Loans Receivable, net - Troubled Debt Restructurings (Detail) (USD $)					9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2013 Commercial Mortgage Loans [Member] SecurityLoan	Dec. 31, 2012 Commercial Mortgage Loans [Member] SecurityLoan	Dec. 31, 2012 SBA 7(a) Loans [Member] SecurityLoan
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings requiring reserves, Unpaid Principal Balance					$ 6,649,000	$ 10,531,000	$ 846,000
Troubled debt restructurings without reserves, Unpaid Principal Balance					1,976,000	2,172,000
Total troubled debt restructurings, Unpaid Principal Balance					8,625,000	12,703,000	846,000
Troubled debt restructurings requiring reserves, Recorded Investment					6,203,000	10,049,000	854,000
Troubled debt restructurings without reserves, Recorded Investment					1,933,000	2,123,000
Total troubled debt restructurings, Recorded Investment					8,136,000	12,172,000	854,000
Number of loans					6	8	1
Loan loss reserves	2,852,000	3,413,000			697,000
Loan loss reserves	$ 2,852,000	$ 3,413,000	$ 2,067,000	$ 1,812,000		$ 1,382,000	$ 130,000