Loans and Leases (Troubled Debt Restructurings By Class Segment) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012		Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable Modifications [Line Items]
Total performing TDRs	$ 69,975				$ 69,975				$ 67,775
TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	69,975		56,823		69,975		56,823		67,775		63,822	66,777	72,852
Non-performing TDRs	22,166	[1],[2]	17,895	[1]	22,166	[1],[2]	17,895	[1]	24,603	[2]
Total TDRs	92,141				92,141				92,378
Performing TDRs	76.00%		76.00%		76.00%		76.00%		73.00%
Non-performing TDRs	24.00%		24.00%		24.00%		24.00%		27.00%
Commercial, Financial, And Agricultural [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	9,609				9,609				8,744
Real Estate - Construction [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	331				331				940
Real Estate Secured - Residential [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	26,848				26,848				23,224
Real Estate Secured - Commercial [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	31,766				31,766				33,589
Consumer [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	$ 1,421				$ 1,421				$ 1,278

[1] Included in Age Analysis of Past Due Financing Receivables.

[2] These loans are included in the 90 day past due and non-accrual categories.