Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation TriCo Bancshares (the “Company” or “we”) is a California corporation organized to act as a bank holding company for Tri Counties Bank (the “Bank”). The Company and the Bank are headquartered in Chico, California. The Bank is a California-chartered bank that is engaged in the general commercial banking business in 26 California counties. The Bank operates from 57 traditional branches, 9 in-store branches and 2 loan production offices. The Company has five capital subsidiary business trusts (collectively, the “Capital Trusts”) that issued trust preferred securities, including two organized by TriCo and three acquired with the acquisition of North Valley Bancorp. See Note 17 – Junior Subordinated Debt. The consolidated financial statements are prepared in accordance with accounting policies generally accepted in the United States of America and general practices in the banking industry. The financial statements include the accounts of the Company. All inter-company accounts and transactions have been eliminated in consolidation. For financial reporting purposes, the Company’s investments in the Capital Trusts of $1,721,000 are accounted for under the equity method and, accordingly, are not consolidated and are included in other assets on the consolidated balance sheet. The subordinated debentures issued and guaranteed by the Company and held by the Capital Trusts are reflected as debt on the Company’s consolidated balance sheet.
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires Management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.
Significant Group Concentration of Credit Risk	Significant Group Concentration of Credit Risk The Company grants agribusiness, commercial, consumer, and residential loans to customers located throughout the northern San Joaquin Valley, the Sacramento Valley and northern mountain regions of California. The Company has a diversified loan portfolio within the business segments located in this geographical area. Management has determined that because all of the banking products and services offered by the Company are available in each branch of the Bank, all branches are located within the same economic environment and management does not allocate resources based on the performance of different lending or transaction activities, it is appropriate to aggregate the Bank branches and report them as a single operating segment.
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, amounts due from banks, and federal funds sold. Net cash flows are reported for loan and deposit transactions and other borrowings.
Investment Securities	Investment Securities The Company classifies its debt and marketable equity securities into one of three categories: trading, available for sale or held to maturity. Trading securities are bought and held principally for the purpose of selling in the near term. Held to maturity securities are those securities which the Company has the ability and intent to hold until maturity. These securities are carried at cost adjusted for amortization of premium and accretion of discount, computed by the effective interest method over their contractual lives. All other securities not included in trading or held to maturity are classified as available for sale. Available for sale securities are recorded at fair value. Unrealized gains and losses, net of the related tax effect, on available for sale securities are reported as a separate component of other accumulated comprehensive income in shareholders’ equity until realized. Premiums and discounts are amortized or accreted over the life of the related investment security as an adjustment to yield using the effective interest method. Dividend and interest income are recognized when earned. Realized gains and losses are derived from the amortized cost of the security sold using the specific identification method. During the year ended December 31, 2017, the Company sold $24,796,000 of available for sale classified investment securities for $25,757,000 realizing a gain of $961,000. During the year ended December 31, 2016, the Company did not sell any investment securities. At December 31, 2017 and 2016, the Company did not have any securities classified as trading. The Company assesses other-than-temporary impairment (“OTTI”) based on whether it intends to sell a security or if it is likely that the Company would be required to sell the security before recovery of the amortized cost basis of the investment, which may be maturity. For debt securities, if we intend to sell the security or it is more likely than not that we will be required to sell the security before recovering its cost basis, the entire impairment loss would be recognized in earnings as an OTTI. If we do not intend to sell the security and it is not likely that we will be required to sell the security but we do not expect to recover the entire amortized cost basis of the security, only the portion of the impairment loss representing credit losses would be recognized in earnings. The credit loss on a security is measured as the difference between the amortized cost basis and the present value of the cash flows expected to be collected. Projected cash flows are discounted by the original or current effective interest rate depending on the nature of the security being measured for potential OTTI. The remaining impairment related to all other factors, the difference between the present value of the cash flows expected to be collected and fair value, is recognized as a charge to other comprehensive income (“OCI”). Impairment losses related to all other factors are presented as separate categories within OCI. The accretion of the amount recorded in OCI increases the carrying value of the investment and does not affect earnings. If there is an indication of additional credit losses the security is re-evaluated according to the procedures described above. No OTTI losses were recognized during the years ended December 31, 2017, 2016, and 2015.
