Changes in Shareholders' Equity - Changes in Shareholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Beginning Balance			$ 79,412
Issuance of 2,851 common shares for stock options exercised, employee stock purchases and employee stock awards			48
Share-based compensation, options granted			96
Dividends:
Preferred stock, $5.00 per share			(3)
Common stock, $.12 per share			(584)
Net income for the period	$ 462	$ 453	391	$ 401
Ending Balance	79,360		79,360
Preferred Stock [Member]
Beginning Balance			32
Dividends:
Ending Balance	32		32
Common Stock [Member]
Beginning Balance			2,430
Issuance of 2,851 common shares for stock options exercised, employee stock purchases and employee stock awards			1
Dividends:
Ending Balance	2,431		2,431
Additional Paid-in Capital [Member]
Beginning Balance			37,891
Issuance of 2,851 common shares for stock options exercised, employee stock purchases and employee stock awards			47
Share-based compensation, options granted			96
Dividends:
Ending Balance	38,034		38,034
Retained Earnings [Member]
Beginning Balance			39,059
Dividends:
Preferred stock, $5.00 per share			(3)
Common stock, $.12 per share			(584)
Net income for the period			391
Ending Balance	$ 38,863		$ 38,863