| **Short-Term Borrowings and Long-Term Debt (Tables)**                | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
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| **Debt Instrument [Line Items]**                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Schedule of Short-term and Long-term Borrowings                      | The following table stratifies COB’s borrowings as short-term and long-term at the periods indicated.   December 31,(dollars in thousands) 2013 2012  Balance Rate Balance RateShort-term borrowings:        Retail customer repurchase agreements $6,917 0.21% $8,675 0.19%Total short-term borrowings $6,917   $8,675  Long-term debt:        Federal Home Loan Bank advances $73,283 1.80 $58,328 2.62Long-term notes payable 5,263 1.41 — —Junior subordinated debt 56,702 1.77 56,702 1.83Total long-term debt $135,248   $115,030                                                                                                                                                                       |
| Schedule of Retail Repurchase Agreements and Federal Funds Purchased | Information concerning retail repurchase agreements and federal funds purchased is as follows: (dollars in thousands) 201320122011   RetailRepurchaseAgreements RetailRepurchaseAgreements RetailRepurchaseAgreements Balance at December 31 $6,917 $8,675 $8,838 Average balance during the year 9,852 9,861 8,973 Maximum month end balance 13,064 12,720 10,917 Weighted average interest rate:       At December 31 0.21% 0.19% 0.42% During the year 0.21 0.29 0.58                                                                                                                                                                                                                                                                                                                                                  |
| FHLB advance [Member]                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| **Debt Instrument [Line Items]**                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Scheduled Maturities of Long-term Debt                               | At December 31, 2013, the scheduled maturities of FHLB advances payable over the next five years and thereafter, certain of which are convertible to a variable rate at the option of the FHLB before scheduled maturity, are as follows:(dollars in thousands) Twelve Months Ended December 31, 2014$5,00020153,00020165,00020175,00020185,2832019 and thereafter50,000Total FHLB advances$73,283                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Schedule of Long-term Debt                                           | Long-term debt included of the following advances from the FHLB at the periods indicated. (dollars in thousands)          December 31,Maturity Interest Rate 2013 2012December 29, 2014 3.3125% $5,000 $5,000September 8, 2015 3.7100% 3,000 3,000September 27, 2016 0.9300% 5,000 —September 27, 2017 1.4200% 5,000 —March 19, 2018 2.8100% — 10,000July 16, 2018 2.4300% — 20,000July 18, 2018 2.3300% — 20,000August 27, 2018 6.1500% 283 328September 27, 2018 1.8400% 5,000 —June 15, 2020 1.6247% 50,000 —    $73,283 $58,328                                                                                                                                         |
| Junior Subordinated Debentures [Member]                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| **Debt Instrument [Line Items]**                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Schedule of Long-term Debt                                           | Information concerning the Junior Subordinated Debentures is as follows at the periods indicated. (dollars in thousands)   Commencement           Stated of Early As of December 31,   Maturity Redemption 2013 2012 Issuer Date Period Principal Unpaid Interest Principal Unpaid InterestInterest RateFNB Trust I 12/15/2035 12/15/2010 $20,619 $753 $20,619 $4033 month LIBOR + 1.37% =1.616% at 12/31/13FNB Trust II 6/30/2036 6/30/2011 30,928 1,078 30,928 5673 month LIBOR + 1.32% =1.566% at 12/31/13Catawba Trust II 12/30/2032 12/30/2007 5,155 404 5,155 2043 month LIBOR + 3.35% =3.596% at 12/31/13Total Junior Subordinated Debentures     $56,702 $2,235 $56,702 $1,174  |

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| - Definition
Schedule of Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned [Table Text Block]
+ References
No definition available.
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| - Definition
Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.
+ References
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| - Definition
Tabular disclosure of information pertaining to short-term and long-debt instruments or arrangements, including but not limited to identification of terms, features, collateral requirements and other information necessary to a fair presentation.
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No definition available.
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| - Definition
Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented.
+ References
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