Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2017
Accounting Policies [Abstract]
Nature Of Operations	Nature of Operations - Access National Corporation (the “Corporation “) is a bank holding company incorporated under the laws of the Commonwealth of Virginia. The holding company was formed on June 15, 2002. The Corporation has three active wholly owned subsidiaries: Access National Bank (the “Bank” or “ANB”); Middleburg Investment Group ("MIG"); and MFC Capital Trust II. The Bank has three active wholly-owned subsidiaries: Access Real Estate LLC (“Access Real Estate”), a real estate company; ACME Real Estate LLC, a real estate holding company of foreclosed property; and Access Capital Management Holding, LLC (“ACM”), a holding company for Capital Fiduciary Advisors, L.L.C., Access Investment Services, L.L.C. and Access Insurance Group, L.L.C.
Basis of Presentation	Basis of Presentation - The accompanying consolidated financial statements include the accounts of Access National Corporation and its wholly-owned subsidiaries: Access National Bank and Middleburg Investment Group. All significant inter-company accounts and transactions have been eliminated in consolidation. The accounting and reporting policies of the Corporation and its subsidiaries conform to accounting principles generally accepted in the United States of America and to predominant practices within the banking industry.
Use of Estimates	Use of Estimates - 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 based on available information. These estimates and assumptions 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. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses, the fair values and impairments of financial instruments, the status of contingencies and the valuation of deferred tax assets.
Cash Flow Reporting	Cash Flow Reporting - For purposes of the statements of cash flows, cash and cash equivalents consists of cash and due from banks, federal funds sold and interest-bearing deposits at other banks.
Restrictions on Cash and Cash Equivalents	Restrictions on Cash and Cash Equivalents - As a member of the Federal Reserve System, the Bank is required to maintain certain average reserve balances. Those balances include usable vault cash and amounts on deposit with the Federal Reserve Bank of Richmond (“FRB”).
Securities	Securities - Debt securities that management has both the positive intent and ability to hold to maturity are classified as “held-to-maturity” and are recorded at amortized cost. Securities not classified as held-to-maturity, including equity securities with readily determinable fair values, are classified as “available-for-sale” and recorded at fair value, with unrealized gains and losses excluded from net income and reported in other comprehensive income. Purchase premiums and discounts are recognized in interest income using the effective interest method over the terms of the securities or call dates if applicable. Declines in the fair value of held-to-maturity and available-for-sale securities below their cost that are deemed to be other than temporary are reflected in net income as realized losses. Gains and losses on the sale of securities are recorded on the trade date and are determined using the specific identification method.
Restricted Stock	Restricted Stock - Restricted stock consists of Federal Home Loan Bank of Atlanta (“FHLB”) stock and FRB stock. These stocks are classified as restricted stocks because their ownership is restricted to certain types of entities and they lack a market. Restricted stock is carried at cost on the Corporation's financial statements. Dividends are paid semiannually on FRB stock and quarterly on FHLB stock.
Other Than Temporary Impairment Of Investment Securities	Other Than Temporary Impairment of Investment Securities – Securities are evaluated quarterly for potential other than temporary impairment. Management considers the facts of each security including the nature of the security, the amount and duration of the loss, credit quality of the issuer, the expectations for that security’s performance, and the Corporation’s intent and ability to hold the security until recovery. Declines in equity securities that are considered to be other than temporary are recorded as a charge to net income in the Consolidated Statements of Income. Declines in debt securities that are considered to be other than temporary are separated into (1) the amount of the total impairment related to credit loss and (2) the amount of the total impairment related to all other factors. The amount of the total other than temporary impairment related to the credit loss is recognized in net income. The amount of the total impairment related to all other factors is recognized in other comprehensive income.
Loans	Loans - The Corporation grants commercial, real estate, and consumer loans to customers in the community in and around the Central and Northern Virginia areas. The loan portfolio is well diversified and generally collateralized by assets of the customers. The loans are expected to be repaid from cash flow or proceeds from the sale of selected assets of the borrowers. The ability of the Corporation’s debtors to honor their contracts is dependent upon the real estate and general economic conditions in the Corporation’s market area. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off generally are reported at their outstanding unpaid principal balances less the allowance for loan losses and any deferred fees or costs on originated loans. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized as an adjustment of the related loan yield using the effective interest method. The accrual of interest on mortgage and commercial loans is discontinued at the time the loan is 90 days delinquent unless the credit is well-secured and in process of collection. Consumer loans are typically charged off no later than 180 days past due. In all cases, loans are placed on non-accrual status or charged-off at an earlier date if collection of principal or interest is considered doubtful. All interest accrued but not collected for loans that are placed on non-accrual status or charged-off is reversed against interest income. The interest on these loans is accounted for on the cash-basis or cost-recovery method, until qualifying for return to accrual. Loans are returned to accrual status when all of the principal and interest amounts contractually due are brought current and future payments are reasonably assured.
