Loans and Allowance for Credit Losses Summary Of Gross Loans (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 12,744,009	$ 12,792,016
Unearned income	(10,217)	(9,796)
Loans, net of unearned income	12,733,792	12,782,220	12,377,288
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	5,137,454	5,101,922
Loans, net of unearned income	5,137,454	5,101,922	4,729,930
Commercial - industrial, financial, and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	3,574,130	3,628,420
Loans, net of unearned income	3,574,130	3,628,420	3,658,483
Real-estate - home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,740,496	1,764,197
Loans, net of unearned income	1,740,496	1,764,197	1,689,446
Real-estate - residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,331,465	1,337,380
Loans, net of unearned income	1,331,465	1,337,380	1,303,454
Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	584,217	573,672
Loans, net of unearned income	584,217	573,672	597,597
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	270,021	283,124
Loans, net of unearned income	270,021	283,124	309,138
Leasing and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	103,192	99,256
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 3,034	$ 4,045