Summary of Status of Company's Stock Option Plan (Detail) (Stock Option Plan, USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Stock Option Plan
Shares
Outstanding at beginning of period	3,348,935	3,435,443
Cancelled	(8,617)	(8,313)
Exercised	(945,761)	(109,038)
Granted	50,000	30,843
Outstanding at end of period	2,444,557	3,348,935
Weighted Average Exercise Price
Outstanding at beginning of period	$ 1.23	$ 1.22
Cancelled	$ 1.10	$ 1.10
Exercised	$ 1.20	$ 1.42
Granted	$ 4.25	$ 3.27
Outstanding at end of period	$ 1.31	$ 1.23