Assets and Liabilities Measured at Fair Value on Recurring or Non-recurring Basis Using Significant Unobservable Inputs (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 26,244	$ 24,765
Non Performing Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	16,604	16,367
Valuation Technique	Appraised Value/ Discounted Cash Flows/ Market Value of the Note	Appraised Value/ Discounted Cash Flows/ Market Value of the Note
Significant Unobservable Inputs	Appraisals and/or sales of comparable properties/ Independent quotes	Appraisals and/or sales of comparable properties/ Independent quotes
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 9,640	$ 8,398
Valuation Technique	Appraised Value/ Comparable Sales/ Other Estimates from Independent Sources	Appraised Value/ Comparable Sales/ Other Estimates from Independent Sources
Significant Unobservable Inputs	Appraisals and/or sales of comparable properties/ Independent quotes/bids	Appraisals and/or sales of comparable properties/ Independent quotes/bids