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, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (unaudited) [Abstract]
Sales	$ 381,603	$ 307,942	$ 730,107	$ 598,039
Cost of sales	270,557	216,427	517,354	417,417
Gross profit	111,046	91,515	212,753	180,622
Selling, general and administrative expense	82,647	68,250	162,193	134,653
Operating income	28,399	23,265	50,560	45,969
Other expense (income), net	141	21	(9)	22
Interest expense	3,176	1,689	6,573	3,316
Income before income taxes	25,082	21,555	43,996	42,631
Provision for income taxes	9,543	7,806	16,839	15,650
Net income	15,539	13,749	27,157	26,981
Preferred stock dividend	22	22	45	45
Net income attributable to common shareholders	15,517	13,727	27,112	26,936
Net income	15,539	13,749	27,157	26,981
Loss on long-term investment, net of income taxes	0	(18)	(55)	(742)
Cumulative translation adjustment	675	(1,630)	(615)	(1,698)
Comprehensive income	$ 16,214	$ 12,101	$ 26,487	$ 24,541
Basic earnings per share (in dollars per share)	$ 1.06	$ 0.95	$ 1.84	$ 1.87
Weighted average common shares outstanding (in shares)	14,708	14,451	14,716	14,424
Diluted earnings per share (in dollars per share)	$ 1.00	$ 0.90	$ 1.75	$ 1.77
Weighted average common shares and common equivalent shares outstanding (in shares)	15,548	15,291	15,556	15,264