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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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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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