| **Investment Securities (Tables)**                                                                                                                          | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
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| **Investments, Debt and Equity Securities [Abstract]**                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale                                                                       | Below is an analysis of the amortized cost and fair values of securities available for sale at December 31: 2013 2012 AmortizedCost GrossUnrealizedGains GrossUnrealizedLosses EstimatedFair Value AmortizedCost GrossUnrealizedGains GrossUnrealizedLosses EstimatedFair Value (dollars in thousands)Obligations of U.S. Government Agencies:               Mortgage-Backed Securities – Residential$22,639 $2,624 $(59) $25,204 $27,883 $3,781 $— $31,664Obligations of U.S. Government-Sponsored Enterprises:               Mortgage-Backed Securities – Residential1,009,519 12,531 (27,163) 994,887 839,102 25,691 (392) 864,401Mortgage-Backed Securities – Commercial104 1 — 105 148 1 — 149Other Government-Sponsored Enterprises267,971 81 (1,927) 266,125 241,970 766 (72) 242,664Obligations of States and Political Subdivisions80 — — 80 82 4 — 86Corporate Securities6,693 328 — 7,021 6,703 288 — 6,991Pooled Trust Preferred Collateralized Debt Obligations42,040 — (18,517) 23,523 51,866 3 (28,496) 23,373Total Debt Securities1,349,046 15,565 (47,666) 1,316,945 1,167,754 30,534 (28,960) 1,169,328Equities1,420 — — 1,420 1,859 116 — 1,975Total Securities Available for Sale$1,350,466 $15,565 $(47,666) $1,318,365 $1,169,613 $30,650 $(28,960) $1,171,303The amortized cost and fair value of debt securities at December 31, 2013, by contractual maturity, are shown below: AmortizedCost EstimatedFair Value (dollars in thousands)Due within 1 year$33,080 $33,141Due after 1 but within 5 years234,971 233,065Due after 5 but within 10 years— —Due after 10 years48,733 30,543 316,784 296,749Mortgage-Backed Securities (a)1,032,262 1,020,196Total Debt Securities$1,349,046 $1,316,945 (a)Mortgage Backed Securities include an amortized cost of $22.6 million and a fair value of $25.2 million for Obligations of U.S. Government agencies issued by Ginnie Mae and Obligations of U.S. Government-sponsored enterprises issued by Fannie Mae and Freddie Mac which had an amortized cost of $1,009.6 million and a fair value of $995.0 million. |
| Proceeds from Sale, Gross Gains (Losses) Realized on Sales, Maturities and Other-Than-Temporary Impairment Charges Related to Securities Available for Sale | Proceeds from sale, gross gains (losses) realized on sales, maturities and other-than-temporary impairment charges related to securities available for sale were as follows for the years ended December 31: 2013 2012 2011 (dollars in thousands)Proceeds from sales$671 $— $76,914Gross (losses) gains realized:     Sales Transactions:     Gross gains$233 $— $2,368Gross losses— — (258) 233 — 2,110Maturities and impairment     Gross gains4 192 75Gross losses(1,395) — —Other-than-temporary impairment— — — (1,391) 192 75Net gains and impairment$(1,158) $192 $2,185                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |

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| - Definition
Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.
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| - Definition
Tabular disclosure of the proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses that have been included in earnings as a result of those sales.
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