Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Beginning Balance	$ 216,431		$ 235,736		$ 223,903		$ 256,471
Loans charged off	(18,108)		(29,966)		(61,597)		(110,765)
Recoveries of loans previously charged off	3,820		4,918		10,996		11,356
Net loans charged off	(14,288)		(25,048)		(50,601)		(99,409)
Provision for loan losses	8,343	[1]	23,176		37,184	[1]	76,802
Ending Balance	210,486		233,864		210,486		233,864
Real-estate commercial mortage [Member]
Beginning Balance	58,696		69,868		62,928		85,112
Loans charged off	(3,724)		(7,463)		(13,050)		(43,053)
Recoveries of loans previously charged off	185		1,317		2,754		3,286
Net loans charged off	(3,539)		(6,146)		(10,296)		(39,767)
Provision for loan losses	3,470	[1]	8,447		5,995	[1]	26,824
Ending Balance	58,627		72,169		58,627		72,169
Commercial - industrial, financial, and agricultural
Beginning Balance	57,557		71,931		60,205		74,896
Loans charged off	(9,394)		(10,471)		(24,856)		(29,157)
Recoveries of loans previously charged off	2,295		1,693		3,430		3,046
Net loans charged off	(7,099)		(8,778)		(21,426)		(26,111)
Provision for loan losses	1,437	[1]	4,721		13,116	[1]	19,089
Ending Balance	51,895		67,874		51,895		67,874
Real-estate - home equity [Member]
Beginning Balance	25,736		14,444		22,776		12,841
Loans charged off	(2,365)		(1,688)		(6,735)		(6,683)
Recoveries of loans previously charged off	198		343		721		641
Net loans charged off	(2,167)		(1,345)		(6,014)		(6,042)
Provision for loan losses	4,451	[1]	2,337		11,258	[1]	8,637
Ending Balance	28,020		15,436		28,020		15,436
Real-estate - residential mortgage [Member]
Beginning Balance	32,684		26,711		34,536		22,986
Loans charged off	(767)		(670)		(8,282)		(3,009)
Recoveries of loans previously charged off	245		25		442		169
Net loans charged off	(522)		(645)		(7,840)		(2,840)
Provision for loan losses	1,595	[1]	2,790		7,061	[1]	8,710
Ending Balance	33,757		28,856		33,757		28,856
Real-estate - construction
Beginning Balance	14,471		25,559		17,287		30,066
Loans charged off	(598)		(8,364)		(5,181)		(25,377)
Recoveries of loans previously charged off	379		1,040		1,794		2,643
Net loans charged off	(219)		(7,324)		(3,387)		(22,734)
Provision for loan losses	(1,221)	[1]	3,893		(869)	[1]	14,796
Ending Balance	13,031		22,128		13,031		22,128
Consumer
Beginning Balance	2,497		1,816		2,367		2,083
Loans charged off	(473)		(685)		(1,456)		(1,790)
Recoveries of loans previously charged off	294		202		1,206		833
Net loans charged off	(179)		(483)		(250)		(957)
Provision for loan losses	610	[1]	530		811	[1]	737
Ending Balance	2,928		1,863		2,928		1,863
Leasing and other and overdrafts [Member]
Beginning Balance	2,925		3,243		2,752		2,397
Loans charged off	(787)		(625)		(2,037)		(1,696)
Recoveries of loans previously charged off	224		298		649		738
Net loans charged off	(563)		(327)		(1,388)		(958)
Provision for loan losses	620	[1]	77		1,618	[1]	1,554
Ending Balance	2,982		2,993		2,982		2,993
Unallocated
Beginning Balance	21,865		22,164		21,052		26,090
Loans charged off	0		0		0		0
Recoveries of loans previously charged off	0		0		0		0
Net loans charged off	0		0		0		0
Provision for loan losses	(2,619)	[1]	381		(1,806)	[1]	(3,545)
Ending Balance	$ 19,246	[2]	$ 22,545	[2]	$ 19,246	[2]	$ 22,545	[2]

[1] The provision for loan losses excluded a $1.2 million and $816,000 increase, respectively, in the reserve for unfunded lending commitments for the three and nine months ended September 30, 2013 and was gross of a $176,000 and $302,000 decrease, respectively, in the reserve for unfunded lending commitments for the three and nine months ended September 30, 2012. The total provision for credit losses, comprised of allocations for both funded and unfunded loans, was $9.5 million and $38.0 million, respectively, for the three and nine months ended September 30, 2013 and $23.0 million and $76.5 million, respectively, for the three and nine months ended September 30, 2012.

[2] The unallocated allowance, which was approximately 9% and 10% of the total allowance for credit losses as of September 30, 2013 and September 30, 2012, respectively, was, in the opinion of management, reasonable and appropriate given that the estimates used in the allocation process are inherently imprecise.