Other Comprehensive Income (Loss) (Schedule Of Accumulated Other Comprehensive Income, Net Of Tax) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income	$ 244,396	$ 154,818	$ 247,734	$ 154,250
Other comprehensive income (loss)	(3,338)	568
Securities Available For Sale [Member]
Accumulated Other Comprehensive Income	228,595	101,397	227,052	96,012
Other comprehensive income (loss)	1,543	5,385
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income	(42,159)	(27,848)	(42,958)	(28,357)
Other comprehensive income (loss)	799	509
Derivatives [Member]
Accumulated Other Comprehensive Income	57,960	81,269	63,640	86,595
Other comprehensive income (loss)	$ (5,680)	$ (5,326)