Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012		Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), before Tax	$ (156,536)				$ (156,536)						$ (134,923)
Long-term obligations	179,183		215,356		563,593		651,740
Deferred tax expense (benefit)	(60,991)				(60,991)						(52,817)
Accumulated other comprehensive income (loss), net of tax	(95,545)	[1]	(51,986)		(95,545)	[1]	(51,986)		(100,176)		(82,106)	[2]	(62,407)		(66,574)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(2,668)	[3]	(2,142)	[3]	(8,887)	[3]	(6,458)	[3]
Securities gains (losses)	0		31		0		(11)
Reclassification adjustment for losses included in income before income taxes	4,298		2,788		12,896		8,368
Unrealized Gains on Investment Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), before Tax	(3,189)				(3,189)						33,809
Deferred tax expense (benefit)	(1,365)				(1,365)						13,292
Accumulated other comprehensive income (loss), net of tax	(1,824)	[4]	25,888	[4]	(1,824)	[4]	25,888	[4]	(4,117)	[4]	20,517	[4]	17,073	[4]	16,115	[4]
Income taxes	0	[3]	(12)	[3]	0	[3]	(13)	[3]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	[3],[4]	19	[3],[4]	0	[3],[4]	21	[3],[4]
Securities gains (losses)	0	[3]	31	[3]	0	[3]	34	[3]
Funded Status of Defined Benefit Plan
Accumulated Other Comprehensive Income (Loss), before Tax	(145,438)				(145,438)						(158,334)
Deferred tax expense (benefit)	(56,575)				(56,575)						(62,003)
Accumulated other comprehensive income (loss), net of tax	(88,863)	[4]	(71,114)	[4]	(88,863)	[4]	(71,114)	[4]	(91,100)	[4]	(96,331)	[4]	(72,810)	[4]	(76,205)	[4]
Income taxes	2,061	[3]	1,092	[3]	5,428	[3]	3,277	[3]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(2,237)	[3],[4]	(1,696)	[3],[4]	(7,468)	[3],[4]	(5,091)	[3],[4]
Employee Benefits, prior service costs	(53)	[3]	(53)	[3]	(158)	[3]	(158)	[3]
Reclassification adjustment for losses included in income before income taxes	(4,245)	[3]	(2,735)	[3]	(12,738)	[3]	(8,210)	[3]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	(4,298)		(2,788)	[3]	(12,896)		(8,368)	[3]
Unrealized Loss on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), before Tax	(7,909)				(7,909)						(10,398)
Long-term obligations	(831)	[3]	(769)	[3]	(2,463)	[3]	(2,294)	[3]
Deferred tax expense (benefit)	(3,051)				(3,051)						(4,106)
Accumulated other comprehensive income (loss), net of tax	(4,858)	[4]	(6,760)	[4]	(4,858)	[4]	(6,760)	[4]	(4,959)	[4]	(6,292)	[4]	(6,670)	[4]	(6,484)	[4]
Income taxes	400	[3]	304	[3]	1,044	[3]	906	[3]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (431)	[3],[4]	$ (465)	[3],[4]	$ (1,419)	[3],[4]	$ (1,388)	[3],[4]

[1] Unaudited

[2] Derived from 2012 Annual Report on Form 10-K.

[3] Amounts in parentheses indicate debits to profit/loss.Details about accumulated other comprehensive loss Amount reclassified from accumulated other comprehensive loss1 Affected line item in the statement where net income is presented (dollars in thousands) Nine months ended September 30, 2013 Gains and losses on cash flow hedges Interest rate swap contracts $(2,463) Long-term obligations 1,044 Income taxes $(1,419) Net incomeUnrealized gains and losses on available for sale securities $— Securities gains (losses) — Income taxes $— Net incomeAmortization of defined benefit pension items Prior service costs $(158) Employee benefits Actuarial gains (12,738) Employee benefits (12,896) Income before income taxes 5,428 Income taxes $(7,468) Net incomeTotal reclassifications for the period $(8,887) Nine months ended September 30, 2012 Gains and losses on cash flow hedges Interest rate swap contracts $(2,294) Long-term obligations 906 Income taxes $(1,388) Net income Unrealized gains and losses on available for sale securities $34 Securities gains (losses) (13) Income taxes $21 Net income Amortization of defined benefit pension items Prior service costs $(158) Employee benefits Actuarial gains (8,210) Employee benefits (8,368) Income before income taxes 3,277 Income taxes $(5,091) Net incomeTotal reclassifications for the period $(6,458) 1 Amounts in parentheses indicate debits to profit/loss.

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