Comprehensive Income (Components Of Other Comprehensive Income (Loss) And Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Change in net unrealized holding gains (losses) on available-for-sale securities:
Change arising during the period		$ 8,442		$ 7,214		$ (408)	$ 15,631
Tax effect		2,528		2,151		(121)	4,687
Total		5,914		5,063		(287)	10,944
Change in funded status of pension plan:
Amortization of net actuarial loss included in net income	[1]			88			176
Tax effect				65			92
Total				23			84
Change in net unrealized loss on derivative instrument:
Amount of loss recognized during the period		(494)		(2,627)		(4,768)	(4,241)
Reclassification adjustment for net interest expense included in net income	[2]	856		114		1,366	183
Change in unrealized loss on derivative instruments		362		(2,513)		(3,402)	(4,058)
Tax effect		108		(747)		(1,021)	(1,212)
Total		254		(1,766)		(2,381)	(2,846)
Other comprehensive income (loss)		$ 6,168	$ (8,836)	$ 3,320	$ 4,862	$ (2,668)	$ 8,182

[1] 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 and included in the consolidated statements of income in the line item “Other noninterest income.”

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