Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Beginning Balance	$ 220,041		$ 256,496		$ 223,903		$ 256,471
Loans charged off	(21,383)		(50,540)		(43,489)		(80,799)
Recoveries of loans previously charged off	3,982		4,219		7,176		6,438
Net loans charged off	(17,401)		(46,321)		(36,313)		(74,361)
Provision for loan losses	13,791	[1]	25,562		28,841	[1]	53,627
Ending Balance	216,431		235,737		216,431		235,737
Real-estate commercial mortage [Member]
Beginning Balance	63,985		81,652		62,928		85,112
Loans charged off	(5,193)		(23,699)		(9,326)		(35,590)
Recoveries of loans previously charged off	1,505		1,153		2,569		1,969
Net loans charged off	(3,688)		(22,546)		(6,757)		(33,621)
Provision for loan losses	(1,601)	[1]	10,763		2,525	[1]	18,378
Ending Balance	58,696		69,869		58,696		69,869
Commercial - industrial, financial, and agricultural
Beginning Balance	56,672		79,756		60,205		74,896
Loans charged off	(5,960)		(13,017)		(15,462)		(18,686)
Recoveries of loans previously charged off	756		717		1,135		1,353
Net loans charged off	(5,204)		(12,300)		(14,327)		(17,333)
Provision for loan losses	6,089	[1]	4,475		11,679	[1]	14,368
Ending Balance	57,557		71,931		57,557		71,931
Real-estate - home equity [Member]
Beginning Balance	23,701		13,083		22,776		12,841
Loans charged off	(1,966)		(2,789)		(4,370)		(4,995)
Recoveries of loans previously charged off	192		278		523		298
Net loans charged off	(1,774)		(2,511)		(3,847)		(4,697)
Provision for loan losses	3,809	[1]	3,872		6,807	[1]	6,300
Ending Balance	25,736		14,444		25,736		14,444
Real-estate - residential mortgage [Member]
Beginning Balance	33,484		24,851		34,536		22,986
Loans charged off	(4,465)		(1,492)		(7,515)		(2,339)
Recoveries of loans previously charged off	116		71		197		144
Net loans charged off	(4,349)		(1,421)		(7,318)		(2,195)
Provision for loan losses	3,549	[1]	3,281		5,466	[1]	5,920
Ending Balance	32,684		26,711		32,684		26,711
Real-estate - construction
Beginning Balance	16,004		31,186		17,287		30,066
Loans charged off	(2,597)		(8,442)		(4,583)		(17,013)
Recoveries of loans previously charged off	744		1,539		1,415		1,603
Net loans charged off	(1,853)		(6,903)		(3,168)		(15,410)
Provision for loan losses	320	[1]	1,276		352	[1]	10,903
Ending Balance	14,471		25,559		14,471		25,559
Consumer
Beginning Balance	2,286		1,643		2,367		2,083
Loans charged off	(433)		(471)		(983)		(1,105)
Recoveries of loans previously charged off	406		281		912		631
Net loans charged off	(27)		(190)		(71)		(474)
Provision for loan losses	238	[1]	363		201	[1]	207
Ending Balance	2,497		1,816		2,497		1,816
Leasing and other and overdrafts [Member]
Beginning Balance	2,787		3,274		2,752		2,397
Loans charged off	(769)		(630)		(1,250)		(1,071)
Recoveries of loans previously charged off	263		180		425		440
Net loans charged off	(506)		(450)		(825)		(631)
Provision for loan losses	644	[1]	419		998	[1]	1,477
Ending Balance	2,925		3,243		2,925		3,243
Unallocated
Beginning Balance	21,122		21,051		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	743	[1]	1,113		813	[1]	(3,926)
Ending Balance	$ 21,865	[2]	$ 22,164	[2]	$ 21,865	[2]	$ 22,164	[2]

[1] The provision for loan losses was gross of a $291,000 and $341,000 decrease, respectively, in the reserve for unfunded lending commitments for the three and six months ended June 30, 2013 and was gross of a $62,000 and $127,000 decrease, respectively, for the three and six months ended June 30, 2012. The total provision for credit losses, comprised of allocations for both funded and unfunded loans, was $13.5 million and $28.5 million, respectively, for the three and six months ended June 30, 2013 and $25.5 million and $53.5 million, respectively, for the three and six months ended June 30, 2012.

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