Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 53,317	$ 68,698	$ 18,420	$ 38,351	$ 54,135	$ 60,772	$ 16,389	$ 32,730	$ 178,786	$ 164,026	$ 159,669
Cost of sales	13,361	16,662	5,402	10,846	11,290	11,620	3,906	5,839	46,271	32,655	59,977
Gross profit	39,956	52,036	13,018	27,505	42,845	49,152	12,483	26,891	132,515	131,371	99,692
(Loss) income before taxes	(289)	3,972	(22,777)	(9,306)	30,754	13,178	(14,302)	(10,647)
Net (loss) income	$ (1,916)	$ 2,954	$ (18,402)	$ (12,876)	$ 23,438	$ 9,546	$ 2,607	$ (12,029)	$ (30,060)	$ 23,471	$ (111,560)
Net (loss) income per common share:
Basic (in dollars per share)	$ (0.04)	$ 0.06	$ (0.37)	$ (0.26)	$ 0.47	$ 0.19	$ 0.05	$ (0.24)	$ (0.60)	$ 0.47	$ (2.26)
Diluted (in dollars per share)	$ (0.04)	$ 0.06	$ (0.37)	$ (0.26)	$ 0.47	$ 0.19	$ 0.05	$ (0.24)	$ (0.60)	$ 0.47	$ (2.26)