Valuation Techniques, Significant Unobservable Inputs, Quantitative Information Non-recurring Basis (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation Technique	Market Approach	Market Approach
Unobservable Input	Discount to reflect realizable value	Discount to reflect realizable value
Discount, Minimum	15.00%	15.00%
Discount, Maximum	30.00%	30.00%
Other Real Estate Owned
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation Technique	Market Approach	Market Approach
Unobservable Input	Discount to reflect realizable value	Discount to reflect realizable value
Discount, Minimum	15.00%	15.00%
Discount, Maximum	30.00%	30.00%