Loans by Class Modified as Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 Loan
Financing Receivable, Modifications [Line Items]
Number of Loans	45
Recorded Investment	$ 5,690
Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans	3
Recorded Investment	329
Home Equity
Financing Receivable, Modifications [Line Items]
Number of Loans	6
Recorded Investment	367
Residential Real Estate | Residential Real Estate - Owner Occupied
Financing Receivable, Modifications [Line Items]
Number of Loans	31
Recorded Investment	3,154
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of Loans	1
Recorded Investment	1,763
Consumer | Other Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans	4
Recorded Investment	$ 77