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Accumulated Other Comprehensive Income (Loss) (Components of unrealized holding gains on AFS securities) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Unrealized gains (losses) on AFS securities arising during the period | $ 4,876 | $ (1,978) | $ 10,830 | $ (10,035)
Tax effect | (1,018) | 442 | (2,213) | 2,126
Unrealized gains (losses), net of tax | 3,757 | (1,511) | 8,452 | (7,788)
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 | 4,876 | (1,978) | 10,830 | (10,035)
Tax effect | (1,018) | 442 | (2,213) | 2,126
Unrealized gains (losses), net of tax | 3,858 | (1,536) | 8,617 | (7,909)
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 | 30 | 123 | 295 | 86
Tax effect | 0 | 0 | 0 | 0
Unrealized gains (losses), net of tax | 30 | 123 | 295 | 86
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 | 4,846 | (2,101) | 10,535 | (10,121)
Tax effect | (1,018) | 442 | (2,213) | 2,126
Unrealized gains (losses), net of tax | 3,828 | (1,659) | 8,322 | (7,995)
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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- Definition Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669646-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e640-108580 + Details
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