Loans and Allowance for Loan Losses - Summary of Troubled Debt Restructurings by Class of Loans, Payment Default (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	30	30	42	35
Recorded Investment	$ 1,189	$ 116	$ 1,448	$ 269
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1		1
Recorded Investment	764		764
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts			1
Recorded Investment			32
Commercial Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Recorded Investment
Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1		2
Recorded Investment	764		796
Direct Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	24	26	32	29
Recorded Investment	276	79	375	83
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	1	4	2
Recorded Investment	114	35	232	182
Indirect Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	2	4	3
Recorded Investment	35	1	45	3
Consumer Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts		1		1
Recorded Investment		1		1
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Recorded Investment