Information in Regard to Troubled Debt Restructurings that Occurred During Period (Detail) (Troubled Debt Restructuring, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	2
Pre-Modification Outstanding Balance	$ 113
Post-Modification Outstanding Balance	113
Residential
Financing Receivable, Modifications [Line Items]
Number of Contracts	1
Pre-Modification Outstanding Balance	88
Post-Modification Outstanding Balance	88
Home Equity and Second Mortgage
Financing Receivable, Modifications [Line Items]
Number of Contracts	1
Pre-Modification Outstanding Balance	25
Post-Modification Outstanding Balance	25
Construction
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Pre-Modification Outstanding Balance	0
Post-Modification Outstanding Balance	0
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Pre-Modification Outstanding Balance	0
Post-Modification Outstanding Balance	0
Commercial Business
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Pre-Modification Outstanding Balance	0
Post-Modification Outstanding Balance	0
Other Consumer
Financing Receivable, Modifications [Line Items]
Number of Contracts	0
Pre-Modification Outstanding Balance	0
Post-Modification Outstanding Balance	$ 0