Allowance for Loan Losses - Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 SecurityLoan	Dec. 31, 2012 SecurityLoan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number	42	43
Pre-mod outstanding principal balance	$ 17,389	$ 7,100
Post-mod outstanding principal balance	17,408	7,394
Financial impact due to TDR taken as additional provision	602	578
Number that defaulted during the period	21	28
Recorded investment of TDRs that defaulted during the period	3,746	11,915
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	12	36
RE Mortgage [Member] | Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number	9	4
Pre-mod outstanding principal balance	2,173	822
Post-mod outstanding principal balance	2,177	842
Financial impact due to TDR taken as additional provision	148	(11)
Number that defaulted during the period	4	1
Recorded investment of TDRs that defaulted during the period	443	112
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	(3)
RE Mortgage [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number	11	15
Pre-mod outstanding principal balance	13,145	3,220
Post-mod outstanding principal balance	13,146	3,402
Financial impact due to TDR taken as additional provision	27	212
Number that defaulted during the period	8	13
Recorded investment of TDRs that defaulted during the period	1,702	8,904
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	7
Home equity lines of credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number	12	11
Pre-mod outstanding principal balance	1,546	1,598
Post-mod outstanding principal balance	1,557	1,678
Financial impact due to TDR taken as additional provision	340	60
Number that defaulted during the period	3	5
Recorded investment of TDRs that defaulted during the period	150	500
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions		(13)
Home equity loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number	2
Pre-mod outstanding principal balance	251
Post-mod outstanding principal balance	253
Financial impact due to TDR taken as additional provision	(1)
Number that defaulted during the period	1	1
Recorded investment of TDRs that defaulted during the period	15	46
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions		(1)
Auto Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number
Pre-mod outstanding principal balance
Post-mod outstanding principal balance
Financial impact due to TDR taken as additional provision
Number that defaulted during the period
Recorded investment of TDRs that defaulted during the period
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number		1
Pre-mod outstanding principal balance		38
Post-mod outstanding principal balance		38
Financial impact due to TDR taken as additional provision
Number that defaulted during the period
Recorded investment of TDRs that defaulted during the period
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions
C&I [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number	8	9
Pre-mod outstanding principal balance	274	1,105
Post-mod outstanding principal balance	275	1,105
Financial impact due to TDR taken as additional provision	88	317
Number that defaulted during the period	4	3
Recorded investment of TDRs that defaulted during the period	1,363	1,238
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	3	50
Construction [Member] | Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number		3
Pre-mod outstanding principal balance		317
Post-mod outstanding principal balance		328
Financial impact due to TDR taken as additional provision
Number that defaulted during the period	1	2
Recorded investment of TDRs that defaulted during the period	73	139
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	5
Construction [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number
Pre-mod outstanding principal balance
Post-mod outstanding principal balance
Financial impact due to TDR taken as additional provision
Number that defaulted during the period		3
Recorded investment of TDRs that defaulted during the period		256
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions