NET INCOME (LOSS) PER SHARE ATTRIBUTABLE TO CLASS A COMMON SHAREHOLDERS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Apr. 30, 2014
Numerator:
Net income (loss) attributable to holders of shares of Class A common stock - basic	$ 19,730	$ 6,893	$ 35,008	$ 13,863
Class A common stock
Numerator:
Net income (loss) attributable to holders of shares of Class A common stock - basic	19,730	6,893	35,008	13,863
Net income (loss) attributable to holders of shares of Class A common stock - diluted	$ 19,730	$ 6,893	$ 35,008	$ 13,863
Denominator:
Weighted average shares of Class A common stock outstanding - basic	28,165,552	20,745,043	27,325,145	20,654,657
Weighted average number of incremental shares issuable from unvested restricted stock, RSUs and stock options, as calculated using the treasury stock method	6,209,330	2,873,050	6,426,994	2,397,598
Weighted average shares of Class A common stock outstanding—diluted	34,374,882	23,618,093	33,752,139	23,052,255
Net income (loss) per share attributable to holders of shares of Class A common stock
Basic (in dollars per share)	$ 0.70	$ 0.33	$ 1.28	$ 0.67
Diluted (in dollars per share)	$ 0.57	$ 0.29	$ 1.04	$ 0.60
Number of Shares Issuable upon Exchange of Each Unit	1		1		1
Fully diluted shares of common stock outstanding if all Class A partnership units were to be exchanged for common stock immediately following the reorganization	62,971,925	57,386,765	62,588,514	56,911,313
Class A common stock | Restricted stock and RSUs
Net income (loss) per share attributable to holders of shares of Class A common stock
Number of antidilutive securities excluded from calculation of diluted income (loss) per share	190	1,793	161	899
Class A common stock | Stock options
Net income (loss) per share attributable to holders of shares of Class A common stock
Number of antidilutive securities excluded from calculation of diluted income (loss) per share	0	14,505	0	1,053,593