Comprehensive Income (Components Of Other Comprehensive Income (Loss) And Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended						9 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Change in net unrealized holding gains (losses) on available-for-sale securities:
Change arising during the period		$ 848			$ (7,231)			$ 16,479	$ (22,059)
Reclassification adjustment for net loss included in net income	[1]				4,960				4,960
Change in net unrealized holding gains (losses) on available-for-sale securities		848			(2,271)			16,479	(17,099)
Tax effect		254			(686)			4,941	(5,166)
Total		594			(1,585)			11,538	(11,933)
Change in funded status of pension plan:
Amortization of net actuarial loss included in net income	[2]	88						264
Tax effect		26						118
Total		62						146
Change in net unrealized gain (loss) on derivative instruments:
Change arising during the period		(516)			462			(4,757)	(34)
Reclassification adjustment for net interest expense included in net income	[3]	240			225			423	315
Change in unrealized loss on derivative instruments		(276)			687			(4,334)	281
Tax effect		(83)			207			(1,295)	85
Total		(193)			480			(3,039)	196
Other comprehensive income (loss)		$ 463	$ 3,320	$ 4,862	$ (1,105)	$ (2,446)	$ (8,186)	$ 8,645	$ (11,737)

[1] Represents net realized loss arising from the sale of available-for-sale securities. The net realized loss is included in the consolidated statements of income in the line item, “Net loss on sales of securities.” See “Note 4 – Investment Securities” for the income tax benefit related to the net realized loss, which is included in the consolidated statements of income in the line item, “Income tax expense.”

[2] Represents the amortization of net actuarial loss relating to the Corporation’s defined benefit pension plan. This item is a component of net periodic pension cost (see “Note 7 – Defined Benefit Pension Plan”) and included in the consolidated statements of income in the line item, “Other noninterest income.”

[3] Represents the net interest expense recorded on derivative transactions and included in the consolidated statements of income under “Interest expense.”