CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME [Abstract]
Sales	$ 307,942	$ 261,894	$ 598,039	$ 514,181
Cost of sales	216,427	185,265	417,417	366,078
Gross profit	91,515	76,629	180,622	148,103
Selling, general and administrative expense	68,250	55,782	134,653	107,351
Total operating income	23,265	20,847	45,969	40,752
Other expense (income)	21	3	22	(12)
Interest expense	1,689	762	3,316	1,591
Income before income taxes	21,555	20,082	42,631	39,173
Provision for income taxes	7,806	7,905	15,650	15,350
Net income	13,749	12,177	26,981	23,823
Preferred stock dividend	22	22	45	45
Net income attributable to common shareholders	13,727	12,155	26,936	23,778
Net income	13,749	12,177	26,981	23,823
Loss on long-term investment, net of income taxes	(18)	(52)	(742)	(281)
Cumulative translation adjustment	(1,630)	(117)	(1,698)	(117)
Comprehensive income	$ 12,101	$ 12,008	$ 24,541	$ 23,425
Basic earnings per share (in dollars per share)	$ 0.95	$ 0.84	$ 1.87	$ 1.66
Weighted average common shares outstanding (in shares)	14,451	14,392	14,424	14,360
Diluted earnings per share (in dollars per share)	$ 0.90	$ 0.80	$ 1.77	$ 1.57
Weighted average common shares and common equivalent shares outstanding (in shares)	15,291	15,232	15,264	15,200