to sell, on a discounted basis, when determining the fair value of collateral in the measurement of impairment if those costs are expected to reduce the cash flows available to repay or otherwise satisfy the loans. The allowance for loan losses for homogeneous non impaired loans is calculated using a systematic methodology with both a quantitative and a qualitative analysis that is applied on a quarterly basis. For purposes of our allowance methodology, the loan portfolio is segmented as described in Note 5. Each segment has a distinct set of risk characteristics monitored by management. We further assess and monitor risk and performance at a more disaggregated level which includes our internal risk grading system for the commercial segments. We first apply historical loss rates to pools of loans with similar risk characteristics. Loss rates are calculated by historical charge-offs that have occurred within each pool of loans over the lookback period ("LBP"), multiplied by the loss emergence period ("LEP"). The LBP represents the historical data period utilized to calculate loss rates. The LEP is an estimate of the average amount of time from the point at which a loss is incurred on a loan to the point at which the loss is confirmed. In general, the LEP will be shorter in an economic slowdown or recession and longer during times of economic stability or growth, as customers are better able to delay loss confirmation after a potential loss event has occurred. In conjunction with our annual review of the ALL assumptions, we update our study of LEPs for each portfolio segment using our loan charge-off history. After consideration of the historic loss analysis, management applies additional qualitative adjustments so that the allowance for loan losses is reflective of the inherent losses that exist in the loan portfolio at the balance sheet date. Qualitative adjustments are made based upon size, trend, composition, and nature of loans; changes in lending policies and procedures, including underwriting standards and collection, charge-offs and recoveries; trends experienced in nonperforming and delinquent loans; current economic conditions in the Company’s market; portfolio concentrations that may affect loss experience across one of more components of the portfolio; the effect of external factors such as competition, legal and regulatory requirements; and the experience, ability, and depth of lending management and staff. The evaluation of the various components of the allowance for loan losses requires considerable judgment in order to estimate inherent loss exposures. In addition, various regulatory agencies, as an integral component of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to make loan grade changes as well as recognize additions to the allowance based on their examinations. Management believes that the allowance for loan losses is adequate. While management uses available information to recognize loan losses, future additions to the allowance for loan losses may be necessary based on changes in economic conditions or changes in the values of properties securing loans in the process of foreclosure. In addition, various regulatory agencies, as an integral part of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to recognize additions to the allowance for loan losses based on their judgments about information available to them at the time of their examination which may not be currently available to management.
Premises and Equipment	Premises and Equipment Premises and equipment are stated at cost, less accumulated depreciation. Depreciation of premises and equipment is determined using the straight-line method over the estimated useful lives of the respective assets. Expenditures for maintenance, repairs, and minor replacements are charged to expense as incurred.
Other Real Estate Owned	Other Real Estate Owned Other real estate owned ("OREO") consists of properties acquired through foreclosure or by acceptance of a deed in lieu of foreclosure. These assets are recorded at the lower of fair value of the asset acquired less estimated costs to sell or “cost” (defined as the fair value at initial foreclosure). At the time of foreclosure, or when foreclosure occurs in-substance, the excess, if any, of the loan over the fair market value of the assets received, less estimated selling costs, is charged to the allowance for loan losses and any subsequent valuation write-downs are charged to other expense. In connection with the determination of the allowance for loan losses and the valuation of OREO, management obtains appraisals for properties. Operating costs associated with the properties are charged to expense as incurred. Gains on the sale of OREO are included in income when title has passed and the sale has met the minimum down payment requirements prescribed by GAAP. The balance of OREO is recorded in other assets on the consolidated balance sheets.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents the cost of acquired business in excess of the fair value of the related net assets acquired. Goodwill is not amortized but tested at the reporting unit level for impairment on an annual basis and on an interim basis or when events or circumstances dictate. The Company has elected June 30 as the annual impairment testing date for the insurance and retirement services reporting units and December 31 for the Bank reporting unit. The Company has the option to first assess qualitative factors, by performing a step zero qualitative analysis, to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is greater than its carrying amount, the two-step impairment test is not required. If the Company concludes otherwise, the Company is required to perform the first step of the two-step impairment test. In the first step of the goodwill impairment test, the estimated fair value of a reporting unit is compared to the carrying amount in order to determine if impairment is indicated. If the estimated fair value exceeds the carrying amount, the reporting unit is not deemed to be impaired. If the estimated fair value is below the carrying value of the reporting unit, the second step of the goodwill impairment test is required to determine the amount of impairment. The second step of the goodwill impairment test determines the implied fair value of the goodwill that is compared to the carrying value of goodwill for the reporting unit to determine the amount of the impairment. Intangible assets that have indefinite useful lives are not amortized, but are tested at least annually for impairment. Intangible assets that have finite useful lives are amortized over their useful lives. Core deposit intangibles and trust intangibles at the Company are amortized using the sum-of-the-years’-digits method. Covenants not to compete are amortized on a straight-line basis. Customer lists are amortized using an accelerated method. When facts and circumstances indicate potential impairment of amortizable intangible assets, the Company evaluates the recoverability of the asset carrying value, using estimates of undiscounted future cash flows over the remaining asset life. Any impairment loss is measured by the excess of carrying value over fair value. Determining the fair value of a reporting unit under the first step of the goodwill impairment testing and determining the fair value of individual assets and liabilities of a reporting unit under the second step of the goodwill impairment test and in determining the fair value of other intangible assets are judgmental and often involve the use of significant estimates and assumptions. Estimates of fair value are primarily determined using the discounted cash flows method, which uses significant estimates and assumptions including projected future cash flows, discount rates reflecting the market rate of return and projected growth rates. Future events may impact such estimates and assumptions and could cause the Company to conclude that our goodwill or intangible assets have become impaired, which would result in recording an impairment loss.
Bank-Owned Life Insurance	Bank-Owned Life Insurance The Bank has purchased life insurance policies on certain employees, key executives and directors. Bank-owned life insurance is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement.
