General (Policies)	9 Months Ended
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	The consolidated financial statements include the accounts of Fauquier Bankshares, Inc. (the “Company”) and its wholly-owned subsidiary, The Fauquier Bank (the “Bank”), and the Bank’s wholly-owned subsidiaries, Fauquier Bank Services, Inc. and Specialty Properties Acquisitions - VA, LLC. Specialty Properties Acquisitions - VA, LLC was formed with the sole purpose of holding foreclosed property. The consolidated financial statements do not include the accounts of Fauquier Statutory Trust II, a wholly-owned subsidiary of the Company. In consolidation, significant intercompany financial balances and transactions have been eliminated. In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments (consisting of only normal recurring accruals) necessary to present fairly the financial position as of September 30, 2018 and the results of operations for the three and nine months ended September 30, 2018 and 2017, in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The notes included herein should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s 2017 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”).
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, “Leases (Topic 842).” Among other things, in the amendments in ASU 2016-02, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) A lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) A right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company, to date, has not completed its analysis of those leases and is unable to quantify the impact that ASU 2016-02 will have on its consolidated financial statements at this time; however, based on the current nature of its leases, the Company does not expect any significant adjustments. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendments in this ASU, among other things, require the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The amendments in this ASU are effective for SEC filers for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The Company is currently assessing the impact that ASU 2016-13 will have on its consolidated financial statements. The Company’s management is addressing compliance requirements, data gathering and archiving resources, and analyzing the potential impact of this standard. In March 2017, the FASB issued ASU No. 2017‐08, “Receivables—Nonrefundable Fees and Other Costs (Subtopic 310‐20), Premium Amortization on Purchased Callable Debt Securities.” The amendments in this ASU shorten the amortization period for certain callable debt securities purchased at a premium. Upon adoption of the standard, premiums on these qualifying callable debt securities will be amortized to the earliest call date. Discounts on purchased debt securities will continue to be accreted to maturity. The amendments are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Upon transition, entities should apply the guidance on a modified retrospective basis, with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption and provide the disclosures required for a change in accounting principle. The Company is currently assessing the impact that ASU 2017‐08 will have on its consolidated 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 ASU modify the designation and measurement guidance for hedge accounting as well as provide for increased transparency regarding the presentation of economic results on both the financial statements and related footnotes. Certain aspects of hedge effectiveness assessments will also be simplified upon implementation of this update. The amendments are effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted, including adoption in any interim period. The Company is currently assessing the impact that ASU 2017‐12 will have on its consolidated financial statements. In June 2018, the FASB issued ASU No. 2018-07, “Compensation- Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting.” The amendments expand the scope of Topic 718 to include share-based payments issued to nonemployees for goods or services, which were previously excluded. The amendments will align the accounting for share-based payments to nonemployees and employees more similarly. The amendments are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-07 to have a material impact on its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement.” The amendments modify the disclosure requirements in Topic 820 to add disclosures regarding changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty. Certain disclosure requirements in Topic 820 are also removed or modified. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Certain of the amendments are to be applied prospectively while others are to be applied retrospectively. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-13 to have a material impact on its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-14, “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans.” These amendments modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Certain disclosure requirements have been deleted while the following disclosure requirements have been added: the weighted-average interest crediting rates for cash balance plans and other plans with promised interest crediting rates and an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify the disclosure requirements in paragraph 715-20-50-3, which state that the following information for defined benefit pension plans should be disclosed: The projected benefit obligation (PBO) and fair value of plan assets for plans with PBOs in excess of plan assets and the accumulated benefit obligation (ABO) and fair value of plan assets for plans with ABOs in excess of plan assets. The amendments are effective for fiscal years ending after December 15, 2020. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-14 to have a material impact on its consolidated financial statements.

Recent Accounting Pronouncements

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, “Leases (Topic 842).” Among other things, in the amendments in ASU 2016-02, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) A lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) A right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company, to date, has not completed its analysis of those leases and is unable to quantify the impact that ASU 2016-02 will have on its consolidated financial statements at this time; however, based on the current nature of its leases, the Company does not expect any significant adjustments.

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendments in this ASU, among other things, require the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The amendments in this ASU are effective for SEC filers for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The Company is currently assessing the impact that ASU 2016-13 will have on its consolidated financial statements. The Company’s management is addressing compliance requirements, data gathering and archiving resources, and analyzing the potential impact of this standard.

In March 2017, the FASB issued ASU No. 2017‐08, “Receivables—Nonrefundable Fees and Other Costs (Subtopic 310‐20), Premium Amortization on Purchased Callable Debt Securities.” The amendments in this ASU shorten the amortization period for certain callable debt securities purchased at a premium. Upon adoption of the standard, premiums on these qualifying callable debt securities will be amortized to the earliest call date. Discounts on purchased debt securities will continue to be accreted to maturity. The amendments are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. Upon transition, entities should apply the guidance on a modified retrospective basis, with a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption and provide the disclosures required for a change in accounting principle. The Company is currently assessing the impact that ASU 2017‐08 will have on its consolidated 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 ASU modify the designation and measurement guidance for hedge accounting as well as provide for increased transparency regarding the presentation of economic results on both the financial statements and related footnotes. Certain aspects of hedge effectiveness assessments will also be simplified upon implementation of this update. The amendments are effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted, including adoption in any interim period. The Company is currently assessing the impact that ASU 2017‐12 will have on its consolidated financial statements.

In June 2018, the FASB issued ASU No. 2018-07, “Compensation- Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting.” The amendments expand the scope of Topic 718 to include share-based payments issued to nonemployees for goods or services, which were previously excluded. The amendments will align the accounting for share-based payments to nonemployees and employees more similarly. The amendments are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-07 to have a material impact on its consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement.” The amendments modify the disclosure requirements in Topic 820 to add disclosures regarding changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty. Certain disclosure requirements in Topic 820 are also removed or modified. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Certain of the amendments are to be applied prospectively while others are to be applied retrospectively. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-13 to have a material impact on its consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-14, “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans.” These amendments modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Certain disclosure requirements have been deleted while the following disclosure requirements have been added: the weighted-average interest crediting rates for cash balance plans and other plans with promised interest crediting rates and an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. The amendments also clarify the disclosure requirements in paragraph 715-20-50-3, which state that the following information for defined benefit pension plans should be disclosed: The projected benefit obligation (PBO) and fair value of plan assets for plans with PBOs in excess of plan assets and the accumulated benefit obligation (ABO) and fair value of plan assets for plans with ABOs in excess of plan assets. The amendments are effective for fiscal years ending after December 15, 2020. Early adoption is permitted. The Company does not expect the adoption of ASU 2018-14 to have a material impact on its consolidated financial statements.