QUARTERLY RESULTS (UNAUDITED) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
QUARTERLY RESULTS (UNAUDITED)
Sales	$ 250,026	$ 219,794	$ 221,018	$ 196,662	$ 223,148	$ 239,543	$ 238,650	$ 220,858	$ 887,499	$ 922,200	$ 809,467
Gross profit	82,675	74,216	74,407	63,053	70,650	78,851	76,493	68,401	294,350	294,397	264,349
Net Income	$ 17,492	$ 12,197	$ 13,055	$ 7,257	$ 17,443	$ 18,389	$ 12,975	$ 9,202	$ 50,001	$ 58,011	$ 28,024
Earnings per share - Basic	$ 0.37	$ 0.26	$ 0.28	$ 0.16	$ 0.38	$ 0.40	$ 0.28	$ 0.20	$ 1.07	$ 1.25	$ 0.61
Earnings per share - Diluted	$ 0.37	$ 0.26	$ 0.28	$ 0.15	$ 0.37	$ 0.39	$ 0.28	$ 0.20	$ 1.06	$ 1.24	$ 0.61