| **Investment Securities (Continuous Unrealized Loss Position) (Details) (USD $)In Thousands, unless otherwise specified** | Sep. 30, 2013securities | Dec. 31, 2012securities |
|---------------------------------------------------------------------------------------------------------------------------|-------------------------|-------------------------|
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                                         |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | $ 344,772               | $ 134,237               |
| Less than 12 months, gross unrealized losses                                                                              | 19,373                  | 1,375                   |
| 12 months or more, estimated fair value                                                                                   | 0                       | 7,027                   |
| 12 months or more, gross unrealized losses                                                                                | 0                       | 44                      |
| Total, estimated fair value                                                                                               | 344,772                 | 141,264                 |
| Total, gross unrealized losses                                                                                            | 19,373                  | 1,419                   |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                                           |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 146,474                 |                    |
| Less than 12 months, gross unrealized losses                                                                              | 7,210                   |                    |
| 12 months or more, estimated fair value                                                                                   | 0                       |                    |
| 12 months or more, gross unrealized losses                                                                                | 0                       |                    |
| Total, estimated fair value                                                                                               | 146,474                 |                    |
| Total, gross unrealized losses                                                                                            | 7,210                   |                    |
| **Continuous Unrealized Loss Position [Abstract]**                                                                        |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 491,246                 |                    |
| Less than 12 months, gross unrealized losses                                                                              | 26,583                  |                    |
| 12 months or more, estimated fair value                                                                                   | 0                       |                    |
| 12 months or more, gross unrealized losses                                                                                | 0                       |                    |
| Total, estimated fair value                                                                                               | 491,246                 |                    |
| Total, gross unrealized losses                                                                                            | 26,583                  |                    |
| 12 months or more, number of securities                                                                                   | 0                       | 4                       |
| Residential mortgage-backed securities - GSE [Member]                                                                     |                    |                    |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                                         |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 312,145                 | 123,489                 |
| Less than 12 months, gross unrealized losses                                                                              | 17,358                  | 904                     |
| 12 months or more, estimated fair value                                                                                   | 0                       | 7,027                   |
| 12 months or more, gross unrealized losses                                                                                | 0                       | 44                      |
| Total, estimated fair value                                                                                               | 312,145                 | 130,516                 |
| Total, gross unrealized losses                                                                                            | 17,358                  | 948                     |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                                           |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 137,055                 |                    |
| Less than 12 months, gross unrealized losses                                                                              | 6,556                   |                    |
| 12 months or more, estimated fair value                                                                                   | 0                       |                    |
| 12 months or more, gross unrealized losses                                                                                | 0                       |                    |
| Total, estimated fair value                                                                                               | 137,055                 |                    |
| Total, gross unrealized losses                                                                                            | 6,556                   |                    |
| Residential mortgage-backed securities - Private [Member]                                                                 |                    |                    |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                                         |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 1,350                   | 7,499                   |
| Less than 12 months, gross unrealized losses                                                                              | 10                      | 454                     |
| 12 months or more, estimated fair value                                                                                   | 0                       | 0                       |
| 12 months or more, gross unrealized losses                                                                                | 0                       | 0                       |
| Total, estimated fair value                                                                                               | 1,350                   | 7,499                   |
| Total, gross unrealized losses                                                                                            | 10                      | 454                     |
| Commercial mortgage-backed securities - Private [Member]                                                                  |                    |                    |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                                         |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 21,644                  |                    |
| Less than 12 months, gross unrealized losses                                                                              | 1,219                   |                    |
| 12 months or more, estimated fair value                                                                                   | 0                       |                    |
| 12 months or more, gross unrealized losses                                                                                | 0                       |                    |
| Total, estimated fair value                                                                                               | 21,644                  |                    |
| Total, gross unrealized losses                                                                                            | 1,219                   |                    |
| **Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]**                                           |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 9,419                   |                    |
| Less than 12 months, gross unrealized losses                                                                              | 654                     |                    |
| 12 months or more, estimated fair value                                                                                   | 0                       |                    |
| 12 months or more, gross unrealized losses                                                                                | 0                       |                    |
| Total, estimated fair value                                                                                               | 9,419                   |                    |
| Total, gross unrealized losses                                                                                            | 654                     |                    |
| Corporate notes [Member]                                                                                                  |                    |                    |
| **Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]**                                         |                    |                    |
| Less than 12 months, estimated fair value                                                                                 | 9,633                   | 3,249                   |
| Less than 12 months, gross unrealized losses                                                                              | 786                     | 17                      |
| 12 months or more, estimated fair value                                                                                   | 0                       | 0                       |
| 12 months or more, gross unrealized losses                                                                                | 0                       | 0                       |
| Total, estimated fair value                                                                                               | 9,633                   | 3,249                   |
| Total, gross unrealized losses                                                                                            | $ 786                   | $ 17                    |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This represents the number of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer.
+ References
No definition available.
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| - Definition
Amount of the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for securities which are categorized neither as held-to-maturity nor trading securities.
+ References
No definition available.
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| - Definition
Amount of the excess of amortized cost basis over fair value of securities in a loss position and categorized neither as held-to-maturity nor trading securities.
+ References
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| - Definition
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| - Definition
Amount of the excess of amortized cost basis over fair value of securities that have been in a loss position for less than twelve months for securities categorized neither as held-to-maturity nor trading securities.
+ References
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| - Definition
This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for those securities which are categorized as held-to-maturity.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the excess of amortized cost basis over fair value of securities in a loss position and which are categorized as held-to-maturity.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the fair value of securities categorized as held-to-maturity which are in an unrealized loss position.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position for less than twelve months for those securities which are categorized as held-to-maturity.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the fair value of securities categorized as held-to-maturity that have been in a continuous unrealized loss position for less than twelve months.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the fair value of securities categorized as held-to-maturity securities that have been in a continuous unrealized loss position for twelve months or longer.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27337-111563Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27290-111563Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS115-1/124-1 -Paragraph 17 -Subparagraph a(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 03-1 -Paragraph 21 -Subparagraph a(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.
+ Details**Name:**us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |