Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data (Unaudited)
Net revenues	$ 36,236	$ 31,465	$ 32,618	$ 29,471	$ 33,202	$ 28,781	$ 29,055	$ 20,951	$ 25,876	$ 23,705	$ 22,929	$ 13,495	$ 129,790	$ 111,989	$ 86,005
Operating (loss) income	11,079	7,951	8,780	7,056	10,211	5,559	6,612	3,647	5,019	4,110	(1,292)	(117)	34,867	26,027	7,722
Net income (loss)	$ 4,934	$ 2,910	$ 3,431	$ 2,462	$ 4,330	$ 663	$ 5,318	$ 248	$ 2,639	$ (3,985)	$ (2,426)	$ (525)	$ 13,739	$ 10,557	$ (4,297)
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.11	$ 0.07	$ 0.08	$ 0.06	$ 0.10	$ 0.02	$ 0.13	$ 0.01	$ 0.06	$ (0.09)	$ (0.06)	$ (525)	$ 0.32	$ 0.25	$ (0.14)
Dilutive (in dollars per share)	$ 0.11	$ 0.07	$ 0.08	$ 0.06	$ 0.10	$ 0.02	$ 0.13	$ 0.01	$ 0.06	$ (0.09)	$ (0.06)	$ (525)	$ 0.31	$ 0.25	$ (0.14)