Securities - Summary of Gross Unrealized Losses and Fair Value of Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	$ 2,569	$ 99
Fair value, less than 12 months	66,214	20,237
Gross unrealized losses, 12 months or more	9	33
Fair value, 12 months or more	1,410	1,020
Gross unrealized losses, Total	2,578	132
Fair value, Total	67,624	21,257
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	13
Fair value, less than 12 months	993
Gross unrealized losses, Total	13
Fair value, Total	993
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	1,148	43
Fair value, less than 12 months	26,849	15,957
Gross unrealized losses, Total	1,148	43
Fair value, Total	26,849	15,957
Mortgage-Backed Securities in Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	1,218	1
Fair value, less than 12 months	32,565	344
Gross unrealized losses, Total	1,218	1
Fair value, Total	32,565	344
Asset-Backed Securities in Government Sponsored Entities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months		39
Fair value, less than 12 months		1,833
Gross unrealized losses, Total		39
Fair value, Total		1,833
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	183	12
Fair value, less than 12 months	5,239	1,737
Gross unrealized losses, Total	183	12
Fair value, Total	5,239	1,737
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	7	4
Fair value, less than 12 months	568	366
Gross unrealized losses, 12 months or more	8	24
Fair value, 12 months or more	1,357	975
Gross unrealized losses, Total	15	28
Fair value, Total	1,925	1,341
Total Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, less than 12 months	2,569	99
Fair value, less than 12 months	66,214	20,237
Gross unrealized losses, 12 months or more	8	24
Fair value, 12 months or more	1,357	975
Gross unrealized losses, Total	2,577	123
Fair value, Total	67,571	21,212
Equity Securities in Financial Institutions [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized losses, 12 months or more	1	9
Fair value, 12 months or more	53	45
Gross unrealized losses, Total	1	9
Fair value, Total	$ 53	$ 45