Non-Performing Loans and Leases (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	$ 10,613	[1]	$ 14,040	[1]
Total nonperforming loans and leases	10,613	[1]	14,768	[1]
Commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	511	[1]	631	[1]
Home equity lines and loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	1,544	[1]	2,792	[1]
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	3,838	[1]	3,748	[1]
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	1,661	[1]	3,314	[1]
Loans and leases 90 days or more past due and still accruing			728	[1]
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	2,994	[1]	3,506	[1]
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	49	[1]	7	[1]
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans and leases	$ 16	[1]	$ 42	[1]

[1] Purchased credit-impaired loans, which have been recorded at their fair values at acquisition, and which are performing, are excluded from this table, with the exception of $90 thousand of purchased credit-impaired loans as of both September 30, 2013 and December 31, 2012, which became non-performing subsequent to acquisition.