Other Comprehensive Income (Loss) (Component Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax	$ 0	$ 0	$ 0	$ 0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax	113	15	238	(468)
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Reclassification Adjustments, after Tax	4,858	8,359	(8,739)	26,535
Other comprehensive loss before reclassifications	4,971	8,374	(8,501)	26,067
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	113	15	238	(468)
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax	4,858	5,742	(8,739)	23,918
Other comprehensive income (loss)	4,971	5,757	(8,501)	23,450
Changes in pension plan assets and benefit obligations, Net-of-tax amount	(34,421)	(26,674)	(34,421)	(26,674)	$ 34,421	$ 34,421	$ 26,674	$ 26,674
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	(460)	(922)	(460)	(922)	(573)	(698)	(937)	(454)
Unrealized gains on available-for-sale securities, Net-of-tax amount	31,951	41,457	31,951	41,457	27,093	40,690	35,715	17,539
Total accumulated other comprehensive income (loss), Net-of-tax amount	(2,930)	13,861	(2,930)	13,861	$ (7,901)	$ 5,571	$ 8,104	$ (9,589)
Debt Securities, Realized Gain (Loss)	0	(3,313)	0	(3,313)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	$ 0	$ (2,617)	$ 0	$ (2,617)