STOCK BASED COMPENSATION (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	1,779,613	2,673,512	4,667,738	7,536,601
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 8.46	$ 7.46	$ 6.14	$ 5.53
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 50,869	$ 5,485,248	$ 19,357,512	$ 17,493,907
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	(641,710)	(1,802,913)	(3,126,522)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 4.37	$ 3.92	$ 4.51
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 2,209,260	$ 9,162,469	$ 13,035,677
Forfeited, Options	(252,189)	(191,313)	(401,841)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	$ 8.20	$ 10.76	$ 9.33
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	1,552,642	2,037,318	3,513,920
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 8.52	$ 7.19	$ 5.43
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 50,869	$ 4,832,280	$ 17,239,884
Stock based compensation expense	11,145,000	$ 10,185,000	$ 7,501,000
Unrecognized compensation expense	$ 14,847,000
Weighted-average period	1 year 7 months
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number	130,375
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number	24,001
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			1 year 5 months