| **Investment Securities (Tables)**                                 | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
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| **Investments, Debt and Equity Securities [Abstract]**             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Schedule of Available-for-sale Securities Reconciliation           | The following table summarizes the amortized cost and estimated fair value of investment securities and presents the related gross unrealized gains and losses:March 31, 2013        (dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair ValueAvailable for Sale:        Obligations of:        U.S. government sponsored enterprises $2,069 $38 $— $2,107Residential mortgage-backed securities-GSE 409,949 1,794 3,279 408,464Residential mortgage-backed securities-Private 21,992 879 250 22,621Commercial mortgage backed securities-GSE 23,054 — 658 22,396Corporate notes 36,567 240 40 36,767Total $493,631 $2,951 $4,227 $492,355Held to Maturity:        Residential mortgage-backed securities-GSE 73,515 1 271 73,245     Total $567,146 $2,952 $4,498 $565,600         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 $564,850 |
| Available-for-sale Securities, Continuous Unrealized Loss Position | 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 March 31, 2013 and December 31, 2012.  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 LossesMarch 31, 2013        Available for Sale:        Residential mortgage-backed securities-GSE$284,396$3,279 $—$— $284,396$3,279Residential mortgage-backed securities-Private3,365217 4,02533 7,390250Commercial mortgage-backed securities-GSE22,396658 —— 22,396658Corporate notes—— 3,23440 3,23440Total$310,157$4,154 $7,259$73 $317,416$4,227Held to Maturity:        Residential mortgage-backed securities-GSE$48,036$272 $—$— $48,036$272         December 31, 2012        Obligations of:        Residential mortgage-backed securities-GSE$123,489$904 $7,027$44 $130,516$948Residential mortgage-backed securities-Private6,482438 1,01716 7,499454Corporate notes—— 3,24917 3,24917Total$129,971$1,342 $11,293$77 $141,264$1,419                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Available-for-sale Securities, by Maturity Dates                   | The aggregate amortized cost and fair value of securities at March 31, 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 $16,458 $16,551 $— $—Due after one year through five years 18,904 19,089 — —Due after five years through 10 years 3,274 3,234 — —Due after 10 years — — — —Total 38,636 38,874 — —Mortgage-backed securities 454,995 453,481 73,515 73,245Total $493,631 $492,355 $73,515 $73,245                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |

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| - Definition
Tabular disclosure of fair value of investments in debt and equity securities in an unrealized loss position categorized neither as held-to-maturity nor trading securities.
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No definition available.
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| - Definition
Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments.
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| - Definition
Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value.
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No definition available.
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