Organization and Summary of Significant Accounting and Reporting Policies	9 Months Ended
Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Summary of Significant Accounting and Reporting Policies	Organization and Summary of Significant Accounting and Reporting Policies The consolidated financial statements include the accounts of United Security Bancshares, and its wholly owned subsidiary United Security Bank (the “Bank”) and two bank subsidiaries, USB Investment Trust (the “REIT”) and United Security Emerging Capital Fund, (collectively the “Company” or “USB”). Intercompany accounts and transactions have been eliminated in consolidation. These unaudited financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information on a basis consistent with the accounting policies reflected in the audited financial statements of the Company included in its 2013 Annual Report on Form 10-K. These interim financial statements do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of a normal, recurring nature) considered necessary for a fair presentation have been included. Operating results for the interim periods presented are not necessarily indicative of the results that may be expected for any other interim period or for the year as a whole. Recently Issued Accounting Standards: In January 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-01 Accounting for Investments in Qualified Affordable Housing Projects. This ASU provides "guidance on accounting for investments by a reporting entity in flow-through limited liability entities that manage or invest in affordable housing projects that qualify for the low-income housing tax credit." It allows the proportional amortization method to be used by a reporting entity if certain conditions are met. The ASU also defines when a qualified affordable housing project through a limited liability entity should be tested for impairment. If a qualified affordable housing project does not meet the conditions for using the proportional amortization method, the investment should be accounted for using an equity method investment or a cost method investment. The ASU is effective for fiscal years beginning after December 15, 2014, and interim periods therein. In November 2013, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-04 Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. The amendments in the ASU clarify when an in substance repossession or foreclosure occurs - that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. The new ASU requires a creditor to reclassify a collateralized consumer mortgage loan to real estate property upon obtaining legal title to the real estate collateral, or the borrower voluntarily conveying all interest in the real estate property to the lender to satisfy the loan through a deed in lieu of foreclosure or similar legal agreement. The ASU is effective for annual periods, and interim periods within those annual periods, beginning after December 15 2014. In February 2013, The Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2013-02, Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, to improve the transparency of reporting reclassifications out of accumulated other comprehensive income. ASU 2013-02 requires an organization to present (either on the face of the statement where net income is presented or in the notes) the effects on the line items of net income of significant amounts reclassified out of accumulated other comprehensive income–but only if the item reclassified is required under U.S. GAAP to be reclassified to net income in its entirety in the same reporting period. The amendments are effective for reporting periods beginning after December 15, 2012. The amounts reclassified out of net income were not significant and this ASU did not have a significant impact on the Company’s financial statements. In January 2013, the FASB issued ASU No. 2013-01 Balance Sheet (Topic 210) Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities, which clarifies that ordinary trade receivables and receivables are not in the scope of ASU 2011-11. It further clarifies that the scope of ASU No. 2011-11 applies to derivatives, repurchase agreements and reverse purchase agreements, and securities borrowing and securities lending transactions that are either offset in accordance with specific criteria contained in FASB Accounting Standards Codification® or subject to a master netting arrangement or similar agreement. Both ASU 2011-11 and ASU 2013-1 are effective for annual periods beginning on or after January 1, 2013, and interim periods within those annual periods. The Company adopted these ASUs during the first quarter of 2013 and they did not have a material impact on its financial statements.

Organization and Summary of Significant Accounting and Reporting Policies

The consolidated financial statements include the accounts of United Security Bancshares, and its wholly owned subsidiary United Security Bank (the “Bank”) and two bank subsidiaries, USB Investment Trust (the “REIT”) and United Security Emerging Capital Fund, (collectively the “Company” or “USB”). Intercompany accounts and transactions have been eliminated in consolidation.

These unaudited financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information on a basis consistent with the accounting policies reflected in the audited financial statements of the Company included in its 2013 Annual Report on Form 10-K. These interim financial statements do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of a normal, recurring nature) considered necessary for a fair presentation have been included. Operating results for the interim periods presented are not necessarily indicative of the results that may be expected for any other interim period or for the year as a whole.

Recently Issued Accounting Standards:

In January 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-01 Accounting for Investments in Qualified Affordable Housing Projects. This ASU provides "guidance on accounting for investments by a reporting entity in flow-through limited liability entities that manage or invest in affordable housing projects that qualify for the low-income housing tax credit." It allows the proportional amortization method to be used by a reporting entity if certain conditions are met. The ASU also defines when a qualified affordable housing project through a limited liability entity should be tested for impairment. If a qualified affordable housing project does not meet the conditions for using the proportional amortization method, the investment should be accounted for using an equity method investment or a cost method investment. The ASU is effective for fiscal years beginning after December 15, 2014, and interim periods therein.

In November 2013, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-04 Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. The amendments in the ASU clarify when an in substance repossession or foreclosure occurs - that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. The new ASU requires a creditor to reclassify a collateralized consumer mortgage loan to real estate property upon obtaining legal title to the real estate collateral, or the borrower voluntarily conveying all interest in the real estate property to the lender to satisfy the loan through a deed in lieu of foreclosure or similar legal agreement. The ASU is effective for annual periods, and interim periods within those annual periods, beginning after December 15 2014.

In February 2013, The Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2013-02, Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, to improve the transparency of reporting reclassifications out of accumulated other comprehensive income. ASU 2013-02 requires an organization to present (either on the face of the statement where net income is presented or in the notes) the effects on the line items of net income of significant amounts reclassified out of accumulated other comprehensive income–but only if the item reclassified is required under U.S. GAAP to be reclassified to net income in its entirety in the same reporting period. The amendments are effective for reporting periods beginning after December 15, 2012. The amounts reclassified out of net income were not significant and this ASU did not have a significant impact on the Company’s financial statements.

In January 2013, the FASB issued ASU No. 2013-01 Balance Sheet (Topic 210) Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities, which clarifies that ordinary trade receivables and receivables are not in the scope of ASU 2011-11. It further clarifies that the scope of ASU No. 2011-11 applies to derivatives, repurchase agreements and reverse purchase agreements, and securities borrowing and securities lending transactions that are either offset in accordance with specific criteria contained in FASB Accounting Standards Codification® or subject to a master netting arrangement or similar agreement. Both ASU 2011-11 and ASU 2013-1 are effective for annual periods beginning on or after January 1, 2013, and interim periods within those annual periods. The Company adopted these ASUs during the first quarter of 2013 and they did not have a material impact on its financial statements.