Other Comprehensive Income (Loss) (Component Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
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	0	0	0	154,000
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Reclassification Adjustments, after Tax	(19,104,000)	(39,939,000)	(13,496,000)	(140,704,000)
Other comprehensive loss before reclassifications	(19,104,000)	(39,939,000)	(13,496,000)	(140,550,000)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	0	0	0	52,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	0	0	0	206,000
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax	(19,104,000)	(39,939,000)	(13,496,000)	(140,704,000)
Other comprehensive income (loss)	(19,104,000)	(39,939,000)	(13,496,000)	(140,498,000)
Changes in pension plan assets and benefit obligations, Net-of-tax amount	(6,680,000)	(5,792,000)	(6,680,000)	(5,792,000)	$ 6,680,000	$ 6,680,000	$ 5,792,000	$ 5,792,000
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	0	0	0	0	0	0	0	(206,000)
Unrealized gains on available-for-sale securities, Net-of-tax amount	(109,210,000)	(119,551,000)	(109,210,000)	(119,551,000)	(90,106,000)	(95,714,000)	(79,612,000)	21,153,000
Total accumulated other comprehensive income (loss), Net-of-tax amount	$ (115,890,000)	$ (125,343,000)	$ (115,890,000)	(125,343,000)	$ (96,786,000)	$ (102,394,000)	$ (85,404,000)	$ 15,155,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				52,000
Other Comprehensive Income (Loss), Cash Flow Hedge, Reclassification for Discontinuance, before Tax				$ 66,000