Loan Portfolio Segment Balances (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 2,531,128	$ 2,239,692
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	346,708	260,327
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	3,421	6,954
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	356,990	360,080
Residential Real Estate Portfolio Segment | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	523,364	448,662
Residential Real Estate Portfolio Segment | Residential Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	120,314	108,699
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	571,510	522,076
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	456,888	371,948
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 151,933	$ 160,946