Loans and Leases - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Loans	Jun. 30, 2012 Loans	Jun. 30, 2013 Loans	Jun. 30, 2012 Loans
Financing Receivable, Recorded Investment [Line Items]
Minimum aging of past due loans and leases current			90 days
Maximum modification period on short-term basis			Up to one year
Restructured loan past due period			Less than ninety days past due
Nonaccrual Troubled Debt Restructured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of troubled debt loan restructurings				3
Minimum [Member]
Financing Receivable, Recorded Investment [Line Items]
Amount of loan relationship with risk ratings of grade 1-5 reviewed annually	$ 500,000		$ 500,000
Amount of loan relationship with risk ratings of grade 1-5 reviewed quarterly	2,500,000		2,500,000
Amount of loan relationship with risk ratings of grade six reviewed annually	500,000		500,000
Amount of loan relationship with risk rates of grade six reviewed quarterly	2,000,000		2,000,000
Aging period due of reviewing loans rated 1 through 6			60 days
Loan-to-value ratio for residential mortgage loans with private mortgage insurance	80.00%		80.00%
Maximum [Member]
Financing Receivable, Recorded Investment [Line Items]
Amount of loan relationship with risk ratings of grade 1-5 reviewed annually	2,500,000		2,500,000
Amount of loan relationship due for review after 60 or more past due days	500,000		500,000
Amount of loan relationship with risk ratings of grade six reviewed annually	$ 2,000,000		$ 2,000,000
Loan-to-value ratio for residential mortgage loans without private mortgage insurance	80.00%		80.00%
Combined loan-to-value ratio for home equity loans without private mortgage insurance	80.00%		80.00%
Combined loan-to-value ratio for home equity loans without private mortgage insurance for corporations strongest profile borrower	85.00%		85.00%