Loans and Leases (Troubled Debt Restructurings By Class Segment) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended				12 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012		Dec. 31, 2012		Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable Modifications [Line Items]
Total performing TDRs	$ 63,822				$ 63,822				$ 67,775
TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	63,822		66,777		63,822		66,777		67,775		65,773	72,081	72,852
Non-performing TDRs	20,500	[1],[2]	19,977	[1]	20,500	[1],[2]	19,977	[1]	24,603	[2]
Total TDRs	84,322				84,322				92,378
Performing TDRs	76.00%		77.00%		76.00%		77.00%		73.00%
Non-performing TDRs	24.00%		23.00%		24.00%		23.00%		27.00%
Commercial, Financial, And Agricultural [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	9,200				9,200				8,744
Real Estate - Construction [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	334				334				940
Real Estate Secured - Residential [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	23,207				23,207				23,224
Real Estate Secured - Commercial [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	29,482				29,482				33,589
Consumer [Member] | TDRs [Member]
Financing Receivable Modifications [Line Items]
Total performing TDRs	$ 1,599				$ 1,599				$ 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.