Dental Loan Portfolio - Dental Loan Total by Market (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable	$ 270,782	$ 208,489
In Market [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable	191,908	166,133
Out-of-Market [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable	$ 78,874	$ 42,356