Loans and Leases - Concessions Granted on Accruing and Nonaccrual Loans Restructured (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Loans	Sep. 30, 2013 Loans	Sep. 30, 2014 Loans	Sep. 30, 2013 Loans
Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	4	4	4	5
Amount	$ 2,424	$ 2,028	$ 2,424	$ 3,028
Accrual Troubled Debt Restructuring Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	1
Amount	0	0	0	1,000
Accrual Troubled Debt Restructuring Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	1	0	1
Amount	0	756	0	756
Accrual Troubled Debt Restructuring Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Accrual Troubled Debt Restructuring Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	3	3	3	3
Amount	2,299	1,272	2,299	1,272
Accrual Troubled Debt Restructuring Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	1	0	1	0
Amount	125	0	125	0
Nonaccrual Troubled Debt Restructured Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	3	0
Amount	0	0	738	0
Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Nonaccrual Troubled Debt Restructured Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	2	0
Amount	0	0	105	0
Nonaccrual Troubled Debt Restructured Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	1	0
Amount	0	0	633	0
Nonaccrual Troubled Debt Restructured Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	3	0	3	1
Amount	1,424		1,424	1,000
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0		0	1
Amount	0		0	1,000
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0		0	0
Amount	0		0	0
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0		0	0
Amount	0		0	0
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	2		2	0
Amount	1,299		1,299	0
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	1		1	0
Amount	125		125	0
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	1	3	1	3
Amount	1,000	1,569	1,000	1,569
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	1	0	1
Amount	0	756	0	756
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	1	2	1	2
Amount	1,000	813	1,000	813
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	0	0	0
Amount	0	0	0	0
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			1	0
Amount			50
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			0
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			0
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			1
Amount			50
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			0
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			0
Commercial Real Estate Construction Financing Receivable [Member] | Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans	0	1	0	1
Amount		459		459
Commercial Real Estate Construction Financing Receivable [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans		0		0
Amount		0		0
Commercial Real Estate Construction Financing Receivable [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans		0		0
Amount		0		0
Commercial Real Estate Construction Financing Receivable [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans		0		0
Amount		0		0
Commercial Real Estate Construction Financing Receivable [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans		1		1
Amount		459		459
Commercial Real Estate Construction Financing Receivable [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans		0		0
Amount		0		0
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			2	0
Amount			688
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Only Term Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			0
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			0
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			1
Amount			55
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			1
Amount			633
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans			0
Amount			$ 0