Treasury Stock	Treasury Stock Treasury stock acquisitions are recorded at cost. Subsequent sales of treasury stock are recorded on an average cost basis. Gains on the sale of treasury stock are credited to additional paid-in-capital. Losses on the sale of treasury stock are charged to additional paid-in-capital to the extent of previous gains, otherwise charged to retained earnings.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred income taxes are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred taxes of a change in tax rates is recognized in income in the period that includes the enactment date. The Company recognizes interest accrued and penalties related to unrecognized tax benefits in income tax expense. Tax positions are recognized as a benefit only if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit that is greater than 50 percent likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded.
Pension Costs	Pension Costs The Company maintains a noncontributory, defined benefit pension plan covering substantially all employees, as well as supplemental employee retirement plans covering certain executives and a defined benefit postretirement healthcare plan that covers certain employees. Costs associated with these plans, based on actuarial computations of current and future benefits for employees, are charged to current operating expenses.
Stock-Based Compensation	Stock-Based Compensation We maintain various long-term incentive stock benefit plans under which we grant stock options, restricted stock awards, and restricted stock units to certain directors and key employees. We recognize compensation expense in our consolidated statements of income over the requisite service period, based on the grant-date fair value of the award. For restricted stock awards and units, we recognize compensation expense ratably over the vesting period for the fair value of the award, measured at the grant date. The fair values of options are estimated using the Black-Scholes option pricing model. The Company’s stock-based employee compensation plan is described in Note 14.
Earnings Per Share	Earnings Per Share Basic earnings per share ("EPS") excludes dilution and is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity (such as the Company’s dilutive stock options and restricted stock).
Comprehensive Income	Comprehensive Income At the Company, comprehensive income represents net income plus other comprehensive income (loss), which consists primarily of the net change in unrealized gains or losses on securities available for sale for the period and changes in the funded status of employee benefit plans. Accumulated other comprehensive (loss) income represents the net unrealized gains or losses on securities available for sale and the previously unrecognized portion of the funded status of employee benefit plans, net of income taxes, as of the consolidated balance sheet dates.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in other comprehensive income. When the cash flows associated with the hedged item are realized, the gain or loss included in other comprehensive income is recognized in the consolidated statements of income. When the Company purchases a portion of a commercial loan that has an existing interest rate swap, it enters a risk participation agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to the Company under a risk participation agreement is in consideration of the credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties.
Fair Value Measurements	Fair Value Measurements Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value measurements are not adjusted for transaction costs. A fair value hierarchy prioritizes the inputs to valuation techniques 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 described below: 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 for similar assets or liabilities in active markets, 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 by little or no market activity). A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The types of instruments valued based on quoted market prices in active markets include most U.S. government and agency securities, many other sovereign government obligations, liquid mortgage products, active listed equities and most money market securities. Such instruments are generally classified within Level 1 or Level 2 of the fair value hierarchy. The Company does not adjust the quoted price for such instruments. The types of instruments valued based on quoted prices in markets that are not active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency include most investment-grade and high-yield corporate bonds, less liquid mortgage products, less liquid agency securities, less liquid listed equities, state, municipal and provincial obligations, and certain physical commodities. Such instruments are generally classified within Level 2 of the fair value hierarchy. Level 3 is for positions that are not traded in active markets or are subject to transfer restrictions, valuations are adjusted to reflect illiquidity and/or non-transferability, and such adjustments are generally based on available market evidence. In the absence of such evidence, management’s best estimate will be used. Management’s best estimate consists of both internal and external support on certain Level 3 investments. Subsequent to inception, management only changes Level 3 inputs and assumptions when corroborated by evidence such as transactions in similar instruments, completed or pending third-party transactions in the underlying investment or comparable entities, subsequent rounds of financing, recapitalizations and other transactions across the capital structure, offerings in the equity or debt markets, and changes in financial ratios or cash flows.
Other Financial Instruments	Other Financial Instruments The Company is a party to certain other financial instruments with off-balance-sheet risk such as commitments to extend credit, unused lines of credit, as well as certain mortgage loans sold to investors with recourse. The Company’s policy is to record such instruments when funded. Standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. Under the standby letters of credit, the Company is required to make payments to the beneficiary of the letters of credit upon request by the beneficiary contingent upon the customer's failure to perform under the terms of the underlying contract with the beneficiary. Standby letters of credit typically have one year expirations with an option to renew upon annual review. The Company typically receives a fee for these transactions. The fair value of stand-by letters of credit is recorded upon inception.
Loan Sales and Loan Servicing	Loan Sales and Loan Servicing Loan sales are recorded when the sales are funded. Mortgage servicing rights are recorded at fair value upon sale of the loan. Loans held for sale are recorded at the lower of cost or market.
Repurchase Agreements	Repurchase Agreements Repurchase agreements are accounted for as secured financing transactions since the Company maintains effective control over the transferred securities and the transfer meets the other criteria for such accounting. Obligations to repurchase securities sold are reflected as a liability in the consolidated balance sheets. The securities underlying the agreements are delivered to a custodial account for the benefit of the dealer or bank with whom each transaction is executed. The dealers or banks, who may sell, loan or otherwise dispose of such securities to other parties in the normal course of their operations, agree to resell to the Company the same securities at the maturities of the agreements.
Trust Operations	Trust Operations Assets held by the Company in a fiduciary or agency capacity for its customers are not included in the accompanying consolidated balance sheets, since such assets are not assets of the Company. Trust income is recognized on the accrual method based on contractual rates applied to the balances of trust accounts.
Reclassification	Reclassifications Amounts in prior period consolidated financial statements are reclassified whenever necessary to confirm with current period presentation.
Subsequent Events	Subsequent Events The Company has evaluated subsequent events for potential recognition and/or disclosure and there were none identified.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

