| **Investment Securities (Continuous Unrealized Loss Position) (Details) - USD ($) $ in Thousands** | Sep. 30, 2015 | Dec. 31, 2014 |
|----------------------------------------------------------------------------------------------------|---------------|---------------|
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                  |          |          |
| Less than 12 months, estimated fair value                                                          | $ 124,493     | $ 1,154       |
| Less than 12 months, gross unrealized losses                                                       | 994           | 4             |
| 12 months or more, estimated fair value                                                            | 138,683       | 277,630       |
| 12 months or more, gross unrealized losses                                                         | 3,569         | 6,162         |
| Total, estimated fair value                                                                        | 263,176       | 278,784       |
| Total, gross unrealized losses                                                                     | 4,563         | 6,166         |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                    |          |          |
| Less than 12 months, estimated fair value                                                          | 64,333        | 0             |
| Less than 12 months, gross unrealized losses                                                       | 714           | 0             |
| 12 months or more, estimated fair value                                                            | 36,624        | 122,876       |
| 12 months or more, gross unrealized losses                                                         | 304           | 1,702         |
| Total, estimated fair value                                                                        | 100,957       | 122,876       |
| Total, gross unrealized losses                                                                     | 1,018         | 1,702         |
| **Continuous Unrealized Loss Position [Abstract]**                                                 |          |          |
| Less than 12 months, estimated fair value                                                          | 188,826       | 1,154         |
| Less than 12 months, gross unrealized losses                                                       | 1,708         | 4             |
| 12 months or more, estimated fair value                                                            | 175,307       | 400,506       |
| 12 months or more, gross unrealized losses                                                         | 3,873         | 7,864         |
| Total, estimated fair value                                                                        | 364,133       | 401,660       |
| Total, gross unrealized losses                                                                     | 5,581         | 7,868         |
| Residential mortgage-backed securities - GSE [Member]                                              |          |          |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                  |          |          |
| Less than 12 months, estimated fair value                                                          | 91,601        | 0             |
| Less than 12 months, gross unrealized losses                                                       | 880           | 0             |
| 12 months or more, estimated fair value                                                            | 137,652       | 245,457       |
| 12 months or more, gross unrealized losses                                                         | 3,565         | 5,593         |
| Total, estimated fair value                                                                        | 229,253       | 245,457       |
| Total, gross unrealized losses                                                                     | 4,445         | 5,593         |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                    |          |          |
| Less than 12 months, estimated fair value                                                          | 45,712        | 0             |
| Less than 12 months, gross unrealized losses                                                       | 459           | 0             |
| 12 months or more, estimated fair value                                                            | 36,624        | 112,878       |
| 12 months or more, gross unrealized losses                                                         | 304           | 1,635         |
| Total, estimated fair value                                                                        | 82,336        | 112,878       |
| Total, gross unrealized losses                                                                     | 763           | 1,635         |
| Residential mortgage-backed securities - Private [Member]                                          |          |          |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                  |          |          |
| Less than 12 months, estimated fair value                                                          | 0             | 1,154         |
| Less than 12 months, gross unrealized losses                                                       | 0             | 4             |
| 12 months or more, estimated fair value                                                            | 1,031         | 0             |
| 12 months or more, gross unrealized losses                                                         | 4             | 0             |
| Total, estimated fair value                                                                        | 1,031         | 1,154         |
| Total, gross unrealized losses                                                                     | 4             | 4             |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                    |          |          |
| Less than 12 months, estimated fair value                                                          | 18,621        |          |
| Less than 12 months, gross unrealized losses                                                       | 255           |          |
| 12 months or more, estimated fair value                                                            | 0             |          |
| 12 months or more, gross unrealized losses                                                         | 0             |          |
| Total, estimated fair value                                                                        | 18,621        |          |
| Total, gross unrealized losses                                                                     | 255           |          |
| Commercial mortgage-backed securities - GSE [Member]                                               |          |          |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                  |          |          |
| Less than 12 months, estimated fair value                                                          | 0             | 0             |
| Less than 12 months, gross unrealized losses                                                       | 0             | 0             |
| 12 months or more, estimated fair value                                                            | 0             | 21,958        |
| 12 months or more, gross unrealized losses                                                         | 0             | 419           |
| Total, estimated fair value                                                                        | 0             | 21,958        |
| Total, gross unrealized losses                                                                     | 0             | 419           |
| Commercial mortgage-backed securities - Private [Member]                                           |          |          |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                  |          |          |
| Less than 12 months, estimated fair value                                                          | 12,564        | 0             |
| Less than 12 months, gross unrealized losses                                                       | 86            | 0             |
| 12 months or more, estimated fair value                                                            | 0             | 10,215        |
| 12 months or more, gross unrealized losses                                                         | 0             | 150           |
| Total, estimated fair value                                                                        | 12,564        | 10,215        |
| Total, gross unrealized losses                                                                     | 86            | 150           |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                    |          |          |
| Less than 12 months, estimated fair value                                                          | 0             | 0             |
| Less than 12 months, gross unrealized losses                                                       | 0             | 0             |
| 12 months or more, estimated fair value                                                            | 0             | 9,998         |
| 12 months or more, gross unrealized losses                                                         | 0             | 67            |
| Total, estimated fair value                                                                        | 0             | 9,998         |
| Total, gross unrealized losses                                                                     | 0             | $ 67          |
| Corporate notes [Member]                                                                           |          |          |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                  |          |          |
| Less than 12 months, estimated fair value                                                          | 20,328        |          |
| Less than 12 months, gross unrealized losses                                                       | 28            |          |
| Total, estimated fair value                                                                        | 20,328        |          |
| Total, gross unrealized losses                                                                     | $ 28          |          |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| - Definition
Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.
+ References
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| - Definition
Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.
+ References
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| - Definition
Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.
+ References
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| - Definition
Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity that have been in a continuous loss position for twelve months or longer.
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| - Definition
Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity in a continuous loss position.
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| - Definition
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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity that have been in a continuous loss position for less than twelve months.
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