| **Investment Securities (Tables)**                                                                                                                          | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
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| **Investments, Debt and Equity Securities [Abstract]**                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Analysis of Amortized Cost and Estimated Fair Value of Securities Available for Sale                                                                        | Below is an analysis of the amortized cost and estimated fair values of securities available for sale at: June 30, 2014 December 31, 2013 AmortizedCost GrossUnrealizedGains GrossUnrealizedLosses EstimatedFair Value AmortizedCost GrossUnrealizedGains GrossUnrealizedLosses EstimatedFair Value (dollars in thousands)Obligations of U.S. Government Agencies:               Mortgage-Backed Securities – Residential$20,686 $2,617 $— $23,303 $22,639 $2,624 $(59) $25,204Obligations of U.S. Government-Sponsored Enterprises:             Mortgage-Backed Securities – Residential1,001,669 15,257 (13,807) 1,003,119 1,009,519 12,531 (27,163) 994,887Mortgage-Backed Securities – Commercial88 2 — 90 104 1 — 105Other Government-Sponsored Enterprises269,175 15 (803) 268,387 267,971 81 (1,927) 266,125Obligations of States and Political Subdivisions15,738 156 (5) 15,889 80 — — 80Corporate Securities6,688 561 — 7,249 6,693 328 — 7,021Pooled Trust Preferred Collateralized Debt Obligations41,851 109 (13,806) 28,154 42,040 — (18,517) 23,523Total Debt Securities1,355,895 18,717 (28,421) 1,346,191 1,349,046 15,565 (47,666) 1,316,945Equities1,420 — — 1,420 1,420 — — 1,420Total Securities Available for Sale$1,357,315 $18,717 $(28,421) $1,347,611 $1,350,466 $15,565 $(47,666) $1,318,365 |
| Amortized Cost and Estimated Fair Value of Debt Securities Available for Sale                                                                               | he amortized cost and estimated fair value of debt securities available for sale at June 30, 2014, by contractual maturity, are shown below.  AmortizedCost EstimatedFair Value (dollars in thousands)Due within 1 year$2,600 $2,601Due after 1 but within 5 years266,575 265,786Due after 5 but within 10 years8,402 8,506Due after 10 years55,875 42,786 333,452 319,679Mortgage-Backed Securities (a)1,022,443 1,026,512Total Debt Securities$1,355,895 $1,346,191 (a)Mortgage Backed Securities include an amortized cost of $20.7 million and a fair value of $23.3 million for Obligations of U.S.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Proceeds from Sale, Gross Gains (Losses) Realized on Sales, Maturities and Other-Than-Temporary Impairment Charges Related to Securities Available for Sale | Proceeds from sales, gross gains (losses) realized on sales, maturities and other-than-temporary impairment charges related to securities available for sale were as follows for the six months endedJune 30: 2014 2013 (dollars in thousands)Proceeds from sales$— $42Gross gains (losses) realized:   Sales Transactions:   Gross gains$— $4Gross losses— — — 4Maturities and impairment   Gross gains2 4Gross losses— — 2 4Net gains and impairment$2 $8                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |

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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 maturities of an entity's investments as well as any other information pertinent to the investments.
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No definition available.
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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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