Comprehensive Income (Components Of Other Comprehensive Income And Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Change in net unrealized holding gains (losses) on available-for-sale securities:
Change arising during the period		$ 8,417	$ (11,734)
Tax effect		2,536	(3,548)
Total		5,881	(8,186)
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 unrealized loss on derivative instrument:
Amount of loss recognized during the period		(1,614)
Reclassification adjustment for net interest expense included in net income	[2]	69
Change in unrealized loss on derivative instruments		(1,545)
Tax effect		(465)
Total		(1,080)
Other comprehensive income (loss)		$ 4,862	$ (8,186)

[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 7 - 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."