Estimated Fair Value of Financial Instruments - Summary of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Carrying Amount [Member]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Cash and due from banks, Federal funds sold and interest bearing deposits in other banks	$ 28,527	$ 40,647
Securities	235,334	226,012
Restricted stock	5,741
Portfolio loans, net	868,128	826,025
Loans held for sale	3,380	3,448
Accrued interest receivable	3,758	3,550
Demand, savings and money market	525,698	486,690
Certificates of deposit	496,011	504,390
Short-term borrowings	988	227
Federal Home Loan Bank advances	47,494	42,497
Junior subordinated debentures	16,238	16,238
Fair Value [Member]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Cash and due from banks, Federal funds sold and interest bearing deposits in other banks	28,527	40,647
Securities	235,334	226,012
Restricted stock	5,741
Portfolio loans, net	863,782	825,662
Loans held for sale	3,380	3,448
Accrued interest receivable	3,758	3,550
Demand, savings and money market	525,698	486,690
Certificates of deposit	499,285	509,449
Short-term borrowings	988	227
Federal Home Loan Bank advances	48,569	43,824
Junior subordinated debentures	17,102	16,130
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Cash and due from banks, Federal funds sold and interest bearing deposits in other banks	28,527
Restricted stock
Portfolio loans, net
Loans held for sale
Accrued interest receivable
Demand, savings and money market	525,698
Certificates of deposit
Short-term borrowings
Federal Home Loan Bank advances
Junior subordinated debentures
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Cash and due from banks, Federal funds sold and interest bearing deposits in other banks
Securities	235,334
Restricted stock	5,741
Portfolio loans, net
Loans held for sale	3,380
Accrued interest receivable	3,758
Certificates of deposit	499,285
Short-term borrowings	988
Federal Home Loan Bank advances	48,569
Junior subordinated debentures	17,102
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Inputs Assets Liabilities Quantitative Information [Line Items]
Cash and due from banks, Federal funds sold and interest bearing deposits in other banks
Securities
Portfolio loans, net	863,782
Loans held for sale
Accrued interest receivable
Demand, savings and money market
Certificates of deposit
Short-term borrowings
Federal Home Loan Bank advances
Junior subordinated debentures