Troubled Debt Restructurings by Class (Detail) (Troubled Debt Restructuring [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Contract	Mar. 31, 2012 Contract
Composition of Loan Portfolio [Line Items]
Number of Contracts	2	1
Pre-Modification Outstanding Recorded Investment	$ 1,408	$ 800
Post-Modification Outstanding Recorded Investment	1,407	800
Commercial [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts		1
Pre-Modification Outstanding Recorded Investment		800
Post-Modification Outstanding Recorded Investment		800
Commercial - credit card [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Real estate - construction [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Real estate - commercial [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts	2
Pre-Modification Outstanding Recorded Investment	1,408
Post-Modification Outstanding Recorded Investment	1,407
Real estate - residential [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Real estate - Home Equity Line of Credit [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Consumer - credit card [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Consumer - other [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Leases [Member]
Composition of Loan Portfolio [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment