Loans and Allowance for Loan Losses - Summary of Troubled Debt Restructurings by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	141	134	475	380
Pre-Modification Outstanding Recorded Investment	$ 2,085	$ 1,783	$ 10,676	$ 6,438
Post-Modification Outstanding Recorded Investment	1,948	1,747	9,876	6,033
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	2	10	7
Pre-Modification Outstanding Recorded Investment	50	212	2,633	1,252
Post-Modification Outstanding Recorded Investment	48	207	2,187	1,031
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2		3
Pre-Modification Outstanding Recorded Investment	126		323
Post-Modification Outstanding Recorded Investment	119		307
Commercial Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment
Total Commercial Loans and Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	2	13	7
Pre-Modification Outstanding Recorded Investment	176	212	2,956	1,252
Post-Modification Outstanding Recorded Investment	167	207	2,494	1,031
Direct Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	116	117	378	300
Pre-Modification Outstanding Recorded Investment	1,323	1,199	4,922	3,078
Post-Modification Outstanding Recorded Investment	1,240	1,168	4,693	2,930
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	9	9	33	39
Pre-Modification Outstanding Recorded Investment	480	346	1,847	1,809
Post-Modification Outstanding Recorded Investment	470	348	1,784	1,784
Indirect Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	7	5	20	20
Pre-Modification Outstanding Recorded Investment	18	20	52	92
Post-Modification Outstanding Recorded Investment	15	18	48	84
Consumer Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	6	1	31	14
Pre-Modification Outstanding Recorded Investment	88	6	899	207
Post-Modification Outstanding Recorded Investment	56	6	857	204
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Pre-Modification Outstanding Recorded Investment
Post-Modification Outstanding Recorded Investment