Loans and Leases (Class of Troubled Debt Restructurings by Class Segment) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended								9 Months Ended		12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2012 TDR's [Member]		Dec. 31, 2011 TDR's [Member]		Sep. 30, 2012 TDR's [Member] Commercial, Financial, And Agricultural [Member]	Dec. 31, 2011 TDR's [Member] Commercial, Financial, And Agricultural [Member]	Sep. 30, 2012 TDR's [Member] Real Estate - Construction [Member]	Dec. 31, 2011 TDR's [Member] Real Estate - Construction [Member]	Sep. 30, 2012 TDR's [Member] Real Estate Secured - Residential [Member]	Dec. 31, 2011 TDR's [Member] Real Estate Secured - Residential [Member]	Sep. 30, 2012 TDR's [Member] Real Estate Secured - Commercial [Member]	Dec. 31, 2011 TDR's [Member] Real Estate Secured - Commercial [Member]	Sep. 30, 2012 TDR's [Member] Consumer [Member]	Dec. 31, 2011 TDR's [Member] Consumer [Member]
Financing Receivable, Modifications [Line Items]
Total performing TDRs	$ 56,823		$ 62,331		$ 56,823		$ 62,331		$ 66,777	$ 72,852	$ 62,143	$ 114,566	$ 56,823		$ 72,852		$ 7,254	$ 12,181	$ 943	$ 3,902	$ 20,828	$ 17,634	$ 27,192	$ 38,565	$ 606	$ 570
Non-performing TDRs	17,895	[1]	15,079	[1]	17,895	[1]	15,079	[1]					17,895	[2]	14,346	[2]
Total TDRS													$ 74,718		$ 87,198
Performing TDRs	76.00%		81.00%		76.00%		81.00%						76.00%		84.00%
Non-performing TDRs	24.00%		19.00%		24.00%		19.00%						24.00%		16.00%

[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.