Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Future Grant, Beginning Balance	381,170	353,953
Shares Available for Future Grant, Options granted at market		(54,250)
Shares Available for Future Grant, Options forfeited or expired	10,167	81,467
Shares Available for Future Grant, Ending Balance	391,337	381,170
Number of Shares Outstanding Under Option, Beginning Balance	706,803	737,020
Number of Shares Outstanding Under Option, Options granted at market		54,250
Number of Shares Outstanding Under Option, Options forfeited or expired	(10,167)	(84,467)
Number of Shares Outstanding Under Option, Ending Balance	696,636	706,803
Weighted Average Exercise Price, Beginning Balance	$ 4.27	$ 4.26
Weighted Average Exercise Price , Options granted at market		$ 0.54
Weighted Average Exercise Price, Options forfeited or expired	$ 3.53	$ 1.83
Weighted Average Exercise Price, Ending Balance	$ 4.28	$ 4.27