General (Policies)	3 Months Ended
Mar. 31, 2019
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 March 31, 2019 and the results of operations for the three months ended March 31, 2019 and 2018, in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The notes included herein should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s 2018 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”). The results of operations for the three months ended March 31, 2019 and 2018 are not necessarily indicative of the results expected for the full year or any other interim period. Certain amounts in the 2018 consolidated financial statements have been reclassified to conform to the 2019 presentation. No reclassifications were significant and there was no effect on net income.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendments, 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 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.

General (Policies)

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

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 March 31, 2019 and the results of operations for the three months ended March 31, 2019 and 2018, in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The notes included herein should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s 2018 Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”).

The results of operations for the three months ended March 31, 2019 and 2018 are not necessarily indicative of the results expected for the full year or any other interim period.

Certain amounts in the 2018 consolidated financial statements have been reclassified to conform to the 2019 presentation. No reclassifications were significant and there was no effect on net income.

Recent Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The amendments, 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 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.