Restricted Equity Securities	Restricted Equity Securities Restricted equity securities represent the Company’s investment in the stock of the Federal Home Loan Bank of San Francisco (“FHLB”) and are carried at par value, which reasonably approximates its fair value. While technically these are considered equity securities, there is no market for the FHLB stock. Therefore, the shares are considered as restricted investment securities. Management periodically evaluates FHLB stock for other-than-temporary impairment. Management’s determination of whether these investments are impaired is based on its assessment of the ultimate recoverability of cost rather than by recognizing temporary declines in value. The determination of whether a decline affects the ultimate recoverability of cost is influenced by criteria such as (1) the significance of any decline in net assets of the FHLB as compared to the capital stock amount for the FHLB and the length of time this situation has persisted, (2) commitments by the FHLB to make payments required by law or regulation and the level of such payments in relation to the operating performance of the FHLB, (3) the impact of legislative and regulatory changes on institutions and, accordingly, the customer base of the FHLB, and (4) the liquidity position of the FHLB. As a member of the FHLB system, the Bank is required to maintain a minimum level of investment in FHLB stock based on specific percentages of its outstanding mortgages, total assets, or FHLB advances. The Bank may request redemption at par value of any stock in excess of the minimum required investment. Stock redemptions are at the discretion of the FHLB.
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 of current investor yield requirements. Net unrealized losses are recognized through a valuation allowance by charges to noninterest income. Mortgage loans held for sale are generally sold with the mortgage servicing rights retained by the Company. Gains or losses on the sale of loans that are held for sale are recognized at the time of the sale and determined by the difference between net sale proceeds and the net book value of the loans less the estimated fair value of any retained mortgage servicing rights.
Loans and Allowance for Loan Losses	Loans and Allowance for Loan Losses Loans originated by the Company, i.e., not purchased or acquired in a business combination, are referred to as originated loans. Originated loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal amount outstanding, net of deferred loan fees and costs. Loan origination and commitment fees and certain direct loan origination costs are deferred, and the net amount is amortized as an adjustment of the related loan’s yield over the actual life of the loan. Originated loans on which the accrual of interest has been discontinued are designated as nonaccrual loans. Originated loans are placed in nonaccrual status when reasonable doubt exists as to the full, timely collection of interest or principal, or a loan becomes contractually past due by 90 days or more with respect to interest or principal and is not well secured and in the process of collection. When an originated loan is placed on nonaccrual status, all interest previously accrued but not collected is reversed. Income on such loans is then recognized only to the extent that cash is received and where the future collection of principal is probable. Interest accruals are resumed on such loans only when they are brought fully current with respect to interest and principal and when, in the judgment of Management, the loan is estimated to be fully collectible as to both principal and interest. An allowance for loan losses for originated loans is established through a provision for loan losses charged to expense. The allowance is maintained at a level which, in Management’s judgment, is adequate to absorb probable incurred credit losses inherent in the loan portfolio as of the balance sheet date. Originated loans and deposit related overdrafts are charged against the allowance for loan losses when Management believes that the collectability of the principal is unlikely or, with respect to consumer installment loans, according to an established delinquency schedule. The allowance is an amount that Management believes will be adequate to absorb probable incurred losses inherent in existing loans, based on evaluations of the collectability, impairment and prior loss experience of loans. The evaluations take into consideration such factors as changes in the nature and size of the portfolio, overall portfolio quality, loan concentrations, specific problem loans, and current economic conditions that may affect the borrower’s ability to pay. The Company defines an originated loan as impaired when it is probable the Company will be unable to collect all amounts due according to the original contractual terms of the loan agreement. Impaired originated loans are measured based on the present value of expected future cash flows discounted at the loan’s original effective interest rate. As a practical expedient, impairment may be measured based on the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. When