Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012		Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012		Dec. 31, 2011
Long-term obligations	$ 179,528		$ 215,432		$ 384,410		$ 436,384
Accumulated other comprehensive income (loss)	(164,591)		(102,541)		(164,591)		(102,541)				(134,923)
Deferred tax expense (benefit)	(64,415)		(40,134)		(64,415)		(40,134)				(52,817)
Accumulated other comprehensive income (loss), net of tax	(100,176)	[1]	(62,407)	[1]	(100,176)	[1]	(62,407)	[1]	(79,905)		(82,106)	[2]	(66,416)		(66,574)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(3,108)	[3]	(2,165)	[3]	(6,219)	[3]	(4,316)	[3]
Securities gains (losses)	0		3		0		(42)
Unrealized Gains on Investment Securities Available for Sale
Accumulated other comprehensive income (loss)	(6,659)		28,155		(6,659)		28,155				33,809
Deferred tax expense (benefit)	(2,542)		11,082		(2,542)		11,082				13,292
Accumulated other comprehensive income (loss), net of tax	(4,117)	[4]	17,073	[4]	(4,117)	[4]	17,073	[4]	19,606	[4]	20,517	[4]	14,340	[4]	16,115	[4]
Income taxes	0	[3]	(1)	[3]	0	[3]	(1)	[3]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	[3],[4]	2	[3],[4]	0	[3],[4]	2	[3],[4]
Securities gains (losses)	0	[3]	3	[3]	0	[3]	3	[3]
Funded Status of Defined Benefit Plan
Accumulated other comprehensive income (loss)	(149,736)		(119,676)		(149,736)		(119,676)				(158,334)
Deferred tax expense (benefit)	(58,636)		(46,865)		(58,636)		(46,865)				(62,003)
Accumulated other comprehensive income (loss), net of tax	(91,100)	[4]	(72,811)	[4]	(91,100)	[4]	(72,811)	[4]	(93,712)	[4]	(96,331)	[4]	(74,508)	[4]	(76,206)	[4]
Income taxes	1,682	[3]	1,093	[3]	3,367	[3]	2,185	[3]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(2,612)	[3],[4]	(1,697)	[3],[4]	(5,231)	[3],[4]	(3,395)	[3],[4]
Employee Benefits, prior service costs	(53)	[3]	(52)	[3]	(105)	[3]	(105)	[3]
Employee Benefits, actuarial gains	(4,241)	[3]	(2,738)	[3]	(8,493)	[3]	(5,475)	[3]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	(4,294)		(2,790)	[3]	(8,598)		(5,580)	[3]
Unrealized Loss on Cash Flow Hedges
Long-term obligations	(819)	[3]	(776)	[3]	(1,632)	[3]	(1,525)	[3]
Accumulated other comprehensive income (loss)	(8,196)		(11,020)		(8,196)		(11,020)				(10,398)
Deferred tax expense (benefit)	(3,237)		(4,351)		(3,237)		(4,351)				(4,106)
Accumulated other comprehensive income (loss), net of tax	(4,959)	[4]	(6,669)	[4]	(4,959)	[4]	(6,669)	[4]	(5,799)	[4]	(6,292)	[4]	(6,248)	[4]	(6,483)	[4]
Income taxes	323	[3]	306	[3]	644	[3]	602	[3]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (496)	[3],[4]	$ (470)	[3],[4]	$ (988)	[3],[4]	$ (923)	[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) Six months ended June 30, 2013 Gains and losses on cash flow hedges Interest rate swap contracts $(1,632) Long-term obligations 644 Income taxes $(988) Net of taxUnrealized gains and losses on available for sale securities $— Securities gains (losses) — Income taxes $— Net of taxAmortization of defined benefit pension items Prior service costs $(105) Employee benefits Actuarial gains (8,493) Employee benefits (8,598) Total before taxes 3,367 Income taxes $(5,231) Net of taxTotal reclassifications for the period $(6,219) Six months ended June 30, 2012 Gains and losses on cash flow hedges Interest rate swap contracts $(1,525) Long-term obligations 602 Income taxes $(923) Net of tax Unrealized gains and losses on available for sale securities $3 Securities gains (losses) (1) Income taxes $2 Net of tax Amortization of defined benefit pension items Prior service costs $(105) Employee benefits Actuarial gains (5,475) Employee benefits (5,580) Total before taxes 2,185 Income taxes $(3,395) Net of taxTotal reclassifications for the period $(4,316) 1 Amounts in parentheses indicate debits to profit/loss.

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