Summary of Other Operating Expenses in Consolidated Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses	$ 1,821	$ 759	$ 4,206	$ 2,656
Insurance
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			51	46
Professional Fees
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			397	354
Merger Expenses
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			1,202
Advertising and Promotional Expenses
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			237	153
Postage, Printing, and Supplies
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			113	108
Data Processing
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			992	731
FDIC Premiums
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			423	407
Other Real Estate Owned
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			248	269
Directors' Fees
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			130	196
Other
Component of Operating Other Cost and Expense [Line Items]
Other Operating Expenses			$ 413	$ 392