Securities - Amortized Costs, Unrealized Gains, Unrealized Losses and Approximate Fair Values of Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Aug. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	$ 220,357	$ 194,423
Available-for-sale securities, Gross Unrealized Gains	1,684	4,096
Available-for-sale securities, Gross Unrealized Losses	(5,401)	(1,165)
Available-for-sale securities, Estimated Fair Value	216,640	197,354	18,800
Held-to-maturity securities, Amortized Costs	36,696	31,483
Estimated Fair Value, Total	34,025
Obligations of states and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity securities, Amortized Costs	36,696	31,483
Held-to-maturity securities, Gross Unrealized Gains	36	60
Held-to-maturity securities, Gross Unrealized Losses	(2,707)	(50)
Estimated Fair Value, Total	34,025	31,493
U.S. government & agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	6,580	2,970
Available-for-sale securities, Gross Unrealized Gains	0	0
Available-for-sale securities, Gross Unrealized Losses	(316)	(24)
Available-for-sale securities, Estimated Fair Value	6,264	2,946
Obligations of state and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	60,370	56,802
Available-for-sale securities, Gross Unrealized Gains	672	1,797
Available-for-sale securities, Gross Unrealized Losses	(1,833)	(115)
Available-for-sale securities, Estimated Fair Value	59,209	58,484
Residential mortgage backed securities and collateralized mortgage obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	64,026	51,177
Available-for-sale securities, Gross Unrealized Gains	318	670
Available-for-sale securities, Gross Unrealized Losses	(1,353)	(317)
Available-for-sale securities, Estimated Fair Value	62,991	51,530
Corporate securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	48,836	60,516
Available-for-sale securities, Gross Unrealized Gains	282	1,358
Available-for-sale securities, Gross Unrealized Losses	(888)	(318)
Available-for-sale securities, Estimated Fair Value	48,230	61,556
Commercial mortgage backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	10,828	4,412
Available-for-sale securities, Gross Unrealized Gains	24	2
Available-for-sale securities, Gross Unrealized Losses	(380)	(90)
Available-for-sale securities, Estimated Fair Value	10,472	4,324
Other asset backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Costs	29,717	18,546
Available-for-sale securities, Gross Unrealized Gains	388	269
Available-for-sale securities, Gross Unrealized Losses	(631)	(301)
Available-for-sale securities, Estimated Fair Value	$ 29,474	$ 18,514