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Accumulated Other Comprehensive Income (Loss) (Components of unrealized holding gains on AFS securities) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Unrealized gains (losses) on AFS securities arising during the period | $ (2,513) | $ (96) | $ (12,548) | $ 4,151
Reclassification adjustment for net (gains) losses included in net income | 0 | 0 | 0 | (142)
Tax effect | 522 | 54 | 2,648 | (1,158)
Unrealized gains (losses), net of tax | (1,986) | (35) | (9,774) | 2,829
Unrealized Holding Gains (Losses) on AFS Securities [Member] |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Unrealized gains (losses) on AFS securities arising during the period | (2,513) | (96) | (12,548) | 4,151
Reclassification adjustment for net (gains) losses included in net income | 0 | 0 | 0 | (142)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent | (2,513) | (96) | (12,548) | 4,009
Tax effect | 522 | 54 | 2,648 | (1,158)
Unrealized gains (losses), net of tax | (1,991) | (42) | (9,900) | 2,851
Unrealized Holding Gains (Losses) on AFS Securities [Member] | Auction Rate Money Market Preferred and Preferred Stocks [Member] |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Unrealized gains (losses) on AFS securities arising during the period | (27) | 63 | 59 | 604
Reclassification adjustment for net (gains) losses included in net income | 0 | 0 | 0 | 0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent | (27) | 63 | 59 | 604
Tax effect | 0 | 0 | 0 | 0
Unrealized gains (losses), net of tax | (27) | 63 | 59 | 604
Unrealized Holding Gains (Losses) on AFS Securities [Member] | All Other AFS Securities [Member] |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Unrealized gains (losses) on AFS securities arising during the period | (2,486) | (159) | (12,607) | 3,547
Reclassification adjustment for net (gains) losses included in net income | 0 | 0 | 0 | (142)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent | (2,486) | (159) | (12,607) | 3,405
Tax effect | 522 | 54 | 2,648 | (1,158)
Unrealized gains (losses), net of tax | (1,964) | (105) | (9,959) | 2,247
Accumulated Defined Benefit Plans Adjustment [Member] |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Unrealized gains (losses), net of tax | $ 0 | $ 0 | $ 0 | $ 0

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