CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME [Abstract]
Sales	$ 290,097	$ 252,287
Cost of sales	200,990	180,813
Gross profit	89,107	71,474
Selling, general and administrative expense	66,403	51,569
Total operating income	22,704	19,905
Other expense (income)	1	(15)
Interest expense	1,627	829
Income before income taxes	21,076	19,091
Provision for income taxes	7,844	7,445
Net income	13,232	11,646
Preferred stock dividend	23	23
Net income attributable to common shareholders	13,209	11,623
Net income	13,232	11,646
(Loss) gain on long-term investment, net of income taxes	(724)	229
Cumulative translation adjustment	(316)	0
Comprehensive income	$ 12,192	$ 11,417
Basic earnings per share (in dollars per share)	$ 0.92	$ 0.81
Weighted average common shares outstanding (in shares)	14,395	14,328
Diluted earnings per share (in dollars per share)	$ 0.87	$ 0.77
Weighted average common shares and common equivalent shares outstanding (in shares)	15,235	15,168