QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 549,460	$ 566,186	$ 613,218	$ 608,218	$ 531,211	$ 575,139	$ 604,879	$ 551,832	$ 2,337,082	$ 2,263,061	$ 1,635,653
Gross profit	99,327	104,335	112,661	106,548	96,665	106,655	114,792	97,754	422,871	415,866	278,915
NET INCOME	$ 19,984	$ 21,317	$ 27,416	$ 20,849	$ 26,970	$ 27,934	$ 34,860	$ 30,068	$ 89,566	$ 119,832	$ 85,718
Net income per common share:
Basic net income per common share (in USD per share)	$ 0.87	$ 0.92	$ 1.19	$ 0.90	$ 1.17	$ 1.17	$ 1.44	$ 1.22	$ 3.88	$ 4.99	$ 3.54
Diluted net income per common share (in USD per share)	0.86	0.92	1.18	0.90	$ 1.15	$ 1.15	$ 1.42	$ 1.20	3.85	4.93	3.48
Cash dividends paid per common share (in USD per share)	$ 0.25	$ 0	$ 0	$ 0					$ 0.25	$ 0	$ 0