Interest Income On Loans	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 when, in the opinion of management, there is an indication that the borrower may be unable to meet payments as they become due. Upon such discontinuance, all unpaid accrued interest is reversed.
Loans Held For Sale	Loans Held for Sale - The Corporation accounts for all one to four unit residential loans originated and intended for sale in the secondary market in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 825-10. Loans held for sale are recorded at fair value, determined individually, as of the balance sheet date.
Allowance for Loan Losses	Allowance for Loan Losses - The allowance for loan losses is established as losses are estimated to have occurred through a provision for loan losses charged to net income. Loan losses are charged against the allowance when management believes the uncollectibility of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The allowance represents an amount that, in management’s judgment, will be adequate to absorb any losses on existing loans that may become uncollectible. Management’s judgment in determining the adequacy of the allowance is based on evaluations of the collectability of loans while taking into consideration such factors as changes in the nature and volume of the loan portfolio, current economic conditions which may affect a borrower’s ability to repay, overall portfolio quality, and review of specific potential losses. This evaluation is inherently subjective, as it requires estimates that are susceptible to significant revision as more information becomes available. The allowance consists of specific and general components. The specific component relates to loans that are classified as doubtful, substandard or special mention. For such loans that are also classified as impaired, an allowance is established when the discounted cash flows (or collateral value or observable market price) of the impaired loan is lower than the carrying value of that loan. The general component covers non-classified loans and is based on historical loss experience adjusted for qualitative factors. A loan is considered impaired when, based on current information and events, it is probable that the Corporation will be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. Impairment is measured on a loan by loan basis by either the present value of the expected future cash flows discounted at the loan’s effective interest rate, the loan’s obtainable market price, or the fair value of the collateral if the loan is collateral dependent.
Derivative Financial Instruments	Derivative Financial Instruments - The Mortgage Division enters into commitments to fund residential mortgage loans with the intention of selling them in the secondary market. The Mortgage Division also enters into forward sales agreements for certain funded loans and loan commitments. The Mortgage Division records unfunded commitments intended for loans held for sale and forward sales agreements at fair value with changes in fair value recorded as a component of other income. Loans originated and intended for sale in the secondary market are carried at fair value. For pipeline loans which are not pre-sold to an investor, the Mortgage Division manages the interest rate risk on rate lock commitments by entering into forward sale contracts of mortgage backed securities, whereby the Mortgage Division obtains the right to deliver securities to investors in the future at a specified price. Such contracts are accounted for as derivatives and are recorded at fair value in derivative assets or liabilities, with changes in fair value recorded in other income. The Mortgage Division has determined these derivative financial instruments do not meet the hedging criteria required by FASB ASC 815 and has not designated these derivative financial instruments as hedges. Accordingly, changes in fair value are recognized currently in income.
Premises and Equipment	Premises and Equipment - Premises and equipment are stated at cost less accumulated depreciation. Premises and equipment are depreciated over their estimated useful lives; leasehold improvements are amortized over the lives of the respective leases or the estimated useful life of the leasehold improvement, whichever is less. Depreciation is computed using the straight-line method over the estimated useful lives of 39 years for office buildings and 3 to 15 years for furniture, fixtures, and equipment. Costs of maintenance and repairs are expensed as incurred; improvements and betterments are capitalized. When items are retired or otherwise disposed of, the related costs and accumulated depreciation are removed from the accounts and any resulting gains or losses are included in the determination of net income.
Real Estate Owned	Real Estate Owned - Real estate properties acquired through loan foreclosures are recorded initially at fair value, less expected sales costs. Subsequent valuations are performed by management, and the carrying amount of a property is adjusted by a charge to expense to reflect any subsequent declines in estimated fair value. Fair value estimates are based on recent appraisals and current market conditions. Gains or losses on sales of real estate owned are recognized upon disposition. Real estate owned is included in other assets. At December 31, 2017 and 2016, the Corporation did not have any real estate owned due to foreclosure. The Corporation did have one property with a balance of $643 thousand at December 31, 2017, which had previously been included in premises and equipment reclassified to other real estate owned when it was determined by management the property was no longer needed. The property was subsequently sold in 2018.
