Estimated Fair Values of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Financial assets
Cash and cash equivalents	$ 24,844	$ 39,164	$ 37,367	$ 23,474
Held-to-maturity securities	235	450
Loans, net of allowance	323,598	313,354
Federal Home Loan Bank stock	4,210	4,210
Accrued interest receivable	787	829
Financial liabilities
Deposits	323,197	322,681
Short term borrowings	10,244	5,098
Federal Home Loan Bank advances	26,587	26,719
Subordinated debentures	4,124	4,124
Interest payable	123	135
Fair Value, Inputs, Level 1
Financial assets
Cash and cash equivalents	24,844	39,164
Held-to-maturity securities	0	0
Loans, net of allowance	0	0
Federal Home Loan Bank stock	0	0
Accrued interest receivable	0	0
Financial liabilities
Deposits	0	0
Short term borrowings	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures	0	0
Interest payable	0	0
Fair Value, Inputs, Level 2
Financial assets
Cash and cash equivalents	0	0
Held-to-maturity securities	236	451
Loans, net of allowance	0	0
Federal Home Loan Bank stock	4,210	4,210
Accrued interest receivable	787	829
Financial liabilities
Deposits	310,493	309,186
Short term borrowings	10,244	5,098
Federal Home Loan Bank advances	27,709	26,703
Subordinated debentures	3,962	3,962
Interest payable	123	135
Fair Value, Inputs, Level 3
Financial assets
Cash and cash equivalents	0	0
Held-to-maturity securities	0	0
Loans, net of allowance	321,027	312,014
Federal Home Loan Bank stock	0	0
Accrued interest receivable	0	0
Financial liabilities
Deposits	0	0
Short term borrowings	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures	0	0
Interest payable	$ 0	$ 0