Summary of Significant Accounting Policies [Abstract]

The accompanying consolidated financial statements include the accounts of NBT Bancorp and its wholly-owned subsidiaries mentioned above. All material intercompany transactions have been eliminated in consolidation. Amounts previously reported in the consolidated financial statements are reclassified whenever necessary to conform to the current year’s presentation. In the “Parent Company Financial Information,” the investment in subsidiaries is recorded using the equity method of accounting.

The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting interest entity or a variable interest entity under GAAP. Voting interest entities are entities in which the total equity investment at risk is sufficient to enable the entity to finance itself independently and provides the equity holders with the obligation to absorb losses, the right to receive residual returns and the right to make decisions about the entity’s activities. The Company consolidates voting interest entities in which it has all, or at least a majority of, the voting interest. As defined in applicable accounting standards, variable interest entities (“VIEs”) are entities that lack one or more of the characteristics of a voting interest entity. A controlling financial interest in a VIE is present when the Company has both the power and ability to direct the activities of the VIE that most significantly impact the VIE's economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The Company’s wholly-owned subsidiaries CNBF Capital Trust I, NBT Statutory Trust I, NBT Statutory Trust II, Alliance Financial Capital Trust I and Alliance Financial Capital Trust II are VIEs for which the Company is not the primary beneficiary. Accordingly, the accounts of these entities are not included in the Company’s consolidated financial statements.

