Loans (Non-Accrual Loans, Segregated By Class Of Loans) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 97,870	$ 94,338	$ 123,811
Commercial And Industrial, Energy [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans
Commercial And Industrial, Other Commercial [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	49,588	43,874	58,681
Commercial Real Estate, Buildings, Land And Other [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	41,892	43,820	53,920
Commercial Real Estate, Construction [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	1,285	1,329	6,888
Consumer Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	4,322	4,587	3,741
Consumer And Other [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 783	$ 728	$ 581