Loans Receivable Held for Investment - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Loans Receivable [Line Items]
Interest income on impaired loans	$ 762,000	$ 1,200,000
Troubled debt restructurings, allowance	2,100,000		2,500,000
Loans classified as a Troubled Debt Restructurings	34,400,000		41,100,000
Non-accrual loans	18,000,000		22,800,000
Accrual loans status	16,400,000		18,300,000
Troubled Debt Restructurings	32,400,000
Troubled debt restructurings, specific reserves	23,000	87,000
Troubled debt restructurings, charge-offs	23,000	0
Payment default classification period	90 days
Loans modified		$ 3,200,000