| **Basis of Presentation (Policies)**                                                | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
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| **Organization, Consolidation and Presentation of Financial Statements [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Use of Estimates                                                                    | 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.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Reclassification                                                                    | 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 Pronouncements                                                    | 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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| - Definition
Disclosure of accounting policy pertaining to new accounting pronouncements that may impact the entity's financial reporting. Includes, but is not limited to, quantification of the expected or actual impact.
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No definition available.
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| - Definition
Disclosure of accounting policy for reclassifications that affects the comparability of the financial statements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6359566&loc=d3e326-107755
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| - Definition
Disclosure of accounting policy for the use of estimates in the preparation of financial statements in conformity with generally accepted accounting principles.
+ References
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