the measure of the impaired loan is less than the recorded investment in the loan, the impairment is recorded through a specific reserve allocation within the allowance for loan losses. In situations related to originated loans where, for economic or legal reasons related to a borrower’s financial difficulties, the Company grants a concession for other than an insignificant period of time to the borrower that the Company would not otherwise consider, the related loan is classified as a troubled debt restructuring (TDR). The Company strives to identify borrowers in financial difficulty early and work with them to modify to more affordable terms before their loan reaches nonaccrual status. These modified terms may include rate reductions, principal forgiveness, payment forbearance and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of the collateral. In cases where the Company grants the borrower new terms that result in the loan being classified as a TDR, the Company measures any impairment on the restructuring as noted above for impaired loans. TDR loans are classified as impaired until they are fully paid off or charged off. Loans that are in nonaccrual status at the time they become TDR loans, remain in nonaccrual status until the borrower demonstrates a sustained period of performance which the Company generally believes to be six consecutive months of payments, or equivalent. Otherwise, TDR loans are subject to the same nonaccrual and charge-off policies as noted above with respect to their restructured principal balance. Credit risk is inherent in the business of lending. As a result, the Company maintains an allowance for loan losses to absorb probable incurred losses inherent in the Company’s originated loan portfolio. This is maintained through periodic charges to earnings. These charges are included in the Consolidated Statements of Income as provision for loan losses. All specifically identifiable and quantifiable losses are immediately charged off against the allowance. However, for a variety of reasons, not all losses are immediately known to the Company and, of those that are known, the full extent of the loss may not be quantifiable at that point in time. The balance of the Company’s allowance for originated loan losses is meant to be an estimate of these probable incurred losses inherent in the portfolio. The Company formally assesses the adequacy of the allowance for originated loan losses on a quarterly basis. Determination of the adequacy is based on ongoing assessments of the probable risk in the outstanding originated loan portfolio, and to a lesser extent the Company’s originated loan commitments. These assessments include the periodic re-grading of credits based on changes in their individual credit characteristics including delinquency, seasoning, recent financial performance of the borrower, economic factors, changes in the interest rate environment, growth of the portfolio as a whole or by segment, and other factors as warranted. Loans are initially graded when originated. They are re-graded as they are renewed, when there is a new loan to the same borrower, when identified facts demonstrate heightened risk of nonpayment, or if they become delinquent. Re-grading of larger problem loans occurs at least quarterly. Confirmation of the quality of the grading process is obtained by independent credit reviews conducted by consultants specifically hired for this purpose and by various bank regulatory agencies. The Company’s method for assessing the appropriateness of the allowance for originated loan losses includes specific allowances for impaired originated loans, formula allowance factors for pools of credits, and allowances for changing environmental factors (e.g., interest rates, growth, economic conditions, etc.). Allowance factors for loan pools were based on historical loss experience by product type and prior risk rating. Loans purchased or acquired in a business combination are referred to as acquired loans. Acquired loans are valued as of the acquisition date in accordance with Financial Accounting Standards Board Accounting Standards Codification (“FASB ASC”) Topic 805, Business Combinations. Loans acquired with evidence of credit deterioration since origination for which it is probable that all contractually required payments will not be collected are referred to as purchased credit impaired (PCI) loans. PCI loans are accounted for under FASB ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality. Under FASB ASC Topic 805 and FASB ASC Topic 310-30, PCI loans are recorded at fair value at acquisition date, factoring in credit losses expected to be incurred over the life of the loan. Accordingly, an allowance for loan losses is not carried over or recorded as of the acquisition date. Fair value is defined as the present value of the future estimated principal and interest payments of the loan, with the discount rate used in the present value calculation representing the estimated effective yield of the loan. Default rates, loss severity, and prepayment speed assumptions are periodically reassessed and our estimate of future payments is adjusted accordingly. The