STOCKHOLDERS EQUITY (Details) $ in Thousands		1 Months Ended		3 Months Ended		12 Months Ended
	Jan. 11, 2017 USD ($) shares	Nov. 30, 2014 USD ($) shares	Apr. 30, 2014 shares	Mar. 31, 2017 USD ($) shares	Mar. 31, 2016 USD ($) shares	Dec. 31, 2016 USD ($) shares
Stockholders Equity
Treasury stock shares acquired (in shares)				205,085	70,431
Treasury stock shares acquired | $				$ 7,534	$ 1,847	$ 1,847
Group LP
Stockholders Equity
Number of units held by noncontrolling interest holders				28,341,424		33,698,300
Noncontrolling interests (as a percent)				52.00%		62.00%
Class A common stock
Stockholders Equity
Aggregate stock issuance (in shares)			15,263,653
Reorganization of equity structure (in shares)			7,699,851
Common Stock issued in connection with settlement of appreciation rights issued in prior years (in shares)			88,802
Common stock, shares issued				27,192,692		20,948,998
Common stock, shares outstanding				26,599,717		20,561,108
Number of shares of common stock to be issued upon exchange of a partnership unit			1	1
Class A common stock | IPO
Stockholders Equity
Shares issued (in shares)			7,475,000
Class A common stock | Follow-on Offering
Stockholders Equity
Issuance of new and sale of existing common stock (in shares)	5,750,000	6,325,000
Issuance of Class A common stock and acquisition of Class A partnership units in connection with follow-on offering (in shares)	5,356,876	4,511,058
Class A common stock | Group LP
Stockholders Equity
Common stock, shares outstanding				26,599,717
Class B common stock
Stockholders Equity
Shares issued (in shares)			36,158,698
Common stock, shares issued				25,781,317		31,138,193
Common stock, shares outstanding				25,781,317		31,138,193
Ratio of subscription price to the initial public offering price of shares of common stock			0.00055
Dividends payable ratio to outstanding shares of publicly traded common stock			0.00055
Class B common stock | Follow-on Offering
Stockholders Equity
Shares converted		2,998,322
Shares issued upon conversion		1,658
Conversion ratio		0.00055
Number of shares repurchased and retired	5,356,876	1,509,131
Value of stock repurchased and retired | $	$ 101	$ 28