Loans and Allowance for Loan Losses - Summary of Troubled Debt Restructurings by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Contract	Dec. 31, 2013 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	648	520
Pre-Modification Outstanding Recorded Investment	$ 12,876	$ 11,366
Post-Modification Outstanding Recorded Investment	11,704	10,175
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	11	10
Pre-Modification Outstanding Recorded Investment	2,946	4,439
Post-Modification Outstanding Recorded Investment	2,282	3,588
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	4
Pre-Modification Outstanding Recorded Investment	573
Post-Modification Outstanding Recorded Investment	540
Total Commercial Loans and Leases [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	15	10
Pre-Modification Outstanding Recorded Investment	3,519	4,439
Post-Modification Outstanding Recorded Investment	2,822	3,588
Direct Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	522	409
Pre-Modification Outstanding Recorded Investment	5,742	4,198
Post-Modification Outstanding Recorded Investment	5,422	3,971
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	46	54
Pre-Modification Outstanding Recorded Investment	2,456	2,464
Post-Modification Outstanding Recorded Investment	2,357	2,366
Indirect Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	24	28
Pre-Modification Outstanding Recorded Investment	70	117
Post-Modification Outstanding Recorded Investment	66	107
Consumer Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	41	19
Pre-Modification Outstanding Recorded Investment	1,089	148
Post-Modification Outstanding Recorded Investment	$ 1,037	$ 143

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524

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- Definition

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