Segment Reporting

The Company’s operations are primarily in the community banking industry and include the provision of traditional banking services. The Company also provides other services through its subsidiaries such as insurance, retirement plan administration, and trust administration. The Company operates solely in the geographical regions of central and upstate New York, northeastern Pennsylvania, western Massachusetts, southern New Hampshire, Vermont, and the greater Portland, Maine area. The Company has no reportable operating segments.

Cash Equivalents

The Company considers amounts due from correspondent banks, cash items in process of collection, and institutional money market mutual funds to be cash equivalents for purposes of the consolidated statements of cash flows.

Securities

The Company classifies its securities at date of purchase as either held to maturity ("HTM"), trading or available for sale ("AFS"). HTM debt securities are those that the Company has the ability and intent to hold until maturity. Trading securities are securities purchased with the intent to sell within a short period of time. AFS securities are securities that are not classified as a HTM or trading securities. AFS securities are recorded at fair value. Unrealized holding gains and losses, net of the related tax effect, on AFS securities are excluded from earnings and are reported in the consolidated statements of stockholders’ equity and the consolidated statements of comprehensive income as a component of accumulated other comprehensive income or loss. HTM securities are recorded at amortized cost. Trading securities are recorded at fair value, with net unrealized gains and losses recognized in income. Transfers of securities between categories are recorded at fair value at the date of transfer. Declines in the fair value of HTM and AFS securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses or in other comprehensive income, depending on whether the Company intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If the Company intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If the Company does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the total OTTI impairment related to the credit loss shall be recognized in earnings. The amount of the total OTTI related to other factors shall be recognized in other comprehensive income, net of applicable taxes.

In estimating OTTI losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) the historical and implied volatility of the fair value of the security.

Non-marketable equity securities are carried at cost.

Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the interest method. Dividend and interest income are recognized when earned. Realized gains and losses on securities sold are derived using the specific identification method for determining the cost of securities sold.

Investments in Federal Reserve Bank (“FRB”) and Federal Home Loan Bank (“FHLB”) stock are required for membership in those organizations and are carried at cost since there is no market value available. The FHLB New York continues to pay dividends and repurchase stock. As such, the Company has not recognized any impairment on its holdings of FHLB stock.

Loans

Loans are recorded at their current unpaid principal balance, net of unearned income and unamortized loan fees and expenses, which are amortized under the effective interest method over the estimated lives of the loans. Interest income on loans is accrued based on the principal amount outstanding.

For all loan classes within the Company’s loan portfolio, loans are placed on nonaccrual status when timely collection of principal and interest in accordance with contractual terms is doubtful. Loans are transferred to nonaccrual status generally when principal or interest payments become ninety days delinquent, unless the loan is well-secured and in the process of collection, or sooner when management concludes circumstances indicate that borrowers may be unable to meet contractual principal or interest payments. When a loan is transferred to a nonaccrual status, all interest previously accrued in the current period but not collected is reversed against interest income in that period. Interest accrued in a prior period and not collected is charged-off against the allowance for loan losses.

If ultimate repayment of a nonaccrual loan is expected, any payments received are applied in accordance with contractual terms. If ultimate repayment of principal is not expected, any payment received on a nonaccrual loan is applied to principal until ultimate repayment becomes expected. For all loan classes within the Company’s loan portfolio, nonaccrual loans are returned to accrual status when they become current as to principal and interest and demonstrate a period of performance under the contractual terms and, in the opinion of management, are fully collectible as to principal and interest. For loans in all portfolios, the principal amount is charged off in full or in part as soon as management determines, based on available facts, that the collection of principal in full is improbable. For commercial loans, management considers specific facts and circumstances relative to individual credits in making such a determination. For consumer and residential loan classes, management uses specific guidance and thresholds from the Federal Financial Institutions Examination Council’s Uniform Retail Credit Classification and Account Management Policy.

