QUARTERLY FINANCIAL DATA (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net revenues	$ 47,286	$ 48,164	$ 44,764	$ 36,628	$ 38,205	$ 38,525	$ 31,337	$ 20,555	$ 176,842	$ 128,622	$ 76,322
Total operating expenses	39,907	38,833	37,770	32,003	36,907	30,604	26,143	14,889	148,513	108,543	43,622
Operating income	7,379	9,331	6,994	4,625	1,298	7,921	5,194	5,666	28,329	20,079	32,700
(Provision)/benefit for income taxes	(13,979)	(1,654)	(1,269)	(523)	524	(2,501)	(1,227)	(1,540)	17,425	4,744	6,358
Net income/(loss)	$ (9,629)	$ 4,720	$ 2,681	$ 1,152	$ (1,080)	$ 2,543	$ 1,125	$ 1,346	$ (1,076)	$ 3,934	$ 15,375
Basic and diluted earnings/(loss) per share:
Basic earnings/(loss) per share	$ (0.83)	$ 0.41	$ 0.23	$ 0.10	$ (0.09)	$ 0.22	$ 0.10	$ 0.12	$ (0.09)	$ 0.34	$ 1.34
Diluted earnings/(loss) per share	$ (0.83)	$ 0.40	$ 0.23	$ 0.10	$ (0.09)	$ 0.22	$ 0.10	$ 0.12	$ (0.09)	$ 0.34	$ 1.32