Activity of Exercisable Common Stock Options (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Number of Shares
Vested common stock options, beginning balance	181,327
Common stock options exercised	(20,668)	(8,534)
Common stock options vested	383,208	189,861
Vested common stock options, ending balance	543,867	181,327
Weighted Average Exercise Price Per Share
Vested common stock options, beginning balance	$ 5.21
Common stock options exercised	$ 3.00	$ 3.00
Common stock options vested	$ 5.47	$ 5.11
Vested common stock options, ending balance	$ 5.76	$ 5.21