STOCKHOLDERS’ EQUITY / DEFICIT - Unvested Restricted Stock (Details) - Restricted shares	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Number of shares
Unvested beginning balance (in shares) | shares	691,668
Granted (in shares) | shares	273,000
Vested (in shares) | shares	(478,334)
Forfeited/cancelled (in shares) | shares	(56,668)
Unvested ending balance (in shares) | shares	429,666
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share) | $ / shares	$ 10.83
Granted (in dollars per share) | $ / shares	26.97
Vested (in dollars per share) | $ / shares	11.56
Forfeited/cancelled (in dollars per share) | $ / shares	13.97
Unvested ending balance (in dollars per share) | $ / shares	$ 20.38