Income Taxes	Income Taxes - Income tax expense is the total of the current year income tax due or refundable, the change in deferred tax assets and liabilities, and any adjustments related to unrecognized tax benefits. Deferred income tax assets and liabilities are determined using the balance sheet method. Under this method, the net deferred tax asset or liability is determined based on the tax effects of the temporary differences between the book and tax bases of the various balance sheet assets and liabilities and gives current recognition to changes in tax rates and laws. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Corporation has not identified any material uncertain tax positions.
Stock-Based Compensation Plans	Stock-Based Compensation Plans –In accordance with FASB ASC 718-10, the Corporation measures the cost of employee services received in exchange for an award of equity instruments based on the fair value of the award on the grant date. That cost is recognized over the period during which the employee is required to provide service in exchange for the award, the requisite service period. No compensation expense is recognized for equity instruments for which employees do not render the requisite service. The Corporation determines the fair value of the employee stock options using the Black-Scholes option pricing model.
Earnings Per Share	Earnings Per Share - Basic earnings per share represents income available to common shareholders divided by the weighted-average number of shares outstanding during the period. Diluted earnings per share reflect additional common shares that would have been outstanding if dilutive potential common shares had been issued, as well as any adjustment to income that would result from the assumed issuance. Common equivalent shares are excluded from the computation if their effect is anti-dilutive.
Fair Value Measurements	Fair Value Measurements - The Corporation records certain of its assets and liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Fair value measurements are classified within one of three levels in a valuation hierarchy based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows: Level 1 - Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date. Level 2 - Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. Level 3 - Significant unobservable inputs that reflect a company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. See Note 16 - Fair Value Measurements.
Securities Sold Under Agreements To Repurchase	Securities Sold Under Agreements to Repurchase - Securities sold under agreements to repurchase are accounted for as collateralized financing transactions and are recorded at the amounts at which the securities were sold plus accrued interest. Securities, generally U.S. government and federal agency securities, pledged as collateral under these financing arrangements cannot be sold or re-pledged by the secured party.
Advertising Costs	Advertising Costs - The Corporation charges the costs of advertising to expense as incurred.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The ASU supersedes most of the existing revenue recognition requirements in GAAP and will require entities to recognize revenue at an amount that reflects the consideration to which the Corporation expects to be entitled in exchange for transferring goods or services to a customer. The new standard also requires significantly expanded disclosures regarding the qualitative and quantitative information of an entity’s nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. On July 9, 2015, the FASB approved amendments deferring the effective date by one year. The pronouncement is now effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Approximately 79% of the Corporation’s revenue comes from net interest income and is explicitly out of scope of the guidance. Additionally, residential mortgage banking income accounts for approximately 16% of revenue and is also out of scope of the guidance. The Corporation has concluded the adoption of the accounting standard will not have a material impact on the Corporation’s revenue recognition patterns or financial presentation and disclosures. The new standard is largely consistent with the existing guidance and current practices applied by our businesses with the primary impact related to a change in the timing of recognition of revenues derived from the Trust and Wealth Management segment. We will adopt this guidance using the modified retrospective approach in first quarter of 2018. In January 2016, the FASB issued ASU 2016-1, Financial Instruments – Overall (Subtopic 825-10). This ASU requires all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The amendments in this update also require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The amendments in the ASU are effective beginning after December 15, 2017. The adoption of this guidance is not expected to have a material effect on the Corporation’s financial condition or results of operations. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The ASU was issued in order to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous GAAP. The ASU requires that a lessee should recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term on the balance sheet. The ASU is effective for interim and annual periods beginning after December 15, 2018, using a modified retrospective approach, and early adoption is permitted. The Corporation is currently evaluating the impact the pronouncement will have on its Consolidated Financial Statements. In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting. The ASU amends ASC Topic 718, Compensation – Stock Compensation. The ASU simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The ASU was effective for interim and annual periods beginning after December 15, 2016. The Corporation adopted the accounting standard during the first quarter of 2017 with no material impact to the financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This ASU amends guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities by eliminating the probable initial recognition threshold (incurred loss methodology) and requiring entities to reflect its current estimate of all expected credit losses. The amendments in the ASU are effective beginning after December 15, 2019 and for interim periods within that year. Early adoption is permitted beginning after December 15, 2018. Entities will apply the amendments in this ASU through a cumulative-effect adjustment to retained earnings in the first period effective. Management is currently evaluating the potential impact of ASU 2016-13 on its financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This ASU was issued to reduce diversity in how certain cash receipts and cash payments are being presented and classified in the statement of cash flows. Guidance provided in the ASU are specific to eight cash flow issues being: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt or other debt instruments with interest rates that are insignificant to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds received from the settlement of life insurance claims; proceeds received from the settlement of bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and application of the predominance principle. