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, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 191,685		$ 216,431		$ 202,780		$ 223,903
Loans charged off	(9,604)		(18,108)		(31,348)		(61,597)
Recoveries of loans previously charged off	3,770		3,820		8,039		10,996
Net loans charged off	(5,834)		(14,288)		(23,309)		(50,601)
Provision for loan losses	3,626	[1]	8,343	[1]	10,006	[1]	37,184	[1]
Ending Balance	189,477		210,486		189,477		210,486
Provision for loan losses gross	126		1,000		506		816
Provision for Loan and Lease Losses	3,500		9,500		9,500		38,000
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	49,842		58,696		55,659		62,928
Loans charged off	(1,557)		(3,724)		(5,084)		(13,050)
Recoveries of loans previously charged off	1,167		185		1,641		2,754
Net loans charged off	(390)		(3,539)		(3,443)		(10,296)
Provision for loan losses	(278)	[1]	3,470	[1]	(3,042)	[1]	5,995	[1]
Ending Balance	49,174		58,627		49,174		58,627
Commercial - industrial, financial, and agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	49,084		57,557		50,330		60,205
Loans charged off	(5,167)		(9,394)		(15,804)		(24,856)
Recoveries of loans previously charged off	1,013		2,295		2,532		3,430
Net loans charged off	(4,154)		(7,099)		(13,272)		(21,426)
Provision for loan losses	6,110	[1]	1,437	[1]	13,982	[1]	13,116	[1]
Ending Balance	51,040		51,895		51,040		51,895
Real-estate - home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	32,041		25,736		28,222		22,776
Loans charged off	(1,492)		(2,365)		(4,377)		(6,735)
Recoveries of loans previously charged off	336		198		869		721
Net loans charged off	(1,156)		(2,167)		(3,508)		(6,014)
Provision for loan losses	406	[1]	4,451	[1]	6,577	[1]	11,258	[1]
Ending Balance	31,291		28,020		31,291		28,020
Real-estate - residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	32,744		32,684		33,082		34,536
Loans charged off	(231)		(767)		(2,166)		(8,282)
Recoveries of loans previously charged off	95		245		319		442
Net loans charged off	(136)		(522)		(1,847)		(7,840)
Provision for loan losses	397	[1]	1,595	[1]	1,770	[1]	7,061	[1]
Ending Balance	33,005		33,757		33,005		33,757
Real-estate - construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	11,331		14,471		12,649		17,287
Loans charged off	(313)		(598)		(745)		(5,181)
Recoveries of loans previously charged off	470		379		852		1,794
Net loans charged off	157		(219)		107		(3,387)
Provision for loan losses	(312)	[1]	(1,221)	[1]	(1,580)	[1]	(869)	[1]
Ending Balance	11,176		13,031		11,176		13,031
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	3,306		2,497		3,260		2,367
Loans charged off	(538)		(473)		(1,738)		(1,456)
Recoveries of loans previously charged off	448		294		1,059		1,206
Net loans charged off	(90)		(179)		(679)		(250)
Provision for loan losses	244	[1]	610	[1]	879	[1]	811	[1]
Ending Balance	3,460		2,928		3,460		2,928
Leasing and other and overdrafts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	1,851		2,925		3,370		2,752
Loans charged off	(306)		(787)		(1,434)		(2,037)
Recoveries of loans previously charged off	241		224		767		649
Net loans charged off	(65)		(563)		(667)		(1,388)
Provision for loan losses	180	[1]	620	[1]	(737)	[1]	1,618	[1]
Ending Balance	1,966		2,982		1,966		2,982
Unallocated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	11,486		21,865		16,208		21,052
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	(3,121)	[1]	(2,619)	[1]	(7,843)	[1]	(1,806)	[1]
Ending Balance	$ 8,365	[2]	$ 19,246	[2]	$ 8,365	[2]	$ 19,246	[2]

[1] The provision for loan losses excluded a $126,000 and $506,000 decrease, respectively, in the reserve for unfunded lending commitments for the three and nine months ended September 30, 2014 and 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. The total provision for credit losses, comprised of allocations for both funded and unfunded loans, was $3.5 million and $9.5 million, respectively, for the three and nine months ended September 30, 2014 and $9.5 million and $38.0 million, respectively, for the three and nine months ended September 30, 2013.

[2] The unallocated allowance, which was approximately 4% and 9% of the total allowance for credit losses as of September 30, 2014 and September 30, 2013, respectively, was, in the opinion of management, reasonable and appropriate given that the estimates used in the allocation process are inherently imprecise.