Loans - Troubled Debt Restructuring Removed from Classification (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 Contract	Sep. 30, 2011 Contract	Sep. 30, 2012 Contract	Sep. 30, 2011 Contract
Financing Receivable, Modifications [Line Items]
Carrying balance	$ 131	$ 276	$ 6,018	$ 1,152
Count	1	1	19	2