Information in Regard to Troubled Debt Restructurings that Occurred During Period (Detail) (Troubled Debt Restructuring, USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012 Contract	Sep. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	4
Pre-Modification Outstanding Balance	$ 190	$ 306
Post-Modification Outstanding Balance	190	303
Residential
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	3
Pre-Modification Outstanding Balance	190	281
Post-Modification Outstanding Balance	190	278
Home Equity and Second Mortgage
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	1
Pre-Modification Outstanding Balance	0	25
Post-Modification Outstanding Balance	0	25
Construction
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Balance	0	0
Post-Modification Outstanding Balance	0	0
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Balance	0	0
Post-Modification Outstanding Balance	0	0
Commercial Business
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Balance	0	0
Post-Modification Outstanding Balance	0	0
Other Consumer
Financing Receivable, Modifications [Line Items]
Number of Contracts	0	0
Pre-Modification Outstanding Balance	0	0
Post-Modification Outstanding Balance	$ 0	$ 0