Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 318,047	$ 306,408	$ 301,471	$ 274,000	$ 197,519	$ 188,029	$ 187,308	$ 184,935	$ 1,199,926	$ 757,791	$ 734,823
Gross Profit	88,419	92,461	85,076	74,437	50,181	47,478	46,516	42,752
Operating income (loss)	21,799	32,077	31,643	27,784	8,942	14,182	3,374	9,298	113,303	35,796	33,833
Net income (loss)	$ 2,433	$ 18,641	$ 12,849	$ 220,606	$ 52,914	$ 12,278	$ (4,998)	$ (12,205)	$ 254,529	$ 47,989	$ (53,629)