Dental Loan Portfolio - Dental Credit Quality Indicators (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	$ 270,782	$ 208,489
In Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	191,908	166,133
Out-of-Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	78,874	42,356
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	263,352	204,791
Pass [Member] | In Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	184,872	162,435
Pass [Member] | Out-of-Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	78,480	42,356
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable
Special Mention [Member] | In Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable
Special Mention [Member] | Out-of-Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	7,430	3,698
Substandard [Member] | In Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	7,036	3,698
Substandard [Member] | Out-of-Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable	394
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable
Doubtful [Member] | In Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable
Doubtful [Member] | Out-of-Market [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans Receivable