Loans and Allowance for Credit Losses Summary Of Gross Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 14,172,721	$ 13,854,118
Unearned income	(17,562)	(15,516)
Loans, net of unearned income	14,155,159	13,838,602	$ 13,244,230
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	5,635,347	5,462,330
Loans, net of unearned income	5,635,347	5,462,330	5,237,800
Commercial - industrial, financial, and agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	4,099,177	4,088,962
Loans, net of unearned income	4,099,177	4,088,962	3,806,699
Real-estate - home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,647,319	1,684,439
Loans, net of unearned income	1,647,319	1,684,439	1,689,688
Real-estate - residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,447,292	1,376,160
Loans, net of unearned income	1,447,292	1,376,160	1,369,103
Real-estate - construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	853,699	799,988
Loans, net of unearned income	853,699	799,988	731,925
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	278,071	268,588
Loans, net of unearned income	278,071	268,588	$ 272,494
Leasing and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	208,602	170,914
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 3,214	$ 2,737