Commercial type loans are considered impaired when it is probable that the borrower will not repay the loan according to the original contractual terms of the loan agreement, and all loan types are considered impaired if the loan is restructured in a troubled debt restructuring (“TDR”). In determining that we will be unable to collect all principal and interest payments due in accordance with the contractual terms of the loan agreements, we consider factors such as payment history and changes in the financial condition of individual borrowers, local economic conditions, historical loss experience and the conditions of the various markets in which the collateral may be liquidated.

A loan is considered to be a TDR when the Company grants a concession to the borrower because of the borrower’s financial condition that the Company would not otherwise consider. Such concessions include the reduction of interest rates, forgiveness of all or a portion of principal or interest, or other modifications at interest rates that are less than the current market rate for new obligations with similar risk. TDR loans are nonaccrual loans; however, they can be returned to accrual status after a period of performance, generally evidenced by six months of compliance with their modified terms.

When the Company modifies a loan, management evaluates any possible impairment based on the present value of the expected future cash flows, discounted at the contractual interest rate of the original loan agreement, except when the sole (remaining) source of repayment for the loan is the operation or liquidation of the collateral. In these cases, management uses the current fair value of the collateral, less selling costs, instead of discounted cash flows. If management determines that the value of the modified loan is less than the recorded investment in the loan (net of previous charge-offs, deferred loan fees or costs and unamortized premium or discount), impairment is recognized.

Acquired Loans

Acquired loans are initially measured at fair value as of the acquisition date without carryover of historical allowance for loan losses.

For loans that meet the criteria stipulated in ASC 310-30 - Receivables - Loans and Debt Securities Acquired with Deteriorated Credit Quality, the Company shall recognize the accretable yield, which is defined as the excess of all cash flows expected at acquisition over the initial fair value of the loan, as interest income on a level-yield basis over the expected remaining life of the loan. The excess of the loan's contractually required payments over the cash flows expected to be collected is the nonaccretable difference. The nonaccretable difference shall not be recognized as an adjustment of yield, a loss accrual, or a valuation allowance. Decreases in the expected cash flows in subsequent periods require the establishment of an allowance for loan losses. Improvements in expected cash flows in future periods result in a reduction of the nonaccretable discount, with such amount reclassified as part of the accretable yield and subsequently recognized in interest income over the remaining lives of the acquired loans on a level-yield basis if the amount and timing of future cash flows is reasonably estimable.

Acquired loans that met the criteria for nonaccrual of interest prior to the acquisition are considered performing upon acquisition, regardless of whether the customer is contractually delinquent, if the Company can reasonably estimate the timing and amount of the expected cash flows on such loans and if the Company expects to fully collect the new carrying value of the loans. As such, the Company may no longer consider the loan to be nonaccrual or nonperforming and may accrue interest on these loans, including the impact of any accretable yield. As such, charge-offs on acquired loans are first applied to the nonaccretable difference and then to any allowance for loan losses recognized subsequent to acquisition.

For loans that meet the criteria stipulated in ASC 310-20 - Receivables - Nonrefundable Fees and Other Costs ("ASC 310-20"), the Company shall amortize/accrete into interest income the premium/discount determined at the date of purchase on a level-yield basis over the life of the loan. Subsequent to the acquisition date, the methods utilized to estimate the required allowance for loan losses are similar to originated loans. Loans accounted for under ASC 310-20 are placed on nonaccrual status when past due in accordance with the Company's nonaccrual policy.

An acquired loan may be resolved either through receipt of payment (in full or in part) from the borrower, the sale of the loan to a third party, or foreclosure of the collateral. In the event of a sale of the loan, a gain or loss on sale is recognized and reported within noninterest income based on the difference between the sales proceeds and the carrying amount of the loan. In other cases, individual loans are removed from the pool based on comparing the amount received from its resolution (fair value of the underlying collateral less costs to sell in the case of a foreclosure) with its outstanding balance. Any difference between these amounts is recorded as a charge-off through the allowance for loan losses. Acquired loans subject to modification are not removed from the pool even if those loans would otherwise be deemed TDRs as the pool, and not the individual loan, represents the unit of account.

