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Fair Value (Recorded amount of assets and liabilities measured at fair value) (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 31, 2017
--- | --- | ---
AFS Securities |  |
AFS securities | $ 547,762 | $ 548,730
Available-for-sale Securities, Equity Securities | 3,575 | 3,577
Fair value, total | 570,684 | 568,554
Level 1 [Member] |  |
AFS Securities |  |
Fair value, total | $ 3,575 | $ 3,577
Percent of assets and liabilities measured at fair value | 0.63% | 0.63%
Level 2 [Member] |  |
AFS Securities |  |
Fair value, total | $ 548,175 | $ 549,021
Percent of assets and liabilities measured at fair value | 96.06% | 96.56%
Level 3 [Member] |  |
AFS Securities |  |
Fair value, total | $ 18,934 | $ 15,956
Percent of assets and liabilities measured at fair value | 3.31% | 2.81%
Recurring items [Member] |  |
AFS Securities |  |
AFS securities | $ 547,762 | $ 548,730
Available-for-sale Securities, Equity Securities | 3,575 | 3,577
Derivative instruments | (413) | 291
Recurring items [Member] | Government sponsored enterprises [Member] |  |
AFS Securities |  |
AFS securities | 202 | 216
Recurring items [Member] | States and political subdivisions [Member] |  |
AFS Securities |  |
AFS securities | 211,633 | 208,474
Recurring items [Member] | Auction rate money market preferred [Member] |  |
AFS Securities |  |
AFS securities | 3,012 | 3,049
Recurring items [Member] | Mortgage-backed securities [Member] |  |
AFS Securities |  |
AFS securities | 206,861 | 208,797
Recurring items [Member] | Collateralized mortgage obligations [Member] |  |
AFS Securities |  |
AFS securities | 126,054 | 128,194
Recurring items [Member] | Level 1 [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Available-for-sale Securities, Equity Securities | 3,575 | 3,577
Derivative instruments | 0 | 0
Recurring items [Member] | Level 1 [Member] | Government sponsored enterprises [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 1 [Member] | States and political subdivisions [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 1 [Member] | Auction rate money market preferred [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 1 [Member] | Mortgage-backed securities [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 1 [Member] | Collateralized mortgage obligations [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 2 [Member] |  |
AFS Securities |  |
AFS securities | 547,762 | 548,730
Available-for-sale Securities, Equity Securities | 0 | 0
Derivative instruments | 413 | 291
Recurring items [Member] | Level 2 [Member] | Government sponsored enterprises [Member] |  |
AFS Securities |  |
AFS securities | 202 | 216
Recurring items [Member] | Level 2 [Member] | States and political subdivisions [Member] |  |
AFS Securities |  |
AFS securities | 211,633 | 208,474
Recurring items [Member] | Level 2 [Member] | Auction rate money market preferred [Member] |  |
AFS Securities |  |
AFS securities | 3,012 | 3,049
Recurring items [Member] | Level 2 [Member] | Mortgage-backed securities [Member] |  |
AFS Securities |  |
AFS securities | 206,861 | 208,797
Recurring items [Member] | Level 2 [Member] | Collateralized mortgage obligations [Member] |  |
AFS Securities |  |
AFS securities | 126,054 | 128,194
Recurring items [Member] | Level 3 [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Available-for-sale Securities, Equity Securities | 0 | 0
Derivative instruments | 0 | 0
Recurring items [Member] | Level 3 [Member] | Government sponsored enterprises [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 3 [Member] | States and political subdivisions [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 3 [Member] | Auction rate money market preferred [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 3 [Member] | Mortgage-backed securities [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Recurring items [Member] | Level 3 [Member] | Collateralized mortgage obligations [Member] |  |
AFS Securities |  |
AFS securities | 0 | 0
Nonrecurring items [Member] |  |
AFS Securities |  |
Impaired loans (net of the allowance for loan losses) | 18,934 | 15,956
Nonrecurring items [Member] | Level 1 [Member] |  |
AFS Securities |  |
Impaired loans (net of the allowance for loan losses) | 0 | 0
Nonrecurring items [Member] | Level 2 [Member] |  |
AFS Securities |  |
Impaired loans (net of the allowance for loan losses) | 0 | 0
Nonrecurring items [Member] | Level 3 [Member] |  |
AFS Securities |  |
Impaired loans (net of the allowance for loan losses) | $ 18,934 | $ 15,956

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