Comprehensive Income (Schedule Of Changes In Accumulated Other Comprehensive Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Comprehensive Income [Line Items]
Total Accumulated Other Comprehensive Income Loss, Beginning Balance	$ (62,441)	[1]
Net change	13,349		2,113
Total Accumulated Other Comprehensive Income Loss, Ending Balance	(49,092)	[1]
Unrealized Gains And Losses On AFS Securities [Member]
Comprehensive Income [Line Items]
Total Accumulated Other Comprehensive Income Loss, Beginning Balance	(3,231)
Net change	4,321
Total Accumulated Other Comprehensive Income Loss, Ending Balance	1,090
Non-Credit Impairment Losses On Securities [Member]
Comprehensive Income [Line Items]
Total Accumulated Other Comprehensive Income Loss, Beginning Balance	(16,566)
Net change	6,880
Total Accumulated Other Comprehensive Income Loss, Ending Balance	(9,686)
Unrealized Gains And Losses On Derivatives [Member]
Comprehensive Income [Line Items]
Total Accumulated Other Comprehensive Income Loss, Beginning Balance	(13,085)
Net change	1,707
Total Accumulated Other Comprehensive Income Loss, Ending Balance	(11,378)
Pension Benefit Adjustment [Member]
Comprehensive Income [Line Items]
Total Accumulated Other Comprehensive Income Loss, Beginning Balance	(29,559)
Net change	441
Total Accumulated Other Comprehensive Income Loss, Ending Balance	(29,118)
Total Accumulated Other Comprehensive Loss [Member]
Comprehensive Income [Line Items]
Total Accumulated Other Comprehensive Income Loss, Beginning Balance	(62,441)
Net change	13,349
Total Accumulated Other Comprehensive Income Loss, Ending Balance	$ (49,092)

[1] Share data reflects the five percent common stock dividend declared on April 18, 2012, to be issued May 25, 2012 to shareholders of record on May 11, 2012.