Allowance for Loan Losses

The allowance for loan losses is the amount which, in the opinion of management, is necessary to absorb probable losses inherent in the loan portfolio. The allowance is determined based upon numerous considerations, including local and regional conditions, the growth and composition of the loan portfolio with respect to the mix between the various types of loans and their related risk characteristics, a review of the value of collateral supporting the loans, comprehensive reviews of the loan portfolio by the independent loan review staff and management, as well as consideration of volume and trends of delinquencies, nonperforming loans, and loan charge-offs. Loan losses are charged off against the allowance, while recoveries of amounts previously charged off are credited to the allowance. As a result of tests of adequacy, required additions to the allowance for loan losses are made periodically by charges to the provision for loan losses.

The allowance for loan losses related to impaired loans specifically allocated for impairment is based on discounted expected cash flows using the loan’s initial effective interest rate or the fair value of the collateral for certain loans where repayment of the loan is expected to be provided solely by the underlying collateral ("collateral dependent"). The Company’s impaired loans are generally collateral dependent. The Company considers the estimated cost to sell, on a discounted basis, when determining the fair value of collateral in the measurement of impairment if those costs are expected to reduce the cash flows available to repay or otherwise satisfy the loans.

The allowance for loan losses for homogeneous non impaired loans is calculated using a systematic methodology with both a quantitative and a qualitative analysis that is applied on a quarterly basis. For purposes of our allowance methodology, the loan portfolio is segmented as described in Note 5. Each segment has a distinct set of risk characteristics monitored by management. We further assess and monitor risk and performance at a more disaggregated level which includes our internal risk grading system for the commercial segments.

We first apply historical loss rates to pools of loans with similar risk characteristics. Loss rates are calculated by historical charge-offs that have occurred within each pool of loans over the lookback period ("LBP"), multiplied by the loss emergence period ("LEP"). The LBP represents the historical data period utilized to calculate loss rates. The LEP is an estimate of the average amount of time from the point at which a loss is incurred on a loan to the point at which the loss is confirmed. In general, the LEP will be shorter in an economic slowdown or recession and longer during times of economic stability or growth, as customers are better able to delay loss confirmation after a potential loss event has occurred. In conjunction with our annual review of the ALL assumptions, we update our study of LEPs for each portfolio segment using our loan charge-off history.

After consideration of the historic loss analysis, management applies additional qualitative adjustments so that the allowance for loan losses is reflective of the inherent losses that exist in the loan portfolio at the balance sheet date. Qualitative adjustments are made based upon size, trend, composition, and nature of loans; changes in lending policies and procedures, including underwriting standards and collection, charge-offs and recoveries; trends experienced in nonperforming and delinquent loans; current economic conditions in the Company’s market; portfolio concentrations that may affect loss experience across one of more components of the portfolio; the effect of external factors such as competition, legal and regulatory requirements; and the experience, ability, and depth of lending management and staff. The evaluation of the various components of the allowance for loan losses requires considerable judgment in order to estimate inherent loss exposures. In addition, various regulatory agencies, as an integral component of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to make loan grade changes as well as recognize additions to the allowance based on their examinations.

Management believes that the allowance for loan losses is adequate. While management uses available information to recognize loan losses, future additions to the allowance for loan losses may be necessary based on changes in economic conditions or changes in the values of properties securing loans in the process of foreclosure. In addition, various regulatory agencies, as an integral part of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to recognize additions to the allowance for loan losses based on their judgments about information available to them at the time of their examination which may not be currently available to management.

Premises and Equipment

Premises and equipment are stated at cost, less accumulated depreciation. Depreciation of premises and equipment is determined using the straight-line method over the estimated useful lives of the respective assets. Expenditures for maintenance, repairs, and minor replacements are charged to expense as incurred.

Other Real Estate Owned

Other real estate owned ("OREO") consists of properties acquired through foreclosure or by acceptance of a deed in lieu of foreclosure. These assets are recorded at the lower of fair value of the asset acquired less estimated costs to sell or “cost” (defined as the fair value at initial foreclosure). At the time of foreclosure, or when foreclosure occurs in-substance, the excess, if any, of the loan over the fair market value of the assets received, less estimated selling costs, is charged to the allowance for loan losses and any subsequent valuation write-downs are charged to other expense. In connection with the determination of the allowance for loan losses and the valuation of OREO, management obtains appraisals for properties. Operating costs associated with the properties are charged to expense as incurred. Gains on the sale of OREO are included in income when title has passed and the sale has met the minimum down payment requirements prescribed by GAAP. The balance of OREO is recorded in other assets on the consolidated balance sheets.

