Unaudited Quarterly Financial Data (Details) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Unaudited Quarterly Financial Data [Abstract]
Net sales	$ 150,735,000	$ 125,574,000	$ 150,374,000	$ 109,148,000	$ 129,077,000	$ 124,113,000	$ 127,939,000	$ 91,668,000	$ 535,831,000	$ 472,797,000	$ 427,548,000
Cost of goods sold	114,152,000	97,913,000	113,801,000	91,565,000	103,127,000	102,952,000	102,228,000	75,316,000	417,431,000	383,623,000	320,515,000
Gross profit	36,583,000	27,661,000	36,573,000	17,583,000	25,950,000	21,161,000	25,711,000	16,352,000	118,400,000	89,174,000	107,033,000
Operating expenses [Abstract]
General and administrative	34,522,000	10,618,000	14,285,000	12,000,000	12,553,000	12,331,000	8,997,000	12,091,000	71,425,000	45,972,000	35,477,000
Sales and marketing	5,047,000	5,623,000	5,448,000	4,919,000	5,464,000	5,149,000	4,537,000	4,392,000	21,037,000	19,542,000	15,030,000
Research and development	2,506,000	2,174,000	2,148,000	2,372,000	2,440,000	2,054,000	1,784,000	1,736,000	9,200,000	8,014,000	5,692,000
Total operating expenses	42,075,000	18,415,000	21,881,000	19,291,000	20,457,000	19,534,000	15,318,000	18,219,000	101,662,000	73,528,000	56,199,000
Operating income	(5,492,000)	9,246,000	14,692,000	(1,708,000)	5,493,000	1,627,000	10,393,000	(1,867,000)	16,738,000	15,646,000	50,834,000
Other expense [Abstract]
Interest expense, net	5,464,000	6,879,000	6,523,000	6,173,000	6,689,000	5,764,000	5,699,000	5,075,000	25,039,000	23,227,000	15,445,000
(Loss) income before income tax (benefit) expense	(10,956,000)	2,367,000	8,169,000	(7,881,000)	(1,196,000)	(4,137,000)	4,694,000	(6,942,000)	(8,301,000)	(7,581,000)	35,389,000
Income tax (benefit) expense	(2,763,000)	1,502,000	1,980,000	(1,730,000)	1,569,000	(1,035,000)	1,181,000	(1,447,000)	(1,011,000)	268,000	16,125,000
Net (loss) income	$ (8,193,000)	$ 865,000	$ 6,189,000	$ (6,151,000)	$ (2,765,000)	$ (3,102,000)	$ 3,513,000	$ (5,495,000)	$ (7,290,000)	$ (7,849,000)	$ 19,264,000
Basic net (loss) income per share (in dollars per share)	$ (0.43)	$ 0.05	$ 0.33	$ (0.33)	$ (0.15)	$ (0.16)	$ 0.19	$ (0.29)	$ (0.39)	$ (0.42)	$ 1.02
Diluted net (loss) income per share (in dollars per share)	$ (0.43)	$ 0.04	$ 0.32	$ (0.33)	$ (0.15)	$ (0.16)	$ 0.18	$ (0.29)	$ (0.39)	$ (0.42)	$ 0.99