Other Comprehensive Income (Loss) (Component Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income before reclassifications	$ 707	$ (2,182)	$ 4,740	$ 13,850
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	0	0	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax	0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	707	(2,182)	4,740	13,850
Other comprehensive income (loss)	707	(2,182)	4,740	13,850
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax	707	(2,182)	4,740	13,850
Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax		0	0	0
Changes in pension plan assets and benefit obligations, Net-of-tax amount	(14,740)	(15,351)	(14,740)	(15,351)	$ 14,740	$ 14,740	$ 15,351	$ 15,351
Unrealized gains on available-for-sale securities, Net-of-tax amount	1,735	13,558	1,735	13,558	1,028	(3,005)	15,740	(292)
Total accumulated other comprehensive income (loss), Net-of-tax amount	$ (13,005)	$ (1,793)	(13,005)	$ (1,793)	$ (13,712)	$ (17,745)	$ 389	$ (15,643)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax			$ 0