Comprehensive Income (Components Of Other Comprehensive Income (Loss) And Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Change in net unrealized holding gains (losses) on available-for-sale securities:
Change arising during the period		$ (8,850)	$ 8,417
Tax effect		(2,649)	2,536
Total		(6,201)	5,881
Change in funded status of pension plan:
Amortization of net actuarial loss included in net income	[1]		88
Tax effect			27
Total			61
Change in net unrealized loss on derivative instruments:
Amount of loss recognized during the period		(4,274)	(1,614)
Reclassification adjustment for net interest expense included in net income	[2]	510	69
Change in unrealized loss on derivative instruments		(3,764)	(1,545)
Tax effect		(1,129)	(465)
Total		(2,635)	(1,080)
Other comprehensive income (loss)		$ (8,836)	$ 4,862

[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 (see “Note 6 – Defined Benefit Pension Plan”) 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.”