Loans - Schedule of Debtor Troubled Debt Restructuring, Subsequent Periods (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Nonaccrual Troubled Debt Restructurings, Total	$ 2,747	$ 3,020
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Nonaccrual Troubled Debt Restructurings, Total	300	446
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Nonaccrual Troubled Debt Restructurings, Total	539	47
Multi-family residential [Member]
Financing Receivable, Modifications [Line Items]
Nonaccrual Troubled Debt Restructurings, Total	$ 1,908	$ 2,527