difference between contractual future payments and estimated future payments is referred to as the nonaccretable difference. The difference between estimated future payments and the present value of the estimated future payments is referred to as the accretable yield. The accretable yield represents the amount that is expected to be recorded as interest income over the remaining life of the loan. If after acquisition, the Company determines that the estimated future cash flows of a PCI loan are expected to be more than originally estimated, an increase in the discount rate (effective yield) would be made such that the newly increased accretable yield would be recognized, on a level yield basis, over the remaining estimated life of the loan. If, thereafter, the Company determines that the estimated future cash flows of a PCI loan are expected to be less than previously estimated, an allowance for loan loss would be established through a provision for loan losses charged to expense to decrease the present value to the required level. If the estimated cash flows improve after an allowance has been established for a loan, the allowance may be partially or fully reversed depending on the improvement in the estimated cash flows. Only after the allowance has been fully reversed may the discount rate be increased. PCI loans are put on nonaccrual status when cash flows cannot be reasonably estimated. PCI loans on nonaccrual status are accounted for using the cost recovery method or cash basis method of income recognition. The Company refers to PCI loans on nonaccrual status that are accounted for using the cash basis method of income recognition as “PCI – cash basis” loans; and the Company refers to all other PCI loans as “PCI – other” loans PCI loans are charged off when evidence suggests cash flows are not recoverable. Foreclosed assets from PCI loans are recorded in foreclosed assets at fair value with the fair value at time of foreclosure representing cash flow from the loan. ASC 310-30 allows PCI loans with similar risk characteristics and acquisition time frame to be “pooled” and have their cash flows aggregated as if they were one loan. The Company elected to use the “pooled” method of ASC 310-30 for PCI – other loans in the acquisition of certain assets and liabilities of Granite Community Bank, N.A. (“Granite”) during 2010 and Citizens Bank of Northern California (“Citizens”) during 2011. Acquired loans that are not PCI loans are referred to as purchased not credit impaired (PNCI) loans. PNCI loans are accounted for under FASB ASC Topic 310-20, Receivables – Nonrefundable Fees and Other Costs, in which interest income is accrued on a level-yield basis for performing loans. For income recognition purposes, this method assumes that all contractual cash flows will be collected, and no allowance for loan losses is established at the time of acquisition. Post-acquisition date, an allowance for loan losses may need to be established for acquired loans through a provision charged to earnings for credit losses incurred subsequent to acquisition. Under ASC 310-20, the loss would be measured based on the probable shortfall in relation to the contractual note requirements, consistent with our allowance for loan loss policy for similar loans. Throughout these financial statements, and in particular in Note 4 and Note 5, when we refer to “Loans” or “Allowance for loan losses” we mean all categories of loans, including Originated, PNCI, PCI – cash basis, and PCI – other. When we are not referring to all categories of loans, we will indicate which we are referring to – Originated, PNCI, PCI – cash basis, or PCI – other. When referring to PNCI and PCI loans we use the terms “nonaccretable difference”, “accretable yield”, or “purchase discount”. Nonaccretable difference is the difference between undiscounted contractual cash flows due and undiscounted cash flows we expect to collect, or put another way, it is the undiscounted contractual cash flows we do not expect to collect. Accretable yield is the difference between undiscounted cash flows we expect to collect and the value at which we have recorded the loan on our financial statements. On the date of acquisition, all purchased loans are recorded on our consolidated financial statements at estimated fair value. Purchase discount is the difference between the estimated fair value of loans on the date of acquisition and the principal amount owed by the borrower, net of charge offs, on the date of acquisition. We may also refer to “discounts to principal balance of loans owed, net of charge-offs”. Discounts to principal balance of loans owed, net of charge-offs is the difference between principal balance of loans owed, net of charge-offs, and loans as recorded on our financial statements. Discounts to principal balance of loans owed, net of charge-offs arise from purchase discounts, and equal the purchase discount on the acquisition date. Loans are also categorized as “covered” or “noncovered”. Covered loans refer to loans covered by a Federal Deposit Insurance Corporation (“FDIC”) loss sharing agreement. Noncovered loans refer to loans not covered by a FDIC loss sharing agreement.
