| **Interest-Bearing Deposits (Tables)**  | 12 Months Ended                                                                                                                                                                                                                                                                                                        |
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| **Deposits [Abstract]**                 |                                                                                                                                                                                                                                                                                                                   |
| Components of Interest-Bearing Deposits | Components of interest-bearing deposits at December 31 were as follows: 2013 2012 (dollars in thousands)Interest-bearing demand deposits$89,149 $97,963Savings deposits2,506,631 2,543,990Time deposits1,095,722 1,032,659Total interest-bearing deposits$3,691,502 $3,674,612 |
| Scheduled Maturities of Time Deposits   | Included in time deposits at December 31, 2013, were certificates of deposit with the following scheduled maturities (dollars in thousands):2014$746,8502015200,927201689,812201728,303201829,830Total$1,095,722                                                                                                  |

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