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	Sep. 30, 2011		Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	$ 11,572,789			$ 164,200	$ 11,359,701
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	322,866			106,000	573,606
Loans and Leases Receivable, Allowance	266,978		266,683		274,271
Loans and Leases Receivable, Net of Deferred Income	11,895,655				11,933,307
Unallocated allowance	9.00%				15.00%
Real-estate commercial mortage
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4,377,383				4,217,660
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	113,772				158,320
Loans and Leases Receivable, Allowance	81,183		73,598		40,831
Loans and Leases Receivable, Net of Deferred Income	4,491,155				4,375,980
Real-estate commercial mortage | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	47,914				22,836
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	33,269				17,995
Commercial - industrial, financial, and agricultural
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	3,603,914				3,469,775
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	86,250				234,609
Loans and Leases Receivable, Allowance	80,137		82,613		101,436
Loans and Leases Receivable, Net of Deferred Income	3,690,164				3,704,384
Commercial - industrial, financial, and agricultural | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	51,510				32,323
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	28,627				69,113
Real-estate - home equity
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,630,880				1,641,777
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0				0
Loans and Leases Receivable, Allowance	9,843		9,560		6,454
Loans and Leases Receivable, Net of Deferred Income	1,630,880				1,641,777
Real-estate - home equity | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	9,843				6,454
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0				0
Real-estate - residential mortgage
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	975,463				956,260
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	66,000				39,730
Loans and Leases Receivable, Allowance	33,336		31,912		17,425
Loans and Leases Receivable, Net of Deferred Income	1,041,463				995,990
Real-estate - residential mortgage | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	7,142				11,475
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	26,194				5,950
Real-estate - construction
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	596,581				660,238
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	51,817				140,947
Loans and Leases Receivable, Allowance	33,045		30,570		58,117
Loans and Leases Receivable, Net of Deferred Income	648,398				801,185
Real-estate - construction | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	20,480				35,247
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	12,565				22,870
Consumer
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	322,113				350,161
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,941				0
Loans and Leases Receivable, Allowance	4,402		1,755		4,669
Loans and Leases Receivable, Net of Deferred Income	327,054				350,161
Consumer | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,773				4,669
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,629				0
Leasing and Other and Overdrafts [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	66,455				63,830
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	86				0
Loans and Leases Receivable, Allowance	2,261		1,787		3,840
Loans and Leases Receivable, Net of Deferred Income	66,541				63,830
Leasing and Other and Overdrafts [Member] | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,205				3,840
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	56				0
Unallocated
Loans and Leases Receivable, Allowance	22,771	[1]	34,888		41,499	[1]
Unallocated | Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	22,771	[1]			41,499	[1]
Allowance for Loan and Lease Losses [Member]
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	163,638				158,343
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 103,340				$ 115,928

[1] The Corporation’s unallocated allowance, which was approximately 9% and 15% as of September 30, 2011 and December 31, 2010, respectively, was reasonable and appropriate as the estimates used in the allocation process are inherently imprecise.