STOCKHOLDERS’ EQUITY / DEFICIT - (Details) - USD ($)				1 Months Ended		6 Months Ended	12 Months Ended
	May 18, 2016	Mar. 24, 2015	May 09, 2014	Mar. 31, 2015	Jan. 31, 2014	Aug. 18, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 08, 2015
Stockholders Equity [Line Items]
Common stock, shares authorized							100,000,000	100,000,000
Common stock, par value (in dollars per share)							$ 0.0001	$ 0.0001
Common stock per shares are entitled to vote							1 vote
Preferred Stock, shares authorized							20,000,000	20,000,000
Preferred stock, par value (in dollars per share)							$ 0.001	$ 0.001
Price per common share (in dollars per share)				$ 19.00	$ 8.50
Net proceeds from the offering							$ 0	$ 149,487,000	$ 40,000,000
Underwriting fees and other offering costs				$ 9,181,991	$ 3,164,990
2014 Incentive Compensation Plan
Stockholders Equity [Line Items]
Shares issued (in shares)			3,000,000.0
2015 Equity Incentive Plan
Stockholders Equity [Line Items]
Common stock, shares authorized										1,400,000.0
Shares remaining available for issuance under the plan (in shares)										600,000.0
2015 Equity Incentive Plan Amended
Stockholders Equity [Line Items]
Common stock, shares authorized	1,600,000.0
Shares remaining available for issuance under the plan (in shares)	700,000.0
Series A Preferred Stock
Stockholders Equity [Line Items]
Preferred Stock, shares authorized							1,000
Preferred stock, par value (in dollars per share)							$ 0.001
Restricted shares
Stockholders Equity [Line Items]
Issuance of stock options to purchase shares (in shares)						230,000
Restricted shares | 2014 Incentive Compensation Plan
Stockholders Equity [Line Items]
Issuance of stock options to purchase shares (in shares)						230,000
Restricted shares | 2015 Equity Incentive Plan Amended
Stockholders Equity [Line Items]
Share-based compensation arrangement by share-based payment award, reduction in number of shares available for grant	200.00%
Stock Options
Stockholders Equity [Line Items]
Shares issued (in shares)							1,687,250	2,285,000	4,168,000
Stock Options | 2015 Equity Incentive Plan Amended
Stockholders Equity [Line Items]
Share-based compensation arrangement by share-based payment award, reduction in number of shares available for grant	100.00%
Common Stock
Stockholders Equity [Line Items]
Number of common stock issued								7,866,000	4,705,882
Shares issued (in shares)							542,183	1,019,788
Issuance of stock options to purchase shares (in shares)						1,928,000
Common Stock | 2014 Incentive Compensation Plan
Stockholders Equity [Line Items]
Issuance of stock options to purchase shares (in shares)						1,928,000
Public Offering | Common Stock
Stockholders Equity [Line Items]
Number of common stock issued		7,866,000
Price per common share (in dollars per share)		$ 19.00
Net proceeds from the offering		$ 140,000,000
Underwriting fees and other offering costs		$ 9,500,000