Foreclosed Assets	Foreclosed Assets Foreclosed assets include assets acquired through, or in lieu of, loan foreclosure. Foreclosed assets are held for sale and are initially recorded at fair value less estimated costs to sell at the date of foreclosure, establishing a new cost basis. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Any write-downs based on the asset’s fair value less costs to sell at the date of acquisition are charged to the allowance for loan and lease losses. Any recoveries based on the asset’s fair value less estimated costs to sell in excess of the recorded value of the loan at the date of acquisition are recorded to the allowance for loan and lease losses. These assets are subsequently accounted for at lower of cost or fair value less estimated costs to sell. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Operating costs after acquisition are expensed. Revenue and expenses from operations and changes in the valuation allowance are included in other noninterest expense. Gain or loss on sale of foreclosed assets is included in noninterest income. Foreclosed assets that are not subject to a FDIC loss-share agreement are referred to as noncovered foreclosed assets. Foreclosed assets acquired through FDIC-assisted acquisitions that are subject to a FDIC loss-share agreement, and all assets acquired via foreclosure of covered loans are referred to as covered foreclosed assets. Covered foreclosed assets are reported exclusive of expected reimbursement cash flows from the FDIC. Foreclosed covered loan collateral is transferred into covered foreclosed assets at the loan’s carrying value, inclusive of the acquisition date fair value discount. Covered foreclosed assets are initially recorded at estimated fair value less estimated costs to sell on the acquisition date based on similar market comparable valuations less estimated selling costs. Any subsequent valuation adjustments due to declines in fair value will be charged to noninterest expense, and will be mostly offset by noninterest income representing the corresponding increase to the FDIC indemnification asset for the offsetting loss reimbursement amount. Any recoveries of previous valuation adjustments will be credited to noninterest expense with a corresponding charge to noninterest income for the portion of the recovery that is due to the FDIC.
Premises and Equipment	Premises and Equipment Land is carried at cost. Land improvements, buildings and equipment, including those acquired under capital lease, are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expenses are computed using the straight-line method over the shorter of the estimated useful lives of the related assets or lease terms. Asset lives range from 3-10 years for furniture and equipment and 15-40 years for land improvements and buildings.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents the excess of costs over fair value of net assets of businesses acquired. Goodwill and other intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized, but instead tested for impairment at least annually. Intangible assets with estimable useful lives are amortized over their respective estimated useful lives to their estimated residual values, and reviewed for impairment. The Company has an identifiable intangible asset consisting of core deposit intangibles (CDI). CDI are amortized over their respective estimated useful lives, and reviewed for impairment.
Impairment of Long-Lived Assets and Goodwill	Impairment of Long-Lived Assets and Goodwill Long-lived assets, such as premises and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset. Assets to be disposed of would be separately presented in the balance sheet and reported at the lower of the carrying amount or fair value less costs to sell, and are no longer depreciated. The assets and liabilities of a disposed group classified as held for sale would be presented separately in the appropriate asset and liability sections of the consolidated balance sheet. As of December 31 of each year, goodwill is tested for impairment, and is tested for impairment more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount exceeds the asset’s fair value. This determination is made at the reporting unit level. The Company may choose to first assess qualitative factors 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 totality of events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then goodwill is deemed not to be impaired. However, if the Company concludes otherwise, or if the Company elected not to first assess qualitative factors, then the Company performs the first step of a two-step impairment test by calculating the fair value of the reporting unit and comparing the fair value with the carrying amount of the reporting unit. Second, if the carrying amount of the reporting unit exceeds its fair value, an impairment loss is recognized for any excess of the carrying amount of the reporting unit’s goodwill over the implied fair value of that goodwill. The implied fair value of goodwill is determined by allocating the fair value of the reporting unit in a manner similar to a purchase price allocation. The residual fair value after this allocation is the implied fair value of the reporting unit goodwill. Currently, and historically, the Company is comprised of only one reporting unit that operates within the business segment it has identified as “community banking”. Goodwill was not impaired as of December 31, 2017 because the fair value of the reporting unit exceeded its carrying value.
Mortgage Servicing Rights	Mortgage Servicing Rights Mortgage servicing rights (MSR) represent the Company’s right to a future stream of cash flows based upon the contractual servicing fee associated with servicing mortgage loans. Our MSR arise from residential and commercial mortgage loans that we originate and sell, but retain the right to service the loans. The net gain from the retention of the servicing right is included in gain on sale of loans in noninterest income when the loan is sold. Fair value is based on market prices for comparable mortgage servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the cost to service, the discount rate, the custodial earnings rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. Servicing fees are recorded in noninterest income when earned. The Company accounts for MSR at fair value. The determination of fair value of our MSR requires management judgment because they are not actively traded. The determination of fair value for MSR requires valuation processes which combine the use of discounted cash flow models and extensive analysis of current market data to arrive at an estimate of fair value. The cash flow and prepayment assumptions used in our discounted cash flow model are based on empirical data drawn from the historical performance of our MSR, which we believe are consistent with assumptions used by market participants valuing similar MSR, and from data obtained on the performance of similar MSR. The key assumptions used in the valuation of MSR include mortgage prepayment speeds and the discount rate. These variables can, and generally will, change from quarter to quarter as market conditions and projected interest rates change. The key risks inherent with MSR are prepayment speed and changes in interest rates. The Company uses an independent third party to determine fair value of MSR.
