STOCKHOLDERS' EQUITY (Details Textual) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
	Aug. 06, 2015	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Stockholders Equity [Line Items]
Preferred stock, shares authorized		10,000,000	10,000,000	10,000,000
Preferred stock, par value (in dollars per share)		$ 0.001	$ 0.001	$ 0.001
Common stock, par value (in dollars per share)		$ 0.001	$ 0.001	$ 0.001
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition			2 years 2 months 12 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total		$ 21,000,000	$ 21,000,000
Shares available from Shelf Registration Statement			248,300,000
Aggregate Offering Price			75,000,000
Proceeds From Issuance Of Common Stock			$ 51,200,000
Common Stock, Shares Authorized		150,000,000	150,000,000	150,000,000
Entities, Stock Issued, Shares, Issued for Cash			3,220,717
Entities, Stock Issued, Value, Issued for Cash			$ 52,200,000
Sale of Stock, Price Per Share		$ 16.19	$ 16.19
Available-for-sale Securities, Equity Securities				$ 250,000,000
Restricted Stock Or Unit Expense		$ 6,242,986	$ 11,600,014
ATM [Member]
Stockholders Equity [Line Items]
Common Stock Value Reserved for Future Issuance			$ 75,000,000
Commission Percentage			3.00%
Subsequent Event [Member] | At-the-Market Issuance Sales Agreement 2015 [Member]
Stockholders Equity [Line Items]
Proceeds From Issuance Of Common Stock	$ 15,800,000
Entities, Stock Issued, Shares, Issued for Cash	873,781
Entities, Stock Issued, Value, Issued for Cash	$ 16,100,000
Sale of Stock, Price Per Share	$ 18.38
Corporate Milestone [Member]
Stockholders Equity [Line Items]
Restricted Stock, Outstanding, Number, Ending Balance		1,863,167	1,863,167
Restricted Stock [Member]
Stockholders Equity [Line Items]
Restricted Stock Or Unit Expense			$ 11,600,000
Incentive Plan 2012
Stockholders Equity [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		6,000,000	6,000,000
Equity Incentive Plans [Member]
Stockholders Equity [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		5,655,574	5,655,574