CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME [Abstract]
Sales	$ 1,241,510	$ 1,097,110	$ 807,005
Cost of sales	869,165	778,019	575,169
Gross profit	372,345	319,091	231,836
Selling, general and administrative expense	271,421	228,569	176,351
Operating income	100,924	90,522	55,485
Other income, net	(75)	(47)	(28)
Interest expense	6,282	5,560	3,518
Income before income taxes	94,717	85,009	51,995
Provision for income taxes	34,480	34,024	20,558
Net income	60,237	50,985	31,437
Preferred stock dividend	90	90	90
Net income attributable to common shareholders	60,147	50,895	31,347
Net income	60,237	50,985	31,437
(Loss) gain on long-term investment, net of income taxes	(387)	378	64
Cumulative translation adjustment, net of income taxes	(3,040)	617	0
Comprehensive income	$ 56,810	$ 51,980	$ 31,501
Basic earnings per share (in dollars per share)	$ 4.17	$ 3.54	$ 2.19
Weighted average common shares outstanding (in shares)	14,439	14,374	14,301
Diluted earnings per share (in dollars per share)	$ 3.94	$ 3.35	$ 2.08
Weighted average common shares and common equivalent shares outstanding (in shares)	15,279	15,214	15,141