Indemnification Asset/Liability	Indemnification Asset/Liability The Company accounts for amounts receivable or payable under its loss-share agreements entered into with the FDIC in connection with its purchase and assumption of certain assets and liabilities of Granite as indemnification assets in accordance with FASB ASC Topic 805, Business Combinations. FDIC indemnification assets are initially recorded at fair value, based on the discounted value of expected future cash flows under the loss-share agreements. The difference between the fair value and the undiscounted cash flows the Company expects to collect from or pay to the FDIC will be accreted into noninterest income over the life of the FDIC indemnification asset. FDIC indemnification assets are reviewed quarterly and adjusted for any changes in expected cash flows based on recent performance and expectations for future performance of the covered portfolios. These adjustments are measured on the same basis as the related covered loans and covered other real estate owned. Any increases in cash flow of the covered assets over those expected will reduce the FDIC indemnification asset and any decreases in cash flow of the covered assets under those expected will increase the FDIC indemnification asset. Increases and decreases to the FDIC indemnification asset are recorded as adjustments to noninterest income.
Reserve for Unfunded Commitments	Reserve for Unfunded Commitments The reserve for unfunded commitments is established through a provision for losses – unfunded commitments charged to noninterest expense. The reserve for unfunded commitments is an amount that Management believes will be adequate to absorb probable losses inherent in existing commitments, including unused portions of revolving lines of credit and other loans, standby letters of credit, and unused deposit account overdraft privileges. The reserve for unfunded commitments is based on evaluations of the collectability, and prior loss experience of unfunded commitments. The evaluations take into consideration such factors as changes in the nature and size of the loan portfolio, overall loan portfolio quality, loan concentrations, specific problem loans and related unfunded commitments, and current economic conditions that may affect the borrower’s or depositor’s ability to pay.
Low Income Housing Tax Credits	Low Income Housing Tax Credits The Company accounts for low income housing tax credits and the related qualified affordable housing projects using the proportional amortization method. Under the proportional amortization method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). Upon entering into a qualified affordable housing project, the Company records, in other liabilities, the entire amount that it has agreed to invest in the project, and an equal amount, in other assets, representing its investment in the project. As the Company disburses cash to satisfy its investment obligation, other liabilities are reduced. Over time, as the tax credits and other tax benefits of the project are realized by the Company, the investment recorded in other assets is reduced using the proportional amortization method.
Income Taxes	Income Taxes The Company’s accounting for income taxes is based on an asset and liability approach. The Company recognizes the amount of taxes payable or refundable for the current year, and deferred tax assets and liabilities for the future tax consequences that have been recognized in its financial statements or tax returns. The measurement of tax assets and liabilities is based on the provisions of enacted tax laws. A valuation allowance, if needed, reduces deferred tax assets to the expected amount most likely to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized. Interest and/or penalties related to income taxes are reported as a component of noninterest income.
Off-Balance Sheet Credit Related Financial Instruments	Off-Balance Sheet Credit Related Financial Instruments In the ordinary course of business, the Company has entered into commitments to extend credit, including commitments under credit card arrangements, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded when they are funded.
Geographical Descriptions	Geographical Descriptions For the purpose of describing the geographical location of the Company’s loans, the Company has defined northern California as that area of California north of, and including, Stockton; central California as that area of the state south of Stockton, to and including, Bakersfield; and southern California as that area of the state south of Bakersfield.
