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, 2014		Mar. 31, 2013
Beginning Balance	$ 202,780		$ 223,903
Loans charged off	(10,268)		(22,106)
Recoveries of loans previously charged off	1,857		3,194
Net loans charged off	(8,411)		(18,912)
Provision for loan losses	2,720	[1]	15,050
Ending Balance	197,089		220,041
Real-estate commercial mortage [Member]
Beginning Balance	55,659		62,928
Loans charged off	(1,386)		(4,133)
Recoveries of loans previously charged off	44		1,064
Net loans charged off	(1,342)		(3,069)
Provision for loan losses	(560)	[1]	4,126
Ending Balance	53,757		63,985
Commercial - industrial, financial, and agricultural
Beginning Balance	50,330		60,205
Loans charged off	(5,125)		(9,502)
Recoveries of loans previously charged off	744		379
Net loans charged off	(4,381)		(9,123)
Provision for loan losses	4,614	[1]	5,590
Ending Balance	50,563		56,672
Real-estate - home equity [Member]
Beginning Balance	28,222		22,776
Loans charged off	(1,651)		(2,404)
Recoveries of loans previously charged off	356		331
Net loans charged off	(1,295)		(2,073)
Provision for loan losses	5,533	[1]	2,998
Ending Balance	32,460		23,701
Real-estate - residential mortgage [Member]
Beginning Balance	33,082		34,536
Loans charged off	(846)		(3,050)
Recoveries of loans previously charged off	116		81
Net loans charged off	(730)		(2,969)
Provision for loan losses	977	[1]	1,917
Ending Balance	33,329		33,484
Real-estate - construction
Beginning Balance	12,649		17,287
Loans charged off	(214)		(1,986)
Recoveries of loans previously charged off	224		671
Net loans charged off	10		(1,315)
Provision for loan losses	(2,817)	[1]	32
Ending Balance	9,842		16,004
Consumer
Beginning Balance	3,260		2,367
Loans charged off	(751)		(550)
Recoveries of loans previously charged off	209		506
Net loans charged off	(542)		(44)
Provision for loan losses	606	[1]	(37)
Ending Balance	3,324		2,286
Leasing and other and overdrafts [Member]
Beginning Balance	3,370		2,752
Loans charged off	(295)		(481)
Recoveries of loans previously charged off	164		162
Net loans charged off	(131)		(319)
Provision for loan losses	(1,228)	[1]	354
Ending Balance	2,011		2,787
Unallocated
Beginning Balance	16,208		21,052
Loans charged off	0		0
Recoveries of loans previously charged off	0		0
Net loans charged off	0		0
Provision for loan losses	(4,405)	[1]	70
Ending Balance	$ 11,803	[2]	$ 21,122	[2]

[1] The provision for loan losses excluded a $220,000 decrease in the reserve for unfunded lending commitments for the three months ended March 31, 2014 and excluded a $50,000 decrease in the reserve for unfunded lending commitments for the three months ended March 31, 2013. The total provision for credit losses, comprised of allocations for both funded and unfunded loans, was $2.5 million for the three months ended March 31, 2014 and $15.0 million for the three months ended March 31, 2013.

[2] The unallocated allowance, which was approximately 6% and 10% of the total allowance for credit losses as of March 31, 2014 and March 31, 2013, respectively, was, in the opinion of management, reasonable and appropriate given that the estimates used in the allocation process are inherently imprecise.