Loans and Allowance for Credit Losses Summary Of Gross Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 13,258,311	$ 13,124,093
Unearned income	(14,081)	(12,377)
Loans, net of unearned income	13,244,230	13,111,716	$ 12,839,511
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	5,237,800	5,197,155
Loans, net of unearned income	5,237,800	5,197,155	5,128,734
Commercial - industrial, financial, and agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	3,806,699	3,725,567
Loans, net of unearned income	3,806,699	3,725,567	3,601,721
Real-estate - home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,689,688	1,736,688
Loans, net of unearned income	1,689,688	1,736,688	1,730,497
Real-estate - residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,369,103	1,377,068
Loans, net of unearned income	1,369,103	1,377,068	1,361,976
Real-estate - construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	731,925	690,601
Loans, net of unearned income	731,925	690,601	634,018
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	272,494	265,431
Loans, net of unearned income	272,494	265,431	$ 280,557
Leasing and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	147,960	127,562
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 2,642	$ 4,021