Acquisition Of Whitney Holding Corporation (Schedule Of Loans At Acquisition Date) (Details) (USD $) In Thousands	Sep. 30, 2011
Business Acquisition [Line Items]
Acquired Impaired	$ 536,833
Acquired Performing	5,919,189
Total Acquired Loans	6,456,022
Commercial Non-Real Estate [Member]
Business Acquisition [Line Items]
Acquired Impaired	131,729
Acquired Performing	2,328,082
Total Acquired Loans	2,459,811
Commercial Real Estate Owner-Occupied [Member]
Business Acquisition [Line Items]
Acquired Impaired	90,231
Acquired Performing	951,661
Total Acquired Loans	1,041,892
Construction And Land Development [Member]
Business Acquisition [Line Items]
Acquired Impaired	161,478
Acquired Performing	566,597
Total Acquired Loans	728,075
Commercial Real Estate Non-Owner Occupied [Member]
Business Acquisition [Line Items]
Acquired Impaired	85,015
Acquired Performing	842,622
Total Acquired Loans	927,637
Total Commercial/Real Estate [Member]
Business Acquisition [Line Items]
Acquired Impaired	468,453
Acquired Performing	4,688,962
Total Acquired Loans	5,157,415
Residential Mortgages [Member]
Business Acquisition [Line Items]
Acquired Impaired	68,380
Acquired Performing	788,999
Total Acquired Loans	857,379
Consumer [Member]
Business Acquisition [Line Items]
Acquired Performing	441,228
Total Acquired Loans	$ 441,228