Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Beginning Balance	$ 223,903		$ 256,471
Loans charged off	(22,106)		(30,259)
Recoveries of loans previously charged off	3,194		2,219
Net loans charged off	(18,912)		(28,040)
Provision for loan losses	15,050	[1]	28,065
Ending Balance	220,041		256,496
Real-estate commercial mortage [Member]
Beginning Balance	62,928		85,112
Loans charged off	(4,133)		(11,891)
Recoveries of loans previously charged off	1,064		816
Net loans charged off	(3,069)		(11,075)
Provision for loan losses	4,126	[1]	7,615
Ending Balance	63,985		81,652
Commercial - industrial, financial, and agricultural
Beginning Balance	60,205		74,896
Loans charged off	(9,502)		(5,669)
Recoveries of loans previously charged off	379		636
Net loans charged off	(9,123)		(5,033)
Provision for loan losses	5,590	[1]	9,893
Ending Balance	56,672		79,756
Real-estate - home equity [Member]
Beginning Balance	22,776		12,841
Loans charged off	(2,404)		(2,206)
Recoveries of loans previously charged off	331		20
Net loans charged off	(2,073)		(2,186)
Provision for loan losses	2,998	[1]	2,428
Ending Balance	23,701		13,083
Real-estate - residential mortgage [Member]
Beginning Balance	34,536		22,986
Loans charged off	(3,050)		(847)
Recoveries of loans previously charged off	81		73
Net loans charged off	(2,969)		(774)
Provision for loan losses	1,917	[1]	2,639
Ending Balance	33,484		24,851
Real-estate - construction
Beginning Balance	17,287		30,066
Loans charged off	(1,986)		(8,571)
Recoveries of loans previously charged off	671		64
Net loans charged off	(1,315)		(8,507)
Provision for loan losses	32	[1]	9,627
Ending Balance	16,004		31,186
Consumer
Beginning Balance	2,367		2,083
Loans charged off	(550)		(634)
Recoveries of loans previously charged off	506		350
Net loans charged off	(44)		(284)
Provision for loan losses	(37)	[1]	(156)
Ending Balance	2,286		1,643
Leasing and other and overdrafts [Member]
Beginning Balance	2,752		2,397
Loans charged off	(481)		(441)
Recoveries of loans previously charged off	162		260
Net loans charged off	(319)		(181)
Provision for loan losses	354	[1]	1,058
Ending Balance	2,787		3,274
Unallocated
Beginning Balance	21,052		26,090
Loans charged off	0		0
Recoveries of loans previously charged off	0		0
Net loans charged off	0		0
Provision for loan losses	70	[1]	(5,039)
Ending Balance	$ 21,122	[2]	$ 21,051	[2]

[1] The provision for loan losses is gross of a $50,000 and $65,000 decrease, respectively, in the reserve for unfunded lending commitments for the three months ended March 31, 2013 and 2012. The total provision for credit losses, comprised of allocations for both funded and unfunded loans, was $15.0 million and $28.0 million, respectively, for the three months ended March 31, 2013 and 2012.

[2] The unallocated allowance, which was approximately 10% and 8% of the total allowance for credit losses as of March 31, 2013 and March 31, 2012, respectively, was, in the opinion of management, reasonable and appropriate given that the estimates used in the allocation process are inherently imprecise.