Accumulated Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), before Tax		$ (24,337)		$ (24,337)			$ (104,352)
Deferred tax expense (benefit)		(9,310)		(9,310)			(39,912)
Accumulated other comprehensive income (loss), net of tax		(15,027)	$ (51,159)	(15,027)	$ (51,159)	$ (23,824)	(64,440)	$ (35,411)	$ (52,981)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		6,573	(1,691)	8,411	(305)
Amortization of actuarial losses and prior service cost		(1,830)	(2,835)	(3,430)	(5,668)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax		1,882	2,887	3,534	5,773
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), before Tax		50,548		50,548			(24,504)
Deferred tax expense (benefit)		19,335		19,335			(9,379)
Accumulated other comprehensive income (loss), net of tax	[1]	31,213	2,604	31,213	2,604	24,034	(15,125)	20,551	5,098
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	7,736	73	10,594	3,222
Funded Status of Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), before Tax		(74,885)		(74,885)			(78,419)
Deferred tax expense (benefit)		(28,645)		(28,645)			(29,996)
Accumulated other comprehensive income (loss), net of tax	[1]	(46,240)	(51,888)	(46,240)	(51,888)	(47,403)	(48,423)	(53,652)	(55,415)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	(1,163)	(1,764)	(2,183)	(3,527)
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), before Tax		0		0			(1,429)
Deferred tax expense (benefit)		0		0			(537)
Accumulated other comprehensive income (loss), net of tax	[1]	0	(1,875)	0	(1,875)	$ (455)	$ (892)	$ (2,310)	$ (2,664)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	$ 0	$ 0	$ 0	$ 0

[1] All amounts are net of tax.