Loans Receivable - Schedule of Loans Receivable on Nonaccrual Status (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	$ 6,665	$ 7,393
Commercial [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	33	35
Commercial Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	2,631	3,432
Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status
Consumer Home Equity [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	237	293
Dealer Auto and RV Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	168	121
Other Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	80	109
Residential [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Loans receivable on nonaccrual status	$ 3,516	$ 3,403