SHARE-BASED COMPENSATION - RSU Activity - Summary of Change (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Restricted Stock Units [Roll Forward]
RSUs beginning	1,590,417
RSUs awarded	1,122,585	796,000	685,000
RSUs released	(611,383)	(406,000)	(410,000)
RSUs forfeited	(26,825)	(58,000)	(47,000)
RSUs ending	2,074,794	1,590,417
Weighted Average Purchase Price RSUs	$ 0
Weighted Average Remaining Contractual Term (Years) RSUs	1 year 6 months
Aggregate Intrinsic Value RSUs	$ 31,744,348
Number of RSUs vested and expected to vest	1,926,132
Weighted Average Purchase Price of RSUs vested and expected to vest	$ 0
Weighted Average Remaining Contractual Term (Years) of RUSs vested and expected to vest	1 year 6 months
Aggregate Intrinsic Value RSUs vested and expected to vest	$ 28,721,961
Number of RSUs exercisable	48,880
Weighted Average Purchase Price of RUSs exercisable	$ 0
Weighted Average Remaining Contractual Term (Years) of RUSs exercisable	0 years
Aggregate Intrinsic Value RSUs exercisable	$ 747,864
Weighted average remaining recognition period in years	2 years 2 months 12 days
Unamortized compensation expense, net of estimated forfeitures	$ 10,822,456