Loans and Allowance for Credit Losses Present Loans, Net of Unearned Income and Their Related Allowance for Loan Losses, by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	$ 144,728	$ 159,894
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	79,175	96,577
Loans and Leases Receivable, Allowance	223,903	256,471	274,271
Loans and Leases Receivable, Net of Deferred Income	12,144,604	11,968,970
Unallocated allowance	9.00%	10.00%
Real-estate commercial mortage
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	41,316	49,052
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	21,612	36,060
Loans and Leases Receivable, Allowance	62,928	85,112	40,831
Loans and Leases Receivable, Net of Deferred Income	4,664,426	4,602,596
Commercial - industrial, financial, and agricultural
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	41,421	46,471
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	18,784	28,425
Loans and Leases Receivable, Allowance	60,205	74,896	101,436
Loans and Leases Receivable, Net of Deferred Income	3,612,065	3,639,368
Real Estate - Home Equity [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	14,396	9,765
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	8,380	3,076
Loans and Leases Receivable, Allowance	22,776	12,841	6,454
Loans and Leases Receivable, Net of Deferred Income	1,632,390	1,624,562
Real-estate - residential mortgage
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	10,428	6,691
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	24,108	16,295
Loans and Leases Receivable, Allowance	34,536	22,986	17,425
Loans and Leases Receivable, Net of Deferred Income	1,256,991	1,097,192
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	11,028	17,610
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	6,259	12,456
Loans and Leases Receivable, Allowance	17,287	30,066	58,117
Loans and Leases Receivable, Net of Deferred Income	584,118	615,445
Consumer
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,342	1,855
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	25	228
Loans and Leases Receivable, Allowance	2,367	2,083	4,669
Loans and Leases Receivable, Net of Deferred Income	309,220	318,101
Leasing and Other and Overdrafts [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,745	2,360
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	7	37
Loans and Leases Receivable, Allowance	2,752	2,397	3,840
Loans and Leases Receivable, Net of Deferred Income	85,394	71,706
Unallocated
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	21,052	26,090
Loans and Leases Receivable, Allowance	$ 21,052	$ 26,090	$ 41,499