| **Investment Securities**                              | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                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| **Investments, Debt and Equity Securities [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       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| Investment Securities                                  | Investment SecuritiesSecurities designated as available-for-sale are carried at fair value.  However, the unrealized difference between amortized cost and fair value of securities available-for-sale is excluded from net income unless there is an other than temporary impairment and is reported, net of deferred taxes, as a component of shareholders' equity as accumulated other comprehensive income (loss).  Securities held-to-maturity are carried at amortized cost, as the bank has the ability, and management has the positive intent, to hold these securities to maturity.  Premiums and discounts on securities are amortized and accreted according to the interest method.Our primary objective in managing the investment portfolio is to maintain a portfolio of high quality, highly liquid investments yielding competitive returns.  We are required under federal regulations to maintain adequate liquidity to ensure safe and sound operations.  We maintain investment balances based on a continuing assessment of cash flows, the level of loan production, current interest rate risk strategies and an assessment of the potential future direction of market interest rate changes.  Investment securities differ in terms of default, interest rate, liquidity and expected rate of return risks.The following table summarizes the amortized cost and estimated fair value of investment securities and presents the related gross unrealized gains and losses:June 30, 2013        (dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair ValueAvailable for Sale:        Obligations of:        U.S. government sponsored enterprises $2,063 $21 $— $2,084Residential mortgage-backed securities-GSE 386,628 1,013 18,658 368,983Residential mortgage-backed securities-Private 21,220 1,614 10 22,824Commercial mortgage backed securities-GSE 22,959 — 1,461 21,498Commercial mortgage-backed securities-Private 10,430 — 855 9,575Corporate notes 28,242 204 — 28,446Total available for sale $471,542 $2,852 $20,984 $453,410Held to Maturity:        Residential mortgage-backed securities-GSE 144,723 — 5,324 139,399Commercial mortgage-backed securities-Private 10,074 — 728 9,346     Total held to maturity $154,797 $— $6,052 $148,745Total investment securities $626,339 $2,852 $27,036 $602,155         December 31, 2012        (dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair ValueAvailable for Sale:        Obligations of:        U.S. Treasury and government agencies $6,646 $335 $— $6,981U.S. government sponsored enterprises 22,118 55 — 22,173States and political subdivisions 5,918 120 — 6,038Residential mortgage-backed securities-GSE 436,344 5,678 948 441,074Residential mortgage-backed securities-Private 22,649 750 454 22,945Commercial mortgage backed securities-GSE 23,150 209 — 23,359Commercial mortgage backed securities-Private 5,283 34 — 5,317Corporate notes 36,710 270 17 36,963Total $558,818 $7,451 $1,419 $564,850As a member of the Federal Home Loan Bank of Atlanta (“FHLB”), the Bank is required to own capital stock in the FHLB based generally upon the balances of total assets and FHLB advances.  FHLB capital stock is pledged to secure FHLB advances.  This investment is carried at cost since no ready market exists for FHLB stock and there is no quoted market value.  However, redemption of this stock has historically been at par value.  The Bank owned a total of $5.2 million of FHLB stock at June 30, 2013 and $6.3 million at December 31, 2012.  Due to the redemption provisions of FHLB stock, we have estimated that fair value approximated cost and that this investment was not impaired at June 30, 2013.  FHLB stock is included in other assets at its original cost basis.As a member bank of the Federal Reserve Bank of Richmond (“FRBR”), the Bank also is required to own capital stock of the FRBR based upon a percentage of the bank's common stock and surplus.  This investment is carried at cost since no ready market exists for FRBR stock and there is no quoted market value.  At June 30, 2013 and December 31, 2012, the Bank owned a total of $2.6 million and $3.1 million of FRBR stock, respectively.  Due to the nature of this investment in an entity of the U.S. government, we have estimated that fair value approximated the cost and that this investment was not impaired at June 30, 2013.  FRBR stock is included in other assets at its original cost basis.At June 30, 2013, $97.0 million of the investment securities portfolio was pledged to secure public deposits, $13.0 million was pledged to retail repurchase agreements and $2.1 million was pledged to others, leaving $490.1 million available as lendable collateral.During the three and six months ended June 30, 2013, the Bank sold securities with a book value of  $25.7 million and $171.8 million respectively, and recognized gains of $0.3 million and $2.7 million, respectively. During the three and six months ended June 30, 2012, the Bank sold securities with a book value of $112.7 million and recognized gains of $2.0 million. The Bank sold these securities in order to manage our interest rate sensitivity profile.The following tables show our investments' estimated fair value and gross unrealized losses, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position, at June 30, 2013 and December 31, 2012.  The change in unrealized losses during the three and six month periods ending June 30, 2013 was attributed to changes in interest rates and not to changes in the credit quality of these securities. All unrealized losses on investment securities are considered by management to be temporary given the credit ratings on these investment securities or the short duration of the unrealized loss, or both. Less than 12 Months 12 Months or More Total(dollars in thousands)Estimated Fair ValueGross Unrealized Losses Estimated Fair ValueGross Unrealized Losses Estimated Fair ValueGross Unrealized LossesJune 30, 2013        Available for Sale:        Residential mortgage-backed securities-GSE$322,395$18,658 $—$— $322,395$18,658Residential mortgage-backed securities-Private—— 64310 64310Commercial mortgage-backed securities-GSE21,4981,461 —— 21,4981,461Commercial mortgage-backed securities-Private9,575855 —— 9,575855Total available for sale$353,468$20,974 $643$10 $354,111$20,984Held to Maturity:        Residential mortgage-backed securities-GSE$119,794$5,324 $—$— $119,794$5,324Commercial mortgage-backed securities-Private9,346728 —— 9,346728Total held to maturity$129,140$6,052 $—$— $129,140$6,052Total$482,608$27,026 $643$10 $483,251$27,036         December 31, 2012        Obligations of:        Residential mortgage-backed securities-GSE$123,489$904 $7,027$44 $130,516$948Residential mortgage-backed securities-Private7,499454 —— 7,499454Corporate notes3,24917 —— 3,24917Total$134,237$1,375 $7,027$44 $141,264$1,419At June 30, 2013 and December 31, 2012, there were one and four available-for-sale securities that were in an unrealized loss position for longer than 12 months, respectively.If an entity has a debt security that has been in a loss position for over 12 months and it cannot assert it is more likely than not that it will not have to sell the security before recovery, then other than temporary impairment ("OTTI") must be taken.  The amount of impairment is bifurcated between impairment due to credit (which is recorded through earnings) and noncredit impairment (which becomes a component of other comprehensive income (“OCI”) for both available-for-sale and held-to-maturity securities).  For held-to-maturity securities, the amount in OCI will be amortized prospectively over the security's remaining life. After analyzing its securities portfolio at June 30, 2013, and after considering ratings, fair value, cash flows and other factors,  we did not have any OTTI during the three or six months ended June 30, 2013 and June 30, 2012.The aggregate amortized cost and fair value of securities at June 30, 2013, by remaining contractual maturity, are shown in the following table.  Actual expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations.  Available-for-Sale Held-to-Maturity(dollars in thousands) Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair ValueDue in one year or less $8,139 $8,193 $— $—Due after one year through five years 18,884 18,994 — —Due after five years through 10 years 3,282 3,342 — —Due after 10 years — — — —Total 30,305 30,529 — —Mortgage-backed securities 441,237 422,881 154,797 148,745Total $471,542 $453,410 $154,797 $148,745 |

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| - Definition
The entire disclosure for  investments in certain debt and equity securities.
+ References
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