Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), before Tax		$ (104,352)	$ (86,690)
Long-term obligations		924,905	710,097		$ 740,186
Deferred tax expense (benefit)		(39,912)	(33,709)
Accumulated other comprehensive income (loss), net of tax		(64,440)	(52,981)		(25,268)
Income taxes		(122,028)	(65,032)		(101,574)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	81	14,598
Securities gains (losses)		10,817	29,096		0
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), before Tax		(24,504)	8,343
Deferred tax expense (benefit)		(9,379)	3,245
Accumulated other comprehensive income (loss), net of tax	[2]	(15,125)	5,098		(10,091)
Income taxes	[1]	(4,138)	(11,224)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]	6,679	17,872
Securities gains (losses)	[1]	10,817	29,096
Funded Status of Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), before Tax		(78,419)	(90,696)
Deferred tax expense (benefit)		(29,996)	(35,281)
Accumulated other comprehensive income (loss), net of tax	[2]	(48,423)	(55,415)		(10,743)
Income taxes	[1]	4,988	2,084
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]	(6,598)	(3,274)
Employee Benefits, prior service costs	[1]	(210)	(210)
Reclassification adjustment for losses included in income before income taxes	[1]	(11,376)	(5,148)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax		(11,586)	(5,358)	[1]
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), before Tax		(1,429)	(4,337)
Deferred tax expense (benefit)		(537)	(1,673)
Accumulated other comprehensive income (loss), net of tax	[2]	(892)	(2,664)		$ (4,434)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]	$ 0	$ 0

[1] (Dollars in thousands) Year ended December 31, 2015Details about accumulated other comprehensive income (loss) Amount reclassified from accumulated other comprehensive income (loss)(1) Affected line item in the statement where net income is presentedUnrealized gains and losses on available for sale securities $10,817 Securities gains (4,138) Income taxes $6,679 Net income Amortization of defined benefit pension items Prior service costs $(210) Employee benefitsActuarial losses (11,376) Employee benefits (11,586) Employee benefits 4,988 Income taxes $(6,598) Net incomeTotal reclassifications for the period $81 Year ended December 31, 2014Details about accumulated other comprehensive income (loss) Amount reclassified from accumulated other comprehensive income (loss)(1) Affected line item in the statement where net income is presentedUnrealized gains and losses on available for sale securities $29,096 Securities gains (11,224) Income taxes $17,872 Net income Amortization of defined benefit pension items Prior service costs $(210) Employee benefitsActuarial losses (5,148) Employee benefits (5,358) Employee benefits 2,084 Income taxes $(3,274) Net incomeTotal reclassifications for the period $14,598 (1) Amounts in parentheses indicate debits to profit/loss.

[2] All amounts are net of tax. Amounts in parentheses indicate debits.