Activity of Non-Vested Stock Options (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Number of Shares
Nonvested common stock options, beginning balance	8,723,748	8,816,000
Common stock options granted	2,050,000	1,846,000
Common stock options vested	(3,332,083)	(1,898,586)
Common stock options forfeited	(83,333)	(39,666)
Nonvested common stock options, ending balance	7,358,332	8,723,748
Weighted Average Exercise Price Per Share
Nonvested common stock options, beginning balance	$ 0.54	$ 0.57
Common stock options granted	$ 0.95	$ 0.36
Common stock options vested	$ 0.55	$ 0.54
Common stock options forfeited	$ 0.30	$ 0.30
Nonvested common stock options, ending balance	$ 0.54	$ 0.54