Investment Securities - Recorded Book Value, Fair Value and Approximate Yield of Investment Securities by Contractual Maturity (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Within One Year, Amortized Cost	$ 1,291,000
After One But Within Five Years, Amortized Cost	7,103,000
After Five But Within Ten Years, Amortized Cost	72,224,000
After Ten Years, Amortized Cost	32,106,000
Amortized Cost, Total	112,724,000
Available-for-sale securities, Amortized Cost	207,455,000	204,313,000
Within One year, Fair Value	1,312,000
After One But Within Five Years, Fair value	7,133,000
After Five But Within Ten Years, Fair Value	71,428,000
After Ten Years, Fair Value	32,963,000
Fair Value, Total	112,836,000
Available-for-sale (at fair value)	205,678,778	199,955,367
Available-for-sale securities, Yield	3.06%	3.02%
U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One Year, Amortized Cost	2,000	9,000
After One But Within Five Years, Amortized Cost	5,494,000	7,490,000
After Five But Within Ten Years, Amortized Cost	45,099,000	43,099,000
After Ten Years, Amortized Cost
Amortized Cost, Total	50,595,000	50,598,000
Available-for-sale securities, Amortized Cost	50,595,000	50,598,000
Within One year, Fair Value	2,000	9,000
After One But Within Five Years, Fair value	5,468,000	7,416,000
After Five But Within Ten Years, Fair Value	43,665,000	41,021,000
After Ten Years, Fair Value
Fair Value, Total	49,135,000	48,446,000
Available-for-sale (at fair value)	49,135,000	48,446,000
Within One Year, Yield	0.01%	0.01%
After One But Within Five Years, Yield	1.73%	1.81%
After Five But Within Ten years, Yield	1.82%	1.81%
After Ten Years, Yield
Yield, total	1.81%	1.81%
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One Year, Amortized Cost	1,288,000	1,288,000
After One But Within Five Years, Amortized Cost	1,610,000	1,246,000
After Five But Within Ten Years, Amortized Cost	27,125,000	25,960,000
After Ten Years, Amortized Cost	32,106,000	31,555,000
Amortized Cost, Total	62,129,000	60,049,000
Available-for-sale securities, Amortized Cost	62,129,000	60,049,000
Within One year, Fair Value	1,310,000	1,321,000
After One But Within Five Years, Fair value	1,665,000	1,305,000
After Five But Within Ten Years, Fair Value	27,763,000	26,125,000
After Ten Years, Fair Value	32,963,000	31,663,000
Fair Value, Total	63,701,000	60,414,000
Available-for-sale (at fair value)	63,701,000	60,414,000
Within One Year, Yield	6.59%	6.59%
After One But Within Five Years, Yield	5.99%	5.95%
After Five But Within Ten years, Yield	5.10%	5.11%
After Ten Years, Yield	5.64%	5.65%
Yield, total	5.43%	5.44%
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	94,567,000	93,501,000
Available-for-sale (at fair value)	92,647,000	90,900,000
Available-for-sale securities, Yield	2.09%	2.06%
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	164,000	165,000
Available-for-sale (at fair value)	$ 196,000	$ 195,000
Available-for-sale securities, Yield	3.64%	4.02%