Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Net sales	$ 183,688	$ 152,497	$ 151,925	$ 149,013	$ 155,088		$ 159,738	$ 146,041	$ 136,236
Gross profit	50,335	44,821	49,729	48,047	48,393		48,341	46,945	43,584	$ 192,932	$ 187,263	$ 181,607
Income (loss) from operations	(3,164)	5,317	12,619	11,201	11,809		10,958	6,512	11,291	$ 25,973	$ 40,570	$ 54,648
Net income (loss)	$ (4,738)	$ 505	$ 6,816	$ 6,401	$ 5,889	[1]	$ 7,227	$ (448)	$ 6,911
Net income per share - basic (in dollars per share)	$ (0.22)	$ 0.02	$ 0.34	$ 0.32	$ 0.29		$ 0.36	$ (0.02)	$ 0.35	$ 0.44	$ 0.98	$ 1.36
Net income per share - diluted (in dollars per share)	$ (0.22)	$ 0.02	$ 0.33	$ 0.32	$ 0.29		$ 0.36	$ (0.02)	$ 0.34	$ 0.43	$ 0.96	$ 1.34

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