Goodwill and Other Intangible Assets

Goodwill represents the cost of acquired business in excess of the fair value of the related net assets acquired. Goodwill is not amortized but tested at the reporting unit level for impairment on an annual basis and on an interim basis or when events or circumstances dictate. The Company has elected June 30 as the annual impairment testing date for the insurance and retirement services reporting units and December 31 for the Bank reporting unit.

The Company has the option to first assess qualitative factors, by performing a step zero qualitative analysis, to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is greater than its carrying amount, the two-step impairment test is not required. If the Company concludes otherwise, the Company is required to perform the first step of the two-step impairment test. In the first step of the goodwill impairment test, the estimated fair value of a reporting unit is compared to the carrying amount in order to determine if impairment is indicated. If the estimated fair value exceeds the carrying amount, the reporting unit is not deemed to be impaired. If the estimated fair value is below the carrying value of the reporting unit, the second step of the goodwill impairment test is required to determine the amount of impairment. The second step of the goodwill impairment test determines the implied fair value of the goodwill that is compared to the carrying value of goodwill for the reporting unit to determine the amount of the impairment.

Intangible assets that have indefinite useful lives are not amortized, but are tested at least annually for impairment. Intangible assets that have finite useful lives are amortized over their useful lives. Core deposit intangibles and trust intangibles at the Company are amortized using the sum-of-the-years’-digits method. Covenants not to compete are amortized on a straight-line basis. Customer lists are amortized using an accelerated method. When facts and circumstances indicate potential impairment of amortizable intangible assets, the Company evaluates the recoverability of the asset carrying value, using estimates of undiscounted future cash flows over the remaining asset life. Any impairment loss is measured by the excess of carrying value over fair value.

Determining the fair value of a reporting unit under the first step of the goodwill impairment testing and determining the fair value of individual assets and liabilities of a reporting unit under the second step of the goodwill impairment test and in determining the fair value of other intangible assets are judgmental and often involve the use of significant estimates and assumptions. Estimates of fair value are primarily determined using the discounted cash flows method, which uses significant estimates and assumptions including projected future cash flows, discount rates reflecting the market rate of return and projected growth rates. Future events may impact such estimates and assumptions and could cause the Company to conclude that our goodwill or intangible assets have become impaired, which would result in recording an impairment loss.

Bank-Owned Life Insurance

The Bank has purchased life insurance policies on certain employees, key executives and directors. Bank-owned life insurance is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement.

Treasury Stock

Treasury stock acquisitions are recorded at cost. Subsequent sales of treasury stock are recorded on an average cost basis. Gains on the sale of treasury stock are credited to additional paid-in-capital. Losses on the sale of treasury stock are charged to additional paid-in-capital to the extent of previous gains, otherwise charged to retained earnings.

Income Taxes

Income taxes are accounted for under the asset and liability method. Deferred income taxes are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred taxes of a change in tax rates is recognized in income in the period that includes the enactment date. The Company recognizes interest accrued and penalties related to unrecognized tax benefits in income tax expense.

Tax positions are recognized as a benefit only if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit that is greater than 50 percent likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded.

Pension Costs

The Company maintains a noncontributory, defined benefit pension plan covering substantially all employees, as well as supplemental employee retirement plans covering certain executives and a defined benefit postretirement healthcare plan that covers certain employees. Costs associated with these plans, based on actuarial computations of current and future benefits for employees, are charged to current operating expenses.

Stock-Based Compensation

We maintain various long-term incentive stock benefit plans under which we grant stock options, restricted stock awards, and restricted stock units to certain directors and key employees. We recognize compensation expense in our consolidated statements of income over the requisite service period, based on the grant-date fair value of the award. For restricted stock awards and units, we recognize compensation expense ratably over the vesting period for the fair value of the award, measured at the grant date. The fair values of options are estimated using the Black-Scholes option pricing model.

The Company’s stock-based employee compensation plan is described in Note 14.

Earnings Per Share

Basic earnings per share ("EPS") excludes dilution and is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity (such as the Company’s dilutive stock options and restricted stock).