Reclassifications	Reclassifications During the three months ended September 30, 2017, the Company changed its classification of 1^st lien and 2^nd lien non-owner occupied 1-4 residential real estate mortgage loans from commercial real estate mortgage loans to residential real estate mortgage loans and consumer home equity loans, respectively. This change in loan category classification was made to better align the Company’s financial reporting classifications with regulatory reporting classifications, and to properly classify these loans for regulatory risk-based capital ratio calculations. As a result of these reclassifications, at September 30, 2017, loans with balances of $60,957,000, and $5,620,000, that would have been classified as commercial real estate mortgage loans prior to this change, were classified as residential real estate mortgage loans, and consumer home equity loans, respectively; and the Company’s, and the Bank’s, Total risk based capital ratios, Tier 1 capital ratios, and Tier 1 common equity ratios were all recalculated to be 0.10%-0.20% higher than they would have been prior to this change. Certain amounts reported in previous consolidated financial statements have been reclassified and recalculated to conform to the presentation in this report. These reclassifications did not affect previously reported net income, total loans or total shareholders’ equity.
Recent Accounting Pronouncements	Recent Accounting Pronouncements FASB Accounting Standards Update (ASU) No.2014-09, Revenue from Contracts with Customers (Topic 606): ASU 2014-09 is intended to clarify the principles for recognizing revenue, and to develop common revenue standards and disclosure requirements that would: (1) remove inconsistencies and weaknesses in revenue requirements; (2) provide a more robust framework for addressing revenue issues; (3) improve comparability of revenue recognition practices across entities, industries, jurisdictions, and capital markets; (4) provide more useful information to users of financial statements through improved disclosures; and (5) simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. The guidance affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets. The core principle is that an entity should recognize revenue to depict 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 guidance provides steps to follow to achieve the core principle. An entity should disclose sufficient information to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Qualitative and quantitative information is required with regard to contracts with customers, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017, including interim periods therein, with early adoption permitted for reporting periods beginning after December 15, 2016. ASU 2014-09 does not apply to revenue associated with financial instruments such as loans and investments, which are accounted for under other provisions of GAAP. The Company adopted ASU 2014-09 on January 1, 2018 utilizing the modified retrospective approach, and the adoption of ASU 2014-09 did not have a significant impact on the Company’s consolidated financial statements. FASB issued Accounting Standard Update (ASU) No. 2016-02, Leases (Topic 842). ASU 2016-2, among other things, requires lessees to recognize most leases on-balance sheet, increasing reported assets and liabilities. Lessor accounting remains substantially similar to current U.S. GAAP. ASU 2016-02 will be effective for the Company on January 1, 2019, utilizing the modified retrospective transition approach. The Company is currently evaluating the provisions of ASU No. 2016-02 and has determined that the adoption of this standard will result in an increase in assets to recognize the present value of the lease obligations with a corresponding increase in liabilities; however, the Company does not expect this to have a material impact on the Company’s results of operations or cash flows. FASB issued Accounting Standard Update (ASU) No. 2016-09, Compensation – Stock Compensation (Topic 718). ASU 2016-09, among other things, requires: (i) that all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) should be recognized as income tax expense or benefit in the income statement, (ii) the tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur, (iii) an entity also should recognize excess tax benefits regardless of whether the benefit reduces taxes payable in the current period, (iv) excess tax benefits should be classified along with other income tax cash flows as an operating activity, (v) an entity can make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest (current GAAP) or account for forfeitures when they occur, (vi) the threshold to qualify for equity classification permits withholding up to the maximum statutory tax rates in the applicable jurisdictions, and (vii) cash paid by an employer when directly withholding shares for tax withholding purposes should be classified as a financing activity. ASU 2016-09 was effective for the Company on January 1, 2017 and due to options exercised and restricted stock units released during the year ended December, 2017, the Company recognized excess tax benefits totaling $906,000 during the year ended December 31, 2017. FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326). ASU 2016-13 is the final guidance on the new current expected credit loss (‘‘CECL’’) model. ASU 2016-13, among other things, requires the incurred loss impairment methodology in current GAAP be replaced with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to estimate future credit loss estimates. As CECL encompasses all financial assets carried at amortized cost, the requirement that reserves be established based on an organization’s reasonable and supportable estimate of expected credit losses extends to held to maturity (‘‘HTM’’) debt securities. ASU 2016-13 amends the accounting for credit losses on available-for-sale securities (‘‘AFS’’), whereby credit