Investment Securities (Roll Forward Of OTTI Recognized In Earnings) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Investment Securities [Abstract]
Balance of credit related OTTI, beginning of period	$ 26,320	$ 43,492
Additions for credit related OTTI not previously recognized		5,771
Reduction for payment of deferred interest	(16)
Reduction for securities sold	(15,844)	(22,943)
Subtotal of additions and reductions, net	(15,860)	(17,172)
Balance of credit-related OTTI, end of period	$ 10,460	$ 26,320