Allowance for Loan Losses - Summary of Nonaccrual Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total, Non-Accrual Status	$ 17,612	$ 20,459
Commercial and Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Total, Non-Accrual Status	1,187	1,590
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total, Non-Accrual Status	8,468	9,609
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total, Non-Accrual Status	7,898	9,210
Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total, Non-Accrual Status	$ 59	$ 50