Allowance For Credit Losses (Summary Of Allowance For Credit Losses) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Allowance For Credit Losses [Abstract]
Allowance for loan losses	$ 119,342	$ 120,274
Allowance for covered loans	13,528	13,528
Total allowance for loan losses	132,870	133,802	139,847	124,704
Allowance for unfunded letters of credit	2,706	2,383
Total allowance for credit losses	$ 135,576	$ 136,185