b"temporary impairment losses on debt securities, which are recognized in other comprehensive income.In estimating other-than-temporary impairment losses, management considers (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, and (3) the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value.Realized gains and losses from the sales of securities are determined using the specific identification method.Impaired loans: Impaired loans are defined as those loans for which it is probable that contractual amounts due will not be received in accordance with the contractual terms.The measurement of impaired loans is based on the present value of expected future cash flows discounted at the historical effective interest rate, except that all collateral-dependent loans are measured for impairment based on the fair value of the collateral.Larger groups of small-balance loans such as residential mortgage and installment loans that are considered to be part of homogeneous loan pools are aggregated for the purpose of measuring impairment, and therefore, are not subject to these statements unless they are considered troubled debt restructuring (TDR).Commercial loans and commercial real estate loans that are risk rated substandard, doubtful or loss with a current balance greater than the average loan balance for that call report code are evaluated for impairment.Also, troubled debt restructurings and loans in process of foreclosure, not included in the criteria above, are evaluated individually for impairment. At December 31, 2019, there are twenty loans considered to be impaired with a current balance of $2.6 million.At December 31, 2018, there were twenty-two loans considered to be impaired with a current balance of $3.3 million.See Note 4: Loans and Leases Receivable in the Notes to Consolidated Financial Statements for additional discussion.Allowance for Loan Losses: The allowance for loan losses is maintained at a level which, in management's judgment, is adequate to absorb credit losses inherent in the loan portfolio.The amount of the allowance is based on management's evaluation of the collectability of the loan portfolio, including the nature of the portfolio, credit concentrations, trends in historical loss experience, specific impaired loans and current economic conditions.Allowances for loan losses on impaired loans are generally determined based on collateral values or the present value of estimated cash flows.The allowance is increased by a provision for loan losses, which is charged to expense and reduced by partial or complete charge-offs, net of recoveries.Changes in the allowance are charged or credited to the provision for loan losses.Because of uncertainties inherent in the estimation process, management's estimate of credit losses inherent in the loan portfolio and the related allowance may change in the near term.Loans Held for Sale: Mortgage loans held for sale are recorded at the lower of cost or market value.Gains and losses realized from the sale of loans and adjustments to market value are included in non-interest income.Mortgage loans are sometimes sold to secondary market investors and other commercial banks.Since 2007, the majority of residential mortgage loans with a fixed rate of fifteen years or longer have been sold to secondary market investors with servicing released.At December 31, 2019 and 2018, the Bank had no loans held for sale. Loan Servicing: The cost of mortgage servicing rights is amortized in proportion to, and over the period of, estimated net servicing revenues.Impairment of mortgage servicing rights is assessed based on the fair value of those rights.Fair values are estimated using discounted cash flows based on a current market interest rate.For purposes of measuring impairment, the rights are stratified based on the predominant risk characteristics of the underlying loans: product type, investor type, interest rate, term and geographic location.An analysis of the risk characteristics of CNBs loan servicing portfolio allows for all loans to be defined by one risk category. As of December 31, 2019 and 2018, there were no mortgage servicing assets or liabilities.See Note 5: Loan Servicing in the Notes to Consolidated Financial Statements for additional discussion.Interest Income on Loans: Interest on loans is accrued and credited to income based on the principal amount outstanding.The accrual of interest on loans is discontinued at the time the loan becomes 90 days past due unless in managements judgment collectability of interest is assured. 7"