Investment Securities - Investment Securities Available-for-Sale and Held-to-Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost	$ 177,479	$ 134,908
Available-for-Sale, Gross Unrealized Gains	2,825	2,422
Available-for-Sale, Gross Unrealized Losses	(958)	(1,576)
Available-for-Sale, Estimated Fair Value	179,346	135,754
Held-to-Maturity, Amortized Cost	36,524	35,050
Held-to-Maturity, Gross Unrealized Gains	17
Held-to-Maturity, Gross Unrealized Losses	(450)
Held-to-Maturity, Estimated Fair Value	36,091
Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost	122,911	82,840
Available-for-Sale, Gross Unrealized Gains	1,450	1,479
Available-for-Sale, Gross Unrealized Losses	(594)	(885)
Available-for-Sale, Estimated Fair Value	123,767	83,434
Commercial [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost	34,331	30,677
Available-for-Sale, Gross Unrealized Gains	167	143
Available-for-Sale, Gross Unrealized Losses	(152)	(355)
Available-for-Sale, Estimated Fair Value	34,346	30,465
Held-to-Maturity, Amortized Cost	3,281
Held-to-Maturity, Gross Unrealized Gains	17
Held-to-Maturity, Gross Unrealized Losses	(5)
Held-to-Maturity, Estimated Fair Value	3,293
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost	15,695	16,230
Available-for-Sale, Gross Unrealized Gains	1,207	799
Available-for-Sale, Gross Unrealized Losses	(3)	(2)
Available-for-Sale, Estimated Fair Value	16,899	17,027
Held-to-Maturity, Amortized Cost	586
Held-to-Maturity, Gross Unrealized Losses	(2)
Held-to-Maturity, Estimated Fair Value	584
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost	4,155	4,161
Available-for-Sale, Gross Unrealized Losses	(209)	(334)
Available-for-Sale, Estimated Fair Value	3,946	3,827
Obligations of U.S. Government Sponsored Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost	387	1,000
Available-for-Sale, Gross Unrealized Gains	1	1
Available-for-Sale, Estimated Fair Value	388	1,001
Held-to-Maturity, Amortized Cost	32,657	35,050
Held-to-Maturity, Gross Unrealized Losses	(443)	(1,685)
Held-to-Maturity, Estimated Fair Value	$ 32,214	$ 33,365

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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