Stock Based Compensation - Schedule of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of stock options, Outstanding, Beginning of period	86,500	104,970	312,190
Number of stock options, Outstanding, Exercised	(86,500)	(18,470)	(207,220)
Number of stock options, Outstanding, End of period		86,500	104,970
Weighted average exercise price, outstanding, Beginning of period	$ 0.71	$ 0.71	$ 1.06
Weighted average exercise price, Outstanding, Exercised	$ 0.71	$ 0.71	$ 1.24
Weighted average exercise price, outstanding, End of period		$ 0.71	$ 0.71
Number of stock options, Exercisable, Beginning of period	86,500	104,970	312,190
Number of stock options, Exercisable, End of period		86,500	104,970
Weighted average exercise price, Exercisable, Beginning of period	$ 0.71	$ 0.71	$ 1.06
Weighted average exercise price, Exercisable, End of period		$ 0.71	$ 0.71