Loans and Leases - Concessions Granted on Accruing and Nonaccrual Loans Restructured (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($) loan
Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	6	7
Amount | $	$ 1,898	$ 2,824
Accrual Troubled Debt Restructuring Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	2	0
Amount | $	$ 496	$ 0
Accrual Troubled Debt Restructuring Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	0
Amount | $	$ 0	$ 0
Accrual Troubled Debt Restructuring Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	6
Amount | $	$ 500	$ 2,699
Accrual Troubled Debt Restructuring Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	1
Amount | $	$ 0	$ 125
Accrual Troubled Debt Restructuring Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	3	0
Amount | $	$ 902	$ 0
Nonaccrual Troubled Debt Restructured Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	3
Amount | $	$ 122	$ 738
Nonaccrual Troubled Debt Restructured Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	0
Amount | $	$ 122	$ 0
Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	2
Amount | $	$ 0	$ 105
Nonaccrual Troubled Debt Restructured Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	1
Amount | $	$ 0	$ 633
Nonaccrual Troubled Debt Restructured Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	0
Amount | $	$ 0	$ 0
Nonaccrual Troubled Debt Restructured Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	0
Amount | $	$ 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 | loan	4	6
Amount | $	$ 1,140	$ 1,824
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 | loan	1	0
Amount | $	$ 143	$ 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 | loan	0	0
Amount | $	$ 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 | loan	1	5
Amount | $	$ 500	$ 1,699
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 | loan	0	1
Amount | $	$ 0	$ 125
Commercial, Financial and Agricultural [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	2	0
Amount | $	$ 497	$ 0
Commercial, Financial and Agricultural [Member] | Nonaccrual Troubled Debt Restructured Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	0
Amount | $	$ 122
Commercial, Financial and Agricultural [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1
Amount | $	$ 122
Commercial, Financial and Agricultural [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Commercial, Financial and Agricultural [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Commercial, Financial and Agricultural [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Commercial, Financial and Agricultural [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	1
Amount | $	$ 405	$ 1,000
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 | loan	0	0
Amount | $	$ 0	$ 0
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 | loan	0	0
Amount | $	$ 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 | loan	0	1
Amount | $	$ 0	$ 1,000
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 | loan	0	0
Amount | $	$ 0	$ 0
Real Estate-Commercial [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	0
Amount | $	$ 405	$ 0
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0	1
Amount | $		$ 50
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 | loan		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 | loan		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 | loan		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 | loan		0
Amount | $		$ 0
Real Estate-Commercial [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan		0
Amount | $		$ 0
Real Estate-Residential Secured for Business Purpose [Member] | Accrual Troubled Debt Restructuring Loans [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1	0
Amount | $	$ 353
Real Estate-Residential Secured for Business Purpose [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Temporary Payment Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	1
Amount | $	$ 353
Real Estate-Residential Secured for Business Purpose [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Interest Rate Reduction [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Real Estate-Residential Secured for Business Purpose [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Maturity Date Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Real Estate-Residential Secured for Business Purpose [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Payments Suspended [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 0
Real Estate-Residential Secured for Business Purpose [Member] | Accrual Troubled Debt Restructuring Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan	0
Amount | $	$ 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 | loan	0	2
Amount | $		$ 688
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 | loan		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 | loan		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 | loan		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 | loan		0
Amount | $		$ 0
Real Estate-Residential Secured for Business Purpose [Member] | Nonaccrual Troubled Debt Restructured Loans [Member] | Amortization Period Extension [Member]
Concessions granted on accruing and non-accrual loans restructured
No. of Loans | loan		0
Amount | $		$ 0