Loans and Allowance for Credit Losses Summary Of Gross Loans (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 12,653,095	$ 12,154,209
Unearned income	(7,677)	(7,238)
Loans, net of unearned income	12,645,418	12,146,971	11,985,115
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	4,856,916	4,664,426
Loans, net of unearned income	4,856,916		4,653,097
Commercial - industrial, financial, and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	3,712,974	3,612,065
Loans, net of unearned income	3,712,974		3,538,188
Real-estate - home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,760,268	1,632,390
Loans, net of unearned income	1,760,268		1,599,468
Real-estate - residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,313,345	1,257,432
Loans, net of unearned income	1,313,345		1,184,192
Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	610,280	584,118
Loans, net of unearned income	610,280		619,060
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	300,233	309,864
Loans, net of unearned income	300,233		309,097
Leasing and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	83,855	75,521
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 15,224	$ 18,393