Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Values of Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 229,019	$ 219,923
Unrealized Gains	6,559	6,426
Unrealized Losses	(244)	(337)
Fair Value	235,334	226,012
U.S. Government agencies and corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	47,379	56,762
Unrealized Gains	119	120
Unrealized Losses	(7)	(1)
Fair Value	47,491	56,881
Mortgage backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	126,237	103,624
Unrealized Gains	3,899	3,705
Unrealized Losses	(149)	(292)
Fair Value	129,987	107,037
Collateralized mortgage obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25,825	29,537
Unrealized Gains	317	700
Unrealized Losses	(88)
Fair Value	26,054	30,237
State and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	29,578	30,000
Unrealized Gains	2,224	1,901
Unrealized Losses		(44)
Fair Value	$ 31,802	$ 31,857

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details