| **Basis of Presentation**                                                           | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   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| **Organization, Consolidation and Presentation of Financial Statements [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           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| Basis of Presentation                                                               | Basis of PresentationNature of OperationsCommunityOne Bancorp, or "COB" or the "Company" (which also refers to us and our subsidiaries on a consolidated basis), is a bankholding company incorporated in 1984 under the laws of the State of North Carolina. Through our ownership of CommunityOneBank, N.A., or the "Bank," a national banking association headquartered in Asheboro, North Carolina, we offer a complete line ofconsumer, wealth management, mortgage and business banking services, including loan, deposit, cash management, investmentmanagement and trust services, to individual and business customers through operations located throughout central, southern andwestern North Carolina.In addition to the Bank, we own FNB United Statutory Trust I, FNB United Statutory Trust II, and Catawba Valley Capital Trust II, which were formed to facilitate the issuance of trust preferred securities. COB also owned Granite Mortgage, Inc., which ceased mortgage operations in 2009, filed for Chapter 11 bankruptcy on February 15, 2012 and was dissolved on May 5, 2014.The Bank holds the stock of First National Investor Services, Inc., which holds deeds of trust for the Bank. The Bank had also owned Dover Mortgage, which had previously engaged in the business of originating, underwriting and closing mortgage loans for sale in the secondary market. Dover ceased operations in the first quarter of 2011, filed for Chapter 11 bankruptcy on February 15, 2012 and was dissolved on April 28, 2014.On October 21, 2011, as part of the recapitalization of COB, COB acquired Bank of Granite Corporation and its subsidiary bank, Bank of Granite, through the merger of a wholly owned subsidiary of ours into Granite Corp. (the “Merger”).  Bank of Granite was merged into the Bank on June 8, 2013.We earn revenue primarily from interest on loans and securities investments, mortgage banking income and fees charged for financial services provided to our customers.  Offsetting these revenues are the cost of deposits and other funding sources, provision for loan losses and write-downs in the value of, gains and losses on disposition of and holding costs associated with our OREO, and other operating costs such as:  salaries and employee benefits, occupancy, data processing expenses, merger related expenses and tax expense.GeneralIn the accompanying consolidated financial statements, prepared without audit, all significant intercompany balances and transactions have been eliminated.  Descriptions of the organization and business of COB, accounting policies followed by COB and other relevant information are contained in our Annual Report on Form 10-K for the year ended December 31, 2013 (the "Form 10-K"), including the Notes to the consolidated financial statements filed as part of that report.  This quarterly report should be read in conjunction with the Form 10-K.In the opinion of management, the accompanying consolidated financial statements contain the adjustments, all of which are normal recurring adjustments, necessary to present fairly the financial position of COB as of March 31, 2014 and December 31, 2013, and the results of its operations and cash flows for the three months ended March 31, 2014 and 2013, respectively.Use of EstimatesWe have made a number of estimates and assumptions relating to the reporting of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period to prepare these consolidated financial statements in conformity with accounting principles generally accepted in the United States ("GAAP").  Actual results could differ from those estimates.  Material estimates subject to change in the near term include, among other items, the allowances for loan losses (“ALL”), estimated cash flows of purchased impaired loans, the carrying value of other real estate owned (“OREO”), the carrying value of intangible assets and the realization of deferred tax assets.ReclassificationCertain reclassifications have been made to the prior period consolidated financial statements to place them on a comparable basis with the current period consolidated financial statements.  These reclassifications have no effect on net income or shareholders' equity as previously reported.Recent Accounting PronouncementsTroubled Debt Restructurings - In January 2014, the Financial Accounting Standards Board (“FASB”)  issued ASU No. 2014-04 Troubled Debt Restructurings by Creditors (Subtopic 310-40): "Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure" (“ASU No. 2014-04”). This pronouncement clarifies the criteria for concluding that an in substance repossession or foreclosure has occurred, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan.  The amendments also outline interim and annual disclosure requirements.  The amendments will be effective for the Company for interim and annual reporting periods beginning after December 15, 2014. Companies are allowed to use either a modified retrospective transition method or a prospective transition method when adopting this update.  Early adoption is permitted.  The Company does not expect these amendments to have a material effect on its financial statements.FASB - From time to time, the FASB issues exposure drafts for proposed statements of financial accounting standards. Such exposure drafts are subject to comment from the public, to revisions by the FASB and to final issuance by the FASB as statements of financial accounting standards. Management considers the effect of the proposed statements on the consolidated financial statements of COB and monitors the status of changes to and proposed effective dates of exposure drafts. Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies are not expected to have a material impact on our financial position, results of operations or cash flows. |

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The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.
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