Loans and Allowance for Credit Losses Summary Of Gross Loans (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 12,789,675	$ 12,154,209
Unearned income	(8,776)	(7,238)
Loans, net of unearned income	12,780,899	12,146,971	11,935,260
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	5,063,373	4,664,426
Loans, net of unearned income	5,063,373		4,632,509
Commercial - industrial, financial, and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	3,645,270	3,612,065
Loans, net of unearned income	3,645,270		3,507,846
Real-estate - home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,773,554	1,632,390
Loans, net of unearned income	1,773,554		1,603,456
Real-estate - residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,327,469	1,257,432
Loans, net of unearned income	1,327,469		1,214,322
Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	577,342	584,118
Loans, net of unearned income	577,342		597,358
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	296,142	309,864
Loans, net of unearned income	296,142		301,717
Leasing and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	89,819	75,521
Overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 16,706	$ 18,393