Loans and Leases - Average Recorded Investment in Impaired Loans and Leases and Analysis of Interest on Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 44,651	$ 43,517	$ 43,556	$ 42,847
Interest Income Recognized	228	126	604	301
Interest Income That Would Have Been Recognized Under Original Terms	417	525	1,293	1,595
Loans Held For Sale [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		650		260
Commercial, financial and agricultural [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	5,971	5,474	3,985	5,542
Interest Income Recognized	29	23	45	56
Interest Income That Would Have Been Recognized Under Original Terms	70	71	132	223
Real estate-commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	22,789	20,525	23,138	20,417
Interest Income Recognized	171	69	473	156
Interest Income That Would Have Been Recognized Under Original Terms	150	257	566	783
Real estate-construction [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	14,544	16,324	15,291	16,238
Interest Income Recognized	25	33	81	85
Interest Income That Would Have Been Recognized Under Original Terms	184	190	553	575
Real estate-residential secured for business purpose [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	585	176	341	150
Interest Income Recognized	2		2
Interest Income That Would Have Been Recognized Under Original Terms	2	2	7	5
Real estate-residential secured for personal purpose [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	725	320	758	188
Interest Income Recognized
Interest Income That Would Have Been Recognized Under Original Terms	11	5	35	9
Real estate-home equity secured for personal purpose [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			2	3
Interest Income Recognized
Interest Income That Would Have Been Recognized Under Original Terms
Loans to individuals [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	37	48	41	49
Interest Income Recognized	1	1	3	4
Interest Income That Would Have Been Recognized Under Original Terms