SHARE-BASED COMPENSATION - RSU Activity - Summary of Change (Details)	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Number of Restricted Stock Units [Roll Forward]
RSUs beginning	2,074,794
RSUs awarded	206,603
RSUs released	(468,153)
RSUs forfeited	(22,623)
RSUs ending	1,790,621
Weighted Average Purchase Price RSUs | $ / shares	$ 0
Weighted Average Remaining Contractual Term (Years) RSUs	1 year 2 months 12 days
Aggregate Intrinsic Value RSUs | $	$ 20,413,079
Number of RSUs vested and expected to vest	1,790,621
Weighted Average Purchase Price of RSUs vested and expected to vest | $ / shares	$ 0
Weighted Average Remaining Contractual Term (Years) of RUSs vested and expected to vest	1 year 2 months 12 days
Aggregate Intrinsic Value RSUs vested and expected to vest | $	$ 20,413,079
Number of RSUs exercisable	48,880
Weighted Average Purchase Price of RUSs exercisable | $ / shares	$ 0
Weighted Average Remaining Contractual Term (Years) of RUSs exercisable	0 years
Aggregate Intrinsic Value RSUs exercisable | $	$ 557,232
Weighted average remaining recognition period in years	1 year 10 months 24 days
Unamortized compensation expense, net of estimated forfeitures | $	$ 8,259,906