Accounting Policies - Summary of Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Basic earnings per share
Net income	$ 5,358us-gaap_NetIncomeLoss	$ 3,417us-gaap_NetIncomeLoss
Less: Preferred stock dividends	31	31
Net income available to common shareholders	5,327	3,386
Weighted average common shares outstanding	9,216,011	8,630,966
Basic Earnings Per Share	$ 0.58us-gaap_EarningsPerShareBasic	$ 0.39us-gaap_EarningsPerShareBasic
Diluted earnings per share
Net income available to common shareholders	$ 5,327	$ 3,386
Weighted average common shares outstanding	9,216,011	8,630,966
Effect of dilutive securities:
Warrants	321,652	311,278
Weighted average shares outstanding	9,609,506	9,021,786
Diluted Earnings Per Share	$ 0.55us-gaap_EarningsPerShareDiluted	$ 0.38us-gaap_EarningsPerShareDiluted
Restricted Stock [Member]
Effect of dilutive securities:
Effect of dilutive securities	30,510	39,519
Stock Options [Member]
Effect of dilutive securities:
Effect of dilutive securities	41,333	40,023

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of call options and warrants using the treasury stock method.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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