CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME [Abstract]
Sales	$ 1,097,110	$ 807,005	$ 656,202
Cost of sales	778,019	575,169	467,807
Gross profit	319,091	231,836	188,395
Selling, general and administrative expense	228,569	176,351	151,304
Operating income	90,522	55,485	37,091
Other (income) expense	(47)	(28)	(249)
Interest expense	5,560	3,518	5,208
Income before income taxes	85,009	51,995	32,132
Provision for income taxes	34,024	20,558	12,751
Net income	50,985	31,437	19,381
Preferred stock dividend	90	90	90
Net income attributable to common shareholders	50,895	31,347	19,291
Net income	50,985	31,437	19,381
Gain from interest rate swap, net of income taxes	0	0	26
Loss (gain) on long-term investment, net of income taxes	378	64	0
Cumulative translation adjustment	617	0	0
Comprehensive income	$ 51,980	$ 31,501	$ 19,407
Basic earnings per share (in dollars per share)	$ 3.54	$ 2.19	$ 1.40
Weighted average common shares outstanding (in shares)	14,374	14,301	13,821
Diluted earnings per share (in dollars per share)	$ 3.35	$ 2.08	$ 1.32
Weighted average common and common equivalent shares outstanding (in shares)	15,214	15,141	14,821