Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), before Tax	$ 12,696	$ 15,926
Deferred tax expense (benefit)	2,920	3,663
Accumulated other comprehensive income (loss), net of tax	9,776	12,263
Income taxes	(154,202)	(126,159)	$ (134,677)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,776	27,276
Unrealized (losses) gains on securities available for sale
Accumulated Other Comprehensive Income (Loss), before Tax	(11,792)	102,278
Deferred tax expense (benefit)	(2,712)	23,524
Accumulated other comprehensive income (loss), net of tax	(9,080)	78,754
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	25,502	46,395
Defined benefit pension items
Accumulated Other Comprehensive Income (Loss), before Tax	33,223	(91,751)
Deferred tax expense (benefit)	7,641	(21,103)
Accumulated other comprehensive income (loss), net of tax	25,582	(70,648)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(20,862)	(19,500)
Reclassification adjustment for losses included in income before income taxes		(25,324)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax	(27,093)
Unrealized (losses) gains on securities available for sale transferred to held to maturity
Other Comprehensive Income (Loss) Reclassification Adjustment Of Unrealized Losses From AOCI For Securities Available For Sale Transferred To Held To Maturity Before Tax	1,475	495
Accumulated Other Comprehensive Income (Loss), before Tax	(8,735)	5,399
Deferred tax expense (benefit)	(2,009)	1,242
Accumulated other comprehensive income (loss), net of tax	(6,726)	4,157
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,136	381
Other Comprehensive Income (Loss) Reclassification Adjustment Of Unrealized Losses From AOCI For Securities Available For Sale Transferred To Held To Maturity Tax	(339)	(114)
Other Comprehensive Income (Loss) Reclassification Adjustment Of Unrealized Losses From AOCI For Securities Available For Sale Transferred To Held To Maturity Net Of Tax	$ 1,136	$ 381