Activity of Exercisable Common Stock Options (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Number of Shares
Vested common stock options, beginning balance	543,867	181,327
Common stock options exercised		(20,668)
Common stock options vested	472,200	383,208
Vested common stock options, ending balance	1,016,067	543,867
Weighted Average Exercise Price Per Share
Vested common stock options, beginning balance	$ 5.76	$ 5.21
Common stock options exercised		$ 3.00
Common stock options vested	$ 5.59	$ 5.47
Vested common stock options, ending balance	$ 5.68	$ 5.76