Comprehensive Income

At the Company, comprehensive income represents net income plus other comprehensive income (loss), which consists primarily of the net change in unrealized gains or losses on securities available for sale for the period and changes in the funded status of employee benefit plans. Accumulated other comprehensive (loss) income represents the net unrealized gains or losses on securities available for sale and the previously unrecognized portion of the funded status of employee benefit plans, net of income taxes, as of the consolidated balance sheet dates.

Derivative Instruments and Hedging Activities

The Company records all derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk, even though hedge accounting does not apply or the Company elects not to apply hedge accounting.

For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in other comprehensive income. When the cash flows associated with the hedged item are realized, the gain or loss included in other comprehensive income is recognized in the consolidated statements of income.

When the Company purchases a portion of a commercial loan that has an existing interest rate swap, it enters a risk participation agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to the Company under a risk participation agreement is in consideration of the credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties.

Fair Value Measurements

Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value measurements are not adjusted for transaction costs. A fair value hierarchy prioritizes the inputs to valuation techniques 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 described below:

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 for similar assets or liabilities in active markets, 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 by little or no market activity).

A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement.

The types of instruments valued based on quoted market prices in active markets include most U.S. government and agency securities, many other sovereign government obligations, liquid mortgage products, active listed equities and most money market securities. Such instruments are generally classified within Level 1 or Level 2 of the fair value hierarchy. The Company does not adjust the quoted price for such instruments.

The types of instruments valued based on quoted prices in markets that are not active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency include most investment-grade and high-yield corporate bonds, less liquid mortgage products, less liquid agency securities, less liquid listed equities, state, municipal and provincial obligations, and certain physical commodities. Such instruments are generally classified within Level 2 of the fair value hierarchy.

Level 3 is for positions that are not traded in active markets or are subject to transfer restrictions, valuations are adjusted to reflect illiquidity and/or non-transferability, and such adjustments are generally based on available market evidence. In the absence of such evidence, management’s best estimate will be used. Management’s best estimate consists of both internal and external support on certain Level 3 investments. Subsequent to inception, management only changes Level 3 inputs and assumptions when corroborated by evidence such as transactions in similar instruments, completed or pending third-party transactions in the underlying investment or comparable entities, subsequent rounds of financing, recapitalizations and other transactions across the capital structure, offerings in the equity or debt markets, and changes in financial ratios or cash flows.

Other Financial Instruments

The Company is a party to certain other financial instruments with off-balance-sheet risk such as commitments to extend credit, unused lines of credit, as well as certain mortgage loans sold to investors with recourse. The Company’s policy is to record such instruments when funded.

Standby letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. Under the standby letters of credit, the Company is required to make payments to the beneficiary of the letters of credit upon request by the beneficiary contingent upon the customer's failure to perform under the terms of the underlying contract with the beneficiary. Standby letters of credit typically have one year expirations with an option to renew upon annual review. The Company typically receives a fee for these transactions. The fair value of stand-by letters of credit is recorded upon inception.

Loan Sales and Loan Servicing

Loan sales are recorded when the sales are funded. Mortgage servicing rights are recorded at fair value upon sale of the loan. Loans held for sale are recorded at the lower of cost or market.

Repurchase Agreements

Repurchase agreements are accounted for as secured financing transactions since the Company maintains effective control over the transferred securities and the transfer meets the other criteria for such accounting. Obligations to repurchase securities sold are reflected as a liability in the consolidated balance sheets. The securities underlying the agreements are delivered to a custodial account for the benefit of the dealer or bank with whom each transaction is executed. The dealers or banks, who may sell, loan or otherwise dispose of such securities to other parties in the normal course of their operations, agree to resell to the Company the same securities at the maturities of the agreements.

Trust Operations

Assets held by the Company in a fiduciary or agency capacity for its customers are not included in the accompanying consolidated balance sheets, since such assets are not assets of the Company. Trust income is recognized on the accrual method based on contractual rates applied to the balances of trust accounts.

Reclassification

Reclassifications

Amounts in prior period consolidated financial statements are reclassified whenever necessary to confirm with current period presentation.

Subsequent Events

The Company has evaluated subsequent events for potential recognition and/or disclosure and there were none identified.