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Accumulated Other Comprehensive Income (Loss) (Components of unrealized holding gains on AFS securities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gains (losses) on AFS securities arising during the period	$ 6,311	$ 5,954
Reclassification adjustment for net (gains) losses included in net income	(71)	0
Tax effect	(1,393)	(1,195)
Unrealized gains (losses), net of tax	4,739	4,695
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	6,311	5,954
Reclassification adjustment for net (gains) losses included in net income	(71)	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	6,240	5,954
Tax effect	(1,393)	(1,195)
Unrealized gains (losses), net of tax	4,847	4,759
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	(393)	265
Reclassification adjustment for net (gains) losses included in net income	0	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	(393)	265
Tax effect	0	0
Unrealized gains (losses), net of tax	(393)	265
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	6,704	5,689
Reclassification adjustment for net (gains) losses included in net income	(71)	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	6,633	5,689
Tax effect	(1,393)	(1,195)
Unrealized gains (losses), net of tax	5,240	4,494
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized gains (losses), net of tax	$ 0	$ 0

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Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.

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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.

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