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The amendments should be applied using a retrospective transition method to each period presented. The adoption of this guidance should not have a material effect on the Corporation’s financial condition or results of operations. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. Under current GAAP, recognition of current and deferred income taxes for an intra-entity asset transfer is prohibited until the asset has been sold to a third party. The amendments in this ASU eliminate the exception for an intra-entity transfer of an asset other than inventory thereby requiring an entity to recognize the income tax consequences when the transfer occurs. The amendments in the ASU are effective beginning after December 15, 2017 and for interim periods within that year. Early adoption is permitted. Entities will apply the amendments in this ASU through a cumulative-effect adjustment to retained earnings in the first period effective. The adoption of this guidance should not have a material effect on the Corporation’s financial condition or results of operations. In January 2017, the FASB issued ASU No. 2017-4, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. The ASU was issued with the intent to simplify goodwill impairment testing by eliminating the second step of the analysis under which the implied fair value of goodwill is determined as if the reporting unit were being acquired in a business combination. The update instead requires entities to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for any amount by which the carrying amount exceeds the reporting unit’s fair value, to the extent that the loss recognized does not exceed the amount of goodwill allocated to that reporting unit. ASU 2017-4 must be applied prospectively and is effective for the Corporation on January 1, 2020. Early adoption is permitted. The Corporation does not expect the new guidance to have a material impact on its Consolidated Financial Statements. In February 2017, the FASB issued ASU 2017-05, Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets, to clarify the scope of the guidance on nonfinancial asset derecognition as well as the accounting for partial sales of nonfinancial assets. The amendments conform the derecognition guidance on nonfinancial assets with the model for transactions in the new revenue standard. The amendments will be effective for the Corporation for reporting periods beginning after December 15, 2017. The Corporation does not expect these amendments to have a material effect on its consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-08, Premium Amortization on Purchased Callable Debt Securities, which is intended to enhance the accounting for the amortization of premiums for purchased callable debt securities. The amendments shorten the amortization period for the premium to the earliest call date. The amendments will be effective for the Corporation for interim and annual periods beginning after December 15, 2018. Early adoption is permitted. The Corporation does not expect these amendments to have a material effect on its consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation, which amended the requirements in the Compensation-Stock Compensation Topic of the ASC related to changes to the terms or conditions of a share-based payment award. The amendments provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The amendments will be effective for the Corporation for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted. The Corporation does not expect these amendments to have a material effect on its financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments in this update better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The ASU is effective for the Corporation in annual and interim periods beginning after December 15, 2018, with early adoption permitted. The Corporation is currently evaluating the impact of this guidance, but does not expect the guidance to have a material impact on its Consolidated Financial Statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The ASU was issued to address the income tax accounting treatment of the stranded tax effects within accumulated other comprehensive income due to the prohibition of backward tracing due to an income tax rate change that was initially recorded in other comprehensive income. This issue came about from the enactment of the Tax Reform Act on December 22, 2017 that changed the Corporation’s income tax rate from 35% to 21% effective January 1, 2018. The ASU changed current accounting whereby an entity may elect to reclassify the stranded tax effect from accumulated other comprehensive income to retained earnings. The ASU is effective for fiscal years, and interim periods within those years, beginning after December 31, 2018; however, public business entities are allowed to early adopt in any interim period for which the financial statements have not yet been issued. The amendments of the ASU may be applied either at the beginning of the period (annual or interim) of adoption or retrospectively to each of the period(s) in which the effect of the change in the U.S. federal corporate tax rate in the Tax Reform Act is recognized. The Corporation intends to early adopt the new standard during 2018 and plans to make an election to reclassify the stranded tax effects from accumulated other comprehensive loss to retaining earnings at the beginning of the period of adoption.