Stock-based compensation arrangements (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation expense	$ 197,807	$ 191,828
Stock option grants beginning of period [Member]
Stock-based compensation expense	92,187	182,064
Stock option grants [Member]
Stock-based compensation expense	100,638	6,188
Employee Stock Purchase Plan [Member]
Stock-based compensation expense	5,522	1,332
Director Agreements [Member]
Stock-based compensation expense	$ (540)	$ 2,244