Dental Loan Portfolio - Major Classifications of Dental Loans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	$ 270,782	$ 208,489
Commercial and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	206,259	158,263
Real estate secured loans [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	64,523	50,226
Real estate secured loans [Member] | Residential Portfolio Segment [Member] | Owner-occupied commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	59,327	35,949
Real estate secured loans [Member] | Residential Portfolio Segment [Member] | Other dental real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	3,103	12,284
Real estate secured loans [Member] | Residential Portfolio Segment [Member] | Dental Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	2,093	1,993
Real estate secured loans [Member] | Real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans Receivable	$ 62,430	$ 48,233