losses will be presented as an allowance as opposed to a write-down. In addition, CECL will modify the accounting for purchased loans with credit deterioration since origination, so that reserves are established at the date of acquisition for purchased loans. Lastly, ASU 2016-13 requires enhanced disclosures on the significant estimates and judgments used to estimate credit losses, as well as on the credit quality and underwriting standards of an organization’s portfolio. These disclosures require organizations to present the currently required credit quality disclosures disaggregated by the year of origination or vintage. ASU 2016-13 allows for a modified retrospective approach with a cumulative effect adjustment to the balance sheet upon adoption (charge to retained earnings instead of the income statement). ASU 2016-13 will be effective for the Company on January 1, 2020, and early adoption is permitted. While the Company is currently evaluating the provisions of ASU 2016-13 to determine the potential impact the new standard will have on the Company’s Consolidated Financial Statements, it has taken steps to prepare for the implementation when it becomes effective, such as forming an internal task force, gathering pertinent data, consulting with outside professionals, and evaluating its current IT systems. Management expects to recognize a one-time cumulative effect adjustment to the allowance for loan losses as of the first reporting period in which the new standard is effective, but cannot yet estimate the magnitude of the one-time adjustment or the overall impact of the new guidance on the Company’s financial position, results of operations or cash flows. FASB issued ASU No. 2016-18, Statement of Cash Flows - Restricted Cash (Topic 230). ASU 2016-18 requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. ASU 2016-18 was effective for the Company on January 1, 2018 and did not have a significant impact on the Company’s consolidated financial statements. FASB issued ASU No. 2017-01, Business Combinations - Clarifying the Definition of a Business (Topic 805). ASU 2017-01 clarifies the definition and provides a more robust framework to use in determining when a set of assets and activities constitutes a business. ASU 2017-01 is intended to provide guidance when evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU 2017-01 was effective for the Company on January 1, 2018 and did not have a significant impact on the Company’s consolidated financial statements. FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment (Topic 350). ASU 2017-04 eliminates step two of the goodwill impairment test (the hypothetical purchase price allocation used to determine the implied fair value of goodwill) when step one (determining if the carrying value of a reporting unit exceeds its fair value) is failed. Instead, entities simply will compare the fair value of a reporting unit to its carrying amount and record goodwill impairment for the amount by which the reporting unit’s carrying amount exceeds its fair value. ASU 2017-04 will be effective for the Company on January 1, 2020 and is not expected to have a significant impact on the Company’s consolidated financial statements. FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715). ASU 2017-07 requires that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component. ASU 2017-07 was effective for the Company on January 1, 2018 and did not have a significant impact on the Company’s consolidated financial statements. FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Topic 310). ASU 2017-08 shortens the amortization period for certain callable debt securities held at a premium to require such premiums to be amortized to the earliest call date unless applicable guidance related to certain pools of securities is applied to consider estimated prepayments. Under prior guidance, entities were generally required to amortize premiums on individual, non-pooled callable debt securities as a yield adjustment over the contractual life of the security. ASU 2017-08 does not change the accounting for callable debt securities held at a discount. ASU 2017-08 will be effective for the Company on January 1, 2019, and is not expected to have a significant impact on the Company’s consolidated financial statements. FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718). ASU 2017-09 clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if all of the following are the same immediately before and after the change: (i) the award’s fair value, (ii) the award’s vesting conditions and (iii) the award’s classification as an equity or liability instrument. ASU 2017-09 was effective for the Company on January 1, 2018 and did not have a significant impact on the Company’s consolidated financial statements. FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220). ASU 2018-02 allows, but does not require, entities to reclassify certain income tax effects in accumulated other comprehensive income (AOCI) to retained earnings that resulted from the Tax Cuts and Jobs Act (Tax Act) that was enacted on December 22, 2017. The Tax Act included a reduction to the Federal corporate income tax rate from 35 percent to 21 percent effective January 1, 2018. The amount of the reclassification would be the difference between the income tax effects in AOCI calculated using the historical Federal corporate income tax rate of 35 percent and the income tax effects in AOCI calculated using the newly enacted 21 percent Federal corporate income tax rate. The amendments in ASU 2018-02 are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company adopted ASU 2018-02 on January 1, 2018, and elected to reclassify certain income tax effects in AOCI to retained earnings. This change in accounting principle was accounted for as a cumulative-effect adjustment to the balance sheet resulting in a $1,093,000 increase to retained earnings and a corresponding decrease to AOCI on January 1, 2018.